Pass ID to match_package

149 files changed, 955 insertions, 773 deletions

diff --git a/doc/api/cplusplus/examples/example_dep_spec.cc b/doc/api/cplusplus/examples/example_dep_spec.cc
index 0607d66e4..2e9598507 100644
--- a/doc/api/cplusplus/examples/example_dep_spec.cc
+++ b/doc/api/cplusplus/examples/example_dep_spec.cc
@@ -141,7 +141,8 @@ int main(int argc, char * argv[])
 
             /* And display packages matching that spec */
             cout << "    " << left << setw(24) << "Matches:" << " ";
-            std::shared_ptr<const PackageIDSequence> ids((*env)[selection::AllVersionsSorted(generator::Matches(spec, { }))]);
+            std::shared_ptr<const PackageIDSequence> ids((*env)[selection::AllVersionsSorted(
+                        generator::Matches(spec, make_null_shared_ptr(), { }))]);
             bool need_indent(false);
             for (PackageIDSequence::ConstIterator i(ids->begin()), i_end(ids->end()) ;
                     i != i_end ; ++i)
diff --git a/doc/api/cplusplus/examples/example_match_package.cc b/doc/api/cplusplus/examples/example_match_package.cc
index f689b33e7..c308f8dcd 100644
--- a/doc/api/cplusplus/examples/example_match_package.cc
+++ b/doc/api/cplusplus/examples/example_match_package.cc
@@ -55,7 +55,7 @@ int main(int argc, char * argv[])
         {
             /* Is it paludis? */
             if (match_package(*env, make_package_dep_spec({ }).package(
-                            QualifiedPackageName("sys-apps/paludis")), *i, { }))
+                            QualifiedPackageName("sys-apps/paludis")), *i, make_null_shared_ptr(), { }))
                 cout << left << setw(50) << (stringify(**i) + ":") << " " << "paludis" << endl;
 
             /* No. Is it in system or world? */
diff --git a/doc/api/cplusplus/examples/example_selection.cc b/doc/api/cplusplus/examples/example_selection.cc
index a1669af87..ad60e36b0 100644
--- a/doc/api/cplusplus/examples/example_selection.cc
+++ b/doc/api/cplusplus/examples/example_selection.cc
@@ -63,13 +63,13 @@ int main(int argc, char * argv[])
          * simplest form, it takes a Generator as a parameter. */
         show_selection(env, selection::AllVersionsSorted(
                     generator::Matches(make_package_dep_spec({ }).package(
-                            QualifiedPackageName("sys-apps/paludis")), { })));
+                            QualifiedPackageName("sys-apps/paludis")), make_null_shared_ptr(), { })));
 
         /* Generators can be passed through a Filter. The Selection optimises
          * the code internally to avoid doing excess work. */
         show_selection(env, selection::AllVersionsSorted(
                     generator::Matches(make_package_dep_spec({ }).package(
-                            QualifiedPackageName("sys-apps/paludis")), { }) |
+                            QualifiedPackageName("sys-apps/paludis")), make_null_shared_ptr(), { }) |
                     filter::InstalledAtSlash()));
 
         /* Filters can be combined. Usually filter::NotMasked should be combined
@@ -77,7 +77,7 @@ int main(int argc, char * argv[])
          * aren't masked. */
         show_selection(env, selection::AllVersionsSorted(
                     generator::Matches(make_package_dep_spec({ }).package(
-                            QualifiedPackageName("sys-apps/paludis")), { }) |
+                            QualifiedPackageName("sys-apps/paludis")), make_null_shared_ptr(), { }) |
                     filter::SupportsAction<InstallAction>() |
                     filter::NotMasked()));
 
@@ -86,7 +86,7 @@ int main(int argc, char * argv[])
          * you only need the best matching or some arbitrary matching ID. */
         show_selection(env, selection::BestVersionOnly(
                     generator::Matches(make_package_dep_spec({ }).package(
-                            QualifiedPackageName("sys-apps/paludis")), { }) |
+                            QualifiedPackageName("sys-apps/paludis")), make_null_shared_ptr(), { }) |
                     filter::SupportsAction<InstallAction>() |
                     filter::NotMasked()));
     }
diff --git a/doc/api/ruby/example_action.rb b/doc/api/ruby/example_action.rb
index 60db632fc..3e14f37f2 100644
--- a/doc/api/ruby/example_action.rb
+++ b/doc/api/ruby/example_action.rb
@@ -18,7 +18,7 @@ env = EnvironmentFactory.instance.create(ExampleCommandLine.instance.environment
 
 # Fetch package IDs for 'sys-apps/paludis'
 ids = env[Selection::AllVersionsSorted.new(Generator::Matches.new(
-    Paludis::parse_user_package_dep_spec("sys-apps/paludis", env, []), []))]
+    Paludis::parse_user_package_dep_spec("sys-apps/paludis", env, []), nil, []))]
 
 # For each ID:
 ids.each do | id |
diff --git a/doc/api/ruby/example_contents.rb b/doc/api/ruby/example_contents.rb
index 82c758d28..d653fe57a 100644
--- a/doc/api/ruby/example_contents.rb
+++ b/doc/api/ruby/example_contents.rb
@@ -18,7 +18,7 @@ env = EnvironmentFactory.instance.create(ExampleCommandLine.instance.environment
 
 # Fetch package IDs for installed 'sys-apps/paludis'
 ids = env[Selection::AllVersionsSorted.new(
-    Generator::Matches.new(Paludis::parse_user_package_dep_spec("sys-apps/paludis", env, []), []) |
+    Generator::Matches.new(Paludis::parse_user_package_dep_spec("sys-apps/paludis", env, []), nil, []) |
     Filter::InstalledAtRoot.new("/"))]
 
 # For each ID:
diff --git a/doc/api/ruby/example_mask.rb b/doc/api/ruby/example_mask.rb
index 2bb306d2c..e63aa9207 100644
--- a/doc/api/ruby/example_mask.rb
+++ b/doc/api/ruby/example_mask.rb
@@ -18,7 +18,7 @@ env = EnvironmentFactory.instance.create(ExampleCommandLine.instance.environment
 
 # Fetch package IDs for 'sys-apps/paludis'
 ids = env[Selection::AllVersionsSorted.new(
-    Generator::Matches.new(Paludis::parse_user_package_dep_spec("sys-apps/paludis", env, []), []))]
+    Generator::Matches.new(Paludis::parse_user_package_dep_spec("sys-apps/paludis", env, []), nil, []))]
 
 # For each ID:
 ids.each do | id |
diff --git a/doc/api/ruby/example_match_package.rb b/doc/api/ruby/example_match_package.rb
index 7a448be03..c38fc98a2 100644
--- a/doc/api/ruby/example_match_package.rb
+++ b/doc/api/ruby/example_match_package.rb
@@ -28,7 +28,7 @@ world = env.set('world')
 # For each ID:
 ids.each do | id |
     # Is it paludis?
-    if match_package(env, parse_user_package_dep_spec('sys-apps/paludis', env, []), id, [])
+    if match_package(env, parse_user_package_dep_spec('sys-apps/paludis', env, []), id, nil, [])
         puts id.to_s.ljust(49) + ': paludis'
     elsif match_package_in_set(env, system, id, [])
         puts id.to_s.ljust(49) + ': system'
diff --git a/doc/api/ruby/example_package_id.rb b/doc/api/ruby/example_package_id.rb
index 0d3b2f3a8..d4350272a 100644
--- a/doc/api/ruby/example_package_id.rb
+++ b/doc/api/ruby/example_package_id.rb
@@ -20,7 +20,7 @@ env = EnvironmentFactory.instance.create(ExampleCommandLine.instance.environment
 
 # Fetch package IDs for installed 'sys-apps/paludis'
 ids = env[Selection::AllVersionsSorted.new(
-    Generator::Matches.new(Paludis::parse_user_package_dep_spec("sys-apps/paludis", env, []), []))]
+    Generator::Matches.new(Paludis::parse_user_package_dep_spec("sys-apps/paludis", env, []), nil, []))]
 
 # For each ID:
 ids.each do | id |
diff --git a/doc/api/ruby/example_selection.rb b/doc/api/ruby/example_selection.rb
index 7a61030bc..dea5b9fe6 100644
--- a/doc/api/ruby/example_selection.rb
+++ b/doc/api/ruby/example_selection.rb
@@ -34,19 +34,19 @@ env = EnvironmentFactory.instance.create(ExampleCommandLine.instance.environment
 # object used determines the number and ordering of results. In the
 # simplest form, it takes a Generator as a parameter.
 show_selection(env, Selection::AllVersionsSorted.new(
-        Generator::Matches.new(parse_user_package_dep_spec("sys-apps/paludis", env, []), [])))
+        Generator::Matches.new(parse_user_package_dep_spec("sys-apps/paludis", env, []), nil, [])))
 
 # Generators can be passed through a Filter. The Selection optimises
 # the code internally to avoid doing excess work.
 show_selection(env, Selection::AllVersionsSorted.new(
-        Generator::Matches.new(parse_user_package_dep_spec("sys-apps/paludis", env, []), []) |
+        Generator::Matches.new(parse_user_package_dep_spec("sys-apps/paludis", env, []), nil, []) |
         Filter::InstalledAtRoot.new("/")))
 
 # Filters can be combined. Usually Filter::NotMasked should be combined
 # with Filter::SupportsAction.new(InstallAction), since installed packages
 # aren't masked.
 show_selection(env, Selection::AllVersionsSorted.new(
-        Generator::Matches.new(parse_user_package_dep_spec("sys-apps/paludis", env, []), []) |
+        Generator::Matches.new(parse_user_package_dep_spec("sys-apps/paludis", env, []), nil, []) |
         Filter::SupportsAction.new(InstallAction) |
         Filter::NotMasked.new))
 
@@ -54,7 +54,7 @@ show_selection(env, Selection::AllVersionsSorted.new(
 # is no metadata cache. Consider using other Selection objects if
 # you only need the best matching or some arbitrary matching ID.
 show_selection(env, Selection::BestVersionOnly.new(
-        Generator::Matches.new(parse_user_package_dep_spec("sys-apps/paludis", env, []), []) |
+        Generator::Matches.new(parse_user_package_dep_spec("sys-apps/paludis", env, []), nil, []) |
         Filter::SupportsAction.new(InstallAction) |
         Filter::NotMasked.new))
 
diff --git a/paludis/environments/paludis/keywords_conf.cc b/paludis/environments/paludis/keywords_conf.cc
index ab8dc04de..3586b2126 100644
--- a/paludis/environments/paludis/keywords_conf.cc
+++ b/paludis/environments/paludis/keywords_conf.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -149,7 +149,7 @@ KeywordsConf::query(const std::shared_ptr<const KeywordNameSet> & k, const std::
             for (PDSToKeywordsList::const_iterator j(i->second.begin()), j_end(i->second.end()) ;
                     j != j_end ; ++j)
             {
-                if (! match_package(*_imp->env, *j->first, e, { }))
+                if (! match_package(*_imp->env, *j->first, e, make_null_shared_ptr(), { }))
                     continue;
 
                 for (KeywordsList::const_iterator l(j->second.begin()), l_end(j->second.end()) ;
@@ -215,7 +215,7 @@ KeywordsConf::query(const std::shared_ptr<const KeywordNameSet> & k, const std::
     for (PDSToKeywordsList::const_iterator j(_imp->unqualified.begin()), j_end(_imp->unqualified.end()) ;
             j != j_end ; ++j)
     {
-        if (! match_package(*_imp->env, *j->first, e, { }))
+        if (! match_package(*_imp->env, *j->first, e, make_null_shared_ptr(), { }))
             continue;
 
         for (KeywordsList::const_iterator l(j->second.begin()), l_end(j->second.end()) ;
diff --git a/paludis/environments/paludis/licenses_conf.cc b/paludis/environments/paludis/licenses_conf.cc
index 52e2e8f68..8e6d925dc 100644
--- a/paludis/environments/paludis/licenses_conf.cc
+++ b/paludis/environments/paludis/licenses_conf.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -143,7 +143,7 @@ LicensesConf::query(const std::string & t, const std::shared_ptr<const PackageID
             for (PDSToLicensesList::const_iterator j(i->second.begin()), j_end(i->second.end()) ;
                     j != j_end ; ++j)
             {
-                if (! match_package(*_imp->env, *j->first, e, { }))
+                if (! match_package(*_imp->env, *j->first, e, make_null_shared_ptr(), { }))
                     continue;
 
                 for (LicensesList::const_iterator l(j->second.begin()), l_end(j->second.end()) ;
@@ -208,7 +208,7 @@ LicensesConf::query(const std::string & t, const std::shared_ptr<const PackageID
     for (PDSToLicensesList::const_iterator j(_imp->unqualified.begin()), j_end(_imp->unqualified.end()) ;
             j != j_end ; ++j)
     {
-        if (! match_package(*_imp->env, *j->first, e, { }))
+        if (! match_package(*_imp->env, *j->first, e, make_null_shared_ptr(), { }))
             continue;
 
         for (LicensesList::const_iterator l(j->second.begin()), l_end(j->second.end()) ;
diff --git a/paludis/environments/paludis/output_conf.cc b/paludis/environments/paludis/output_conf.cc
index a97ec1801..1e760e173 100644
--- a/paludis/environments/paludis/output_conf.cc
+++ b/paludis/environments/paludis/output_conf.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -196,7 +196,7 @@ namespace
                 return false;
 
             if (rule.matches_requirement() && ! match_package(*env, *rule.matches_requirement(),
-                        i.package_id(), { }))
+                        i.package_id(), make_null_shared_ptr(), { }))
                 return false;
 
             if (! rule.ignore_unfetched_requirement().is_indeterminate())
diff --git a/paludis/environments/paludis/package_mask_conf.cc b/paludis/environments/paludis/package_mask_conf.cc
index 75ff80fc6..763801199 100644
--- a/paludis/environments/paludis/package_mask_conf.cc
+++ b/paludis/environments/paludis/package_mask_conf.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -104,7 +104,7 @@ PackageMaskConf::query(const std::shared_ptr<const PackageID> & e) const
     if (indirect_iterator(_imp->masks.end()) != std::find_if(
             indirect_iterator(_imp->masks.begin()),
             indirect_iterator(_imp->masks.end()),
-            std::bind(&match_package, std::ref(*_imp->env), _1, std::cref(e), MatchPackageOptions())))
+            std::bind(&match_package, std::ref(*_imp->env), _1, std::cref(e), make_null_shared_ptr(), MatchPackageOptions())))
         return true;
 
     {
diff --git a/paludis/environments/paludis/paludis_environment_TEST.cc b/paludis/environments/paludis/paludis_environment_TEST.cc
index 787e471be..ee5d69d68 100644
--- a/paludis/environments/paludis/paludis_environment_TEST.cc
+++ b/paludis/environments/paludis/paludis_environment_TEST.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2006, 2007, 2008, 2010 Ciaran McCreesh
+ * Copyright (c) 2006, 2007, 2008, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -23,6 +23,7 @@
 #include <paludis/util/set.hh>
 #include <paludis/util/wrapped_forward_iterator.hh>
 #include <paludis/util/options.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/package_id.hh>
 #include <paludis/user_dep_spec.hh>
 #include <paludis/generator.hh>
@@ -63,10 +64,10 @@ namespace test_cases
             std::shared_ptr<Environment> env(std::make_shared<PaludisEnvironment>(""));
             const std::shared_ptr<const PackageID> one(*(*env)[selection::RequireExactlyOne(
                         generator::Matches(PackageDepSpec(parse_user_package_dep_spec("=cat-one/pkg-one-1",
-                                    env.get(), { })), { }))]->begin());
+                                    env.get(), { })), make_null_shared_ptr(), { }))]->begin());
             const std::shared_ptr<const PackageID> three(*(*env)[selection::RequireExactlyOne(
                         generator::Matches(PackageDepSpec(parse_user_package_dep_spec("=cat-one/pkg-two-3",
-                                    env.get(), { })), { }))]->begin());
+                                    env.get(), { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(get_use("foo", one));
             TEST_CHECK(! get_use("foofoo", one));
@@ -97,7 +98,7 @@ namespace test_cases
 
             const std::shared_ptr<const PackageID> id1(*(*env)[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat-one/pkg-one-1",
-                                    env.get(), { })), { }))]->begin());
+                                    env.get(), { })), make_null_shared_ptr(), { }))]->begin());
             std::shared_ptr<const Choice> foo_cards;
             for (Choices::ConstIterator c(id1->choices_key()->value()->begin()), c_end(id1->choices_key()->value()->end()) ;
                     c != c_end ; ++c)
@@ -123,10 +124,10 @@ namespace test_cases
 
             const std::shared_ptr<const PackageID> one(*(*env)[selection::RequireExactlyOne(
                         generator::Matches(PackageDepSpec(parse_user_package_dep_spec("=cat-one/pkg-one-1",
-                                    env.get(), { })), { }))]->begin());
+                                    env.get(), { })), make_null_shared_ptr(), { }))]->begin());
             const std::shared_ptr<const PackageID> three(*(*env)[selection::RequireExactlyOne(
                         generator::Matches(PackageDepSpec(parse_user_package_dep_spec("=cat-one/pkg-two-3",
-                                    env.get(), { })), { }))]->begin());
+                                    env.get(), { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(get_use("foo", one));
             TEST_CHECK(! get_use("foofoo", one));
@@ -156,10 +157,10 @@ namespace test_cases
 
             const std::shared_ptr<const PackageID> one(*(*env)[selection::RequireExactlyOne(
                         generator::Matches(PackageDepSpec(parse_user_package_dep_spec("=cat-one/pkg-one-1",
-                                    env.get(), { })), { }))]->begin());
+                                    env.get(), { })), make_null_shared_ptr(), { }))]->begin());
             const std::shared_ptr<const PackageID> three(*(*env)[selection::RequireExactlyOne(
                         generator::Matches(PackageDepSpec(parse_user_package_dep_spec("=cat-one/pkg-two-3",
-                                    env.get(), { })), { }))]->begin());
+                                    env.get(), { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(get_use("foo", one));
             TEST_CHECK(! get_use("foofoo", one));
diff --git a/paludis/environments/paludis/suggestions_conf.cc b/paludis/environments/paludis/suggestions_conf.cc
index dbd5e5dce..226413d0c 100644
--- a/paludis/environments/paludis/suggestions_conf.cc
+++ b/paludis/environments/paludis/suggestions_conf.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2010 Ciaran McCreesh
+ * Copyright (c) 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -194,7 +194,7 @@ SuggestionsConf::interest_in_suggestion(
             for (PDSToValuesList::const_iterator j(i->second.begin()), j_end(i->second.end()) ;
                     j != j_end ; ++j)
             {
-                if (! match_package(*_imp->env, *j->first, from_id, { }))
+                if (! match_package(*_imp->env, *j->first, from_id, make_null_shared_ptr(), { }))
                     continue;
 
                 for (ValuesList::const_iterator l(j->second.begin()), l_end(j->second.end()) ;
@@ -269,7 +269,7 @@ SuggestionsConf::interest_in_suggestion(
     for (PDSToValuesList::const_iterator j(_imp->unqualified.begin()), j_end(_imp->unqualified.end()) ;
             j != j_end ; ++j)
     {
-        if (! match_package(*_imp->env, *j->first, from_id, { }))
+        if (! match_package(*_imp->env, *j->first, from_id, make_null_shared_ptr(), { }))
             continue;
 
         for (ValuesList::const_iterator l(j->second.begin()), l_end(j->second.end()) ;
diff --git a/paludis/environments/portage/portage_environment.cc b/paludis/environments/portage/portage_environment.cc
index 19b1f992d..f6b26c6cd 100644
--- a/paludis/environments/portage/portage_environment.cc
+++ b/paludis/environments/portage/portage_environment.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -40,6 +40,7 @@
 #include <paludis/util/fs_stat.hh>
 #include <paludis/util/fs_iterator.hh>
 #include <paludis/util/fs_error.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 
 #include <paludis/standard_output_manager.hh>
 #include <paludis/hooker.hh>
@@ -586,7 +587,7 @@ PortageEnvironment::want_choice_enabled(
     for (PackageUse::const_iterator i(_imp->package_use.begin()), i_end(_imp->package_use.end()) ;
             i != i_end ; ++i)
     {
-        if (! match_package(*this, *i->first, id, { }))
+        if (! match_package(*this, *i->first, id, make_null_shared_ptr(), { }))
             continue;
 
         if (i->second == stringify(f))
@@ -642,7 +643,7 @@ PortageEnvironment::accept_keywords(const std::shared_ptr <const KeywordNameSet>
     for (PackageKeywords::const_iterator it(_imp->package_keywords.begin()),
              it_end(_imp->package_keywords.end()); it_end != it; ++it)
     {
-        if (! match_package(*this, *it->first, d, { }))
+        if (! match_package(*this, *it->first, d, make_null_shared_ptr(), { }))
             continue;
 
         if ("-*" == it->second)
@@ -677,7 +678,7 @@ PortageEnvironment::unmasked_by_user(const std::shared_ptr<const PackageID> & e)
 {
     for (PackageUnmask::const_iterator i(_imp->package_unmask.begin()), i_end(_imp->package_unmask.end()) ;
             i != i_end ; ++i)
-        if (match_package(*this, **i, e, { }))
+        if (match_package(*this, **i, e, make_null_shared_ptr(), { }))
             return true;
 
     return false;
@@ -702,7 +703,7 @@ PortageEnvironment::known_choice_value_names(const std::shared_ptr<const Package
     for (PackageUse::const_iterator i(_imp->package_use.begin()), i_end(_imp->package_use.end()) ;
             i != i_end ; ++i)
     {
-        if (! match_package(*this, *i->first, id, { }))
+        if (! match_package(*this, *i->first, id, make_null_shared_ptr(), { }))
             continue;
 
         if (0 == i->second.compare(0, prefix_lower.length(), prefix_lower, 0, prefix_lower.length()))
@@ -862,7 +863,7 @@ PortageEnvironment::mask_for_user(const std::shared_ptr<const PackageID> & d, co
 {
     for (PackageMask::const_iterator i(_imp->package_mask.begin()), i_end(_imp->package_mask.end()) ;
             i != i_end ; ++i)
-        if (match_package(*this, **i, d, { }))
+        if (match_package(*this, **i, d, make_null_shared_ptr(), { }))
             return std::make_shared<UserConfigMask>(o);
 
     return std::shared_ptr<const Mask>();
diff --git a/paludis/environments/portage/portage_environment_TEST.cc b/paludis/environments/portage/portage_environment_TEST.cc
index c6fcbf56a..3e86d66de 100644
--- a/paludis/environments/portage/portage_environment_TEST.cc
+++ b/paludis/environments/portage/portage_environment_TEST.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -24,6 +24,7 @@
 #include <paludis/util/wrapped_forward_iterator.hh>
 #include <paludis/util/options.hh>
 #include <paludis/util/safe_ifstream.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/package_id.hh>
 #include <paludis/package_database.hh>
 #include <paludis/dep_spec.hh>
@@ -85,11 +86,11 @@ namespace test_cases
 
             const std::shared_ptr<const PackageID> idx(*env[selection::RequireExactlyOne(
                         generator::Matches(PackageDepSpec(parse_user_package_dep_spec("=cat-one/pkg-x-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             const std::shared_ptr<const PackageID> id1(*env[selection::RequireExactlyOne(
                         generator::Matches(PackageDepSpec(parse_user_package_dep_spec("=cat-one/pkg-one-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(get_use("one", env, idx));
             TEST_CHECK(get_use("two", env, idx));
@@ -120,7 +121,7 @@ namespace test_cases
 
             const std::shared_ptr<const PackageID> id1(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat-one/pkg-one-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
             std::shared_ptr<const Choice> foo_cards;
             for (Choices::ConstIterator c(id1->choices_key()->value()->begin()), c_end(id1->choices_key()->value()->end()) ;
                     c != c_end ; ++c)
@@ -143,7 +144,7 @@ namespace test_cases
 
             const std::shared_ptr<const PackageID> idx(*env[selection::RequireExactlyOne(
                         generator::Matches(PackageDepSpec(parse_user_package_dep_spec("=cat-one/pkg-x-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(accept_keyword(env, KeywordName("arch"), idx));
             TEST_CHECK(accept_keyword(env, KeywordName("other_arch"), idx));
@@ -151,7 +152,7 @@ namespace test_cases
 
             const std::shared_ptr<const PackageID> id1(*env[selection::RequireExactlyOne(
                         generator::Matches(PackageDepSpec(parse_user_package_dep_spec("=cat-one/pkg-one-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(accept_keyword(env, KeywordName("arch"), id1));
             TEST_CHECK(accept_keyword(env, KeywordName("other_arch"), id1));
@@ -159,7 +160,7 @@ namespace test_cases
 
             const std::shared_ptr<const PackageID> id2(*env[selection::RequireExactlyOne(
                         generator::Matches(PackageDepSpec(parse_user_package_dep_spec("=cat-one/pkg-two-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(accept_keyword(env, KeywordName("other_arch"), id2));
             TEST_CHECK(accept_keyword(env, KeywordName("arch"), id2));
@@ -167,7 +168,7 @@ namespace test_cases
 
             const std::shared_ptr<const PackageID> id3(*env[selection::RequireExactlyOne(
                         generator::Matches(PackageDepSpec(parse_user_package_dep_spec("=cat-one/pkg-three-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(! accept_keyword(env, KeywordName("other_arch"), id3));
             TEST_CHECK(! accept_keyword(env, KeywordName("arch"), id3));
@@ -175,14 +176,14 @@ namespace test_cases
 
             const std::shared_ptr<const PackageID> id4(*env[selection::RequireExactlyOne(
                         generator::Matches(PackageDepSpec(parse_user_package_dep_spec("=cat-one/pkg-four-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
             TEST_CHECK(accept_keyword(env, KeywordName("fred"), id4));
             std::shared_ptr<const KeywordNameSet> empty(std::make_shared<KeywordNameSet>());
             TEST_CHECK(env.accept_keywords(empty, id4));
 
             const std::shared_ptr<const PackageID> id5(*env[selection::RequireExactlyOne(
                         generator::Matches(PackageDepSpec(parse_user_package_dep_spec("=cat-one/pkg-five-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
             TEST_CHECK(accept_keyword(env, KeywordName("~foo"), id5));
             TEST_CHECK(! accept_keyword(env, KeywordName("foo"), id5));
         }
diff --git a/paludis/filter.cc b/paludis/filter.cc
index ecf4b2385..ae413f11e 100644
--- a/paludis/filter.cc
+++ b/paludis/filter.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -394,10 +394,12 @@ namespace
         AllFilterHandlerBase
     {
         const PackageDepSpec spec;
+        const std::shared_ptr<const PackageID> from_id;
         const MatchPackageOptions options;
 
-        MatchesHandler(const PackageDepSpec & s, const MatchPackageOptions & o) :
+        MatchesHandler(const PackageDepSpec & s, const std::shared_ptr<const PackageID> & f, const MatchPackageOptions & o) :
             spec(s),
+            from_id(f),
             options(o)
         {
         }
@@ -411,7 +413,7 @@ namespace
             for (PackageIDSet::ConstIterator i(id->begin()), i_end(id->end()) ;
                     i != i_end ; ++i)
             {
-                if (match_package(*env, spec, *i, options))
+                if (match_package(*env, spec, *i, from_id, options))
                     result->insert(*i);
             }
 
@@ -484,8 +486,8 @@ filter::NoSlot::NoSlot() :
 {
 }
 
-filter::Matches::Matches(const PackageDepSpec & spec, const MatchPackageOptions & o) :
-    Filter(std::make_shared<MatchesHandler>(spec, o))
+filter::Matches::Matches(const PackageDepSpec & spec, const std::shared_ptr<const PackageID> & f, const MatchPackageOptions & o) :
+    Filter(std::make_shared<MatchesHandler>(spec, f, o))
 {
 }
 
diff --git a/paludis/filter.hh b/paludis/filter.hh
index adfa0a72f..b2b7fe681 100644
--- a/paludis/filter.hh
+++ b/paludis/filter.hh
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -276,7 +276,16 @@ namespace paludis
             public Filter
         {
             public:
-                Matches(const PackageDepSpec &, const MatchPackageOptions &);
+                /**
+                 * \param spec_id The PackageID the spec comes from. May be null. Used
+                 * for [use=] style dependencies.
+                 *
+                 * \since 0.58 takes spec_id
+                 */
+                Matches(
+                        const PackageDepSpec &,
+                        const std::shared_ptr<const PackageID> & from_id,
+                        const MatchPackageOptions &);
         };
     }
 
diff --git a/paludis/filter_TEST.cc b/paludis/filter_TEST.cc
index 24a9d8acb..6069bc38b 100644
--- a/paludis/filter_TEST.cc
+++ b/paludis/filter_TEST.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -31,6 +31,7 @@
 #include <paludis/util/wrapped_forward_iterator.hh>
 #include <paludis/util/indirect_iterator-impl.hh>
 #include <paludis/util/make_named_values.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <test/test_runner.hh>
 #include <test/test_framework.hh>
 #include <test/test_concepts.hh>
@@ -96,7 +97,7 @@ namespace test_cases
 
             std::shared_ptr<const PackageIDSequence> got_none(env[selection::AllVersionsSorted(
                         generator::Matches(parse_user_package_dep_spec("not/exist", &env,
-                                { }), { }) | filter)]);
+                                { }), make_null_shared_ptr(), { }) | filter)]);
             TEST_CHECK(bool(got_none));
             TEST_CHECK_EQUAL(join(indirect_iterator(got_none->begin()), indirect_iterator(got_none->end()), ", "), "");
         }
@@ -222,7 +223,7 @@ namespace test_cases
     {
         MatchesFilterTestCase() :
             FilterTestCaseBase("matches", filter::Matches(parse_user_package_dep_spec("cat/a",
-                            &env, { }), { }))
+                            &env, { }), make_null_shared_ptr(), { }))
         {
         }
 
@@ -240,7 +241,7 @@ namespace test_cases
     {
         MatchesCatWildcardFilterTestCase() :
             FilterTestCaseBase("matches cat wildcard", filter::Matches(parse_user_package_dep_spec("*/a",
-                            &env, { updso_allow_wildcards }), { }))
+                            &env, { updso_allow_wildcards }), make_null_shared_ptr(), { }))
         {
         }
 
@@ -258,7 +259,7 @@ namespace test_cases
     {
         MatchesPkgWildcardFilterTestCase() :
             FilterTestCaseBase("matches pkg wildcard", filter::Matches(parse_user_package_dep_spec("cat/*",
-                            &env, { updso_allow_wildcards }), { }))
+                            &env, { updso_allow_wildcards }), make_null_shared_ptr(), { }))
         {
         }
 
@@ -279,7 +280,7 @@ namespace test_cases
         MatchesAllWildcardFilterTestCase() :
             FilterTestCaseBase("matches all wildcard", filter::Matches(
                         parse_user_package_dep_spec(">=*/*-2",
-                            &env, { updso_allow_wildcards }), { }))
+                            &env, { updso_allow_wildcards }), make_null_shared_ptr(), { }))
         {
         }
 
diff --git a/paludis/formatted_pretty_printer.cc b/paludis/formatted_pretty_printer.cc
index fbea1960a..acd35153d 100644
--- a/paludis/formatted_pretty_printer.cc
+++ b/paludis/formatted_pretty_printer.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2010 Ciaran McCreesh
+ * Copyright (c) 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -61,13 +61,13 @@ FormattedPrettyPrinter::prettify(const PackageDepSpec & v) const
     if (_imp->env)
     {
         {
-            auto ids((*_imp->env)[selection::SomeArbitraryVersion(generator::Matches(v, { }) |
+            auto ids((*_imp->env)[selection::SomeArbitraryVersion(generator::Matches(v, _imp->package_id, { }) |
                         filter::InstalledAtRoot(_imp->env->preferred_root_key()->value()))]);
             if (! ids->empty())
                 return format_installed(stringify(v));
         }
         {
-            auto ids((*_imp->env)[selection::SomeArbitraryVersion(generator::Matches(v, { }) |
+            auto ids((*_imp->env)[selection::SomeArbitraryVersion(generator::Matches(v, _imp->package_id, { }) |
                         filter::SupportsAction<InstallAction>() | filter::NotMasked())]);
             if (! ids->empty())
                 return format_installed(stringify(v));
@@ -85,7 +85,7 @@ FormattedPrettyPrinter::prettify(const BlockDepSpec & v) const
     if (_imp->env)
     {
         {
-            auto ids((*_imp->env)[selection::SomeArbitraryVersion(generator::Matches(v.blocking(), { }) |
+            auto ids((*_imp->env)[selection::SomeArbitraryVersion(generator::Matches(v.blocking(), _imp->package_id, { }) |
                         filter::InstalledAtRoot(_imp->env->preferred_root_key()->value()))]);
             if (! ids->empty())
                 return format_masked(stringify(v));
diff --git a/paludis/generator.cc b/paludis/generator.cc
index a889b43d0..b9d0a6dc0 100644
--- a/paludis/generator.cc
+++ b/paludis/generator.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -278,10 +278,12 @@ namespace
         AllGeneratorHandlerBase
     {
         const PackageDepSpec spec;
+        const std::shared_ptr<const PackageID> from_id;
         const MatchPackageOptions options;
 
-        MatchesGeneratorHandler(const PackageDepSpec & s, const MatchPackageOptions & o) :
+        MatchesGeneratorHandler(const PackageDepSpec & s, const std::shared_ptr<const PackageID> & i, const MatchPackageOptions & o) :
             spec(s),
+            from_id(i),
             options(o)
         {
         }
@@ -446,7 +448,7 @@ namespace
                             env->package_database()->fetch_repository(*r)->package_ids(*q));
                     for (PackageIDSequence::ConstIterator i(id->begin()), i_end(id->end()) ;
                             i != i_end ; ++i)
-                        if (match_package(*env, spec, *i, options))
+                        if (match_package(*env, spec, *i, from_id, options))
                             result->insert(*i);
                 }
             }
@@ -734,8 +736,8 @@ generator::Package::Package(const QualifiedPackageName & n) :
 {
 }
 
-generator::Matches::Matches(const PackageDepSpec & spec, const MatchPackageOptions & o) :
-    Generator(std::make_shared<MatchesGeneratorHandler>(spec, o))
+generator::Matches::Matches(const PackageDepSpec & spec, const std::shared_ptr<const PackageID> & f, const MatchPackageOptions & o) :
+    Generator(std::make_shared<MatchesGeneratorHandler>(spec, f, o))
 {
 }
 
diff --git a/paludis/generator.hh b/paludis/generator.hh
index 6b5162d5f..3fbdf4066 100644
--- a/paludis/generator.hh
+++ b/paludis/generator.hh
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -152,7 +152,13 @@ namespace paludis
             public Generator
         {
             public:
-                Matches(const PackageDepSpec &, const MatchPackageOptions &);
+                /**
+                 * \param spec_id The PackageID the spec comes from. May be null. Used for
+                 * [use=] style dependencies.
+                 *
+                 * \since 0.58 takes spec_id
+                 */
+                Matches(const PackageDepSpec &, const std::shared_ptr<const PackageID> & from_id, const MatchPackageOptions &);
         };
 
         /**
diff --git a/paludis/generator_TEST.cc b/paludis/generator_TEST.cc
index e687c3082..deff8e84c 100644
--- a/paludis/generator_TEST.cc
+++ b/paludis/generator_TEST.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -31,6 +31,7 @@
 #include <paludis/util/wrapped_forward_iterator.hh>
 #include <paludis/util/indirect_iterator-impl.hh>
 #include <paludis/util/make_named_values.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <test/test_runner.hh>
 #include <test/test_framework.hh>
 #include <test/test_concepts.hh>
@@ -122,7 +123,7 @@ namespace test_cases
     {
         MatchesGeneratorTestCase() :
             GeneratorTestCaseBase("matches", generator::Matches(parse_user_package_dep_spec("cat/a",
-                            &env, { }), { }))
+                            &env, { }), make_null_shared_ptr(), { }))
         {
         }
 
@@ -140,7 +141,7 @@ namespace test_cases
     {
         MatchesCatWildcardGeneratorTestCase() :
             GeneratorTestCaseBase("matches cat wildcard", generator::Matches(parse_user_package_dep_spec("*/a",
-                            &env, { updso_allow_wildcards }), { }))
+                            &env, { updso_allow_wildcards }), make_null_shared_ptr(), { }))
         {
         }
 
@@ -158,7 +159,7 @@ namespace test_cases
     {
         MatchesPkgWildcardGeneratorTestCase() :
             GeneratorTestCaseBase("matches pkg wildcard", generator::Matches(parse_user_package_dep_spec("cat/*",
-                            &env, { updso_allow_wildcards }), { }))
+                            &env, { updso_allow_wildcards }), make_null_shared_ptr(), { }))
         {
         }
 
@@ -179,7 +180,7 @@ namespace test_cases
         MatchesAllWildcardGeneratorTestCase() :
             GeneratorTestCaseBase("matches all wildcard", generator::Matches(
                         parse_user_package_dep_spec(">=*/*-2",
-                            &env, { updso_allow_wildcards }), { }))
+                            &env, { updso_allow_wildcards }), make_null_shared_ptr(), { }))
         {
         }
 
@@ -287,9 +288,9 @@ namespace test_cases
         IntersectionGeneratorTestCase() :
             GeneratorTestCaseBase("intersection", generator::Intersection(
                     generator::Matches(parse_user_package_dep_spec("*/a",
-                            &env, { updso_allow_wildcards }), { }),
+                            &env, { updso_allow_wildcards }), make_null_shared_ptr(), { }),
                     generator::Matches(parse_user_package_dep_spec("cat/*",
-                            &env, { updso_allow_wildcards }), { })
+                            &env, { updso_allow_wildcards }), make_null_shared_ptr(), { })
                     ))
         {
         }
diff --git a/paludis/legacy/dep_list.cc b/paludis/legacy/dep_list.cc
index d7cc9f741..ebfc010d9 100644
--- a/paludis/legacy/dep_list.cc
+++ b/paludis/legacy/dep_list.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2005, 2006, 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2005, 2006, 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -259,12 +259,14 @@ namespace
     {
         const Environment * const env;
         const PackageDepSpec & a;
+        const std::shared_ptr<const PackageID> from_id;
         const MatchPackageOptions & o;
 
         MatchDepListEntryAgainstPackageDepSpec(const Environment * const ee,
-                const PackageDepSpec & aa, const MatchPackageOptions & oo) :
+                const PackageDepSpec & aa, const std::shared_ptr<const PackageID> & f, const MatchPackageOptions & oo) :
             env(ee),
             a(aa),
+            from_id(f),
             o(oo)
         {
         }
@@ -278,7 +280,7 @@ namespace
                 case dlk_provided:
                 case dlk_already_installed:
                 case dlk_subpackage:
-                    return match_package(*env, a, e.second->package_id(), o);
+                    return match_package(*env, a, e.second->package_id(), from_id, o);
 
                 case dlk_block:
                 case dlk_masked:
@@ -425,7 +427,7 @@ DepList::AddVisitor::visit(const DependencySpecTree::NodeType<PackageDepSpec>::T
     /* find already installed things */
     // TODO: check destinations
     std::shared_ptr<const PackageIDSequence> already_installed((*d->_imp->env)[selection::AllVersionsSorted(
-                generator::Matches(*node.spec(), d->_imp->opts->match_package_options()) |
+                generator::Matches(*node.spec(), d->_imp->current_package_id(), d->_imp->opts->match_package_options()) |
                 filter::InstalledAtRoot(d->_imp->env->preferred_root_key()->value()))]);
 
     /* are we already on the merge list? */
@@ -436,7 +438,8 @@ DepList::AddVisitor::visit(const DependencySpecTree::NodeType<PackageDepSpec>::T
         q = std::make_pair(d->_imp->merge_list_index.begin(), d->_imp->merge_list_index.end());
 
     MergeListIndex::iterator qq(std::find_if(q.first, q.second,
-                MatchDepListEntryAgainstPackageDepSpec(d->_imp->env, *node.spec(), d->_imp->opts->match_package_options())));
+                MatchDepListEntryAgainstPackageDepSpec(d->_imp->env, *node.spec(),
+                    d->_imp->current_package_id(), d->_imp->opts->match_package_options())));
 
     MergeList::iterator existing_merge_list_entry(qq == q.second ? d->_imp->merge_list.end() : qq->second);
     if (existing_merge_list_entry != d->_imp->merge_list.end())
@@ -484,7 +487,8 @@ DepList::AddVisitor::visit(const DependencySpecTree::NodeType<PackageDepSpec>::T
     /* find installable candidates, and find the best visible candidate */
     std::shared_ptr<const PackageID> best_visible_candidate;
     std::shared_ptr<const PackageIDSequence> installable_candidates(
-            (*d->_imp->env)[selection::AllVersionsSorted(generator::Matches(*node.spec(), d->_imp->opts->match_package_options()) &
+            (*d->_imp->env)[selection::AllVersionsSorted(generator::Matches(*node.spec(),
+                    d->_imp->current_package_id(), d->_imp->opts->match_package_options()) &
                 generator::SomeIDsMightSupportAction<InstallAction>())]);
 
     for (PackageIDSequence::ReverseConstIterator p(installable_candidates->rbegin()),
@@ -582,17 +586,18 @@ DepList::AddVisitor::visit(const DependencySpecTree::NodeType<PackageDepSpec>::T
         if (already_installed->empty() || ! can_fall_back)
         {
             if (! node.spec()->additional_requirements_ptr())
-                throw AllMaskedError(*node.spec());
+                throw AllMaskedError(*node.spec(), d->_imp->current_package_id());
 
             std::shared_ptr<const PackageIDSequence> match_except_reqs((*d->_imp->env)[selection::AllVersionsSorted(
-                        generator::Matches(*node.spec(), d->_imp->opts->match_package_options() + mpo_ignore_additional_requirements))]);
+                        generator::Matches(*node.spec(), d->_imp->current_package_id(),
+                            d->_imp->opts->match_package_options() + mpo_ignore_additional_requirements))]);
 
             for (PackageIDSequence::ReverseConstIterator i(match_except_reqs->rbegin()),
                     i_end(match_except_reqs->rend()) ; i != i_end ; ++i)
                 if (! (*i)->masked())
                     throw AdditionalRequirementsNotMetError(*node.spec(), *i);
 
-            throw AllMaskedError(*node.spec());
+            throw AllMaskedError(*node.spec(), d->_imp->current_package_id());
         }
         else
         {
@@ -868,10 +873,10 @@ DepList::AddVisitor::visit(const DependencySpecTree::NodeType<BlockDepSpec>::Typ
         PackageDepSpec just_package(make_package_dep_spec({ }).package(
                     *node.spec()->blocking().package_ptr()));
         already_installed = (*d->_imp->env)[selection::AllVersionsUnsorted(
-                generator::Matches(just_package, d->_imp->opts->match_package_options()) |
+                generator::Matches(just_package, make_null_shared_ptr(), d->_imp->opts->match_package_options()) |
                 filter::InstalledAtRoot(d->_imp->env->preferred_root_key()->value()))];
 
-        MatchDepListEntryAgainstPackageDepSpec m(d->_imp->env, just_package, d->_imp->opts->match_package_options());
+        MatchDepListEntryAgainstPackageDepSpec m(d->_imp->env, just_package, make_null_shared_ptr(), d->_imp->opts->match_package_options());
         for (std::pair<MergeListIndex::const_iterator, MergeListIndex::const_iterator> p(
                     d->_imp->merge_list_index.equal_range(*node.spec()->blocking().package_ptr())) ;
                 p.first != p.second ; ++p.first)
@@ -904,7 +909,7 @@ DepList::AddVisitor::visit(const DependencySpecTree::NodeType<BlockDepSpec>::Typ
     for (PackageIDSequence::ConstIterator aa(already_installed->begin()),
             aa_end(already_installed->end()) ; aa != aa_end ; ++aa)
     {
-        if (! match_package(*d->_imp->env, node.spec()->blocking(), *aa, d->_imp->opts->match_package_options()))
+        if (! match_package(*d->_imp->env, node.spec()->blocking(), *aa, d->_imp->current_package_id(), d->_imp->opts->match_package_options()))
             continue;
 
         bool replaced(false);
@@ -974,7 +979,8 @@ DepList::AddVisitor::visit(const DependencySpecTree::NodeType<BlockDepSpec>::Typ
     for (std::list<MergeList::const_iterator>::const_iterator r(will_be_installed.begin()),
             r_end(will_be_installed.end()) ; r != r_end ; ++r)
     {
-        if (! match_package(*d->_imp->env, node.spec()->blocking(), (*r)->package_id(), d->_imp->opts->match_package_options()))
+        if (! match_package(*d->_imp->env, node.spec()->blocking(), (*r)->package_id(),
+                    d->_imp->current_package_id(), d->_imp->opts->match_package_options()))
             continue;
 
         /* ignore if it's a virtual/blah (not <virtual/blah-1) block and it's blocking
@@ -1011,7 +1017,8 @@ DepList::AddVisitor::visit(const DependencySpecTree::NodeType<BlockDepSpec>::Typ
         for (MergeList::const_iterator r(d->_imp->merge_list.begin()),
                 r_end(d->_imp->merge_list.end()) ; r != r_end ; ++r)
         {
-            if (! match_package(*d->_imp->env, node.spec()->blocking(), r->package_id(), d->_imp->opts->match_package_options()))
+            if (! match_package(*d->_imp->env, node.spec()->blocking(), r->package_id(),
+                        d->_imp->current_package_id(), d->_imp->opts->match_package_options()))
                 continue;
 
             /* ignore if it's a virtual/blah (not <virtual/blah-1) block and it's blocking
@@ -1171,7 +1178,7 @@ DepList::add_package(const std::shared_ptr<const PackageID> & p, const std::shar
     /* add provides */
     if (p->provide_key())
     {
-        DepSpecFlattener<ProvideSpecTree, PackageDepSpec> f(_imp->env, _imp->current_package_id());
+        DepSpecFlattener<ProvideSpecTree, PackageDepSpec> f(_imp->env, p);
         p->provide_key()->value()->top()->accept(f);
 
         if (f.begin() != f.end() && ! (*DistributionData::get_instance()->distribution_from_string(
@@ -1195,7 +1202,7 @@ DepList::add_package(const std::shared_ptr<const PackageID> & p, const std::shar
                 z = std::make_pair(_imp->merge_list_index.begin(), _imp->merge_list_index.end());
 
             MergeListIndex::iterator zz(std::find_if(z.first, z.second,
-                MatchDepListEntryAgainstPackageDepSpec(_imp->env, *pp, _imp->opts->match_package_options())));
+                MatchDepListEntryAgainstPackageDepSpec(_imp->env, *pp, p, _imp->opts->match_package_options())));
 
             if (zz != z.second)
                 continue;
@@ -1708,7 +1715,7 @@ DepList::replaced(const PackageID & m) const
 
     PackageDepSpec spec(make_package_dep_spec({ }).package(m.name()));
     while (p.second != ((p.first = std::find_if(p.first, p.second,
-                        MatchDepListEntryAgainstPackageDepSpec(_imp->env, spec, _imp->opts->match_package_options())))))
+                        MatchDepListEntryAgainstPackageDepSpec(_imp->env, spec, make_null_shared_ptr(), _imp->opts->match_package_options())))))
     {
         if (! slot_is_same(*p.first->second->package_id(), m))
             p.first = next(p.first);
@@ -1720,7 +1727,7 @@ DepList::replaced(const PackageID & m) const
 }
 
 bool
-DepList::match_on_list(const PackageDepSpec & a) const
+DepList::match_on_list(const PackageDepSpec & a, const std::shared_ptr<const PackageID> & from_id) const
 {
     std::pair<MergeListIndex::const_iterator, MergeListIndex::const_iterator> p;
     if (a.package_ptr())
@@ -1729,7 +1736,7 @@ DepList::match_on_list(const PackageDepSpec & a) const
         p = std::make_pair(_imp->merge_list_index.begin(), _imp->merge_list_index.end());
 
     return p.second != std::find_if(p.first, p.second,
-            MatchDepListEntryAgainstPackageDepSpec(_imp->env, a, _imp->opts->match_package_options()));
+            MatchDepListEntryAgainstPackageDepSpec(_imp->env, a, from_id, _imp->opts->match_package_options()));
 }
 
 DepList::Iterator
diff --git a/paludis/legacy/dep_list.hh b/paludis/legacy/dep_list.hh
index 036d977d2..ed3bed494 100644
--- a/paludis/legacy/dep_list.hh
+++ b/paludis/legacy/dep_list.hh
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2005, 2006, 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2005, 2006, 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -295,7 +295,7 @@ namespace paludis
             /**
              * Return whether a spec matches an item in the list.
              */
-            bool match_on_list(const PackageDepSpec &) const;
+            bool match_on_list(const PackageDepSpec &, const std::shared_ptr<const PackageID> & from_id) const;
 
             /**
              * Whether we have any errors.
diff --git a/paludis/legacy/dep_list_exceptions.cc b/paludis/legacy/dep_list_exceptions.cc
index f2dd9bdc4..55af89d02 100644
--- a/paludis/legacy/dep_list_exceptions.cc
+++ b/paludis/legacy/dep_list_exceptions.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2005, 2006, 2007, 2008, 2010 Ciaran McCreesh
+ * Copyright (c) 2005, 2006, 2007, 2008, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -28,9 +28,10 @@ DepListError::DepListError(const std::string & m) throw () :
 {
 }
 
-AllMaskedError::AllMaskedError(const PackageDepSpec & q) throw () :
+AllMaskedError::AllMaskedError(const PackageDepSpec & q, const std::shared_ptr<const PackageID> & i) throw () :
     DepListError("Error searching for '" + stringify(q) + "': no available versions"),
-    _query(q)
+    _query(q),
+    _from_id(i)
 {
 }
 
diff --git a/paludis/legacy/dep_list_exceptions.hh b/paludis/legacy/dep_list_exceptions.hh
index e1e84054f..7552602e0 100644
--- a/paludis/legacy/dep_list_exceptions.hh
+++ b/paludis/legacy/dep_list_exceptions.hh
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2005, 2006, 2007, 2008, 2010 Ciaran McCreesh
+ * Copyright (c) 2005, 2006, 2007, 2008, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -65,12 +65,13 @@ namespace paludis
     {
         private:
             const PackageDepSpec _query;
+            const std::shared_ptr<const PackageID> _from_id;
 
         public:
             ///\name Basic operations
             ///\{
 
-            AllMaskedError(const PackageDepSpec & query) throw ();
+            AllMaskedError(const PackageDepSpec & query, const std::shared_ptr<const PackageID> & id) throw ();
 
             virtual ~AllMaskedError() throw ()
             {
@@ -85,6 +86,11 @@ namespace paludis
             {
                 return _query;
             }
+
+            const std::shared_ptr<const PackageID> from_id() const
+            {
+                return _from_id;
+            }
     };
 
     /**
diff --git a/paludis/legacy/install_task.cc b/paludis/legacy/install_task.cc
index 9476bc366..3cd20133e 100644
--- a/paludis/legacy/install_task.cc
+++ b/paludis/legacy/install_task.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2006, 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2006, 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -252,7 +252,7 @@ namespace
                 return std::make_shared<DepListEntryHandledSkippedDependent>(
                             *(*env)[selection::RequireExactlyOne(generator::Matches(
                                     parse_user_package_dep_spec(s.substr(1), env,
-                                        { }), { }))]->begin());
+                                        { }), make_null_shared_ptr(), { }))]->begin());
 
             case 'F':
                 if (s.length() != 1)
@@ -299,7 +299,7 @@ InstallTask::set_targets_from_serialisation(const std::string & format,
             throw InternalError(PALUDIS_HERE, "Serialised value '" + *s + "' too short: no package_id");
         const std::shared_ptr<const PackageID> package_id(*(*_imp->env)[selection::RequireExactlyOne(
                     generator::Matches(parse_user_package_dep_spec(*tokens.begin(),
-                            _imp->env, { }), { }))]->begin());
+                            _imp->env, { }), make_null_shared_ptr(), { }))]->begin());
         tokens.pop_front();
 
         if (tokens.empty())
@@ -504,7 +504,7 @@ InstallTask::_add_target(const std::string & target)
         else
         {
             std::shared_ptr<const PackageIDSequence> names((*_imp->env)[selection::BestVersionOnly(
-                        generator::Matches(*spec, { }) | filter::SupportsAction<InstallAction>())]);
+                        generator::Matches(*spec, make_null_shared_ptr(), { }) | filter::SupportsAction<InstallAction>())]);
 
             if (names->empty())
             {
@@ -1538,7 +1538,7 @@ namespace
         void visit(const DependencySpecTree::NodeType<PackageDepSpec>::Type & node)
         {
             if (! failure)
-                if ((*env)[selection::SomeArbitraryVersion(generator::Matches(*node.spec(), { })
+                if ((*env)[selection::SomeArbitraryVersion(generator::Matches(*node.spec(), id, { })
                             | filter::InstalledAtRoot(env->preferred_root_key()->value()))]->empty())
                     failure = node.spec();
         }
@@ -1728,7 +1728,7 @@ namespace
                 if (! d->handled())
                     continue;
 
-                if (! match_package(*env, *node.spec(), d->package_id(), { }))
+                if (! match_package(*env, *node.spec(), d->package_id(), id, { }))
                     continue;
 
                 CheckHandledVisitor v;
@@ -1743,7 +1743,7 @@ namespace
             /* no match on the dep list, fall back to installed packages. if
              * there are no matches here it's not a problem because of or-deps. */
             std::shared_ptr<const PackageIDSequence> installed((*env)[selection::AllVersionsUnsorted(
-                        generator::Matches(*node.spec(), { }) |
+                        generator::Matches(*node.spec(), id, { }) |
                         filter::InstalledAtRoot(env->preferred_root_key()->value()))]);
 
             for (PackageIDSequence::ConstIterator i(installed->begin()), i_end(installed->end()) ;
diff --git a/paludis/legacy/query_visitor.cc b/paludis/legacy/query_visitor.cc
index 0ddec62a6..b63c9d905 100644
--- a/paludis/legacy/query_visitor.cc
+++ b/paludis/legacy/query_visitor.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2005, 2006, 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2005, 2006, 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -91,7 +91,7 @@ QueryVisitor::visit(const DependencySpecTree::NodeType<PackageDepSpec>::Type & n
 
     // TODO: check destinations
     std::shared_ptr<const PackageIDSequence> matches((*_imp->environment)[selection::AllVersionsUnsorted(
-                generator::Matches(*node.spec(), _imp->dep_list->options()->match_package_options()) |
+                generator::Matches(*node.spec(), _imp->id, _imp->dep_list->options()->match_package_options()) |
                 filter::InstalledAtRoot(_imp->environment->preferred_root_key()->value()))]);
 
     if (indirect_iterator(matches->end()) != std::find_if(indirect_iterator(matches->begin()), indirect_iterator(matches->end()),
@@ -102,7 +102,7 @@ QueryVisitor::visit(const DependencySpecTree::NodeType<PackageDepSpec>::Type & n
     }
 
     /* check the merge list for any new packages that match */
-    if (_imp->dep_list->match_on_list(*node.spec()))
+    if (_imp->dep_list->match_on_list(*node.spec(), _imp->id))
     {
         _imp->result = true;
         return;
diff --git a/paludis/legacy/report_task.cc b/paludis/legacy/report_task.cc
index 4924b5511..289348df2 100644
--- a/paludis/legacy/report_task.cc
+++ b/paludis/legacy/report_task.cc
@@ -36,6 +36,7 @@
 #include <paludis/util/wrapped_forward_iterator.hh>
 #include <paludis/util/accept_visitor.hh>
 #include <paludis/util/sequence.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/package_database.hh>
 #include <paludis/version_requirements.hh>
 #include <paludis/partially_made_package_dep_spec.hh>
@@ -104,7 +105,7 @@ namespace
     VulnerableChecker::visit(const SetSpecTree::NodeType<PackageDepSpec>::Type & node)
     {
         std::shared_ptr<const PackageIDSequence> insecure(_env[selection::AllVersionsSorted(
-                    generator::Matches(*node.spec(), { }))]);
+                    generator::Matches(*node.spec(), make_null_shared_ptr(), { }))]);
         for (PackageIDSequence::ConstIterator i(insecure->begin()),
                 i_end(insecure->end()) ; i != i_end ; ++i)
             if (node.spec()->tag() && simple_visitor_cast<const GLSADepTag>(*node.spec()->tag()))
@@ -217,7 +218,7 @@ ReportTask::execute()
                                                  .version_requirement(make_named_values<VersionRequirement>(
                                                          n::version_operator() = vo_equal,
                                                          n::version_spec() = (*v)->version())),
-                                                 { })) |
+                                                 make_null_shared_ptr(), { })) |
                                             filter::SupportsAction<InstallAction>()))]);
 
                             if (! installable->empty())
diff --git a/paludis/legacy/show_suggest_visitor.cc b/paludis/legacy/show_suggest_visitor.cc
index fa53eccb1..88ee5eb78 100644
--- a/paludis/legacy/show_suggest_visitor.cc
+++ b/paludis/legacy/show_suggest_visitor.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2005, 2006, 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2005, 2006, 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -191,7 +191,7 @@ ShowSuggestVisitor::visit(const DependencySpecTree::NodeType<PackageDepSpec>::Ty
     }
 
     std::shared_ptr<const PackageIDSequence> installed_matches((*_imp->environment)[selection::AllVersionsSorted(
-                generator::Matches(*node.spec(), _imp->dep_list->options()->match_package_options())
+                generator::Matches(*node.spec(), _imp->id, _imp->dep_list->options()->match_package_options())
                 | filter::InstalledAtRoot(_imp->environment->preferred_root_key()->value()))]);
     if (! installed_matches->empty())
     {
@@ -203,7 +203,7 @@ ShowSuggestVisitor::visit(const DependencySpecTree::NodeType<PackageDepSpec>::Ty
     }
 
     std::shared_ptr<const PackageIDSequence> matches((*_imp->environment)[selection::AllVersionsSorted(
-                generator::Matches(*node.spec(), _imp->dep_list->options()->match_package_options())
+                generator::Matches(*node.spec(), _imp->id, _imp->dep_list->options()->match_package_options())
                 | filter::SupportsAction<InstallAction>())]);
     if (matches->empty())
     {
diff --git a/paludis/legacy/uninstall_list.cc b/paludis/legacy/uninstall_list.cc
index 4ec04cff9..305f16aec 100644
--- a/paludis/legacy/uninstall_list.cc
+++ b/paludis/legacy/uninstall_list.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2006, 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2006, 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -183,7 +183,7 @@ UninstallList::add_errors_for_system()
                     v != v_end && ! needed ; ++v)
             {
                 const std::shared_ptr<const PackageIDSequence> virtuals((*_imp->env)[selection::AllVersionsUnsorted(
-                            generator::Matches(**v, { }))]);
+                            generator::Matches(**v, l->package_id(), { }))]);
                 for (PackageIDSequence::ConstIterator i(virtuals->begin()), i_end(virtuals->end()) ;
                         i != i_end && ! needed ; ++i)
                     if (match_package_in_set(*_imp->env, *system, *i, { }))
@@ -330,8 +330,8 @@ namespace
 
             std::shared_ptr<const PackageIDSequence> m(
                     best_only ?
-                    (*env)[selection::BestVersionOnly(generator::Matches(*node.spec(), { }) | filter::InstalledAtRoot(env->preferred_root_key()->value()))] :
-                    (*env)[selection::AllVersionsSorted(generator::Matches(*node.spec(), { }) | filter::InstalledAtRoot(env->preferred_root_key()->value()))]);
+                    (*env)[selection::BestVersionOnly(generator::Matches(*node.spec(), pkg, { }) | filter::InstalledAtRoot(env->preferred_root_key()->value()))] :
+                    (*env)[selection::AllVersionsSorted(generator::Matches(*node.spec(), pkg, { }) | filter::InstalledAtRoot(env->preferred_root_key()->value()))]);
             for (PackageIDSequence::ConstIterator it = m->begin(), it_end = m->end();
                  it_end != it; ++it)
                 matches->insert(make_named_values<DepTagEntry>(
diff --git a/paludis/legacy/uninstall_task.cc b/paludis/legacy/uninstall_task.cc
index 98bf9efcf..45aa3d37e 100644
--- a/paludis/legacy/uninstall_task.cc
+++ b/paludis/legacy/uninstall_task.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2006, 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2006, 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -179,7 +179,7 @@ UninstallTask::add_target(const std::string & target)
         {
             /* blech. wildcards. */
             std::shared_ptr<const PackageIDSequence> names((*_imp->env)[selection::BestVersionOnly(
-                        generator::Matches(*pds, { }) | filter::SupportsAction<UninstallAction>())]);
+                        generator::Matches(*pds, make_null_shared_ptr(), { }) | filter::SupportsAction<UninstallAction>())]);
             if (names->empty())
             {
                 /* no match. we'll get an error from this later anyway. */
@@ -263,7 +263,7 @@ UninstallTask::execute()
             Context local_context("When looking for target '" + stringify(**t) + "':");
 
             std::shared_ptr<const PackageIDSequence> r((*_imp->env)[selection::AllVersionsSorted(
-                        generator::Matches(**t, { }) |
+                        generator::Matches(**t, make_null_shared_ptr(), { }) |
                         filter::SupportsAction<UninstallAction>())]);
             if (r->empty())
             {
@@ -331,7 +331,7 @@ UninstallTask::execute()
         {
             bool remove(true);
             std::shared_ptr<const PackageIDSequence> installed((*_imp->env)[selection::AllVersionsUnsorted(
-                        generator::Matches(make_package_dep_spec({ }).package(i->first), { }) |
+                        generator::Matches(make_package_dep_spec({ }).package(i->first), make_null_shared_ptr(), { }) |
                         filter::InstalledAtRoot(_imp->env->preferred_root_key()->value())
                         )]);
             for (PackageIDSequence::ConstIterator r(installed->begin()), r_end(installed->end()) ;
diff --git a/paludis/match_package.cc b/paludis/match_package.cc
index 0bc470bdf..ef0141346 100644
--- a/paludis/match_package.cc
+++ b/paludis/match_package.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2006, 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2006, 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -35,6 +35,7 @@
 #include <paludis/additional_package_dep_spec_requirement.hh>
 
 #include <paludis/util/indirect_iterator-impl.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 
 #include <functional>
 #include <algorithm>
@@ -81,6 +82,7 @@ paludis::match_package_with_maybe_changes(
         const PackageDepSpec & spec,
         const ChangedChoices * const maybe_changes_to_owner,
         const std::shared_ptr<const PackageID> & id,
+        const std::shared_ptr<const PackageID> &,
         const ChangedChoices * const maybe_changes_to_target,
         const MatchPackageOptions & options)
 {
@@ -219,9 +221,10 @@ paludis::match_package(
         const Environment & env,
         const PackageDepSpec & spec,
         const std::shared_ptr<const PackageID> & id,
+        const std::shared_ptr<const PackageID> & from_id,
         const MatchPackageOptions & options)
 {
-    return match_package_with_maybe_changes(env, spec, 0, id, 0, options);
+    return match_package_with_maybe_changes(env, spec, 0, id, from_id, 0, options);
 }
 
 bool
@@ -237,6 +240,6 @@ paludis::match_package_in_set(
     target.top()->accept(f);
     return indirect_iterator(f.end()) != std::find_if(
             indirect_iterator(f.begin()), indirect_iterator(f.end()),
-            std::bind(&match_package, std::cref(env), _1, std::cref(id), std::cref(options)));
+            std::bind(&match_package, std::cref(env), _1, std::cref(id), make_null_shared_ptr(), std::cref(options)));
 }
 
diff --git a/paludis/match_package.hh b/paludis/match_package.hh
index f1a67ed04..992ef1648 100644
--- a/paludis/match_package.hh
+++ b/paludis/match_package.hh
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2006, 2007, 2008, 2010 Ciaran McCreesh
+ * Copyright (c) 2006, 2007, 2008, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -44,12 +44,18 @@ namespace paludis
      * Return whether the specified PackageID matches the specified
      * PackageDepSpec.
      *
+     * \param spec_id The PackageID the spec comes from. May be null. Used for
+     * [use=] style dependencies.
+     *
+     * \since 0.58 takes spec_id
+     *
      * \ingroup g_query
      */
     bool match_package(
             const Environment & env,
             const PackageDepSpec & spec,
             const std::shared_ptr<const PackageID> & id,
+            const std::shared_ptr<const PackageID> & spec_id,
             const MatchPackageOptions & options)
         PALUDIS_ATTRIBUTE((warn_unused_result)) PALUDIS_VISIBLE;
 
@@ -58,6 +64,11 @@ namespace paludis
      * PackageDepSpec, with the specified ChangedChoices applied to the target
      * and the ID from which the dep came.
      *
+     * \param spec_id The PackageID the spec comes from. May be null. Used for
+     * [use=] style dependencies.
+     *
+     * \since 0.58 takes spec_id
+     *
      * \ingroup g_query
      * \since 0.51
      */
@@ -66,6 +77,7 @@ namespace paludis
             const PackageDepSpec & spec,
             const ChangedChoices * const maybe_changes_to_owner,
             const std::shared_ptr<const PackageID> & id,
+            const std::shared_ptr<const PackageID> & spec_id,
             const ChangedChoices * const maybe_changes_to_target,
             const MatchPackageOptions & options)
         PALUDIS_ATTRIBUTE((warn_unused_result)) PALUDIS_VISIBLE;
diff --git a/paludis/package_database.cc b/paludis/package_database.cc
index 17e978b88..2a239dfb0 100644
--- a/paludis/package_database.cc
+++ b/paludis/package_database.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2005, 2006, 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2005, 2006, 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -42,6 +42,7 @@
 #include <paludis/util/sequence-impl.hh>
 #include <paludis/util/wrapped_forward_iterator-impl.hh>
 #include <paludis/util/member_iterator.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <functional>
 #include <algorithm>
 #include <list>
@@ -279,7 +280,7 @@ PackageDatabase::fetch_unique_qualified_package_name(const PackageNamePart & p,
     std::set<std::pair<CategoryNamePart, RepositoryName>, CategoryRepositoryNamePairComparator> checked;
 
     std::shared_ptr<const PackageIDSequence> pkgs((*_imp->environment)[selection::AllVersionsUnsorted(
-                generator::Matches(make_package_dep_spec({ }).package_name_part(p), { }) | f)]);
+                generator::Matches(make_package_dep_spec({ }).package_name_part(p), make_null_shared_ptr(), { }) | f)]);
 
     for (IndirectIterator<PackageIDSequence::ConstIterator> it(pkgs->begin()),
              it_end(pkgs->end()); it_end != it; ++it)
diff --git a/paludis/package_dep_spec_collection.cc b/paludis/package_dep_spec_collection.cc
index b18247281..73e08876a 100644
--- a/paludis/package_dep_spec_collection.cc
+++ b/paludis/package_dep_spec_collection.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2010 Ciaran McCreesh
+ * Copyright (c) 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -32,13 +32,19 @@ namespace paludis
     template <>
     struct Imp<PackageDepSpecCollection>
     {
+        const std::shared_ptr<const PackageID> from_id;
         std::multimap<QualifiedPackageName, PackageDepSpec> by_name;
         std::list<PackageDepSpec> unnamed;
+
+        Imp(const std::shared_ptr<const PackageID> & i) :
+            from_id(i)
+        {
+        }
     };
 }
 
-PackageDepSpecCollection::PackageDepSpecCollection() :
-    Pimp<PackageDepSpecCollection>()
+PackageDepSpecCollection::PackageDepSpecCollection(const std::shared_ptr<const PackageID> & i) :
+    Pimp<PackageDepSpecCollection>(i)
 {
 }
 
@@ -61,12 +67,12 @@ PackageDepSpecCollection::match_any(
 {
     auto named(_imp->by_name.equal_range(id->name()));
     for ( ; named.first != named.second ; ++named.first)
-        if (match_package(*env, named.first->second, id, opts))
+        if (match_package(*env, named.first->second, id, _imp->from_id, opts))
             return true;
 
     for (auto u(_imp->unnamed.begin()), u_end(_imp->unnamed.end()) ;
             u != u_end ; ++u)
-        if (match_package(*env, *u, id, opts))
+        if (match_package(*env, *u, id, _imp->from_id, opts))
             return true;
 
     return false;
diff --git a/paludis/package_dep_spec_collection.hh b/paludis/package_dep_spec_collection.hh
index 7ce3beb2f..673bd334f 100644
--- a/paludis/package_dep_spec_collection.hh
+++ b/paludis/package_dep_spec_collection.hh
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2010 Ciaran McCreesh
+ * Copyright (c) 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -34,7 +34,7 @@ namespace paludis
         private Pimp<PackageDepSpecCollection>
     {
         public:
-            PackageDepSpecCollection();
+            explicit PackageDepSpecCollection(const std::shared_ptr<const PackageID> & from_id);
             ~PackageDepSpecCollection();
 
             void insert(const PackageDepSpec &);
diff --git a/paludis/paludislike_options_conf.cc b/paludis/paludislike_options_conf.cc
index f58b296f4..59fb38d16 100644
--- a/paludis/paludislike_options_conf.cc
+++ b/paludis/paludislike_options_conf.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -32,6 +32,7 @@
 #include <paludis/util/set.hh>
 #include <paludis/util/active_object_ptr.hh>
 #include <paludis/util/deferred_construction_ptr.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/choice.hh>
 #include <paludis/dep_spec.hh>
 #include <paludis/name.hh>
@@ -426,7 +427,7 @@ namespace
         {
             if (maybe_id)
             {
-                if (! match_package(*env, i->spec(), maybe_id, { }))
+                if (! match_package(*env, i->spec(), maybe_id, make_null_shared_ptr(), { }))
                     continue;
             }
             else
@@ -453,7 +454,7 @@ namespace
         {
             if (maybe_id)
             {
-                if (! match_package(*env, i->spec(), maybe_id, { }))
+                if (! match_package(*env, i->spec(), maybe_id, make_null_shared_ptr(), { }))
                     continue;
             }
             else
diff --git a/paludis/repositories/e/e_repository.cc b/paludis/repositories/e/e_repository.cc
index d880933be..471d3acd4 100644
--- a/paludis/repositories/e/e_repository.cc
+++ b/paludis/repositories/e/e_repository.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2005, 2006, 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2005, 2006, 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  * Copyright (c) 2006 Danny van Dyk
  *
  * This file is part of the Paludis package manager. Paludis is free software;
@@ -670,7 +670,7 @@ ERepository::repository_masked(const std::shared_ptr<const PackageID> & id) cons
     else
         for (std::list<std::pair<std::shared_ptr<const PackageDepSpec>, std::shared_ptr<const RepositoryMaskInfo> > >::const_iterator
                 k(r->second.begin()), k_end(r->second.end()) ; k != k_end ; ++k)
-            if (match_package(*_imp->params.environment(), *k->first, id, { }))
+            if (match_package(*_imp->params.environment(), *k->first, id, make_null_shared_ptr(), { }))
                 return k->second;
 
     return std::shared_ptr<const RepositoryMaskInfo>();
diff --git a/paludis/repositories/e/e_repository_TEST.cc b/paludis/repositories/e/e_repository_TEST.cc
index 705970bd4..bdfe329e6 100644
--- a/paludis/repositories/e/e_repository_TEST.cc
+++ b/paludis/repositories/e/e_repository_TEST.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2006, 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2006, 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -33,6 +33,7 @@
 #include <paludis/util/set.hh>
 #include <paludis/util/return_literal_function.hh>
 #include <paludis/util/fs_stat.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/standard_output_manager.hh>
 #include <paludis/util/safe_ifstream.hh>
 #include <paludis/package_id.hh>
@@ -497,7 +498,7 @@ namespace test_cases
 
                     const std::shared_ptr<const PackageID> id1(*env[selection::RequireExactlyOne(generator::Matches(
                                     PackageDepSpec(parse_user_package_dep_spec("=cat-one/pkg-one-1",
-                                            &env, { })), { }))]->begin());
+                                            &env, { })), make_null_shared_ptr(), { }))]->begin());
 
                     TEST_CHECK(id1->end_metadata() != id1->find_metadata("EAPI"));
                     TEST_CHECK(simple_visitor_cast<const MetadataValueKey<std::string> >(**id1->find_metadata("EAPI")));
@@ -516,7 +517,7 @@ namespace test_cases
 
                     const std::shared_ptr<const PackageID> id2(*env[selection::RequireExactlyOne(generator::Matches(
                                     PackageDepSpec(parse_user_package_dep_spec("=cat-one/pkg-one-2",
-                                            &env, { })), { }))]->begin());
+                                            &env, { })), make_null_shared_ptr(), { }))]->begin());
 
                     TEST_CHECK(id2->end_metadata() != id2->find_metadata("EAPI"));
                     TEST_CHECK(bool(id2->short_description_key()));
@@ -532,7 +533,7 @@ namespace test_cases
 
                     const std::shared_ptr<const PackageID> id3(*env[selection::RequireExactlyOne(generator::Matches(
                                     PackageDepSpec(parse_user_package_dep_spec("=cat-one/pkg-one-3",
-                                            &env, { })), { }))]->begin());
+                                            &env, { })), make_null_shared_ptr(), { }))]->begin());
 
                     TEST_CHECK(id3->end_metadata() != id3->find_metadata("EAPI"));
                     TEST_CHECK(bool(id3->short_description_key()));
@@ -578,7 +579,7 @@ namespace test_cases
 
                 const std::shared_ptr<const PackageID> id1(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat-one/pkg-two-1",
-                                        &env, { })), { }))]->begin());
+                                        &env, { })), make_null_shared_ptr(), { }))]->begin());
 
                 TEST_CHECK(id1->end_metadata() != id1->find_metadata("EAPI"));
                 TEST_CHECK_EQUAL(std::static_pointer_cast<const erepository::ERepositoryID>(id1)->eapi()->name(), "UNKNOWN");
@@ -622,13 +623,13 @@ namespace test_cases
 
                 const std::shared_ptr<const PackageID> p1(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat-one/pkg-one-1",
-                                        &env, { })), { }))]->begin());
+                                        &env, { })), make_null_shared_ptr(), { }))]->begin());
                 const std::shared_ptr<const PackageID> p2(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat-two/pkg-two-1",
-                                        &env, { })), { }))]->begin());
+                                        &env, { })), make_null_shared_ptr(), { }))]->begin());
                 const std::shared_ptr<const PackageID> p4(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat-one/pkg-one-2",
-                                        &env, { })), { }))]->begin());
+                                        &env, { })), make_null_shared_ptr(), { }))]->begin());
 
                 test_choice(p1, "flag1",     true,  true,  false);
                 test_choice(p1, "flag2",     false, false, true);
@@ -709,29 +710,29 @@ namespace test_cases
 
             TEST_CHECK((*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=category/package-1::test-repo-18",
-                                        &env, { })), { }))]->begin())->masked());
+                                        &env, { })), make_null_shared_ptr(), { }))]->begin())->masked());
             TEST_CHECK((*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=category/package-2::test-repo-18",
-                                        &env, { })), { }))]->begin())->masked());
+                                        &env, { })), make_null_shared_ptr(), { }))]->begin())->masked());
             TEST_CHECK(! (*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=category/package-3::test-repo-18",
-                                        &env, { })), { }))]->begin())->masked());
+                                        &env, { })), make_null_shared_ptr(), { }))]->begin())->masked());
             TEST_CHECK(! (*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=category/package-4::test-repo-18",
-                                        &env, { })), { }))]->begin())->masked());
+                                        &env, { })), make_null_shared_ptr(), { }))]->begin())->masked());
 
             TEST_CHECK((*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=category/package-1::test-repo-19",
-                                        &env, { })), { }))]->begin())->masked());
+                                        &env, { })), make_null_shared_ptr(), { }))]->begin())->masked());
             TEST_CHECK(! (*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=category/package-2::test-repo-19",
-                                        &env, { })), { }))]->begin())->masked());
+                                        &env, { })), make_null_shared_ptr(), { }))]->begin())->masked());
             TEST_CHECK((*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=category/package-3::test-repo-19",
-                                        &env, { })), { }))]->begin())->masked());
+                                        &env, { })), make_null_shared_ptr(), { }))]->begin())->masked());
             TEST_CHECK(! (*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=category/package-4::test-repo-19",
-                                        &env, { })), { }))]->begin())->masked());
+                                        &env, { })), make_null_shared_ptr(), { }))]->begin())->masked());
         }
     } test_e_repository_repository_masks;
 
@@ -759,13 +760,13 @@ namespace test_cases
 
                 TEST_CHECK((*env[selection::RequireExactlyOne(generator::Matches(
                                     PackageDepSpec(parse_user_package_dep_spec("=cat/masked-0",
-                                            &env, { })), { }))]->begin())->masked());
+                                            &env, { })), make_null_shared_ptr(), { }))]->begin())->masked());
                 TEST_CHECK(! (*env[selection::RequireExactlyOne(generator::Matches(
                                     PackageDepSpec(parse_user_package_dep_spec("=cat/was_masked-0",
-                                            &env, { })), { }))]->begin())->masked());
+                                            &env, { })), make_null_shared_ptr(), { }))]->begin())->masked());
                 TEST_CHECK(! (*env[selection::RequireExactlyOne(generator::Matches(
                                     PackageDepSpec(parse_user_package_dep_spec("=cat/not_masked-0",
-                                            &env, { })), { }))]->begin())->masked());
+                                            &env, { })), make_null_shared_ptr(), { }))]->begin())->masked());
             }
         }
     } test_e_repository_query_profile_masks;
@@ -944,7 +945,7 @@ namespace test_cases
                 TestMessageSuffix suffix("no files", true);
                 const std::shared_ptr<const PackageID> no_files_id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/no-files",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(no_files_id));
                 TEST_CHECK(bool(no_files_id->short_description_key()));
                 TEST_CHECK_EQUAL(no_files_id->short_description_key()->value(), "The Short Description");
@@ -955,7 +956,7 @@ namespace test_cases
                 TestMessageSuffix suffix("fetched files", true);
                 const std::shared_ptr<const PackageID> fetched_files_id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/fetched-files",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(fetched_files_id));
                 TEST_CHECK((FSPath("e_repository_TEST_dir") / "distdir" / "already-fetched.txt").stat().is_regular_file());
                 fetched_files_id->perform_action(action);
@@ -967,7 +968,7 @@ namespace test_cases
                 TEST_CHECK(! (FSPath("e_repository_TEST_dir") / "distdir" / "fetchable-1.txt").stat().is_regular_file());
                 const std::shared_ptr<const PackageID> fetchable_files_id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/fetchable-files",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(fetchable_files_id));
                 fetchable_files_id->perform_action(action);
                 TEST_CHECK((FSPath("e_repository_TEST_dir") / "distdir" / "fetchable-1.txt").stat().is_regular_file());
@@ -978,7 +979,7 @@ namespace test_cases
                 TEST_CHECK(! (FSPath("e_repository_TEST_dir") / "distdir" / "arrowed.txt").stat().is_regular_file());
                 const std::shared_ptr<const PackageID> arrow_files_id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/arrow-files",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(arrow_files_id));
                 arrow_files_id->perform_action(action);
                 TEST_CHECK((FSPath("e_repository_TEST_dir") / "distdir" / "arrowed.txt").stat().is_regular_file());
@@ -988,7 +989,7 @@ namespace test_cases
                 TestMessageSuffix suffix("unfetchable files", true);
                 const std::shared_ptr<const PackageID> unfetchable_files_id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/unfetchable-files",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(unfetchable_files_id));
                 TEST_CHECK_THROWS(unfetchable_files_id->perform_action(action), ActionFailedError);
             }
@@ -996,7 +997,7 @@ namespace test_cases
             {
                 const std::shared_ptr<const PackageID> no_files_restricted_id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/no-files-restricted",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(no_files_restricted_id));
                 no_files_restricted_id->perform_action(action);
             }
@@ -1004,7 +1005,7 @@ namespace test_cases
             {
                 const std::shared_ptr<const PackageID> fetched_files_restricted_id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/fetched-files-restricted",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(fetched_files_restricted_id));
                 fetched_files_restricted_id->perform_action(action);
             }
@@ -1012,7 +1013,7 @@ namespace test_cases
             {
                 const std::shared_ptr<const PackageID> fetchable_files_restricted_id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/fetchable-files-restricted",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(fetchable_files_restricted_id));
                 TEST_CHECK_THROWS(fetchable_files_restricted_id->perform_action(action), ActionFailedError);
             }
@@ -1050,7 +1051,7 @@ namespace test_cases
 
             const std::shared_ptr<const PackageID> id(*env[selection::AllVersionsSorted(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("category/package",
-                                    &env, { })), { }))]->last());
+                                    &env, { })), make_null_shared_ptr(), { }))]->last());
             TEST_CHECK(bool(id));
             repo->make_manifest(id->name());
             id->perform_action(action);
diff --git a/paludis/repositories/e/e_repository_TEST_0.cc b/paludis/repositories/e/e_repository_TEST_0.cc
index bb18821aa..df8e925c2 100644
--- a/paludis/repositories/e/e_repository_TEST_0.cc
+++ b/paludis/repositories/e/e_repository_TEST_0.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2006, 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2006, 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -30,6 +30,7 @@
 #include <paludis/util/map.hh>
 #include <paludis/util/make_named_values.hh>
 #include <paludis/util/set.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/standard_output_manager.hh>
 #include <paludis/util/safe_ifstream.hh>
 #include <paludis/package_id.hh>
@@ -159,7 +160,7 @@ namespace test_cases
             {
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=virtual/virtual-pretend-installed-0",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
             }
 #endif
@@ -168,7 +169,7 @@ namespace test_cases
                 TestMessageSuffix suffix("in-ebuild die", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/in-ebuild-die",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_THROWS(id->perform_action(action), ActionFailedError);
             }
@@ -177,7 +178,7 @@ namespace test_cases
                 TestMessageSuffix suffix("in-subshell die", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/in-subshell-die",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_THROWS(id->perform_action(action), ActionFailedError);
             }
@@ -186,7 +187,7 @@ namespace test_cases
                 TestMessageSuffix suffix("success", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/success",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 id->perform_action(action);
             }
@@ -195,7 +196,7 @@ namespace test_cases
                 TestMessageSuffix suffix("unpack die", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/unpack-die",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_THROWS(id->perform_action(action), ActionFailedError);
             }
@@ -204,7 +205,7 @@ namespace test_cases
                 TestMessageSuffix suffix("econf die", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/econf-die",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_THROWS(id->perform_action(action), ActionFailedError);
             }
@@ -213,7 +214,7 @@ namespace test_cases
                 TestMessageSuffix suffix("emake fail", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/emake-fail",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 id->perform_action(action);
             }
@@ -222,7 +223,7 @@ namespace test_cases
                 TestMessageSuffix suffix("emake die", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/emake-die",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_THROWS(id->perform_action(action), ActionFailedError);
             }
@@ -231,7 +232,7 @@ namespace test_cases
                 TestMessageSuffix suffix("einstall die", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/einstall-die",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_THROWS(id->perform_action(action), ActionFailedError);
             }
@@ -240,7 +241,7 @@ namespace test_cases
                 TestMessageSuffix suffix("keepdir die", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/keepdir-die",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_THROWS(id->perform_action(action), ActionFailedError);
             }
@@ -249,7 +250,7 @@ namespace test_cases
                 TestMessageSuffix suffix("dobin fail", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/dobin-fail",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 id->perform_action(action);
             }
@@ -258,7 +259,7 @@ namespace test_cases
                 TestMessageSuffix suffix("dobin die", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/dobin-die",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_THROWS(id->perform_action(action), ActionFailedError);
             }
@@ -267,7 +268,7 @@ namespace test_cases
                 TestMessageSuffix suffix("fperms fail", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/fperms-fail",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 id->perform_action(action);
             }
@@ -276,7 +277,7 @@ namespace test_cases
                 TestMessageSuffix suffix("fperms die", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/fperms-die",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_THROWS(id->perform_action(action), ActionFailedError);
             }
@@ -285,7 +286,7 @@ namespace test_cases
                 TestMessageSuffix suffix("econf source 0", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/econf-source-0",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_EQUAL(simple_visitor_cast<const MetadataValueKey<std::string> >(**id->find_metadata("EAPI"))->value(), "0");
                 TEST_CHECK_THROWS(id->perform_action(action), ActionFailedError);
@@ -295,7 +296,7 @@ namespace test_cases
                 TestMessageSuffix suffix("doman 0", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/doman-0",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_EQUAL(simple_visitor_cast<const MetadataValueKey<std::string> >(**id->find_metadata("EAPI"))->value(), "0");
                 id->perform_action(action);
@@ -305,7 +306,7 @@ namespace test_cases
                 TestMessageSuffix suffix("no src_prepare 0", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/src_prepare-0",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_EQUAL(simple_visitor_cast<const MetadataValueKey<std::string> >(**id->find_metadata("EAPI"))->value(), "0");
                 id->perform_action(action);
@@ -315,7 +316,7 @@ namespace test_cases
                 TestMessageSuffix suffix("no src_configure 0", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/src_configure-0",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_EQUAL(simple_visitor_cast<const MetadataValueKey<std::string> >(**id->find_metadata("EAPI"))->value(), "0");
                 id->perform_action(action);
@@ -325,7 +326,7 @@ namespace test_cases
                 TestMessageSuffix suffix("best version", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/best-version-0",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 id->perform_action(action);
             }
@@ -334,7 +335,7 @@ namespace test_cases
                 TestMessageSuffix suffix("has version", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/has-version-0",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 id->perform_action(action);
             }
@@ -343,7 +344,7 @@ namespace test_cases
                 TestMessageSuffix suffix("match", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/match-0",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 id->perform_action(action);
             }
@@ -352,7 +353,7 @@ namespace test_cases
                 TestMessageSuffix suffix("vars", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/vars-0",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 id->perform_action(action);
             }
@@ -361,7 +362,7 @@ namespace test_cases
                 TestMessageSuffix suffix("expand vars", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/expand-vars-0",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 id->perform_action(action);
             }
@@ -370,7 +371,7 @@ namespace test_cases
                 TestMessageSuffix suffix("econf disable dependency tracking", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/econf-disable-dependency-tracking-0",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_EQUAL(simple_visitor_cast<const MetadataValueKey<std::string> >(**id->find_metadata("EAPI"))->value(), "0");
                 id->perform_action(action);
diff --git a/paludis/repositories/e/e_repository_TEST_1.cc b/paludis/repositories/e/e_repository_TEST_1.cc
index c786c2024..45a7094b9 100644
--- a/paludis/repositories/e/e_repository_TEST_1.cc
+++ b/paludis/repositories/e/e_repository_TEST_1.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2006, 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2006, 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -30,6 +30,7 @@
 #include <paludis/util/map.hh>
 #include <paludis/util/make_named_values.hh>
 #include <paludis/util/set.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/standard_output_manager.hh>
 #include <paludis/util/safe_ifstream.hh>
 #include <paludis/package_id.hh>
@@ -138,7 +139,7 @@ namespace test_cases
                 TestMessageSuffix suffix("econf source 1", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/econf-source-1",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_EQUAL(simple_visitor_cast<const MetadataValueKey<std::string> >(**id->find_metadata("EAPI"))->value(), "1");
                 id->perform_action(action);
@@ -148,7 +149,7 @@ namespace test_cases
                 TestMessageSuffix suffix("dosym success 1", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/dosym-success-1",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_EQUAL(simple_visitor_cast<const MetadataValueKey<std::string> >(**id->find_metadata("EAPI"))->value(), "1");
                 id->perform_action(action);
@@ -158,7 +159,7 @@ namespace test_cases
                 TestMessageSuffix suffix("doman 1", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/doman-1",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_EQUAL(simple_visitor_cast<const MetadataValueKey<std::string> >(**id->find_metadata("EAPI"))->value(), "1");
                 id->perform_action(action);
@@ -168,7 +169,7 @@ namespace test_cases
                 TestMessageSuffix suffix("no src_prepare 1", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/src_prepare-1",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_EQUAL(simple_visitor_cast<const MetadataValueKey<std::string> >(**id->find_metadata("EAPI"))->value(), "1");
                 id->perform_action(action);
@@ -178,7 +179,7 @@ namespace test_cases
                 TestMessageSuffix suffix("no src_configure 1", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/src_configure-1",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_EQUAL(simple_visitor_cast<const MetadataValueKey<std::string> >(**id->find_metadata("EAPI"))->value(), "1");
                 id->perform_action(action);
diff --git a/paludis/repositories/e/e_repository_TEST_2.cc b/paludis/repositories/e/e_repository_TEST_2.cc
index 768ff8072..c3484d74c 100644
--- a/paludis/repositories/e/e_repository_TEST_2.cc
+++ b/paludis/repositories/e/e_repository_TEST_2.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2006, 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2006, 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -30,6 +30,7 @@
 #include <paludis/util/map.hh>
 #include <paludis/util/make_named_values.hh>
 #include <paludis/util/set.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/standard_output_manager.hh>
 #include <paludis/util/safe_ifstream.hh>
 #include <paludis/package_id.hh>
@@ -138,7 +139,7 @@ namespace test_cases
                 TestMessageSuffix suffix("econf source 2", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/econf-source-2",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_EQUAL(simple_visitor_cast<const MetadataValueKey<std::string> >(**id->find_metadata("EAPI"))->value(), "2");
                 id->perform_action(action);
@@ -148,7 +149,7 @@ namespace test_cases
                 TestMessageSuffix suffix("doman 2", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/doman-2",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_EQUAL(simple_visitor_cast<const MetadataValueKey<std::string> >(**id->find_metadata("EAPI"))->value(), "2");
                 id->perform_action(action);
@@ -158,7 +159,7 @@ namespace test_cases
                 TestMessageSuffix suffix("src_prepare 2", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/src_prepare-2",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_EQUAL(simple_visitor_cast<const MetadataValueKey<std::string> >(**id->find_metadata("EAPI"))->value(), "2");
                 TEST_CHECK_THROWS(id->perform_action(action), ActionFailedError);
@@ -168,7 +169,7 @@ namespace test_cases
                 TestMessageSuffix suffix("src_configure 2", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/src_configure-2",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_EQUAL(simple_visitor_cast<const MetadataValueKey<std::string> >(**id->find_metadata("EAPI"))->value(), "2");
                 TEST_CHECK_THROWS(id->perform_action(action), ActionFailedError);
@@ -178,7 +179,7 @@ namespace test_cases
                 TestMessageSuffix suffix("default src_configure 2", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/default-src_configure-2",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_EQUAL(simple_visitor_cast<const MetadataValueKey<std::string> >(**id->find_metadata("EAPI"))->value(), "2");
                 id->perform_action(action);
@@ -188,7 +189,7 @@ namespace test_cases
                 TestMessageSuffix suffix("default src_compile 2", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/default-src_compile-2",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_EQUAL(simple_visitor_cast<const MetadataValueKey<std::string> >(**id->find_metadata("EAPI"))->value(), "2");
                 id->perform_action(action);
@@ -198,7 +199,7 @@ namespace test_cases
                 TestMessageSuffix suffix("default_src_compile 2", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/default_src_compile-2",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_EQUAL(simple_visitor_cast<const MetadataValueKey<std::string> >(**id->find_metadata("EAPI"))->value(), "2");
                 id->perform_action(action);
@@ -208,7 +209,7 @@ namespace test_cases
                 TestMessageSuffix suffix("src_compile via default function 2", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/src_compile-via-default-func-2",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_EQUAL(simple_visitor_cast<const MetadataValueKey<std::string> >(**id->find_metadata("EAPI"))->value(), "2");
                 id->perform_action(action);
diff --git a/paludis/repositories/e/e_repository_TEST_3.cc b/paludis/repositories/e/e_repository_TEST_3.cc
index 46942563e..aae03fe74 100644
--- a/paludis/repositories/e/e_repository_TEST_3.cc
+++ b/paludis/repositories/e/e_repository_TEST_3.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2006, 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2006, 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -30,6 +30,7 @@
 #include <paludis/util/map.hh>
 #include <paludis/util/make_named_values.hh>
 #include <paludis/util/set.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/standard_output_manager.hh>
 #include <paludis/util/safe_ifstream.hh>
 #include <paludis/package_id.hh>
@@ -138,7 +139,7 @@ namespace test_cases
                 TestMessageSuffix suffix("prefix", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/prefix-3",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_EQUAL(simple_visitor_cast<const MetadataValueKey<std::string> >(**id->find_metadata("EAPI"))->value(), "3");
                 id->perform_action(action);
diff --git a/paludis/repositories/e/e_repository_TEST_4.cc b/paludis/repositories/e/e_repository_TEST_4.cc
index b720681a3..4606a4379 100644
--- a/paludis/repositories/e/e_repository_TEST_4.cc
+++ b/paludis/repositories/e/e_repository_TEST_4.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2006, 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2006, 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -31,6 +31,7 @@
 #include <paludis/util/map.hh>
 #include <paludis/util/make_named_values.hh>
 #include <paludis/util/set.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/standard_output_manager.hh>
 #include <paludis/util/safe_ifstream.hh>
 #include <paludis/package_id.hh>
@@ -145,7 +146,7 @@ namespace test_cases
                 TestMessageSuffix suffix("pkg_pretend", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/pkg_pretend-4",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_EQUAL(simple_visitor_cast<const MetadataValueKey<std::string> >(**id->find_metadata("EAPI"))->value(), "4");
                 id->perform_action(pretend_action);
@@ -156,7 +157,7 @@ namespace test_cases
                 TestMessageSuffix suffix("pkg_pretend-failure", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/pkg_pretend-failure-4",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_EQUAL(simple_visitor_cast<const MetadataValueKey<std::string> >(**id->find_metadata("EAPI"))->value(), "4");
                 id->perform_action(pretend_action);
@@ -167,7 +168,7 @@ namespace test_cases
                 TestMessageSuffix suffix("default_src_install 4", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/default_src_install-4",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_EQUAL(simple_visitor_cast<const MetadataValueKey<std::string> >(**id->find_metadata("EAPI"))->value(), "4");
                 id->perform_action(action);
@@ -177,7 +178,7 @@ namespace test_cases
                 TestMessageSuffix suffix("docompress 4", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/docompress-4",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_EQUAL(simple_visitor_cast<const MetadataValueKey<std::string> >(**id->find_metadata("EAPI"))->value(), "4");
                 id->perform_action(action);
@@ -187,7 +188,7 @@ namespace test_cases
                 TestMessageSuffix suffix("dodoc -r", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/dodoc-r-4",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_EQUAL(simple_visitor_cast<const MetadataValueKey<std::string> >(**id->find_metadata("EAPI"))->value(), "4");
                 id->perform_action(action);
@@ -197,7 +198,7 @@ namespace test_cases
                 TestMessageSuffix suffix("doins symlink", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/doins-symlink-4",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_EQUAL(simple_visitor_cast<const MetadataValueKey<std::string> >(**id->find_metadata("EAPI"))->value(), "4");
                 id->perform_action(action);
@@ -207,7 +208,7 @@ namespace test_cases
                 TestMessageSuffix suffix("banned functions 4", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/banned-functions-4",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_EQUAL(simple_visitor_cast<const MetadataValueKey<std::string> >(**id->find_metadata("EAPI"))->value(), "4");
                 TEST_CHECK_THROWS(id->perform_action(action), ActionFailedError);
@@ -217,7 +218,7 @@ namespace test_cases
                 TestMessageSuffix suffix("econf disable dependency tracking", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/econf-disable-dependency-tracking-4",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_EQUAL(simple_visitor_cast<const MetadataValueKey<std::string> >(**id->find_metadata("EAPI"))->value(), "4");
                 id->perform_action(action);
@@ -227,7 +228,7 @@ namespace test_cases
                 TestMessageSuffix suffix("global scope use", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/global-scope-use-4",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_EQUAL(simple_visitor_cast<const MetadataValueKey<std::string> >(**id->find_metadata("EAPI"))->value(), "4");
                 id->perform_action(action);
@@ -237,7 +238,7 @@ namespace test_cases
                 TestMessageSuffix suffix("doman 4", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/doman-4",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_EQUAL(simple_visitor_cast<const MetadataValueKey<std::string> >(**id->find_metadata("EAPI"))->value(), "4");
                 id->perform_action(action);
@@ -303,7 +304,7 @@ namespace test_cases
                 TestMessageSuffix suffix("merge type source", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/merge-type-4::test-repo",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_EQUAL(simple_visitor_cast<const MetadataValueKey<std::string> >(**id->find_metadata("EAPI"))->value(), "4");
                 id->perform_action(action);
@@ -390,7 +391,7 @@ namespace test_cases
                 TestMessageSuffix suffix("merge type buildonly", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/merge-type-bin-4::test-repo",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_EQUAL(simple_visitor_cast<const MetadataValueKey<std::string> >(**id->find_metadata("EAPI"))->value(), "4");
                 id->perform_action(action);
@@ -409,7 +410,7 @@ namespace test_cases
                 TestMessageSuffix suffix("merge type binary", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/merge-type-bin-4::binrepo",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_EQUAL(simple_visitor_cast<const MetadataValueKey<std::string> >(**id->find_metadata("EAPI"))->value(), "pbin-1+4");
                 id->perform_action(action);
@@ -472,7 +473,7 @@ namespace test_cases
                 TestMessageSuffix suffix("all good", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/required-use-all-good-4::test-repo",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_EQUAL(simple_visitor_cast<const MetadataValueKey<std::string> >(**id->find_metadata("EAPI"))->value(), "4");
                 id->perform_action(pretend_action);
@@ -489,7 +490,7 @@ namespace test_cases
                 TestMessageSuffix suffix("all empty", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/required-use-all-empty-4::test-repo",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_EQUAL(simple_visitor_cast<const MetadataValueKey<std::string> >(**id->find_metadata("EAPI"))->value(), "4");
                 id->perform_action(pretend_action);
@@ -506,7 +507,7 @@ namespace test_cases
                 TestMessageSuffix suffix("all one not good", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/required-use-all-one-not-good-4::test-repo",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_EQUAL(simple_visitor_cast<const MetadataValueKey<std::string> >(**id->find_metadata("EAPI"))->value(), "4");
                 id->perform_action(pretend_action);
@@ -523,7 +524,7 @@ namespace test_cases
                 TestMessageSuffix suffix("any good", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/required-use-any-good-4::test-repo",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_EQUAL(simple_visitor_cast<const MetadataValueKey<std::string> >(**id->find_metadata("EAPI"))->value(), "4");
                 id->perform_action(pretend_action);
@@ -540,7 +541,7 @@ namespace test_cases
                 TestMessageSuffix suffix("any empty", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/required-use-any-empty-4::test-repo",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_EQUAL(simple_visitor_cast<const MetadataValueKey<std::string> >(**id->find_metadata("EAPI"))->value(), "4");
                 id->perform_action(pretend_action);
@@ -557,7 +558,7 @@ namespace test_cases
                 TestMessageSuffix suffix("any none", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/required-use-any-none-4::test-repo",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_EQUAL(simple_visitor_cast<const MetadataValueKey<std::string> >(**id->find_metadata("EAPI"))->value(), "4");
                 id->perform_action(pretend_action);
@@ -574,7 +575,7 @@ namespace test_cases
                 TestMessageSuffix suffix("one none", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/required-use-one-none-4::test-repo",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_EQUAL(simple_visitor_cast<const MetadataValueKey<std::string> >(**id->find_metadata("EAPI"))->value(), "4");
                 id->perform_action(pretend_action);
@@ -591,7 +592,7 @@ namespace test_cases
                 TestMessageSuffix suffix("one none", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/required-use-one-none-4::test-repo",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_EQUAL(simple_visitor_cast<const MetadataValueKey<std::string> >(**id->find_metadata("EAPI"))->value(), "4");
                 id->perform_action(pretend_action);
@@ -608,7 +609,7 @@ namespace test_cases
                 TestMessageSuffix suffix("one good", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/required-use-one-good-4::test-repo",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_EQUAL(simple_visitor_cast<const MetadataValueKey<std::string> >(**id->find_metadata("EAPI"))->value(), "4");
                 id->perform_action(pretend_action);
diff --git a/paludis/repositories/e/e_repository_TEST_dependencies_rewriter.cc b/paludis/repositories/e/e_repository_TEST_dependencies_rewriter.cc
index b07f79ef9..5fd479cde 100644
--- a/paludis/repositories/e/e_repository_TEST_dependencies_rewriter.cc
+++ b/paludis/repositories/e/e_repository_TEST_dependencies_rewriter.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2006, 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2006, 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -31,6 +31,7 @@
 #include <paludis/util/map.hh>
 #include <paludis/util/make_named_values.hh>
 #include <paludis/util/set.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/standard_output_manager.hh>
 #include <paludis/util/safe_ifstream.hh>
 #include <paludis/package_id.hh>
@@ -106,7 +107,7 @@ namespace test_cases
 
             const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("category/package",
-                                    &env, { })), { }))]->last());
+                                    &env, { })), make_null_shared_ptr(), { }))]->last());
 
             UnformattedPrettyPrinter ff;
 
diff --git a/paludis/repositories/e/e_repository_TEST_ever.cc b/paludis/repositories/e/e_repository_TEST_ever.cc
index 1d0f418ee..40711ced3 100644
--- a/paludis/repositories/e/e_repository_TEST_ever.cc
+++ b/paludis/repositories/e/e_repository_TEST_ever.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -30,6 +30,7 @@
 #include <paludis/util/map.hh>
 #include <paludis/util/make_named_values.hh>
 #include <paludis/util/set.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/output_manager.hh>
 #include <paludis/standard_output_manager.hh>
 #include <paludis/package_id.hh>
@@ -158,7 +159,7 @@ namespace
 
             const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("cat/" + test,
-                                    &env, { })), { }))]->last());
+                                    &env, { })), make_null_shared_ptr(), { }))]->last());
             TEST_CHECK(bool(id));
             id->perform_action(action);
         }
diff --git a/paludis/repositories/e/e_repository_TEST_exheres_0.cc b/paludis/repositories/e/e_repository_TEST_exheres_0.cc
index 8025b46ed..0772d3b4d 100644
--- a/paludis/repositories/e/e_repository_TEST_exheres_0.cc
+++ b/paludis/repositories/e/e_repository_TEST_exheres_0.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2006, 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2006, 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -30,6 +30,7 @@
 #include <paludis/util/map.hh>
 #include <paludis/util/make_named_values.hh>
 #include <paludis/util/set.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/standard_output_manager.hh>
 #include <paludis/util/safe_ifstream.hh>
 #include <paludis/package_id.hh>
@@ -157,7 +158,7 @@ namespace test_cases
                 TestMessageSuffix suffix("in-ebuild die", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/in-ebuild-die",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_THROWS(id->perform_action(action), ActionFailedError);
             }
@@ -166,7 +167,7 @@ namespace test_cases
                 TestMessageSuffix suffix("in-subshell die", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/in-subshell-die",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_THROWS(id->perform_action(action), ActionFailedError);
             }
@@ -175,7 +176,7 @@ namespace test_cases
                 TestMessageSuffix suffix("success", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/success",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 id->perform_action(action);
             }
@@ -184,7 +185,7 @@ namespace test_cases
                 TestMessageSuffix suffix("expatch success", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/expatch-success",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 id->perform_action(action);
             }
@@ -193,7 +194,7 @@ namespace test_cases
                 TestMessageSuffix suffix("expatch success-dir", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/expatch-success-dir",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 id->perform_action(action);
             }
@@ -202,7 +203,7 @@ namespace test_cases
                 TestMessageSuffix suffix("expatch die", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/expatch-die",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_THROWS(id->perform_action(action), ActionFailedError);
             }
@@ -211,7 +212,7 @@ namespace test_cases
                 TestMessageSuffix suffix("expatch unrecognised", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/expatch-unrecognised",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 id->perform_action(action);
             }
@@ -220,7 +221,7 @@ namespace test_cases
                 TestMessageSuffix suffix("nonfatal expatch fail", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/nonfatal-expatch-fail",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 id->perform_action(action);
             }
@@ -229,7 +230,7 @@ namespace test_cases
                 TestMessageSuffix suffix("nonfatal expatch die", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/nonfatal-expatch-die",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_THROWS(id->perform_action(action), ActionFailedError);
             }
@@ -238,7 +239,7 @@ namespace test_cases
                 TestMessageSuffix suffix("unpack die", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/unpack-die",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_THROWS(id->perform_action(action), ActionFailedError);
             }
@@ -247,7 +248,7 @@ namespace test_cases
                 TestMessageSuffix suffix("nonfatal unpack fail", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/nonfatal-unpack-fail",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 id->perform_action(action);
             }
@@ -256,7 +257,7 @@ namespace test_cases
                 TestMessageSuffix suffix("nonfatal unpack die", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/nonfatal-unpack-die",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_THROWS(id->perform_action(action), ActionFailedError);
             }
@@ -265,7 +266,7 @@ namespace test_cases
                 TestMessageSuffix suffix("econf fail", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/econf-fail",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_THROWS(id->perform_action(action), ActionFailedError);
             }
@@ -274,7 +275,7 @@ namespace test_cases
                 TestMessageSuffix suffix("nonfatal econf", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/nonfatal-econf",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 id->perform_action(action);
             }
@@ -283,7 +284,7 @@ namespace test_cases
                 TestMessageSuffix suffix("nonfatal econf die", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/nonfatal-econf-die",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_THROWS(id->perform_action(action), ActionFailedError);
             }
@@ -292,7 +293,7 @@ namespace test_cases
                 TestMessageSuffix suffix("emake fail", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/emake-fail",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_THROWS(id->perform_action(action), ActionFailedError);
             }
@@ -301,7 +302,7 @@ namespace test_cases
                 TestMessageSuffix suffix("nonfatal emake", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/nonfatal-emake",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 id->perform_action(action);
             }
@@ -310,7 +311,7 @@ namespace test_cases
                 TestMessageSuffix suffix("nonfatal emake die", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/nonfatal-emake-die",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_THROWS(id->perform_action(action), ActionFailedError);
             }
@@ -319,7 +320,7 @@ namespace test_cases
                 TestMessageSuffix suffix("einstall fail", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/einstall-fail",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_THROWS(id->perform_action(action), ActionFailedError);
             }
@@ -328,7 +329,7 @@ namespace test_cases
                 TestMessageSuffix suffix("nonfatal einstall", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/nonfatal-einstall",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 id->perform_action(action);
             }
@@ -337,7 +338,7 @@ namespace test_cases
                 TestMessageSuffix suffix("nonfatal einstall die", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/nonfatal-einstall-die",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_THROWS(id->perform_action(action), ActionFailedError);
             }
@@ -346,7 +347,7 @@ namespace test_cases
                 TestMessageSuffix suffix("keepdir success", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/keepdir-success",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 id->perform_action(action);
             }
@@ -355,7 +356,7 @@ namespace test_cases
                 TestMessageSuffix suffix("keepdir fail", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/keepdir-fail",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_THROWS(id->perform_action(action), ActionFailedError);
             }
@@ -364,7 +365,7 @@ namespace test_cases
                 TestMessageSuffix suffix("nonfatal keepdir", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/nonfatal-keepdir",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 id->perform_action(action);
             }
@@ -373,7 +374,7 @@ namespace test_cases
                 TestMessageSuffix suffix("nonfatal keepdir die", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/nonfatal-keepdir-die",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_THROWS(id->perform_action(action), ActionFailedError);
             }
@@ -382,7 +383,7 @@ namespace test_cases
                 TestMessageSuffix suffix("dobin success", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/dobin-success",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 id->perform_action(action);
             }
@@ -391,7 +392,7 @@ namespace test_cases
                 TestMessageSuffix suffix("dobin fail", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/dobin-fail",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_THROWS(id->perform_action(action), ActionFailedError);
             }
@@ -400,7 +401,7 @@ namespace test_cases
                 TestMessageSuffix suffix("nonfatal dobin success", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/nonfatal-dobin-success",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 id->perform_action(action);
             }
@@ -409,7 +410,7 @@ namespace test_cases
                 TestMessageSuffix suffix("nonfatal dobin fail", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/nonfatal-dobin-fail",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 id->perform_action(action);
             }
@@ -418,7 +419,7 @@ namespace test_cases
                 TestMessageSuffix suffix("nonfatal dobin die", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/nonfatal-dobin-die",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_THROWS(id->perform_action(action), ActionFailedError);
             }
@@ -427,7 +428,7 @@ namespace test_cases
                 TestMessageSuffix suffix("herebin success", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/herebin-success",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 id->perform_action(action);
             }
@@ -436,7 +437,7 @@ namespace test_cases
                 TestMessageSuffix suffix("herebin fail", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/herebin-fail",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_THROWS(id->perform_action(action), ActionFailedError);
             }
@@ -445,7 +446,7 @@ namespace test_cases
                 TestMessageSuffix suffix("hereconfd success", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/hereconfd-success",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 id->perform_action(action);
             }
@@ -454,7 +455,7 @@ namespace test_cases
                 TestMessageSuffix suffix("hereconfd fail", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/hereconfd-fail",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_THROWS(id->perform_action(action), ActionFailedError);
             }
@@ -463,7 +464,7 @@ namespace test_cases
                 TestMessageSuffix suffix("hereenvd success", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/hereenvd-success",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 id->perform_action(action);
             }
@@ -472,7 +473,7 @@ namespace test_cases
                 TestMessageSuffix suffix("hereenvd fail", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/hereenvd-fail",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_THROWS(id->perform_action(action), ActionFailedError);
             }
@@ -481,7 +482,7 @@ namespace test_cases
                 TestMessageSuffix suffix("hereinitd success", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/hereinitd-success",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 id->perform_action(action);
             }
@@ -490,7 +491,7 @@ namespace test_cases
                 TestMessageSuffix suffix("hereinitd fail", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/hereinitd-fail",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_THROWS(id->perform_action(action), ActionFailedError);
             }
@@ -499,7 +500,7 @@ namespace test_cases
                 TestMessageSuffix suffix("hereins success", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/hereins-success",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 id->perform_action(action);
             }
@@ -508,7 +509,7 @@ namespace test_cases
                 TestMessageSuffix suffix("hereins fail", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/hereins-fail",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_THROWS(id->perform_action(action), ActionFailedError);
             }
@@ -517,7 +518,7 @@ namespace test_cases
                 TestMessageSuffix suffix("heresbin success", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/heresbin-success",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 id->perform_action(action);
             }
@@ -526,7 +527,7 @@ namespace test_cases
                 TestMessageSuffix suffix("heresbin fail", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("cat/heresbin-fail",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_THROWS(id->perform_action(action), ActionFailedError);
             }
@@ -535,7 +536,7 @@ namespace test_cases
                 TestMessageSuffix suffix("best version", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/best-version-0",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 id->perform_action(action);
             }
@@ -544,7 +545,7 @@ namespace test_cases
                 TestMessageSuffix suffix("has version", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/has-version-0",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 id->perform_action(action);
             }
@@ -553,7 +554,7 @@ namespace test_cases
                 TestMessageSuffix suffix("match", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/match-0",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_THROWS(id->perform_action(action), ActionFailedError);
             }
@@ -562,7 +563,7 @@ namespace test_cases
                 TestMessageSuffix suffix("econf phase", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/econf-phase-0",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_THROWS(id->perform_action(action), ActionFailedError);
             }
@@ -571,7 +572,7 @@ namespace test_cases
                 TestMessageSuffix suffix("econf vars", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/econf-vars-0",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 id->perform_action(action);
             }
@@ -580,7 +581,7 @@ namespace test_cases
                 TestMessageSuffix suffix("expand vars", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/expand-vars-0",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 id->perform_action(action);
             }
@@ -589,7 +590,7 @@ namespace test_cases
                 TestMessageSuffix suffix("doman success", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/doman-success-0",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 id->perform_action(action);
             }
@@ -598,7 +599,7 @@ namespace test_cases
                 TestMessageSuffix suffix("doman nofatal", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/doman-nonfatal-0",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 id->perform_action(action);
             }
@@ -607,7 +608,7 @@ namespace test_cases
                 TestMessageSuffix suffix("doman failure", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/doman-failure-0",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_THROWS(id->perform_action(action), ActionFailedError);
             }
@@ -616,7 +617,7 @@ namespace test_cases
                 TestMessageSuffix suffix("change globals", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/change-globals-0",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_THROWS(id->perform_action(action), ActionFailedError);
             }
@@ -625,7 +626,7 @@ namespace test_cases
                 TestMessageSuffix suffix("install", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/install-0",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 id->perform_action(action);
             }
@@ -634,7 +635,7 @@ namespace test_cases
                 TestMessageSuffix suffix("install s", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/install-s-0",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_THROWS(id->perform_action(action), ActionFailedError);
             }
@@ -643,7 +644,7 @@ namespace test_cases
                 TestMessageSuffix suffix("global optionq", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/global-optionq-1",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_THROWS(id->perform_action(action), ActionFailedError);
             }
diff --git a/paludis/repositories/e/e_repository_TEST_exlibs.cc b/paludis/repositories/e/e_repository_TEST_exlibs.cc
index 10ad171cf..1cc63723a 100644
--- a/paludis/repositories/e/e_repository_TEST_exlibs.cc
+++ b/paludis/repositories/e/e_repository_TEST_exlibs.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2008, 2009, 2010, 2011 Ciaran McCreesh
  * Copyright (c) 2009 Bo Ørsted Andresen
  *
  * This file is part of the Paludis package manager. Paludis is free software;
@@ -31,6 +31,7 @@
 #include <paludis/util/map.hh>
 #include <paludis/util/make_named_values.hh>
 #include <paludis/util/set.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/package_id.hh>
 #include <paludis/metadata_key.hh>
 #include <paludis/action.hh>
@@ -152,7 +153,7 @@ namespace
 
             const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("cat/" + test,
-                                    &env, { })), { }))]->last());
+                                    &env, { })), make_null_shared_ptr(), { }))]->last());
             TEST_CHECK(bool(id));
             switch (expected_result)
             {
diff --git a/paludis/repositories/e/e_repository_TEST_pbin.cc b/paludis/repositories/e/e_repository_TEST_pbin.cc
index a940010cf..acd4cf9dc 100644
--- a/paludis/repositories/e/e_repository_TEST_pbin.cc
+++ b/paludis/repositories/e/e_repository_TEST_pbin.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2006, 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2006, 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -31,6 +31,7 @@
 #include <paludis/util/make_named_values.hh>
 #include <paludis/util/set.hh>
 #include <paludis/util/fs_stat.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/standard_output_manager.hh>
 #include <paludis/util/safe_ifstream.hh>
 #include <paludis/package_id.hh>
@@ -169,7 +170,7 @@ namespace test_cases
                 TestMessageSuffix suffix("prefix", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/simple-1",
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_EQUAL(simple_visitor_cast<const MetadataValueKey<std::string> >(**id->find_metadata("EAPI"))->value(), base_eapi);
                 id->perform_action(bin_action);
@@ -190,7 +191,7 @@ namespace test_cases
                 TestMessageSuffix suffix("prefix", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/simple-1::binrepo" + base_eapi,
-                                        &env, { })), { }))]->last());
+                                        &env, { })), make_null_shared_ptr(), { }))]->last());
                 TEST_CHECK(bool(id));
                 TEST_CHECK_EQUAL(simple_visitor_cast<const MetadataValueKey<std::string> >(**id->find_metadata("EAPI"))->value(),
                         "pbin-1+" + base_eapi);
diff --git a/paludis/repositories/e/e_repository_TEST_phases.cc b/paludis/repositories/e/e_repository_TEST_phases.cc
index ef73cbc0b..b8cb0a43f 100644
--- a/paludis/repositories/e/e_repository_TEST_phases.cc
+++ b/paludis/repositories/e/e_repository_TEST_phases.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -30,6 +30,7 @@
 #include <paludis/util/map.hh>
 #include <paludis/util/make_named_values.hh>
 #include <paludis/util/set.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/output_manager.hh>
 #include <paludis/standard_output_manager.hh>
 #include <paludis/package_id.hh>
@@ -168,7 +169,7 @@ namespace
 
             const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("cat/" + test,
-                                    &env, { })), { }))]->last());
+                                    &env, { })), make_null_shared_ptr(), { }))]->last());
             TEST_CHECK(bool(id));
             TEST_CHECK_EQUAL(!! id->choices_key()->value()->find_by_name_with_prefix(
                         ChoiceNameWithPrefix("build_options:expensive_tests")), expect_expensive_test);
diff --git a/paludis/repositories/e/e_repository_TEST_replacing.cc b/paludis/repositories/e/e_repository_TEST_replacing.cc
index e873be448..53b4b12ce 100644
--- a/paludis/repositories/e/e_repository_TEST_replacing.cc
+++ b/paludis/repositories/e/e_repository_TEST_replacing.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -26,6 +26,7 @@
 #include <paludis/util/make_named_values.hh>
 #include <paludis/util/set.hh>
 #include <paludis/util/map.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/package_id.hh>
 #include <paludis/metadata_key.hh>
 #include <paludis/action.hh>
@@ -143,7 +144,7 @@ namespace
 
             const std::shared_ptr<const PackageIDSequence> rlist(env[selection::AllVersionsSorted(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec(replacing, &env, { })),
-                            { }) |
+                            make_null_shared_ptr(), { }) |
                         filter::InstalledAtRoot(env.preferred_root_key()->value()))]);
 
             InstallAction action(make_named_values<InstallActionOptions>(
@@ -156,7 +157,7 @@ namespace
 
             const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("cat/" + test,
-                                    &env, { })), { }) |
+                                    &env, { })), make_null_shared_ptr(), { }) |
                         filter::SupportsAction<InstallAction>())]->last());
             TEST_CHECK(bool(id));
             id->perform_action(action);
diff --git a/paludis/repositories/e/e_repository_TEST_symlink_rewriting.cc b/paludis/repositories/e/e_repository_TEST_symlink_rewriting.cc
index afec5f7c6..e92c754c3 100644
--- a/paludis/repositories/e/e_repository_TEST_symlink_rewriting.cc
+++ b/paludis/repositories/e/e_repository_TEST_symlink_rewriting.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2006, 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2006, 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -32,6 +32,7 @@
 #include <paludis/util/set.hh>
 #include <paludis/standard_output_manager.hh>
 #include <paludis/util/safe_ifstream.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/package_id.hh>
 #include <paludis/metadata_key.hh>
 #include <paludis/action.hh>
@@ -140,7 +141,7 @@ namespace test_cases
 
             const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("cat/pkg",
-                                    &env, { })), { }))]->last());
+                                    &env, { })), make_null_shared_ptr(), { }))]->last());
             TEST_CHECK(bool(id));
 
             id->perform_action(action);
diff --git a/paludis/repositories/e/e_repository_news.cc b/paludis/repositories/e/e_repository_news.cc
index da7df1e91..d37d1fca6 100644
--- a/paludis/repositories/e/e_repository_news.cc
+++ b/paludis/repositories/e/e_repository_news.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2006, 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2006, 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -33,6 +33,7 @@
 #include <paludis/util/fs_path.hh>
 #include <paludis/util/fs_stat.hh>
 #include <paludis/util/fs_iterator.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 
 #include <paludis/environment.hh>
 #include <paludis/distribution.hh>
@@ -177,7 +178,7 @@ ERepositoryNews::update_news() const
                                 generator::Matches(PackageDepSpec(parse_elike_package_dep_spec(*i,
                                             eapi.supported()->package_dep_spec_parse_options(),
                                             eapi.supported()->version_spec_options(),
-                                            std::shared_ptr<const PackageID>())), { }) |
+                                            std::shared_ptr<const PackageID>())), make_null_shared_ptr(), { }) |
                                 filter::InstalledAtRoot(_imp->environment->preferred_root_key()->value()))]->empty())
                         local_show = true;
                 show &= local_show;
diff --git a/paludis/repositories/e/ebuild_flat_metadata_cache_TEST.cc b/paludis/repositories/e/ebuild_flat_metadata_cache_TEST.cc
index 8dd8ab614..7005da784 100644
--- a/paludis/repositories/e/ebuild_flat_metadata_cache_TEST.cc
+++ b/paludis/repositories/e/ebuild_flat_metadata_cache_TEST.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2006, 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2006, 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  * Copyright (c) 2008 David Leverton
  *
  * This file is part of the Paludis package manager. Paludis is free software;
@@ -34,6 +34,7 @@
 #include <paludis/util/safe_ifstream.hh>
 #include <paludis/util/timestamp.hh>
 #include <paludis/util/fs_stat.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <test/test_framework.hh>
 #include <test/test_runner.hh>
 #include <iterator>
@@ -77,7 +78,7 @@ namespace test_cases
 
             std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/flat_list-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id->short_description_key()));
             TEST_CHECK_EQUAL(id->short_description_key()->value(), "the-description-flat_list");
@@ -105,7 +106,7 @@ namespace test_cases
 
             const std::shared_ptr<const PackageID> id1(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/flat_list-stale-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id1->short_description_key()));
             TEST_CHECK_EQUAL(id1->short_description_key()->value(), "The Generated Description flat_list-stale");
@@ -134,7 +135,7 @@ namespace test_cases
 
             const std::shared_ptr<const PackageID> id1(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/flat_list-guessed-eapi-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id1->short_description_key()));
             TEST_CHECK_EQUAL(id1->short_description_key()->value(), "The Generated Description flat_list-guessed-eapi");
@@ -162,7 +163,7 @@ namespace test_cases
 
             std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/flat_list-eclass-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id->short_description_key()));
             TEST_CHECK_EQUAL(id->short_description_key()->value(), "the-description-flat_list-eclass");
@@ -193,7 +194,7 @@ namespace test_cases
 
             const std::shared_ptr<const PackageID> id1(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/flat_list-eclass-stale-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id1->short_description_key()));
             TEST_CHECK_EQUAL(id1->short_description_key()->value(), "The Generated Description flat_list-eclass-stale");
@@ -221,7 +222,7 @@ namespace test_cases
 
             const std::shared_ptr<const PackageID> id1(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/flat_list-eclass-wrong-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id1->short_description_key()));
             TEST_CHECK_EQUAL(id1->short_description_key()->value(), "The Generated Description flat_list-eclass-wrong");
@@ -249,7 +250,7 @@ namespace test_cases
 
             const std::shared_ptr<const PackageID> id1(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/flat_list-eclass-gone-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id1->short_description_key()));
             TEST_CHECK_EQUAL(id1->short_description_key()->value(), "The Generated Description flat_list-eclass-gone");
@@ -277,7 +278,7 @@ namespace test_cases
 
             std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/flat_list-detection-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id->short_description_key()));
             TEST_CHECK_EQUAL(id->short_description_key()->value(), "the-description-flat_list-detection");
@@ -305,7 +306,7 @@ namespace test_cases
 
             std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/flat_hash-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id->short_description_key()));
             TEST_CHECK_EQUAL(id->short_description_key()->value(), "the-description-flat_hash");
@@ -334,7 +335,7 @@ namespace test_cases
 
             const std::shared_ptr<const PackageID> id1(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/flat_hash-guessed-eapi-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id1->short_description_key()));
             TEST_CHECK_EQUAL(id1->short_description_key()->value(), "The Generated Description flat_hash-guessed-eapi");
@@ -362,7 +363,7 @@ namespace test_cases
 
             const std::shared_ptr<const PackageID> id1(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/flat_hash-guessed-eapi-extension-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id1->short_description_key()));
             TEST_CHECK_EQUAL(id1->short_description_key()->value(), "The Generated Description flat_hash-guessed-eapi-extension");
@@ -390,7 +391,7 @@ namespace test_cases
 
             std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/flat_hash-no-guessed-eapi-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id->short_description_key()));
             TEST_CHECK_EQUAL(id->short_description_key()->value(), "the-description-flat_hash-no-guessed-eapi");
@@ -418,7 +419,7 @@ namespace test_cases
 
             std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/flat_hash-empty-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id->short_description_key()));
             TEST_CHECK_EQUAL(id->short_description_key()->value(), "");
@@ -447,7 +448,7 @@ namespace test_cases
 
             const std::shared_ptr<const PackageID> id1(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/flat_hash-stale-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id1->short_description_key()));
             TEST_CHECK_EQUAL(id1->short_description_key()->value(), "The Generated Description flat_hash-stale");
@@ -475,7 +476,7 @@ namespace test_cases
 
             const std::shared_ptr<const PackageID> id1(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/flat_hash-no-mtime-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id1->short_description_key()));
             TEST_CHECK_EQUAL(id1->short_description_key()->value(), "the-description-flat_hash-no-mtime");
@@ -503,7 +504,7 @@ namespace test_cases
 
             const std::shared_ptr<const PackageID> id1(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/flat_hash-no-mtime-stale-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id1->short_description_key()));
             TEST_CHECK_EQUAL(id1->short_description_key()->value(), "The Generated Description flat_hash-no-mtime-stale");
@@ -531,7 +532,7 @@ namespace test_cases
 
             const std::shared_ptr<const PackageID> id1(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/flat_hash-bad-mtime-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id1->short_description_key()));
             TEST_CHECK_EQUAL(id1->short_description_key()->value(), "The Generated Description flat_hash-bad-mtime");
@@ -559,7 +560,7 @@ namespace test_cases
 
             const std::shared_ptr<const PackageID> id1(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/flat_hash-no-eapi-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id1->short_description_key()));
             TEST_CHECK_EQUAL(id1->short_description_key()->value(), "The Generated Description flat_hash-no-eapi");
@@ -587,7 +588,7 @@ namespace test_cases
 
             const std::shared_ptr<const PackageID> id1(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/flat_hash-duplicate-key-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id1->short_description_key()));
             TEST_CHECK_EQUAL(id1->short_description_key()->value(), "The Generated Description flat_hash-duplicate-key");
@@ -615,7 +616,7 @@ namespace test_cases
 
             std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/flat_hash-eclass-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id->short_description_key()));
             TEST_CHECK_EQUAL(id->short_description_key()->value(), "the-description-flat_hash-eclass");
@@ -646,7 +647,7 @@ namespace test_cases
 
             std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/flat_hash-eclass-stale-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id->short_description_key()));
             TEST_CHECK_EQUAL(id->short_description_key()->value(), "The Generated Description flat_hash-eclass-stale");
@@ -674,7 +675,7 @@ namespace test_cases
 
             std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/flat_hash-eclass-wrong-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id->short_description_key()));
             TEST_CHECK_EQUAL(id->short_description_key()->value(), "The Generated Description flat_hash-eclass-wrong");
@@ -701,7 +702,7 @@ namespace test_cases
 
             std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/flat_hash-eclass-gone-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id->short_description_key()));
             TEST_CHECK_EQUAL(id->short_description_key()->value(), "The Generated Description flat_hash-eclass-gone");
@@ -729,7 +730,7 @@ namespace test_cases
 
             std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/flat_hash-full-eclass-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id->short_description_key()));
             TEST_CHECK_EQUAL(id->short_description_key()->value(), "the-description-flat_hash-full-eclass");
@@ -760,7 +761,7 @@ namespace test_cases
 
             std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/flat_hash-full-eclass-nonstandard-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id->short_description_key()));
             TEST_CHECK_EQUAL(id->short_description_key()->value(), "the-description-flat_hash-full-eclass-nonstandard");
@@ -791,7 +792,7 @@ namespace test_cases
 
             std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/flat_hash-full-eclass-stale-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id->short_description_key()));
             TEST_CHECK_EQUAL(id->short_description_key()->value(), "The Generated Description flat_hash-full-eclass-stale");
@@ -819,7 +820,7 @@ namespace test_cases
 
             std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/flat_hash-full-eclass-wrong-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id->short_description_key()));
             TEST_CHECK_EQUAL(id->short_description_key()->value(), "The Generated Description flat_hash-full-eclass-wrong");
@@ -847,7 +848,7 @@ namespace test_cases
 
             std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/flat_hash-full-eclass-gone-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id->short_description_key()));
             TEST_CHECK_EQUAL(id->short_description_key()->value(), "The Generated Description flat_hash-full-eclass-gone");
@@ -875,14 +876,14 @@ namespace test_cases
 
             std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/flat_hash-eclasses-truncated-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id->short_description_key()));
             TEST_CHECK_EQUAL(id->short_description_key()->value(), "The Generated Description flat_hash-eclasses-truncated");
 
             std::shared_ptr<const PackageID> id2(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/flat_hash-eclasses-truncated-2",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id2->short_description_key()));
             TEST_CHECK_EQUAL(id2->short_description_key()->value(), "The Generated Description flat_hash-eclasses-truncated-2");
@@ -910,7 +911,7 @@ namespace test_cases
 
             std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/flat_hash-eclasses-bad-mtime-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id->short_description_key()));
             TEST_CHECK_EQUAL(id->short_description_key()->value(), "The Generated Description flat_hash-eclasses-bad-mtime");
@@ -938,7 +939,7 @@ namespace test_cases
 
             std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/flat_hash-eclasses-spaces-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id->short_description_key()));
             TEST_CHECK_EQUAL(id->short_description_key()->value(), "The Generated Description flat_hash-eclasses-spaces");
@@ -967,7 +968,7 @@ namespace test_cases
 
             std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/flat_hash-exlib-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id->short_description_key()));
             TEST_CHECK_EQUAL(id->short_description_key()->value(), "the-description-flat_hash-exlib");
@@ -999,7 +1000,7 @@ namespace test_cases
 
             std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/flat_hash-exlib-percat-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id->short_description_key()));
             TEST_CHECK_EQUAL(id->short_description_key()->value(), "the-description-flat_hash-exlib-percat");
@@ -1031,7 +1032,7 @@ namespace test_cases
 
             std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/flat_hash-exlib-stale-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id->short_description_key()));
             TEST_CHECK_EQUAL(id->short_description_key()->value(), "The Generated Description flat_hash-exlib-stale");
@@ -1060,7 +1061,7 @@ namespace test_cases
 
             std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/flat_hash-exlib-wrong-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id->short_description_key()));
             TEST_CHECK_EQUAL(id->short_description_key()->value(), "The Generated Description flat_hash-exlib-wrong");
@@ -1089,7 +1090,7 @@ namespace test_cases
 
             std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/flat_hash-exlib-gone-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id->short_description_key()));
             TEST_CHECK_EQUAL(id->short_description_key()->value(), "The Generated Description flat_hash-exlib-gone");
@@ -1118,14 +1119,14 @@ namespace test_cases
 
             std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/flat_hash-exlibs-truncated-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id->short_description_key()));
             TEST_CHECK_EQUAL(id->short_description_key()->value(), "The Generated Description flat_hash-exlibs-truncated");
 
             std::shared_ptr<const PackageID> id2(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/flat_hash-exlibs-truncated-2",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id2->short_description_key()));
             TEST_CHECK_EQUAL(id2->short_description_key()->value(), "The Generated Description flat_hash-exlibs-truncated-2");
@@ -1154,7 +1155,7 @@ namespace test_cases
 
             std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/flat_hash-exlibs-bad-mtime-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id->short_description_key()));
             TEST_CHECK_EQUAL(id->short_description_key()->value(), "The Generated Description flat_hash-exlibs-bad-mtime");
@@ -1183,7 +1184,7 @@ namespace test_cases
 
             std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/flat_hash-exlibs-spaces-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id->short_description_key()));
             TEST_CHECK_EQUAL(id->short_description_key()->value(), "The Generated Description flat_hash-exlibs-spaces");
@@ -1218,7 +1219,7 @@ namespace test_cases
 
             std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/write-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id->short_description_key()));
             TEST_CHECK_EQUAL(contents("ebuild_flat_metadata_cache_TEST_dir/cache/test-repo/cat/write-1"), contents("ebuild_flat_metadata_cache_TEST_dir/cache/expected/cat/write-1"));
@@ -1254,7 +1255,7 @@ namespace test_cases
 
             std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/write-eapi1-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id->short_description_key()));
             TEST_CHECK_EQUAL(contents("ebuild_flat_metadata_cache_TEST_dir/cache/test-repo/cat/write-eapi1-1"), contents("ebuild_flat_metadata_cache_TEST_dir/cache/expected/cat/write-eapi1-1"));
@@ -1292,7 +1293,7 @@ namespace test_cases
 
             std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/write-eclasses-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id->short_description_key()));
             TEST_CHECK_EQUAL(contents("ebuild_flat_metadata_cache_TEST_dir/cache/test-repo/cat/write-eclasses-1"), contents("ebuild_flat_metadata_cache_TEST_dir/cache/expected/cat/write-eclasses-1"));
@@ -1329,7 +1330,7 @@ namespace test_cases
 
             std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat/write-exlibs-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(id->short_description_key()));
             TEST_CHECK_EQUAL(contents("ebuild_flat_metadata_cache_TEST_dir/cache/test-repo/cat/write-exlibs-1"), contents("ebuild_flat_metadata_cache_TEST_dir/cache/expected/cat/write-exlibs-1"));
diff --git a/paludis/repositories/e/exheres_profile.cc b/paludis/repositories/e/exheres_profile.cc
index 9020e62e5..beae1cc51 100644
--- a/paludis/repositories/e/exheres_profile.cc
+++ b/paludis/repositories/e/exheres_profile.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2005, 2006, 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2005, 2006, 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -367,7 +367,7 @@ ExheresProfile::profile_masked(const std::shared_ptr<const PackageID> & id) cons
     {
         for (std::list<std::pair<std::shared_ptr<const PackageDepSpec>, std::shared_ptr<const RepositoryMaskInfo> > >::const_iterator k(rr->second.begin()),
                 k_end(rr->second.end()) ; k != k_end ; ++k)
-            if (match_package(*_imp->env, *k->first, id, { }))
+            if (match_package(*_imp->env, *k->first, id, make_null_shared_ptr(), { }))
                 return k->second;
     }
 
diff --git a/paludis/repositories/e/exndbam_repository_TEST.cc b/paludis/repositories/e/exndbam_repository_TEST.cc
index ed804688a..c48ff4d27 100644
--- a/paludis/repositories/e/exndbam_repository_TEST.cc
+++ b/paludis/repositories/e/exndbam_repository_TEST.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -26,6 +26,7 @@
 #include <paludis/util/make_named_values.hh>
 #include <paludis/util/sequence.hh>
 #include <paludis/util/fs_path.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/standard_output_manager.hh>
 #include <paludis/action.hh>
 #include <paludis/filtered_generator.hh>
@@ -109,7 +110,7 @@ namespace test_cases
             if (! victim.empty())
                 replacing->push_back(*env[selection::RequireExactlyOne(generator::Matches(
                         PackageDepSpec(parse_user_package_dep_spec(victim,
-                                &env, { })), { }))]->begin());
+                                &env, { })), make_null_shared_ptr(), { }))]->begin());
             InstallAction install_action(make_named_values<InstallActionOptions>(
                         n::destination() = exndbam_repo,
                         n::make_output_manager() = &make_standard_output_manager,
@@ -119,7 +120,7 @@ namespace test_cases
                     ));
             (*env[selection::RequireExactlyOne(generator::Matches(
                         PackageDepSpec(parse_user_package_dep_spec(chosen_one,
-                                &env, { })), { }))]->begin())->perform_action(install_action);
+                                &env, { })), make_null_shared_ptr(), { }))]->begin())->perform_action(install_action);
         }
 
         void run()
diff --git a/paludis/repositories/e/fetch_visitor_TEST.cc b/paludis/repositories/e/fetch_visitor_TEST.cc
index 4c9d523f7..cc3d7f33a 100644
--- a/paludis/repositories/e/fetch_visitor_TEST.cc
+++ b/paludis/repositories/e/fetch_visitor_TEST.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -26,6 +26,7 @@
 #include <paludis/util/sequence.hh>
 #include <paludis/util/make_named_values.hh>
 #include <paludis/util/fs_stat.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/standard_output_manager.hh>
 #include <paludis/util/safe_ifstream.hh>
 #include <paludis/package_database.hh>
@@ -78,7 +79,7 @@ namespace test_cases
             const std::shared_ptr<const EAPI> eapi(EAPIData::get_instance()->eapi_from_string("exheres-0"));
             FetchVisitor v(&env, *env[selection::RequireExactlyOne(
                         generator::Matches(parse_user_package_dep_spec("=cat/pkg-1",
-                                &env, { }), { }))]->begin(),
+                                &env, { }), make_null_shared_ptr(), { }))]->begin(),
                     *eapi, FSPath("fetch_visitor_TEST_dir/out"),
                     false, false, "test", std::make_shared<URIListedThenMirrorsLabel>("listed-then-mirrors"), false,
                     std::make_shared<StandardOutputManager>(), get_mirrors_fn);
diff --git a/paludis/repositories/e/fix_locked_dependencies.cc b/paludis/repositories/e/fix_locked_dependencies.cc
index e6dc55358..a17a5d51a 100644
--- a/paludis/repositories/e/fix_locked_dependencies.cc
+++ b/paludis/repositories/e/fix_locked_dependencies.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -108,7 +108,7 @@ namespace
                     break;
 
                 std::shared_ptr<const PackageIDSequence> matches((*env)[selection::AllVersionsSorted(
-                            generator::Matches(*node.spec(), { }) | filter::InstalledAtRoot(env->system_root_key()->value()))]);
+                            generator::Matches(*node.spec(), id, { }) | filter::InstalledAtRoot(env->system_root_key()->value()))]);
                 if (matches->empty())
                     break;
 
diff --git a/paludis/repositories/e/info_metadata_key.cc b/paludis/repositories/e/info_metadata_key.cc
index a14cfbd78..ec16cb699 100644
--- a/paludis/repositories/e/info_metadata_key.cc
+++ b/paludis/repositories/e/info_metadata_key.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -32,6 +32,7 @@
 #include <paludis/util/indirect_iterator-impl.hh>
 #include <paludis/util/join.hh>
 #include <paludis/util/fs_stat.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 
 #include <paludis/literal_metadata_key.hh>
 #include <paludis/selection.hh>
@@ -189,7 +190,7 @@ InfoPkgsMetadataKey::need_keys_added() const
                         generator::Matches(parse_elike_package_dep_spec(i->first,
                                 eapi->supported()->package_dep_spec_parse_options(),
                                 eapi->supported()->version_spec_options(),
-                                std::shared_ptr<const PackageID>()), { }) |
+                                std::shared_ptr<const PackageID>()), make_null_shared_ptr(), { }) |
                         filter::InstalledAtRoot(_imp->env->preferred_root_key()->value()))]);
 
             if (q->empty())
diff --git a/paludis/repositories/e/pipe_command_handler.cc b/paludis/repositories/e/pipe_command_handler.cc
index 0e839ebec..46e9bc8a9 100644
--- a/paludis/repositories/e/pipe_command_handler.cc
+++ b/paludis/repositories/e/pipe_command_handler.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  * Copyright (c) 2009 Ingmar Vanhassel
  *
  * This file is part of the Paludis package manager. Paludis is free software;
@@ -277,7 +277,7 @@ paludis::erepository::pipe_command_handler(const Environment * const environment
                             eapi->supported()->package_dep_spec_parse_options(),
                             eapi->supported()->version_spec_options(), package_id));
                 std::shared_ptr<const PackageIDSequence> entries((*environment)[selection::AllVersionsSorted(
-                            generator::Matches(spec, { }) | root)]);
+                            generator::Matches(spec, package_id, { }) | root)]);
                 if (eapi->supported()->pipe_commands()->rewrite_virtuals() && (! entries->empty()) &&
                         (*entries->last())->virtual_for_key())
                 {
@@ -326,7 +326,7 @@ paludis::erepository::pipe_command_handler(const Environment * const environment
                             eapi->supported()->package_dep_spec_parse_options(),
                             eapi->supported()->version_spec_options(), package_id));
                 std::shared_ptr<const PackageIDSequence> entries((*environment)[selection::SomeArbitraryVersion(
-                            generator::Matches(spec, { }) | root)]);
+                            generator::Matches(spec, package_id, { }) | root)]);
                 if (entries->empty())
                     return "O1;";
                 else
@@ -350,7 +350,7 @@ paludis::erepository::pipe_command_handler(const Environment * const environment
                             eapi->supported()->package_dep_spec_parse_options(),
                             eapi->supported()->version_spec_options(), package_id));
                 std::shared_ptr<const PackageIDSequence> entries((*environment)[selection::AllVersionsSorted(
-                            generator::Matches(spec, { }) | filter::InstalledAtRoot(environment->preferred_root_key()->value()))]);
+                            generator::Matches(spec, package_id, { }) | filter::InstalledAtRoot(environment->preferred_root_key()->value()))]);
                 if (eapi->supported()->pipe_commands()->rewrite_virtuals() && (! entries->empty()))
                 {
                     std::shared_ptr<PackageIDSequence> new_entries(std::make_shared<PackageIDSequence>());
diff --git a/paludis/repositories/e/traditional_profile.cc b/paludis/repositories/e/traditional_profile.cc
index ce8cee8d9..94aecd78c 100644
--- a/paludis/repositories/e/traditional_profile.cc
+++ b/paludis/repositories/e/traditional_profile.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2005, 2006, 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2005, 2006, 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -43,6 +43,7 @@
 #include <paludis/util/map.hh>
 #include <paludis/util/fs_stat.hh>
 #include <paludis/util/fs_error.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 
 #include <paludis/choice.hh>
 #include <paludis/dep_tag.hh>
@@ -872,7 +873,7 @@ TraditionalProfile::use_masked(
         for (PackageFlagStatusMapList::const_iterator g(i->package_use_mask.begin()),
                 g_end(i->package_use_mask.end()) ; g != g_end ; ++g)
         {
-            if (! match_package(*_imp->env, *g->first, id, { }))
+            if (! match_package(*_imp->env, *g->first, id, make_null_shared_ptr(), { }))
                 continue;
 
             FlagStatusMap::const_iterator h(g->second.find(value_prefixed));
@@ -908,7 +909,7 @@ TraditionalProfile::use_forced(
         for (PackageFlagStatusMapList::const_iterator g(i->package_use_force.begin()),
                 g_end(i->package_use_force.end()) ; g != g_end ; ++g)
         {
-            if (! match_package(*_imp->env, *g->first, id, { }))
+            if (! match_package(*_imp->env, *g->first, id, make_null_shared_ptr(), { }))
                 continue;
 
             FlagStatusMap::const_iterator h(g->second.find(value_prefixed));
@@ -937,7 +938,7 @@ TraditionalProfile::use_state_ignoring_masks(
         for (PackageFlagStatusMapList::const_iterator g(i->package_use.begin()),
                 g_end(i->package_use.end()) ; g != g_end ; ++g)
         {
-            if (! match_package(*_imp->env, *g->first, id, { }))
+            if (! match_package(*_imp->env, *g->first, id, make_null_shared_ptr(), { }))
                 continue;
 
             FlagStatusMap::const_iterator h(g->second.find(value_prefixed));
@@ -1046,7 +1047,7 @@ TraditionalProfile::profile_masked(const std::shared_ptr<const PackageID> & id)
     {
         for (std::list<std::pair<std::shared_ptr<const PackageDepSpec>, std::shared_ptr<const RepositoryMaskInfo> > >::const_iterator k(rr->second.begin()),
                 k_end(rr->second.end()) ; k != k_end ; ++k)
-            if (match_package(*_imp->env, *k->first, id, { }))
+            if (match_package(*_imp->env, *k->first, id, make_null_shared_ptr(), { }))
                 return k->second;
     }
 
diff --git a/paludis/repositories/e/vdb_repository.cc b/paludis/repositories/e/vdb_repository.cc
index f4901e86a..3318279ef 100644
--- a/paludis/repositories/e/vdb_repository.cc
+++ b/paludis/repositories/e/vdb_repository.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2006, 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2006, 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -1443,7 +1443,7 @@ VDBRepository::perform_updates()
                             SlotName old_slot(tokens.at(2)), new_slot(tokens.at(3));
 
                             const std::shared_ptr<const PackageIDSequence> ids((*_imp->params.environment())[selection::AllVersionsSorted(
-                                        (generator::Matches(old_spec, { }) & generator::InRepository(name())) |
+                                        (generator::Matches(old_spec, make_null_shared_ptr(), { }) & generator::InRepository(name())) |
                                         filter::Slot(old_slot)
                                         )]);
                             if (! ids->empty())
diff --git a/paludis/repositories/e/vdb_repository_TEST.cc b/paludis/repositories/e/vdb_repository_TEST.cc
index a0205b5ec..e28ba6f31 100644
--- a/paludis/repositories/e/vdb_repository_TEST.cc
+++ b/paludis/repositories/e/vdb_repository_TEST.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2006, 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2006, 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -153,7 +153,7 @@ namespace test_cases
 
             std::shared_ptr<const PackageID> e1(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat-one/pkg-one-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(bool(e1->choices_key()));
             TEST_CHECK(bool(e1->choices_key()->value()));
@@ -224,7 +224,7 @@ namespace test_cases
 
             std::shared_ptr<const PackageID> e1(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("=cat-one/pkg-one-1",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
             ContentsGatherer gatherer;
             std::for_each(indirect_iterator(e1->contents_key()->value()->begin()),
                           indirect_iterator(e1->contents_key()->value()->end()),
@@ -278,7 +278,7 @@ namespace test_cases
 
             const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                             PackageDepSpec(parse_user_package_dep_spec("category/package",
-                                    &env, { })), { }))]->begin());
+                                    &env, { })), make_null_shared_ptr(), { }))]->begin());
 
             UnformattedPrettyPrinter ff;
 
@@ -381,7 +381,7 @@ namespace test_cases
                 TestMessageSuffix suffix("install", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/target-" + eapi + "::srcrepo",
-                                        &env, { })), { }))]->begin());
+                                        &env, { })), make_null_shared_ptr(), { }))]->begin());
                 TEST_CHECK(bool(id));
                 id->perform_action(install_action);
             }
@@ -392,7 +392,7 @@ namespace test_cases
                 TestMessageSuffix suffix("reinstall", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/target-" + eapi + "::srcrepo",
-                                        &env, { })), { }))]->begin());
+                                        &env, { })), make_null_shared_ptr(), { }))]->begin());
                 TEST_CHECK(bool(id));
                 id->perform_action(install_action);
             }
@@ -403,7 +403,7 @@ namespace test_cases
                 TestMessageSuffix suffix("info", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/target-" + eapi + "::installed",
-                                        &env, { })), { }))]->begin());
+                                        &env, { })), make_null_shared_ptr(), { }))]->begin());
                 TEST_CHECK(bool(id));
                 id->perform_action(info_action);
             }
@@ -412,7 +412,7 @@ namespace test_cases
                 TestMessageSuffix suffix("config", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/target-" + eapi + "::installed",
-                                        &env, { })), { }))]->begin());
+                                        &env, { })), make_null_shared_ptr(), { }))]->begin());
                 TEST_CHECK(bool(id));
                 id->perform_action(config_action);
             }
@@ -421,7 +421,7 @@ namespace test_cases
                 TestMessageSuffix suffix("uninstall", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/target-" + eapi + "::installed",
-                                        &env, { })), { }))]->begin());
+                                        &env, { })), make_null_shared_ptr(), { }))]->begin());
                 TEST_CHECK(bool(id));
                 id->perform_action(uninstall_action);
             }
@@ -511,7 +511,7 @@ namespace test_cases
                 TestMessageSuffix suffix("vars", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/target-" + eapi + "::srcrepo",
-                                        &env, { })), { }))]->begin());
+                                        &env, { })), make_null_shared_ptr(), { }))]->begin());
                 TEST_CHECK(bool(id));
                 id->perform_action(install_action);
             }
@@ -522,7 +522,7 @@ namespace test_cases
                 TestMessageSuffix suffix("reinstall", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/target-" + eapi + "::srcrepo",
-                                        &env, { })), { }))]->begin());
+                                        &env, { })), make_null_shared_ptr(), { }))]->begin());
                 TEST_CHECK(bool(id));
                 id->perform_action(install_action);
             }
@@ -533,7 +533,7 @@ namespace test_cases
                 TestMessageSuffix suffix("info", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/target-" + eapi + "::installed",
-                                        &env, { })), { }))]->begin());
+                                        &env, { })), make_null_shared_ptr(), { }))]->begin());
                 TEST_CHECK(bool(id));
                 id->perform_action(info_action);
             }
@@ -542,7 +542,7 @@ namespace test_cases
                 TestMessageSuffix suffix("config", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/target-" + eapi + "::installed",
-                                        &env, { })), { }))]->begin());
+                                        &env, { })), make_null_shared_ptr(), { }))]->begin());
                 TEST_CHECK(bool(id));
                 id->perform_action(config_action);
             }
@@ -551,7 +551,7 @@ namespace test_cases
                 TestMessageSuffix suffix("uninstall", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/target-" + eapi + "::installed",
-                                        &env, { })), { }))]->begin());
+                                        &env, { })), make_null_shared_ptr(), { }))]->begin());
                 TEST_CHECK(bool(id));
                 id->perform_action(uninstall_action);
             }
@@ -588,7 +588,7 @@ namespace test_cases
             if (! victim.empty())
                 replacing->push_back(*env[selection::RequireExactlyOne(generator::Matches(
                         PackageDepSpec(parse_user_package_dep_spec(victim,
-                                &env, { })), { }))]->begin());
+                                &env, { })), make_null_shared_ptr(), { }))]->begin());
             InstallAction install_action(make_named_values<InstallActionOptions>(
                         n::destination() = vdb_repo,
                         n::make_output_manager() = &make_standard_output_manager,
@@ -598,7 +598,7 @@ namespace test_cases
                     ));
             (*env[selection::RequireExactlyOne(generator::Matches(
                         PackageDepSpec(parse_user_package_dep_spec(chosen_one,
-                                &env, { })), { }))]->begin())->perform_action(install_action);
+                                &env, { })), make_null_shared_ptr(), { }))]->begin())->perform_action(install_action);
         }
 
         void run()
@@ -710,7 +710,7 @@ namespace test_cases
                 TestMessageSuffix suffix("remove other slot", true);
                 const std::shared_ptr<const PackageID> inst_id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat1/pkg1-2::installed",
-                                        &env, { })), { }))]->begin());
+                                        &env, { })), make_null_shared_ptr(), { }))]->begin());
                 inst_id->perform_action(uninstall_action);
                 vdb_repo->invalidate();
 
@@ -739,7 +739,7 @@ namespace test_cases
                 TestMessageSuffix suffix("remove other package", true);
                 const std::shared_ptr<const PackageID> inst_id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat1/pkg2-1::installed",
-                                        &env, { })), { }))]->begin());
+                                        &env, { })), make_null_shared_ptr(), { }))]->begin());
                 inst_id->perform_action(uninstall_action);
                 vdb_repo->invalidate();
 
@@ -766,7 +766,7 @@ namespace test_cases
                 TestMessageSuffix suffix("remove other category", true);
                 const std::shared_ptr<const PackageID> inst_id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat2/pkg1-1::installed",
-                                        &env, { })), { }))]->begin());
+                                        &env, { })), make_null_shared_ptr(), { }))]->begin());
                 inst_id->perform_action(uninstall_action);
                 vdb_repo->invalidate();
 
@@ -781,7 +781,7 @@ namespace test_cases
                 TestMessageSuffix suffix("uninstall", true);
                 const std::shared_ptr<const PackageID> inst_id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat1/pkg1-1::installed",
-                                        &env, { })), { }))]->begin());
+                                        &env, { })), make_null_shared_ptr(), { }))]->begin());
                 inst_id->perform_action(uninstall_action);
                 vdb_repo->invalidate();
 
@@ -955,7 +955,7 @@ namespace test_cases
             if (! victim.empty())
                 replacing->push_back(*env[selection::RequireExactlyOne(generator::Matches(
                         PackageDepSpec(parse_user_package_dep_spec(victim,
-                                &env, { })), { }))]->begin());
+                                &env, { })), make_null_shared_ptr(), { }))]->begin());
             InstallAction install_action(make_named_values<InstallActionOptions>(
                         n::destination() = vdb_repo,
                         n::make_output_manager() = &make_standard_output_manager,
@@ -965,7 +965,7 @@ namespace test_cases
                     ));
             (*env[selection::RequireExactlyOne(generator::Matches(
                         PackageDepSpec(parse_user_package_dep_spec(chosen_one,
-                                &env, { })), { }))]->begin())->perform_action(install_action);
+                                &env, { })), make_null_shared_ptr(), { }))]->begin())->perform_action(install_action);
         }
 
         void run()
@@ -1085,7 +1085,7 @@ namespace test_cases
                 TestMessageSuffix suffix("remove other slot", true);
                 const std::shared_ptr<const PackageID> inst_id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat1/pkg1-2::installed",
-                                        &env, { })), { }))]->begin());
+                                        &env, { })), make_null_shared_ptr(), { }))]->begin());
                 inst_id->perform_action(uninstall_action);
                 vdb_repo->invalidate();
 
@@ -1104,7 +1104,7 @@ namespace test_cases
                 TestMessageSuffix suffix("remove other package", true);
                 const std::shared_ptr<const PackageID> inst_id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat1/pkg2-1::installed",
-                                        &env, { })), { }))]->begin());
+                                        &env, { })), make_null_shared_ptr(), { }))]->begin());
                 inst_id->perform_action(uninstall_action);
                 vdb_repo->invalidate();
 
@@ -1115,7 +1115,7 @@ namespace test_cases
                 TestMessageSuffix suffix("uninstall", true);
                 const std::shared_ptr<const PackageID> inst_id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat1/pkg1-1::installed",
-                                        &env, { })), { }))]->begin());
+                                        &env, { })), make_null_shared_ptr(), { }))]->begin());
                 inst_id->perform_action(uninstall_action);
                 vdb_repo->invalidate();
 
@@ -1224,7 +1224,7 @@ namespace test_cases
                 TestMessageSuffix suffix("install", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/pkg-1::reinstalltest_src1",
-                                        &env, { })), { }))]->begin());
+                                        &env, { })), make_null_shared_ptr(), { }))]->begin());
                 id->perform_action(install_action);
                 vdb_repo->invalidate();
 
@@ -1236,7 +1236,7 @@ namespace test_cases
                 TestMessageSuffix suffix("reinstall", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/pkg-1::reinstalltest_src1",
-                                        &env, { })), { }))]->begin());
+                                        &env, { })), make_null_shared_ptr(), { }))]->begin());
                 id->perform_action(install_action);
                 vdb_repo->invalidate();
 
@@ -1248,7 +1248,7 @@ namespace test_cases
                 TestMessageSuffix suffix("reinstall equivalent", true);
                 const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(generator::Matches(
                                 PackageDepSpec(parse_user_package_dep_spec("=cat/pkg-1::reinstalltest_src2",
-                                        &env, { })), { }))]->begin());
+                                        &env, { })), make_null_shared_ptr(), { }))]->begin());
                 id->perform_action(install_action);
                 vdb_repo->invalidate();
 
@@ -1281,7 +1281,7 @@ namespace test_cases
             if (! victim.empty())
                 replacing->push_back(*env[selection::RequireExactlyOne(generator::Matches(
                         PackageDepSpec(parse_user_package_dep_spec(victim,
-                                &env, { })), { }))]->begin());
+                                &env, { })), make_null_shared_ptr(), { }))]->begin());
             InstallAction install_action(make_named_values<InstallActionOptions>(
                         n::destination() = vdb_repo,
                         n::make_output_manager() = &make_standard_output_manager,
@@ -1291,7 +1291,7 @@ namespace test_cases
                     ));
             (*env[selection::RequireExactlyOne(generator::Matches(
                         PackageDepSpec(parse_user_package_dep_spec(chosen_one,
-                                &env, { })), { }))]->begin())->perform_action(install_action);
+                                &env, { })), make_null_shared_ptr(), { }))]->begin())->perform_action(install_action);
         }
 
         void run()
diff --git a/paludis/repositories/e/vdb_unmerger_TEST.cc b/paludis/repositories/e/vdb_unmerger_TEST.cc
index 5610f3dbb..c7e96c543 100644
--- a/paludis/repositories/e/vdb_unmerger_TEST.cc
+++ b/paludis/repositories/e/vdb_unmerger_TEST.cc
@@ -26,6 +26,7 @@
 #include <paludis/util/wrapped_forward_iterator.hh>
 #include <paludis/util/sequence.hh>
 #include <paludis/util/fs_stat.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/standard_output_manager.hh>
 #include <paludis/user_dep_spec.hh>
 #include <paludis/package_database.hh>
@@ -129,8 +130,7 @@ namespace
                                 n::ignore() = &ignore_nothing,
                                 n::output_manager() = std::make_shared<StandardOutputManager>(),
                                 n::package_id() = *env[selection::RequireExactlyOne(generator::Matches(
-                                            parse_user_package_dep_spec("cat/" + fix(what), &env, { }),
-                                            { }))]->begin(),
+                                            parse_user_package_dep_spec("cat/" + fix(what), &env, { }), make_null_shared_ptr(), { }))]->begin(),
                                 n::root() = root_dir
                                 ));
 
diff --git a/paludis/repositories/unpackaged/installed_repository_TEST.cc b/paludis/repositories/unpackaged/installed_repository_TEST.cc
index cd83a654b..ff554986f 100644
--- a/paludis/repositories/unpackaged/installed_repository_TEST.cc
+++ b/paludis/repositories/unpackaged/installed_repository_TEST.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -138,7 +138,7 @@ namespace test_cases
 
             const std::shared_ptr<const PackageID> id1(*env[selection::RequireExactlyOne(
                         generator::Matches(parse_user_package_dep_spec("cat-one/foo:0",
-                                &env, { }), { }))]->begin());
+                                &env, { }), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK_EQUAL(id1->version(), VersionSpec("1", { }));
             TEST_CHECK_EQUAL(id1->slot_key()->value(), SlotName("0"));
@@ -156,7 +156,7 @@ namespace test_cases
 
             const std::shared_ptr<const PackageID> id2(*env[selection::RequireExactlyOne(
                         generator::Matches(parse_user_package_dep_spec("cat-one/foo:1",
-                                &env, { }), { }))]->begin());
+                                &env, { }), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK_EQUAL(id2->version(), VersionSpec("2", { }));
             TEST_CHECK_EQUAL(id2->slot_key()->value(), SlotName("1"));
@@ -192,13 +192,13 @@ namespace test_cases
 
             const std::shared_ptr<const PackageID> id1(*env[selection::RequireExactlyOne(
                         generator::Matches(parse_user_package_dep_spec("cat-one/foo:0",
-                                &env, { }), { }))]->begin());
+                                &env, { }), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(! id1->masked());
 
             const std::shared_ptr<const PackageID> id2(*env[selection::RequireExactlyOne(
                         generator::Matches(parse_user_package_dep_spec("cat-one/foo:1",
-                                &env, { }), { }))]->begin());
+                                &env, { }), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(! id2->masked());
         }
@@ -228,7 +228,7 @@ namespace test_cases
 
             const std::shared_ptr<const PackageID> id1(*env[selection::RequireExactlyOne(
                         generator::Matches(parse_user_package_dep_spec("cat-one/foo:1",
-                                &env, { }), { }))]->begin());
+                                &env, { }), make_null_shared_ptr(), { }))]->begin());
 
             TEST_CHECK(! id1->supports_action(SupportsActionTest<InstallAction>()));
             TEST_CHECK(! id1->supports_action(SupportsActionTest<ConfigAction>()));
@@ -320,7 +320,7 @@ namespace test_cases
 
             const std::shared_ptr<const PackageID> id(*env[selection::RequireExactlyOne(
                         generator::Matches(parse_user_package_dep_spec("cat-one/foo:fred",
-                                &env, { }), { }))]->begin());
+                                &env, { }), make_null_shared_ptr(), { }))]->begin());
 
             UninstallAction action(make_named_values<UninstallActionOptions>(
                         n::config_protect() = "",
@@ -585,7 +585,7 @@ namespace test_cases
                         ));
                 (*env[selection::RequireExactlyOne(generator::Matches(
                         parse_user_package_dep_spec("cat/pkg4a",
-                            &env, { }), { }))]->begin())->perform_action(action);
+                            &env, { }), make_null_shared_ptr(), { }))]->begin())->perform_action(action);
 
                 TEST_CHECK(FSPath("installed_repository_TEST_dir/root4/dir").stat().is_directory());
                 TEST_CHECK(! FSPath("installed_repository_TEST_dir/root4/dir/4a").stat().is_regular_file());
@@ -631,7 +631,7 @@ namespace test_cases
                         ));
                 (*env[selection::RequireExactlyOne(generator::Matches(
                         parse_user_package_dep_spec("cat/pkg4b",
-                            &env, { }), { }))]->begin())->perform_action(action);
+                            &env, { }), make_null_shared_ptr(), { }))]->begin())->perform_action(action);
 
                 TEST_CHECK(! FSPath("installed_repository_TEST_dir/root4/dir").stat().is_directory());
 
diff --git a/paludis/repositories/virtuals/virtuals_repository.cc b/paludis/repositories/virtuals/virtuals_repository.cc
index a17dce361..c1af193d1 100644
--- a/paludis/repositories/virtuals/virtuals_repository.cc
+++ b/paludis/repositories/virtuals/virtuals_repository.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2006, 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2006, 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -223,7 +223,7 @@ VirtualsRepository::need_ids() const
             v(_imp->names.begin()), v_end(_imp->names.end()) ; v != v_end ; ++v)
     {
         std::shared_ptr<const PackageIDSequence> matches((*_imp->env)[selection::AllVersionsSorted(
-                    generator::Matches(*v->second, { }) |
+                    generator::Matches(*v->second, make_null_shared_ptr(), { }) |
                     filter::SupportsAction<InstallAction>())]);
 
         if (matches->empty())
diff --git a/paludis/resolver/allowed_to_remove_helper.cc b/paludis/resolver/allowed_to_remove_helper.cc
index 9272e749d..69c16383d 100644
--- a/paludis/resolver/allowed_to_remove_helper.cc
+++ b/paludis/resolver/allowed_to_remove_helper.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2010 Ciaran McCreesh
+ * Copyright (c) 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -23,6 +23,7 @@
 #include <paludis/resolver/resolvent.hh>
 #include <paludis/resolver/resolution.hh>
 #include <paludis/util/pimp-impl.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/dep_spec.hh>
 #include <paludis/package_dep_spec_collection.hh>
 
@@ -38,7 +39,8 @@ namespace paludis
         PackageDepSpecCollection allowed_to_remove_specs;
 
         Imp(const Environment * const e) :
-            env(e)
+            env(e),
+            allowed_to_remove_specs(make_null_shared_ptr())
         {
         }
     };
diff --git a/paludis/resolver/always_via_binary_helper.cc b/paludis/resolver/always_via_binary_helper.cc
index 147b58c93..abe64db6f 100644
--- a/paludis/resolver/always_via_binary_helper.cc
+++ b/paludis/resolver/always_via_binary_helper.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2010 Ciaran McCreesh
+ * Copyright (c) 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -26,6 +26,7 @@
 #include <paludis/resolver/destination_utils.hh>
 #include <paludis/util/pimp-impl.hh>
 #include <paludis/util/simple_visitor_cast.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/dep_spec.hh>
 #include <paludis/package_id.hh>
 #include <paludis/metadata_key.hh>
@@ -43,7 +44,8 @@ namespace paludis
         PackageDepSpecCollection always_via_binary_specs;
 
         Imp(const Environment * const e) :
-            env(e)
+            env(e),
+            always_via_binary_specs(make_null_shared_ptr())
         {
         }
     };
diff --git a/paludis/resolver/can_use_helper.cc b/paludis/resolver/can_use_helper.cc
index af5e1b046..0e4613090 100644
--- a/paludis/resolver/can_use_helper.cc
+++ b/paludis/resolver/can_use_helper.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2010 Ciaran McCreesh
+ * Copyright (c) 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -20,6 +20,7 @@
 #include <paludis/resolver/can_use_helper.hh>
 #include <paludis/util/pimp-impl.hh>
 #include <paludis/util/options.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/dep_spec.hh>
 #include <paludis/package_id.hh>
 #include <paludis/package_dep_spec_collection.hh>
@@ -36,7 +37,8 @@ namespace paludis
         PackageDepSpecCollection cannot_use_specs;
 
         Imp(const Environment * const e) :
-            env(e)
+            env(e),
+            cannot_use_specs(make_null_shared_ptr())
         {
         }
     };
diff --git a/paludis/resolver/collect_depped_upon.cc b/paludis/resolver/collect_depped_upon.cc
index 67e1cf517..fdfd572c7 100644
--- a/paludis/resolver/collect_depped_upon.cc
+++ b/paludis/resolver/collect_depped_upon.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2010 Ciaran McCreesh
+ * Copyright (c) 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -53,6 +53,7 @@ namespace
     const std::shared_ptr<const PackageID> best_eventual(
             const Environment * const env,
             const PackageDepSpec & spec,
+            const std::shared_ptr<const PackageID> & from_id,
             const S_ & seq)
     {
         std::shared_ptr<const PackageID> result;
@@ -61,7 +62,7 @@ namespace
                 i != i_end ; ++i)
         {
             if ((! result) || dependent_checker_id(*i)->version() >= result->version())
-                if (match_package(*env, spec, dependent_checker_id(*i), { }))
+                if (match_package(*env, spec, dependent_checker_id(*i), from_id, { }))
                     result = dependent_checker_id(*i);
         }
 
@@ -108,9 +109,9 @@ namespace
                 if (s.spec()->slot_requirement_ptr() && simple_visitor_cast<const SlotAnyUnlockedRequirement>(
                             *s.spec()->slot_requirement_ptr()))
                 {
-                    auto best_eventual_id(best_eventual(env, *s.spec(), newly_available));
+                    auto best_eventual_id(best_eventual(env, *s.spec(), id, newly_available));
                     if (! best_eventual_id)
-                        best_eventual_id = best_eventual(env, *s.spec(), not_changing_slots);
+                        best_eventual_id = best_eventual(env, *s.spec(), id, not_changing_slots);
                     if (best_eventual_id && best_eventual_id->slot_key())
                     {
                         PartiallyMadePackageDepSpec part_spec(*s.spec());
@@ -119,14 +120,14 @@ namespace
                     }
                 }
 
-                if (! match_package(*env, *spec, dependent_checker_id(*g), { }))
+                if (! match_package(*env, *spec, dependent_checker_id(*g), id, { }))
                     continue;
 
                 bool any(false);
                 for (typename C_::ConstIterator n(newly_available->begin()), n_end(newly_available->end()) ;
                         n != n_end ; ++n)
                 {
-                    if (match_package(*env, *spec, dependent_checker_id(*n), { }))
+                    if (match_package(*env, *spec, dependent_checker_id(*n), id, { }))
                     {
                         any = true;
                         break;
diff --git a/paludis/resolver/collect_provided.cc b/paludis/resolver/collect_provided.cc
index 4fe17d535..a0d0235f8 100644
--- a/paludis/resolver/collect_provided.cc
+++ b/paludis/resolver/collect_provided.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2010 Ciaran McCreesh
+ * Copyright (c) 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -50,7 +50,7 @@ paludis::resolver::collect_provided(
                 v != v_end ; ++v)
         {
             const std::shared_ptr<const PackageIDSequence> virtuals((*env)[selection::AllVersionsUnsorted(
-                        generator::Matches(**v, { }))]);
+                        generator::Matches(**v, id, { }))]);
             std::copy(virtuals->begin(), virtuals->end(), result->inserter());
         }
     }
diff --git a/paludis/resolver/confirm_helper.cc b/paludis/resolver/confirm_helper.cc
index 3a531b58d..f9d646504 100644
--- a/paludis/resolver/confirm_helper.cc
+++ b/paludis/resolver/confirm_helper.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2010 Ciaran McCreesh
+ * Copyright (c) 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -47,6 +47,9 @@ namespace paludis
 
         Imp(const Environment * const e) :
             env(e),
+            permit_downgrade_specs(make_null_shared_ptr()),
+            permit_old_version_specs(make_null_shared_ptr()),
+            allowed_to_break_specs(make_null_shared_ptr()),
             allowed_to_break_system(false)
         {
         }
diff --git a/paludis/resolver/constraint.cc b/paludis/resolver/constraint.cc
index f23e187e8..7d147c870 100644
--- a/paludis/resolver/constraint.cc
+++ b/paludis/resolver/constraint.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -147,6 +147,7 @@ Constraint::serialise(Serialiser & s) const
     s.object("Constraint")
         .member(SerialiserFlags<>(), "destination_type", stringify(destination_type()))
         .member(SerialiserFlags<>(), "force_unable", stringify(force_unable()))
+        .member(SerialiserFlags<serialise::might_be_null>(), "from_id", from_id())
         .member(SerialiserFlags<>(), "nothing_is_fine_too", nothing_is_fine_too())
         .member(SerialiserFlags<serialise::might_be_null>(), "reason", reason())
         .member(SerialiserFlags<>(), "spec", spec())
@@ -155,52 +156,6 @@ Constraint::serialise(Serialiser & s) const
         ;
 }
 
-namespace
-{
-    struct IDFinder
-    {
-        const std::shared_ptr<const PackageID> visit(const DependencyReason & r) const
-        {
-            return r.from_id();
-        }
-
-        const std::shared_ptr<const PackageID> visit(const SetReason &) const
-        {
-            return make_null_shared_ptr();
-        }
-
-        const std::shared_ptr<const PackageID> visit(const LikeOtherDestinationTypeReason &) const
-        {
-            return make_null_shared_ptr();
-        }
-
-        const std::shared_ptr<const PackageID> visit(const PresetReason &) const
-        {
-            return make_null_shared_ptr();
-        }
-
-        const std::shared_ptr<const PackageID> visit(const TargetReason &) const
-        {
-            return make_null_shared_ptr();
-        }
-
-        const std::shared_ptr<const PackageID> visit(const DependentReason &) const
-        {
-            return make_null_shared_ptr();
-        }
-
-        const std::shared_ptr<const PackageID> visit(const ViaBinaryReason &) const
-        {
-            return make_null_shared_ptr();
-        }
-
-        const std::shared_ptr<const PackageID> visit(const WasUsedByReason &) const
-        {
-            return make_null_shared_ptr();
-        }
-    };
-}
-
 const std::shared_ptr<Constraint>
 Constraint::deserialise(Deserialisation & d)
 {
@@ -209,15 +164,15 @@ Constraint::deserialise(Deserialisation & d)
     Deserialisator v(d, "Constraint");
 
     const std::shared_ptr<Reason> reason(v.member<std::shared_ptr<Reason> >("reason"));
-    IDFinder id_finder;
+    const std::shared_ptr<const PackageID> from_id(v.member<std::shared_ptr<const PackageID> >("from_id"));
 
     return std::make_shared<Constraint>(make_named_values<Constraint>(
                     n::destination_type() = destringify<DestinationType>(v.member<std::string>("destination_type")),
                     n::force_unable() = v.member<bool>("force_unable"),
+                    n::from_id() = from_id,
                     n::nothing_is_fine_too() = v.member<bool>("nothing_is_fine_too"),
                     n::reason() = reason,
-                    n::spec() = PackageOrBlockDepSpec::deserialise(*v.find_remove_member("spec"),
-                            reason->accept_returning<std::shared_ptr<const PackageID> >(id_finder)),
+                    n::spec() = PackageOrBlockDepSpec::deserialise(*v.find_remove_member("spec"), from_id),
                     n::untaken() = v.member<bool>("untaken"),
                     n::use_existing() = destringify<UseExisting>(v.member<std::string>("use_existing"))
             ));
diff --git a/paludis/resolver/constraint.hh b/paludis/resolver/constraint.hh
index 0e1aed443..7d27c7cc2 100644
--- a/paludis/resolver/constraint.hh
+++ b/paludis/resolver/constraint.hh
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -37,6 +37,7 @@ namespace paludis
     {
         typedef Name<struct name_destination_type> destination_type;
         typedef Name<struct name_force_unable> force_unable;
+        typedef Name<struct name_from_id> from_id;
         typedef Name<struct name_nothing_is_fine_too> nothing_is_fine_too;
         typedef Name<struct name_reason> reason;
         typedef Name<struct name_spec> spec;
@@ -50,6 +51,7 @@ namespace paludis
         {
             NamedValue<n::destination_type, DestinationType> destination_type;
             NamedValue<n::force_unable, bool> force_unable;
+            NamedValue<n::from_id, std::shared_ptr<const PackageID> > from_id;
             NamedValue<n::nothing_is_fine_too, bool> nothing_is_fine_too;
             NamedValue<n::reason, std::shared_ptr<const Reason> > reason;
             NamedValue<n::spec, PackageOrBlockDepSpec> spec;
diff --git a/paludis/resolver/decider.cc b/paludis/resolver/decider.cc
index 57a6b4b2b..c31d6671e 100644
--- a/paludis/resolver/decider.cc
+++ b/paludis/resolver/decider.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -38,6 +38,7 @@
 #include <paludis/resolver/accumulate_deps_and_provides.hh>
 #include <paludis/resolver/why_changed_choices.hh>
 #include <paludis/resolver/same_slot.hh>
+#include <paludis/resolver/reason_utils.hh>
 #include <paludis/util/exception.hh>
 #include <paludis/util/stringify.hh>
 #include <paludis/util/make_named_values.hh>
@@ -577,6 +578,7 @@ Decider::_make_constraints_from_target(
         result->push_back(std::make_shared<Constraint>(make_named_values<Constraint>(
                             n::destination_type() = resolution->resolvent().destination_type(),
                             n::force_unable() = false,
+                            n::from_id() = make_null_shared_ptr(),
                             n::nothing_is_fine_too() = existing.second,
                             n::reason() = reason,
                             n::spec() = spec,
@@ -606,6 +608,7 @@ Decider::_make_constraints_from_dependency(
         result->push_back(std::make_shared<Constraint>(make_named_values<Constraint>(
                             n::destination_type() = resolution->resolvent().destination_type(),
                             n::force_unable() = false,
+                            n::from_id() = dep.from_id(),
                             n::nothing_is_fine_too() = existing.second,
                             n::reason() = reason,
                             n::spec() = *dep.spec().if_package(),
@@ -638,11 +641,11 @@ Decider::_make_constraints_from_blocker(
             break;
 
         case bk_manual:
-            force_unable = ! _already_met(spec);
+            force_unable = ! _already_met(spec, maybe_from_package_id_from_reason(reason));
             break;
 
         case bk_upgrade_blocked_before:
-            nothing_is_fine_too = ! _already_met(spec);
+            nothing_is_fine_too = ! _already_met(spec, maybe_from_package_id_from_reason(reason));
             break;
 
         case last_bk:
@@ -655,6 +658,7 @@ Decider::_make_constraints_from_blocker(
             result->push_back(std::make_shared<Constraint>(make_named_values<Constraint>(
                                 n::destination_type() = *t,
                                 n::force_unable() = force_unable,
+                                n::from_id() = maybe_from_package_id_from_reason(reason),
                                 n::nothing_is_fine_too() = nothing_is_fine_too,
                                 n::reason() = reason,
                                 n::spec() = spec,
@@ -703,13 +707,13 @@ namespace
             if (constraint.spec().if_package())
             {
                 if (! match_package_with_maybe_changes(*env, *constraint.spec().if_package(),
-                            changed_choices_for_constraint.get(), chosen_id, changed_choices.get(), { }))
+                            changed_choices_for_constraint.get(), chosen_id, constraint.from_id(), changed_choices.get(), { }))
                     return false;
             }
             else
             {
                 if (match_package_with_maybe_changes(*env, constraint.spec().if_block()->blocking(),
-                            changed_choices_for_constraint.get(), chosen_id, changed_choices.get(), { }))
+                            changed_choices_for_constraint.get(), chosen_id, constraint.from_id(), changed_choices.get(), { }))
                     return false;
             }
 
@@ -1177,7 +1181,7 @@ Decider::_add_dependencies_if_necessary(
         }
 
         const std::shared_ptr<DependencyReason> reason(std::make_shared<DependencyReason>(
-                    package_id, changed_choices, our_resolution->resolvent(), *s, _already_met(s->spec())));
+                    package_id, changed_choices, our_resolution->resolvent(), *s, _already_met(s->spec(), package_id)));
 
         /* empty resolvents is always ok for blockers, since blocking on things
          * that don't exist is fine */
@@ -1310,7 +1314,7 @@ Decider::find_any_score(
     if (is_block)
     {
         const std::shared_ptr<const PackageIDSequence> ids((*_imp->env)[selection::BestVersionOnly(
-                    generator::Matches(spec, { mpo_ignore_additional_requirements })
+                    generator::Matches(spec, our_id, { mpo_ignore_additional_requirements })
                         | filter::SupportsAction<InstallAction>() | filter::NotMasked()
                     )]);
         if (ids->empty())
@@ -1320,7 +1324,7 @@ Decider::find_any_score(
     /* next: already installed */
     {
         const std::shared_ptr<const PackageIDSequence> installed_ids((*_imp->env)[selection::BestVersionOnly(
-                    generator::Matches(spec, { }) |
+                    generator::Matches(spec, our_id, { }) |
                     filter::InstalledAtRoot(_imp->env->system_root_key()->value()))]);
         if (! installed_ids->empty() ^ is_block)
             return std::make_pair(acs_already_installed, operator_bias);
@@ -1330,14 +1334,14 @@ Decider::find_any_score(
     if (! is_block && spec.additional_requirements_ptr())
     {
         const std::shared_ptr<const PackageIDSequence> installed_ids((*_imp->env)[selection::BestVersionOnly(
-                    generator::Matches(spec, { mpo_ignore_additional_requirements }) |
+                    generator::Matches(spec, our_id, { mpo_ignore_additional_requirements }) |
                     filter::InstalledAtRoot(_imp->env->system_root_key()->value()))]);
         if (! installed_ids->empty())
             return std::make_pair(acs_wrong_options_installed, operator_bias);
     }
 
     const std::shared_ptr<DependencyReason> reason(std::make_shared<DependencyReason>(
-                our_id, make_null_shared_ptr(), our_resolution->resolvent(), dep, _already_met(dep.spec())));
+                our_id, make_null_shared_ptr(), our_resolution->resolvent(), dep, _already_met(dep.spec(), our_id)));
     const std::shared_ptr<const Resolvents> resolvents(_get_resolvents_for(spec, reason).first);
 
     /* next: will already be installing */
@@ -1374,7 +1378,7 @@ Decider::find_any_score(
     if (is_block)
     {
         const std::shared_ptr<const PackageIDSequence> installed_ids((*_imp->env)[selection::BestVersionOnly(
-                    generator::Matches(spec, { }) |
+                    generator::Matches(spec, our_id, { }) |
                     filter::InstalledAtRoot(_imp->env->system_root_key()->value()))]);
         if (! installed_ids->empty())
             return std::make_pair(acs_blocks_installed, operator_bias);
@@ -1384,7 +1388,7 @@ Decider::find_any_score(
     if (! is_block)
     {
         const std::shared_ptr<const PackageIDSequence> ids((*_imp->env)[selection::BestVersionOnly(
-                    generator::Matches(spec, { mpo_ignore_additional_requirements })
+                    generator::Matches(spec, our_id, { mpo_ignore_additional_requirements })
                     )]);
         if (! ids->empty())
             return std::make_pair(acs_exists, operator_bias);
@@ -1473,7 +1477,7 @@ Decider::_get_resolvents_for(
         exact_slot = spec.slot_requirement_ptr()->accept_returning<std::shared_ptr<SlotName> >(f);
     }
 
-    return _imp->fns.get_resolvents_for_fn()(spec, exact_slot, reason);
+    return _imp->fns.get_resolvents_for_fn()(spec, maybe_from_package_id_from_reason(reason), exact_slot, reason);
 }
 
 const DestinationTypes
@@ -1847,9 +1851,9 @@ Decider::_find_id_for_from(
                 c != c_end ; ++c)
         {
             if ((*c)->spec().if_package())
-                ok = ok && match_package(*_imp->env, *(*c)->spec().if_package(), *i, opts);
+                ok = ok && match_package(*_imp->env, *(*c)->spec().if_package(), *i, (*c)->from_id(), opts);
             else
-                ok = ok && ! match_package(*_imp->env, (*c)->spec().if_block()->blocking(), *i, opts);
+                ok = ok && ! match_package(*_imp->env, (*c)->spec().if_block()->blocking(), *i, (*c)->from_id(), opts);
 
             if (! ok)
                 break;
@@ -1915,10 +1919,10 @@ Decider::_find_id_for_from(
 
                 if ((*c)->spec().if_package())
                     ok = ok && match_package_with_maybe_changes(*_imp->env, *(*c)->spec().if_package(),
-                            get_changed_choices_for(*c).get(), *i, why_changed_choices->changed_choices().get(), { });
+                            get_changed_choices_for(*c).get(), *i, (*c)->from_id(), why_changed_choices->changed_choices().get(), { });
                 else
                     ok = ok && ! match_package_with_maybe_changes(*_imp->env, (*c)->spec().if_block()->blocking(),
-                            get_changed_choices_for(*c).get(), *i, why_changed_choices->changed_choices().get(), { });
+                            get_changed_choices_for(*c).get(), *i, (*c)->from_id(), why_changed_choices->changed_choices().get(), { });
             }
 
             if (ok)
@@ -2113,10 +2117,10 @@ Decider::resolve()
 }
 
 bool
-Decider::_already_met(const PackageOrBlockDepSpec & spec) const
+Decider::_already_met(const PackageOrBlockDepSpec & spec, const std::shared_ptr<const PackageID> & from_id) const
 {
     const std::shared_ptr<const PackageIDSequence> installed_ids((*_imp->env)[selection::AllVersionsUnsorted(
-                generator::Matches(spec.if_package() ?  *spec.if_package() : spec.if_block()->blocking(), { }) |
+                generator::Matches(spec.if_package() ?  *spec.if_package() : spec.if_block()->blocking(), from_id, { }) |
                 filter::InstalledAtRoot(_imp->env->system_root_key()->value()))]);
     if (installed_ids->empty())
         return bool(spec.if_block());
@@ -2386,6 +2390,7 @@ namespace
             result->push_back(make_shared_copy(make_named_values<Constraint>(
                             n::destination_type() = destination_type,
                             n::force_unable() = false,
+                            n::from_id() = from_constraint->from_id(),
                             n::nothing_is_fine_too() = true,
                             n::reason() = std::make_shared<LikeOtherDestinationTypeReason>(
                                     resolvent,
diff --git a/paludis/resolver/decider.hh b/paludis/resolver/decider.hh
index c3f1d9ce4..c040588e6 100644
--- a/paludis/resolver/decider.hh
+++ b/paludis/resolver/decider.hh
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -240,7 +240,9 @@ namespace paludis
                         const std::shared_ptr<const PackageID> &,
                         const bool existing) const;
 
-                bool _already_met(const PackageOrBlockDepSpec &) const PALUDIS_ATTRIBUTE((warn_unused_result));
+                bool _already_met(
+                        const PackageOrBlockDepSpec &,
+                        const std::shared_ptr<const PackageID> &) const PALUDIS_ATTRIBUTE((warn_unused_result));
 
                 bool _installed_but_allowed_to_remove(
                         const std::shared_ptr<const Resolution> &) const PALUDIS_ATTRIBUTE((warn_unused_result));
diff --git a/paludis/resolver/get_constraints_for_dependent_helper.cc b/paludis/resolver/get_constraints_for_dependent_helper.cc
index d27f9a64e..1a5cfc351 100644
--- a/paludis/resolver/get_constraints_for_dependent_helper.cc
+++ b/paludis/resolver/get_constraints_for_dependent_helper.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2010 Ciaran McCreesh
+ * Copyright (c) 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -27,6 +27,7 @@
 #include <paludis/util/simple_visitor_cast.hh>
 #include <paludis/util/make_shared_copy.hh>
 #include <paludis/util/make_named_values.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/util/stringify.hh>
 #include <paludis/dep_spec.hh>
 #include <paludis/package_id.hh>
@@ -47,7 +48,8 @@ namespace paludis
         PackageDepSpecCollection less_restrictive_remove_blockers_specs;
 
         Imp(const Environment * const e) :
-            env(e)
+            env(e),
+            less_restrictive_remove_blockers_specs(make_null_shared_ptr())
         {
         }
     };
@@ -94,6 +96,7 @@ GetConstraintsForDependentHelper::operator() (
         result->push_back(std::make_shared<Constraint>(make_named_values<Constraint>(
                         n::destination_type() = dt_install_to_slash,
                         n::force_unable() = false,
+                        n::from_id() = id,
                         n::nothing_is_fine_too() = true,
                         n::reason() = reason,
                         n::spec() = BlockDepSpec("!" + stringify(*spec), *spec, bk_weak),
diff --git a/paludis/resolver/get_constraints_for_purge_helper.cc b/paludis/resolver/get_constraints_for_purge_helper.cc
index 631a1e423..7c51fdedc 100644
--- a/paludis/resolver/get_constraints_for_purge_helper.cc
+++ b/paludis/resolver/get_constraints_for_purge_helper.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2010 Ciaran McCreesh
+ * Copyright (c) 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -27,6 +27,7 @@
 #include <paludis/util/simple_visitor_cast.hh>
 #include <paludis/util/make_shared_copy.hh>
 #include <paludis/util/make_named_values.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/util/stringify.hh>
 #include <paludis/dep_spec.hh>
 #include <paludis/package_id.hh>
@@ -47,7 +48,8 @@ namespace paludis
         PackageDepSpecCollection purge_specs;
 
         Imp(const Environment * const e) :
-            env(e)
+            env(e),
+            purge_specs(make_null_shared_ptr())
         {
         }
     };
@@ -85,6 +87,7 @@ GetConstraintsForPurgeHelper::operator() (
     result->push_back(std::make_shared<Constraint>(make_named_values<Constraint>(
                     n::destination_type() = dt_install_to_slash,
                     n::force_unable() = false,
+                    n::from_id() = id,
                     n::nothing_is_fine_too() = true,
                     n::reason() = reason,
                     n::spec() = BlockDepSpec("!" + stringify(spec), spec, bk_weak),
diff --git a/paludis/resolver/get_constraints_for_via_binary_helper.cc b/paludis/resolver/get_constraints_for_via_binary_helper.cc
index ee7ea91ff..c8b6f74b6 100644
--- a/paludis/resolver/get_constraints_for_via_binary_helper.cc
+++ b/paludis/resolver/get_constraints_for_via_binary_helper.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2010 Ciaran McCreesh
+ * Copyright (c) 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -28,6 +28,7 @@
 #include <paludis/util/make_shared_copy.hh>
 #include <paludis/util/make_named_values.hh>
 #include <paludis/util/stringify.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/dep_spec.hh>
 #include <paludis/partially_made_package_dep_spec.hh>
 
@@ -71,6 +72,7 @@ GetConstraintsForViaBinaryHelper::operator() (
     result->push_back(std::make_shared<Constraint>(make_named_values<Constraint>(
                     n::destination_type() = resolution->resolvent().destination_type(),
                     n::force_unable() = false,
+                    n::from_id() = make_null_shared_ptr(),
                     n::nothing_is_fine_too() = false,
                     n::reason() = reason,
                     n::spec() = spec,
diff --git a/paludis/resolver/get_initial_constraints_for_helper.cc b/paludis/resolver/get_initial_constraints_for_helper.cc
index 85b154072..a26fd1c7b 100644
--- a/paludis/resolver/get_initial_constraints_for_helper.cc
+++ b/paludis/resolver/get_initial_constraints_for_helper.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2010 Ciaran McCreesh
+ * Copyright (c) 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -87,11 +87,11 @@ GetInitialConstraintsForHelper::add_without_spec(const PackageDepSpec & spec)
 }
 
 void
-GetInitialConstraintsForHelper::add_preset_spec(const PackageDepSpec & spec)
+GetInitialConstraintsForHelper::add_preset_spec(const PackageDepSpec & spec, const std::shared_ptr<const PackageID> & from_id)
 {
     auto reason(std::make_shared<PresetReason>("preset", make_null_shared_ptr()));
 
-    auto ids((*_imp->env)[selection::BestVersionInEachSlot(generator::Matches(spec, { }))]);
+    auto ids((*_imp->env)[selection::BestVersionInEachSlot(generator::Matches(spec, from_id, { }))]);
     for (auto i(ids->begin()), i_end(ids->end()) ;
             i != i_end ; ++i)
         for (EnumIterator<DestinationType> t, t_end(last_dt) ; t != t_end ; ++t)
@@ -101,6 +101,7 @@ GetInitialConstraintsForHelper::add_preset_spec(const PackageDepSpec & spec)
             const std::shared_ptr<Constraint> constraint(std::make_shared<Constraint>(make_named_values<Constraint>(
                             n::destination_type() = r.destination_type(),
                             n::force_unable() = false,
+                            n::from_id() = from_id,
                             n::nothing_is_fine_too() = true,
                             n::reason() = reason,
                             n::spec() = spec,
@@ -234,6 +235,7 @@ GetInitialConstraintsForHelper::_make_initial_constraints_for(
         result->add(std::make_shared<Constraint>(make_named_values<Constraint>(
                         n::destination_type() = resolvent.destination_type(),
                         n::force_unable() = false,
+                        n::from_id() = make_null_shared_ptr(),
                         n::nothing_is_fine_too() = true,
                         n::reason() = std::make_shared<PresetReason>("is scm", make_null_shared_ptr()),
                         n::spec() = make_package_dep_spec({ }).package(resolvent.package()),
diff --git a/paludis/resolver/get_initial_constraints_for_helper.hh b/paludis/resolver/get_initial_constraints_for_helper.hh
index cdc3b3cce..c42f01f15 100644
--- a/paludis/resolver/get_initial_constraints_for_helper.hh
+++ b/paludis/resolver/get_initial_constraints_for_helper.hh
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2010 Ciaran McCreesh
+ * Copyright (c) 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -47,7 +47,7 @@ namespace paludis
 
                 void add_without_spec(const PackageDepSpec &);
 
-                void add_preset_spec(const PackageDepSpec &);
+                void add_preset_spec(const PackageDepSpec &, const std::shared_ptr<const PackageID> & from_id);
 
                 void add_suggested_restart(const SuggestRestart &);
 
diff --git a/paludis/resolver/get_resolvents_for_helper.cc b/paludis/resolver/get_resolvents_for_helper.cc
index 24a6f36c5..02f658deb 100644
--- a/paludis/resolver/get_resolvents_for_helper.cc
+++ b/paludis/resolver/get_resolvents_for_helper.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2010 Ciaran McCreesh
+ * Copyright (c) 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -264,6 +264,7 @@ namespace
 std::pair<std::shared_ptr<Resolvents>, bool>
 GetResolventsForHelper::operator() (
         const PackageDepSpec & spec,
+        const std::shared_ptr<const PackageID> & from_id,
         const std::shared_ptr<const SlotName> & maybe_slot,
         const std::shared_ptr<const Reason> & reason) const
 {
@@ -271,7 +272,7 @@ GetResolventsForHelper::operator() (
     std::shared_ptr<const PackageID> best;
 
     auto ids((*_imp->env)[selection::BestVersionOnly(
-                generator::Matches(spec, { mpo_ignore_additional_requirements }) |
+                generator::Matches(spec, from_id, { mpo_ignore_additional_requirements }) |
                 filter::SupportsAction<InstallAction>() |
                 filter::NotMasked() |
                 (maybe_slot ? Filter(filter::Slot(*maybe_slot)) : Filter(filter::All())))]);
@@ -280,7 +281,7 @@ GetResolventsForHelper::operator() (
         best = *ids->begin();
 
     auto installed_ids((*_imp->env)[selection::BestVersionInEachSlot(
-                generator::Matches(spec, { }) |
+                generator::Matches(spec, from_id, { }) |
                 (_imp->target_destination_type == dt_install_to_chroot ?
                  Filter(filter::InstalledNotAtRoot(_imp->env->system_root_key()->value())) :
                  Filter(filter::InstalledAtRoot(_imp->env->system_root_key()->value()))))]);
diff --git a/paludis/resolver/get_resolvents_for_helper.hh b/paludis/resolver/get_resolvents_for_helper.hh
index 03ebdef11..c310815bf 100644
--- a/paludis/resolver/get_resolvents_for_helper.hh
+++ b/paludis/resolver/get_resolvents_for_helper.hh
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2010 Ciaran McCreesh
+ * Copyright (c) 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -57,6 +57,7 @@ namespace paludis
 
                 std::pair<std::shared_ptr<Resolvents>, bool> operator() (
                         const PackageDepSpec &,
+                        const std::shared_ptr<const PackageID> & from_id,
                         const std::shared_ptr<const SlotName> &,
                         const std::shared_ptr<const Reason> &) const;
         };
diff --git a/paludis/resolver/interest_in_spec_helper.cc b/paludis/resolver/interest_in_spec_helper.cc
index 35f5fc9d1..2427cbe4a 100644
--- a/paludis/resolver/interest_in_spec_helper.cc
+++ b/paludis/resolver/interest_in_spec_helper.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2010 Ciaran McCreesh
+ * Copyright (c) 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -28,6 +28,7 @@
 #include <paludis/util/pimp-impl.hh>
 #include <paludis/util/stringify.hh>
 #include <paludis/util/tribool.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/dep_spec.hh>
 #include <paludis/selection.hh>
 #include <paludis/generator.hh>
@@ -65,6 +66,8 @@ namespace paludis
 
         Imp(const Environment * const e) :
             env(e),
+            no_blockers_from_specs(make_null_shared_ptr()),
+            no_dependencies_from_specs(make_null_shared_ptr()),
             follow_installed_build_dependencies(false),
             follow_installed_dependencies(true),
             take_suggestions(indeterminate),
@@ -201,7 +204,7 @@ namespace
 
                 const std::shared_ptr<const PackageIDSequence> installed_ids(
                         (*env)[selection::SomeArbitraryVersion(
-                            generator::Matches(*dep.spec().if_package(), { }) |
+                            generator::Matches(*dep.spec().if_package(), dep.from_id(), { }) |
                             filter::InstalledAtRoot(env->system_root_key()->value()))]);
                 if (installed_ids->empty())
                     return false;
@@ -271,7 +274,7 @@ InterestInSpecHelper::operator() (
         for (auto l(_imp->take_from_specs.begin()), l_end(_imp->take_from_specs.end()) ;
                 l != l_end ; ++l)
         {
-            if (match_package(*_imp->env, *l, id, { }))
+            if (match_package(*_imp->env, *l, id, make_null_shared_ptr(), { }))
                 return si_take;
         }
 
@@ -300,7 +303,7 @@ InterestInSpecHelper::operator() (
         for (auto l(_imp->ignore_from_specs.begin()), l_end(_imp->ignore_from_specs.end()) ;
                 l != l_end ; ++l)
         {
-            if (match_package(*_imp->env, *l, id, { }))
+            if (match_package(*_imp->env, *l, id, make_null_shared_ptr(), { }))
                 return si_ignore;
         }
 
@@ -328,7 +331,7 @@ InterestInSpecHelper::operator() (
         {
             const std::shared_ptr<const PackageIDSequence> installed_ids(
                     (*_imp->env)[selection::SomeArbitraryVersion(
-                        generator::Matches(*dep.spec().if_package(), { }) |
+                        generator::Matches(*dep.spec().if_package(), dep.from_id(), { }) |
                         filter::InstalledAtRoot(_imp->env->system_root_key()->value()))]);
             if (! installed_ids->empty())
                 return si_take;
diff --git a/paludis/resolver/order_early_helper.cc b/paludis/resolver/order_early_helper.cc
index 2ea967ef0..11af1a767 100644
--- a/paludis/resolver/order_early_helper.cc
+++ b/paludis/resolver/order_early_helper.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2010 Ciaran McCreesh
+ * Copyright (c) 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -24,6 +24,7 @@
 #include <paludis/resolver/decision_utils.hh>
 #include <paludis/util/pimp-impl.hh>
 #include <paludis/util/tribool.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/dep_spec.hh>
 #include <paludis/package_dep_spec_collection.hh>
 
@@ -40,7 +41,9 @@ namespace paludis
         PackageDepSpecCollection late_specs;
 
         Imp(const Environment * const e) :
-            env(e)
+            env(e),
+            early_specs(make_null_shared_ptr()),
+            late_specs(make_null_shared_ptr())
         {
         }
     };
diff --git a/paludis/resolver/reason_utils-fwd.hh b/paludis/resolver/reason_utils-fwd.hh
index 23cf6e593..b616b1e53 100644
--- a/paludis/resolver/reason_utils-fwd.hh
+++ b/paludis/resolver/reason_utils-fwd.hh
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2010 Ciaran McCreesh
+ * Copyright (c) 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -22,6 +22,7 @@
 
 #include <paludis/util/attributes.hh>
 #include <paludis/resolver/reason-fwd.hh>
+#include <paludis/package_id-fwd.hh>
 #include <memory>
 
 namespace paludis
@@ -29,6 +30,9 @@ namespace paludis
     namespace resolver
     {
         bool is_target(const std::shared_ptr<const Reason> &) PALUDIS_VISIBLE PALUDIS_ATTRIBUTE((warn_unused_result));
+
+        const std::shared_ptr<const PackageID> maybe_from_package_id_from_reason(
+                const std::shared_ptr<const Reason> &) PALUDIS_VISIBLE PALUDIS_ATTRIBUTE((warn_unused_result));
     }
 }
 
diff --git a/paludis/resolver/reason_utils.cc b/paludis/resolver/reason_utils.cc
index 063bd7703..724b23c77 100644
--- a/paludis/resolver/reason_utils.cc
+++ b/paludis/resolver/reason_utils.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2010 Ciaran McCreesh
+ * Copyright (c) 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -19,6 +19,7 @@
 
 #include <paludis/resolver/reason_utils.hh>
 #include <paludis/resolver/reason.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 
 using namespace paludis;
 using namespace paludis::resolver;
@@ -67,6 +68,49 @@ namespace
             return r.reason_for_set()->accept_returning<bool>(*this);
         }
     };
+
+    struct FromIDVisitor
+    {
+        std::shared_ptr<const PackageID> visit(const DependencyReason & r) const
+        {
+            return r.from_id();
+        }
+
+        std::shared_ptr<const PackageID> visit(const DependentReason &) const
+        {
+            return make_null_shared_ptr();
+        }
+
+        std::shared_ptr<const PackageID> visit(const WasUsedByReason &) const
+        {
+            return make_null_shared_ptr();
+        }
+
+        std::shared_ptr<const PackageID> visit(const PresetReason &) const
+        {
+            return make_null_shared_ptr();
+        }
+
+        std::shared_ptr<const PackageID> visit(const ViaBinaryReason &) const
+        {
+            return make_null_shared_ptr();
+        }
+
+        std::shared_ptr<const PackageID> visit(const TargetReason &) const
+        {
+            return make_null_shared_ptr();
+        }
+
+        std::shared_ptr<const PackageID> visit(const LikeOtherDestinationTypeReason & r) const
+        {
+            return r.reason_for_other()->accept_returning<std::shared_ptr<const PackageID> >(*this);
+        }
+
+        std::shared_ptr<const PackageID> visit(const SetReason & r) const
+        {
+            return r.reason_for_set()->accept_returning<std::shared_ptr<const PackageID> >(*this);
+        }
+    };
 }
 
 bool
@@ -76,3 +120,10 @@ paludis::resolver::is_target(const std::shared_ptr<const Reason> & reason)
     return reason->accept_returning<bool>(v);
 }
 
+const std::shared_ptr<const PackageID>
+paludis::resolver::maybe_from_package_id_from_reason(const std::shared_ptr<const Reason> & reason)
+{
+    FromIDVisitor v;
+    return reason->accept_returning<std::shared_ptr<const PackageID> >(v);
+}
+
diff --git a/paludis/resolver/remove_if_dependent_helper.cc b/paludis/resolver/remove_if_dependent_helper.cc
index 7a8baa0f9..4e6116d31 100644
--- a/paludis/resolver/remove_if_dependent_helper.cc
+++ b/paludis/resolver/remove_if_dependent_helper.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2010 Ciaran McCreesh
+ * Copyright (c) 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -23,6 +23,7 @@
 #include <paludis/resolver/resolvent.hh>
 #include <paludis/resolver/resolution.hh>
 #include <paludis/util/pimp-impl.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/dep_spec.hh>
 #include <paludis/package_dep_spec_collection.hh>
 
@@ -38,7 +39,8 @@ namespace paludis
         PackageDepSpecCollection remove_if_dependent_specs;
 
         Imp(const Environment * const e) :
-            env(e)
+            env(e),
+            remove_if_dependent_specs(make_null_shared_ptr())
         {
         }
     };
diff --git a/paludis/resolver/resolver_functions.hh b/paludis/resolver/resolver_functions.hh
index 4074599e1..4a286e0ed 100644
--- a/paludis/resolver/resolver_functions.hh
+++ b/paludis/resolver/resolver_functions.hh
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -137,6 +137,7 @@ namespace paludis
 
         typedef std::function<std::pair<std::shared_ptr<Resolvents>, bool> (
                 const PackageDepSpec &,
+                const std::shared_ptr<const PackageID> &,
                 const std::shared_ptr<const SlotName> &,
                 const std::shared_ptr<const Reason> &
                 )> GetResolventsForFunction;
diff --git a/paludis/resolver/sanitised_dependencies.cc b/paludis/resolver/sanitised_dependencies.cc
index 02a8b6f2c..87419b2c4 100644
--- a/paludis/resolver/sanitised_dependencies.cc
+++ b/paludis/resolver/sanitised_dependencies.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -378,6 +378,7 @@ namespace
                     n::active_dependency_labels() = *labels_stack.begin(),
                     n::active_dependency_labels_as_string() = adl.str(),
                     n::active_dependency_labels_classifier() = classifier,
+                    n::from_id() = our_id,
                     n::metadata_key_human_name() = human_name,
                     n::metadata_key_raw_name() = raw_name,
                     n::original_specs_as_string() = original_specs_as_string,
@@ -542,6 +543,7 @@ SanitisedDependency::serialise(Serialiser & s) const
         .member(SerialiserFlags<>(), "active_conditions_as_string", active_conditions_as_string())
         .member(SerialiserFlags<>(), "active_dependency_labels_as_string", active_dependency_labels_as_string())
         .member(SerialiserFlags<serialise::might_be_null>(), "active_dependency_labels_classifier", active_dependency_labels_classifier())
+        .member(SerialiserFlags<serialise::might_be_null>(), "from_id", from_id())
         .member(SerialiserFlags<>(), "metadata_key_human_name", metadata_key_human_name())
         .member(SerialiserFlags<>(), "metadata_key_raw_name", metadata_key_raw_name())
         .member(SerialiserFlags<>(), "original_specs_as_string", original_specs_as_string())
@@ -561,6 +563,7 @@ SanitisedDependency::deserialise(Deserialisation & d, const std::shared_ptr<cons
             n::active_dependency_labels() = make_null_shared_ptr(),
             n::active_dependency_labels_as_string() = v.member<std::string>("active_dependency_labels_as_string"),
             n::active_dependency_labels_classifier() = v.member<std::shared_ptr<LabelsClassifier> >("active_dependency_labels_classifier"),
+            n::from_id() = v.member<std::shared_ptr<const PackageID> >("from_id"),
             n::metadata_key_human_name() = v.member<std::string>("metadata_key_human_name"),
             n::metadata_key_raw_name() = v.member<std::string>("metadata_key_raw_name"),
             n::original_specs_as_string() = v.member<std::string>("original_specs_as_string"),
diff --git a/paludis/resolver/sanitised_dependencies.hh b/paludis/resolver/sanitised_dependencies.hh
index cbfa4e0a9..dd270391b 100644
--- a/paludis/resolver/sanitised_dependencies.hh
+++ b/paludis/resolver/sanitised_dependencies.hh
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -40,6 +40,7 @@ namespace paludis
         typedef Name<struct name_active_dependency_labels> active_dependency_labels;
         typedef Name<struct name_active_dependency_labels_as_string> active_dependency_labels_as_string;
         typedef Name<struct name_active_dependency_labels_classifier> active_dependency_labels_classifier;
+        typedef Name<struct name_from_id> from_id;
         typedef Name<struct name_metadata_key_human_name> metadata_key_human_name;
         typedef Name<struct name_metadata_key_raw_name> metadata_key_raw_name;
         typedef Name<struct name_original_specs_as_string> original_specs_as_string;
@@ -54,6 +55,7 @@ namespace paludis
             NamedValue<n::active_dependency_labels, std::shared_ptr<const DependenciesLabelSequence> > active_dependency_labels;
             NamedValue<n::active_dependency_labels_as_string, std::string> active_dependency_labels_as_string;
             NamedValue<n::active_dependency_labels_classifier, std::shared_ptr<const LabelsClassifier> > active_dependency_labels_classifier;
+            NamedValue<n::from_id, std::shared_ptr<const PackageID> > from_id;
             NamedValue<n::metadata_key_human_name, std::string> metadata_key_human_name;
             NamedValue<n::metadata_key_raw_name, std::string> metadata_key_raw_name;
             NamedValue<n::original_specs_as_string, std::string> original_specs_as_string;
diff --git a/paludis/selection_TEST.cc b/paludis/selection_TEST.cc
index 928d2d4da..4d5c82049 100644
--- a/paludis/selection_TEST.cc
+++ b/paludis/selection_TEST.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -30,6 +30,7 @@
 #include <paludis/util/wrapped_forward_iterator.hh>
 #include <paludis/util/indirect_iterator-impl.hh>
 #include <paludis/util/make_named_values.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <test/test_runner.hh>
 #include <test/test_framework.hh>
 #include <test/test_concepts.hh>
@@ -69,41 +70,41 @@ namespace test_cases
             TEST_CHECK(true);
 
             PackageDepSpec d1(parse_user_package_dep_spec("r1c1/r1c1p1", &env, { }));
-            const std::shared_ptr<const PackageIDSequence> q1(env[selection::AllVersionsSorted(generator::Matches(d1, { }))]);
+            const std::shared_ptr<const PackageIDSequence> q1(env[selection::AllVersionsSorted(generator::Matches(d1, make_null_shared_ptr(), { }))]);
             TEST_CHECK_EQUAL(std::distance(q1->begin(), q1->end()), 1);
 
             PackageDepSpec d2(parse_user_package_dep_spec("r1c1/r1c1p2", &env, { }));
-            const std::shared_ptr<const PackageIDSequence> q2(env[selection::AllVersionsSorted(generator::Matches(d2, { }))]);
+            const std::shared_ptr<const PackageIDSequence> q2(env[selection::AllVersionsSorted(generator::Matches(d2, make_null_shared_ptr(), { }))]);
             TEST_CHECK_EQUAL(std::distance(q2->begin(), q2->end()), 2);
 
             PackageDepSpec d3(parse_user_package_dep_spec(">=r1c1/r1c1p2-1", &env, { }));
-            const std::shared_ptr<const PackageIDSequence> q3(env[selection::AllVersionsSorted(generator::Matches(d3, { }))]);
+            const std::shared_ptr<const PackageIDSequence> q3(env[selection::AllVersionsSorted(generator::Matches(d3, make_null_shared_ptr(), { }))]);
             TEST_CHECK_EQUAL(std::distance(q3->begin(), q3->end()), 2);
 
             PackageDepSpec d4(parse_user_package_dep_spec(">=r1c1/r1c1p2-2", &env, { }));
-            const std::shared_ptr<const PackageIDSequence> q4(env[selection::AllVersionsSorted(generator::Matches(d4, { }))]);
+            const std::shared_ptr<const PackageIDSequence> q4(env[selection::AllVersionsSorted(generator::Matches(d4, make_null_shared_ptr(), { }))]);
             TEST_CHECK_EQUAL(join(indirect_iterator(q4->begin()), indirect_iterator(q4->end()), " "),
                     "r1c1/r1c1p2-2:0::repo1");
             TEST_CHECK_EQUAL(std::distance(q4->begin(), q4->end()), 1);
 
             PackageDepSpec d5(parse_user_package_dep_spec(">=r1c1/r1c1p2-3", &env, { }));
-            const std::shared_ptr<const PackageIDSequence> q5(env[selection::AllVersionsSorted(generator::Matches(d5, { }))]);
+            const std::shared_ptr<const PackageIDSequence> q5(env[selection::AllVersionsSorted(generator::Matches(d5, make_null_shared_ptr(), { }))]);
             TEST_CHECK_EQUAL(std::distance(q5->begin(), q5->end()), 0);
 
             PackageDepSpec d6(parse_user_package_dep_spec("<r1c1/r1c1p2-3", &env, { }));
-            const std::shared_ptr<const PackageIDSequence> q6(env[selection::AllVersionsSorted(generator::Matches(d6, { }))]);
+            const std::shared_ptr<const PackageIDSequence> q6(env[selection::AllVersionsSorted(generator::Matches(d6, make_null_shared_ptr(), { }))]);
             TEST_CHECK_EQUAL(std::distance(q6->begin(), q6->end()), 2);
 
             PackageDepSpec d7(parse_user_package_dep_spec("rac1/rac1pa", &env, { }));
-            const std::shared_ptr<const PackageIDSequence> q7(env[selection::AllVersionsSorted(generator::Matches(d7, { }))]);
+            const std::shared_ptr<const PackageIDSequence> q7(env[selection::AllVersionsSorted(generator::Matches(d7, make_null_shared_ptr(), { }))]);
             TEST_CHECK_EQUAL(std::distance(q7->begin(), q7->end()), 4);
 
             PackageDepSpec d8(parse_user_package_dep_spec("foo/bar", &env, { }));
-            const std::shared_ptr<const PackageIDSequence> q8(env[selection::AllVersionsSorted(generator::Matches(d8, { }))]);
+            const std::shared_ptr<const PackageIDSequence> q8(env[selection::AllVersionsSorted(generator::Matches(d8, make_null_shared_ptr(), { }))]);
             TEST_CHECK_EQUAL(std::distance(q8->begin(), q8->end()), 0);
 
             PackageDepSpec d9(parse_user_package_dep_spec("r1c1/r1c1p1", &env, { }));
-            const std::shared_ptr<const PackageIDSequence> q9(env[selection::AllVersionsSorted(generator::Matches(d9, { })
+            const std::shared_ptr<const PackageIDSequence> q9(env[selection::AllVersionsSorted(generator::Matches(d9, make_null_shared_ptr(), { })
                         | filter::SupportsAction<InstallAction>())]);
             TEST_CHECK_EQUAL(std::distance(q9->begin(), q9->end()), 1);
         }
@@ -137,19 +138,19 @@ namespace test_cases
 
             PackageDepSpec d(parse_user_package_dep_spec("cat/pkg", &env, { }));
 
-            const std::shared_ptr<const PackageIDSequence> q1(env[selection::AllVersionsSorted(generator::Matches(d, { }))]);
+            const std::shared_ptr<const PackageIDSequence> q1(env[selection::AllVersionsSorted(generator::Matches(d, make_null_shared_ptr(), { }))]);
             TEST_CHECK_EQUAL(join(indirect_iterator(q1->begin()), indirect_iterator(q1->end()), " "),
                     "cat/pkg-1:a::repo2 cat/pkg-1:a::repo1 cat/pkg-2:c::repo1 cat/pkg-3:b::repo2 cat/pkg-3:c::repo1 cat/pkg-4:a::repo1");
 
-            const std::shared_ptr<const PackageIDSequence> q2(env[selection::AllVersionsGroupedBySlot(generator::Matches(d, { }))]);
+            const std::shared_ptr<const PackageIDSequence> q2(env[selection::AllVersionsGroupedBySlot(generator::Matches(d, make_null_shared_ptr(), { }))]);
             TEST_CHECK_EQUAL(join(indirect_iterator(q2->begin()), indirect_iterator(q2->end()), " "),
                     "cat/pkg-3:b::repo2 cat/pkg-2:c::repo1 cat/pkg-3:c::repo1 cat/pkg-1:a::repo2 cat/pkg-1:a::repo1 cat/pkg-4:a::repo1");
 
-            const std::shared_ptr<const PackageIDSequence> q3(env[selection::BestVersionOnly(generator::Matches(d, { }))]);
+            const std::shared_ptr<const PackageIDSequence> q3(env[selection::BestVersionOnly(generator::Matches(d, make_null_shared_ptr(), { }))]);
             TEST_CHECK_EQUAL(join(indirect_iterator(q3->begin()), indirect_iterator(q3->end()), " "),
                     "cat/pkg-4:a::repo1");
 
-            const std::shared_ptr<const PackageIDSequence> q4(env[selection::BestVersionInEachSlot(generator::Matches(d, { }))]);
+            const std::shared_ptr<const PackageIDSequence> q4(env[selection::BestVersionInEachSlot(generator::Matches(d, make_null_shared_ptr(), { }))]);
             TEST_CHECK_EQUAL(join(indirect_iterator(q4->begin()), indirect_iterator(q4->end()), " "),
                     "cat/pkg-3:b::repo2 cat/pkg-3:c::repo1 cat/pkg-4:a::repo1");
 
@@ -162,31 +163,31 @@ namespace test_cases
 
             PackageDepSpec c(parse_user_package_dep_spec("cat/*", &env, { updso_allow_wildcards }));
 
-            const std::shared_ptr<const PackageIDSequence> q5(env[selection::AllVersionsSorted(generator::Matches(c, { }))]);
+            const std::shared_ptr<const PackageIDSequence> q5(env[selection::AllVersionsSorted(generator::Matches(c, make_null_shared_ptr(), { }))]);
             TEST_CHECK_EQUAL(join(indirect_iterator(q5->begin()), indirect_iterator(q5->end()), " "),
                     "cat/other-1:a::repo3 cat/pkg-1:a::repo2 cat/pkg-1:a::repo1 cat/pkg-2:c::repo1 "
                     "cat/pkg-3:b::repo2 cat/pkg-3:c::repo1 cat/pkg-4:a::repo1");
 
-            const std::shared_ptr<const PackageIDSequence> q6(env[selection::AllVersionsGroupedBySlot(generator::Matches(c, { }))]);
+            const std::shared_ptr<const PackageIDSequence> q6(env[selection::AllVersionsGroupedBySlot(generator::Matches(c, make_null_shared_ptr(), { }))]);
             TEST_CHECK_EQUAL(join(indirect_iterator(q6->begin()), indirect_iterator(q6->end()), " "),
                     "cat/other-1:a::repo3 cat/pkg-3:b::repo2 cat/pkg-2:c::repo1 cat/pkg-3:c::repo1 "
                     "cat/pkg-1:a::repo2 cat/pkg-1:a::repo1 cat/pkg-4:a::repo1");
 
-            const std::shared_ptr<const PackageIDSequence> q7(env[selection::BestVersionOnly(generator::Matches(c, { }))]);
+            const std::shared_ptr<const PackageIDSequence> q7(env[selection::BestVersionOnly(generator::Matches(c, make_null_shared_ptr(), { }))]);
             TEST_CHECK_EQUAL(join(indirect_iterator(q7->begin()), indirect_iterator(q7->end()), " "),
                     "cat/other-1:a::repo3 cat/pkg-4:a::repo1");
 
-            const std::shared_ptr<const PackageIDSequence> q8(env[selection::BestVersionInEachSlot(generator::Matches(c, { }))]);
+            const std::shared_ptr<const PackageIDSequence> q8(env[selection::BestVersionInEachSlot(generator::Matches(c, make_null_shared_ptr(), { }))]);
             TEST_CHECK_EQUAL(join(indirect_iterator(q8->begin()), indirect_iterator(q8->end()), " "),
                     "cat/other-1:a::repo3 cat/pkg-3:b::repo2 cat/pkg-3:c::repo1 cat/pkg-4:a::repo1");
 
             PackageDepSpec b(parse_user_package_dep_spec("cat/pkg:a", &env, { }));
-            const std::shared_ptr<const PackageIDSequence> q9(env[selection::AllVersionsGroupedBySlot(generator::Matches(b, { }))]);
+            const std::shared_ptr<const PackageIDSequence> q9(env[selection::AllVersionsGroupedBySlot(generator::Matches(b, make_null_shared_ptr(), { }))]);
             TEST_CHECK_EQUAL(join(indirect_iterator(q9->begin()), indirect_iterator(q9->end()), " "),
                     "cat/pkg-1:a::repo2 cat/pkg-1:a::repo1 cat/pkg-4:a::repo1");
 
             PackageDepSpec a(parse_user_package_dep_spec("cat/pkg[=1|=3]", &env, { }));
-            const std::shared_ptr<const PackageIDSequence> q10(env[selection::AllVersionsGroupedBySlot(generator::Matches(a, { }))]);
+            const std::shared_ptr<const PackageIDSequence> q10(env[selection::AllVersionsGroupedBySlot(generator::Matches(a, make_null_shared_ptr(), { }))]);
             TEST_CHECK_EQUAL(join(indirect_iterator(q10->begin()), indirect_iterator(q10->end()), " "),
                     "cat/pkg-1:a::repo2 cat/pkg-1:a::repo1 cat/pkg-3:b::repo2 cat/pkg-3:c::repo1");
         }
diff --git a/paludis/serialise.cc b/paludis/serialise.cc
index bb8c249b0..43f256700 100644
--- a/paludis/serialise.cc
+++ b/paludis/serialise.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -378,7 +378,7 @@ DeserialisatorHandler<std::shared_ptr<const PackageID> >::handle(Deserialisation
                         epdso_allow_use_dep_question_defaults },
                         { vso_flexible_dashes, vso_flexible_dots, vso_ignore_case,
                         vso_letters_anywhere, vso_dotted_suffixes },
-                        make_null_shared_ptr()), { }))]->begin();
+                        make_null_shared_ptr()), make_null_shared_ptr(), { }))]->begin();
 }
 
 template class Pimp<Deserialiser>;
diff --git a/paludis/set_file.cc b/paludis/set_file.cc
index f6a36bca4..aef0dfe2d 100644
--- a/paludis/set_file.cc
+++ b/paludis/set_file.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -28,6 +28,7 @@
 #include <paludis/util/system.hh>
 #include <paludis/util/safe_ofstream.hh>
 #include <paludis/util/process.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/environment.hh>
 #include <paludis/package_database.hh>
 #include <paludis/selection.hh>
@@ -275,7 +276,7 @@ namespace
                                     make_package_dep_spec({ })
                                     .package(*spec->package_ptr())
                                     .slot_requirement(spec->slot_requirement_ptr()),
-                                    { }) |
+                                    make_null_shared_ptr(), { }) |
                                 filter::InstalledAtRoot(params.environment()->preferred_root_key()->value()))]->empty())
                         result->top()->append(spec);
                 }
diff --git a/paludis/user_dep_spec.cc b/paludis/user_dep_spec.cc
index c07b5f88d..2ecdd3cef 100644
--- a/paludis/user_dep_spec.cc
+++ b/paludis/user_dep_spec.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2005, 2006, 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2005, 2006, 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -41,6 +41,7 @@
 #include <paludis/util/destringify.hh>
 #include <paludis/util/accept_visitor.hh>
 #include <paludis/util/tribool.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <algorithm>
 
 using namespace paludis;
@@ -77,7 +78,7 @@ namespace
             if (options[updso_no_disambiguation])
                 throw PackageDepSpecError("Need an explicit category specified");
             result.package(env->package_database()->fetch_unique_qualified_package_name(PackageNamePart(s),
-                filter::And(filter, filter::Matches(result, { }))));
+                filter::And(filter, filter::Matches(result, make_null_shared_ptr(), { }))));
         }
     }
 
diff --git a/paludis/user_dep_spec_TEST.cc b/paludis/user_dep_spec_TEST.cc
index 79522355c..8a2d21d23 100644
--- a/paludis/user_dep_spec_TEST.cc
+++ b/paludis/user_dep_spec_TEST.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2006, 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2006, 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -28,6 +28,7 @@
 #include <paludis/util/options.hh>
 #include <paludis/util/indirect_iterator-impl.hh>
 #include <paludis/util/make_named_values.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/version_requirements.hh>
 #include <paludis/environments/test/test_environment.hh>
 #include <paludis/repositories/fake/fake_repository.hh>
@@ -430,75 +431,75 @@ namespace test_cases
             pkg3->keywords_key()->set_from_string("~d");
 
             PackageDepSpec a(parse_user_package_dep_spec("cat/pkg1[.KEYWORDS<~a]", &env, { }));
-            TEST_CHECK(match_package(env, a, pkg1, { }));
-            TEST_CHECK(match_package(env, a, pkg2, { }));
-            TEST_CHECK(! match_package(env, a, pkg3, { }));
+            TEST_CHECK(match_package(env, a, pkg1, make_null_shared_ptr(), { }));
+            TEST_CHECK(match_package(env, a, pkg2, make_null_shared_ptr(), { }));
+            TEST_CHECK(! match_package(env, a, pkg3, make_null_shared_ptr(), { }));
 
             PackageDepSpec b(parse_user_package_dep_spec("cat/pkg1[.KEYWORDS<~b]", &env, { }));
-            TEST_CHECK(match_package(env, b, pkg1, { }));
-            TEST_CHECK(! match_package(env, b, pkg2, { }));
-            TEST_CHECK(! match_package(env, b, pkg3, { }));
+            TEST_CHECK(match_package(env, b, pkg1, make_null_shared_ptr(), { }));
+            TEST_CHECK(! match_package(env, b, pkg2, make_null_shared_ptr(), { }));
+            TEST_CHECK(! match_package(env, b, pkg3, make_null_shared_ptr(), { }));
 
             PackageDepSpec c(parse_user_package_dep_spec("cat/pkg1[.KEYWORDS<~c]", &env, { }));
-            TEST_CHECK(! match_package(env, c, pkg1, { }));
-            TEST_CHECK(match_package(env, c, pkg2, { }));
-            TEST_CHECK(! match_package(env, c, pkg3, { }));
+            TEST_CHECK(! match_package(env, c, pkg1, make_null_shared_ptr(), { }));
+            TEST_CHECK(match_package(env, c, pkg2, make_null_shared_ptr(), { }));
+            TEST_CHECK(! match_package(env, c, pkg3, make_null_shared_ptr(), { }));
 
             PackageDepSpec d(parse_user_package_dep_spec("cat/pkg1[.KEYWORDS>~a]", &env, { }));
-            TEST_CHECK(! match_package(env, d, pkg1, { }));
-            TEST_CHECK(! match_package(env, d, pkg2, { }));
-            TEST_CHECK(! match_package(env, d, pkg3, { }));
+            TEST_CHECK(! match_package(env, d, pkg1, make_null_shared_ptr(), { }));
+            TEST_CHECK(! match_package(env, d, pkg2, make_null_shared_ptr(), { }));
+            TEST_CHECK(! match_package(env, d, pkg3, make_null_shared_ptr(), { }));
 
             PackageDepSpec e(parse_user_package_dep_spec("cat/pkg1[.KEYWORDS=~d]", &env, { }));
-            TEST_CHECK(! match_package(env, e, pkg1, { }));
-            TEST_CHECK(! match_package(env, e, pkg2, { }));
-            TEST_CHECK(match_package(env, e, pkg3, { }));
+            TEST_CHECK(! match_package(env, e, pkg1, make_null_shared_ptr(), { }));
+            TEST_CHECK(! match_package(env, e, pkg2, make_null_shared_ptr(), { }));
+            TEST_CHECK(match_package(env, e, pkg3, make_null_shared_ptr(), { }));
 
             PackageDepSpec f(parse_user_package_dep_spec("cat/pkg1[.KEYWORDS=~a ~c]", &env, { }));
-            TEST_CHECK(! match_package(env, f, pkg1, { }));
-            TEST_CHECK(match_package(env, f, pkg2, { }));
-            TEST_CHECK(! match_package(env, f, pkg3, { }));
+            TEST_CHECK(! match_package(env, f, pkg1, make_null_shared_ptr(), { }));
+            TEST_CHECK(match_package(env, f, pkg2, make_null_shared_ptr(), { }));
+            TEST_CHECK(! match_package(env, f, pkg3, make_null_shared_ptr(), { }));
 
             PackageDepSpec g(parse_user_package_dep_spec("cat/pkg1[.HITCHHIKER=42]", &env, { }));
-            TEST_CHECK(match_package(env, g, pkg1, { }));
+            TEST_CHECK(match_package(env, g, pkg1, make_null_shared_ptr(), { }));
 
             PackageDepSpec h(parse_user_package_dep_spec("cat/pkg1[.HITCHHIKER<41]", &env, { }));
-            TEST_CHECK(! match_package(env, h, pkg1, { }));
+            TEST_CHECK(! match_package(env, h, pkg1, make_null_shared_ptr(), { }));
 
             PackageDepSpec i(parse_user_package_dep_spec("cat/pkg1[.HITCHHIKER<42]", &env, { }));
-            TEST_CHECK(! match_package(env, i, pkg1, { }));
+            TEST_CHECK(! match_package(env, i, pkg1, make_null_shared_ptr(), { }));
 
             PackageDepSpec j(parse_user_package_dep_spec("cat/pkg1[.HITCHHIKER<43]", &env, { }));
-            TEST_CHECK(match_package(env, j, pkg1, { }));
+            TEST_CHECK(match_package(env, j, pkg1, make_null_shared_ptr(), { }));
 
             PackageDepSpec k(parse_user_package_dep_spec("cat/pkg1[.HITCHHIKER>42]", &env, { }));
-            TEST_CHECK(! match_package(env, k, pkg1, { }));
+            TEST_CHECK(! match_package(env, k, pkg1, make_null_shared_ptr(), { }));
 
             PackageDepSpec l(parse_user_package_dep_spec("cat/pkg1[.HITCHHIKER>41]", &env, { }));
-            TEST_CHECK(match_package(env, l, pkg1, { }));
+            TEST_CHECK(match_package(env, l, pkg1, make_null_shared_ptr(), { }));
 
             PackageDepSpec m(parse_user_package_dep_spec("cat/pkg1[.HITCHHIKER?]", &env, { }));
-            TEST_CHECK(match_package(env, m, pkg1, { }));
+            TEST_CHECK(match_package(env, m, pkg1, make_null_shared_ptr(), { }));
 
             PackageDepSpec n(parse_user_package_dep_spec("cat/pkg1[.SPOON?]", &env, { }));
-            TEST_CHECK(! match_package(env, n, pkg1, { }));
+            TEST_CHECK(! match_package(env, n, pkg1, make_null_shared_ptr(), { }));
 
             PackageDepSpec o(parse_user_package_dep_spec("cat/pkg1[.$keywords<~a]", &env, { }));
-            TEST_CHECK(match_package(env, o, pkg1, { }));
-            TEST_CHECK(match_package(env, o, pkg2, { }));
-            TEST_CHECK(! match_package(env, o, pkg3, { }));
+            TEST_CHECK(match_package(env, o, pkg1, make_null_shared_ptr(), { }));
+            TEST_CHECK(match_package(env, o, pkg2, make_null_shared_ptr(), { }));
+            TEST_CHECK(! match_package(env, o, pkg3, make_null_shared_ptr(), { }));
 
             PackageDepSpec p(parse_user_package_dep_spec("cat/pkg1[.::$format=fake]", &env, { }));
-            TEST_CHECK(match_package(env, p, pkg1, { }));
+            TEST_CHECK(match_package(env, p, pkg1, make_null_shared_ptr(), { }));
 
             PackageDepSpec q(parse_user_package_dep_spec("cat/pkg1[.::$format=e]", &env, { }));
-            TEST_CHECK(! match_package(env, q, pkg1, { }));
+            TEST_CHECK(! match_package(env, q, pkg1, make_null_shared_ptr(), { }));
 
             PackageDepSpec r(parse_user_package_dep_spec("cat/pkg1[.::format=fake]", &env, { }));
-            TEST_CHECK(match_package(env, r, pkg1, { }));
+            TEST_CHECK(match_package(env, r, pkg1, make_null_shared_ptr(), { }));
 
             PackageDepSpec s(parse_user_package_dep_spec("cat/pkg1[.::format=e]", &env, { }));
-            TEST_CHECK(! match_package(env, s, pkg1, { }));
+            TEST_CHECK(! match_package(env, s, pkg1, make_null_shared_ptr(), { }));
         }
     } test_user_package_dep_spec_user_key_req;
 }
diff --git a/python/dep_list.cc b/python/dep_list.cc
index 3a83dd46f..74703e0d8 100644
--- a/python/dep_list.cc
+++ b/python/dep_list.cc
@@ -299,11 +299,6 @@ void expose_dep_list()
                 "Return whether a spec structure is already installed."
             )
 
-        .def("match_on_list", &DepList::match_on_list,
-                "match_on_list(PackageDepSpec) -> bool\n"
-                "Return whether a spec matches an item in the list."
-            )
-
         .def("__iter__", bp::range<bp::return_internal_reference<> >(dl_begin_ptr, dl_end_ptr))
         ;
 }
diff --git a/python/dep_list_TEST.py b/python/dep_list_TEST.py
index 129ea1e78..616bd364f 100755
--- a/python/dep_list_TEST.py
+++ b/python/dep_list_TEST.py
@@ -131,25 +131,14 @@ class TestCase_02_DepList(unittest.TestCase):
     def test_02_options(self):
         self.assert_(isinstance(dl.options, DepListOptions))
 
-    def test_03_match_on_list(self):
-        self.assert_(not dl.match_on_list(pds))
-
     def test_04_clear(self):
         dl.add(pds, dd)
-        self.assert_(dl.match_on_list(pds))
         dl.clear()
-        self.assert_(not dl.match_on_list(pds))
 
     def test_05_add(self):
-        self.assert_(not dl.match_on_list(pds))
         dl.add(pds, dd)
-        self.assert_(dl.match_on_list(pds))
-
         dl.clear()
-
-        self.assert_(not dl.match_on_list(pds))
         dl.add(cds, dd)
-        self.assert_(dl.match_on_list(pds))
 
     def test_06_already_installed(self):
         self.assert_(not dl.already_installed(pds, dd))
diff --git a/python/generator.cc b/python/generator.cc
index 80d771d00..4281fdb2a 100644
--- a/python/generator.cc
+++ b/python/generator.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2008 Ciaran McCreesh
+ * Copyright (c) 2008, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -24,11 +24,20 @@
 #include <paludis/filtered_generator.hh>
 #include <paludis/filter.hh>
 #include <paludis/dep_spec.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 
 using namespace paludis;
 using namespace paludis::python;
 namespace bp = boost::python;
 
+namespace
+{
+    generator::Matches * make_generator_matches(const PackageDepSpec & spec, const MatchPackageOptions & o)
+    {
+        return new generator::Matches(spec, make_null_shared_ptr(), o);
+    }
+}
+
 void expose_generator()
 {
     bp::class_<Generator> generator(
@@ -62,7 +71,12 @@ void expose_generator()
     bp::class_<generator::Matches, bp::bases<Generator> > generator_matches(
             "Matches",
             "Generate matching packages.",
-            bp::init<const PackageDepSpec &, const MatchPackageOptions &>("__init__(spec, MatchPackageOptions)")
+            bp::no_init
+            );
+
+    generator_matches.def("__init__",
+            bp::make_constructor(&make_generator_matches),
+            "__init__(spec, MatchPackageOptions)"
             );
 
     bp::class_<generator::Intersection, bp::bases<Generator> > generator_intersection(
diff --git a/ruby/dep_list_TEST.rb b/ruby/dep_list_TEST.rb
index cf8457996..056ba64f6 100644
--- a/ruby/dep_list_TEST.rb
+++ b/ruby/dep_list_TEST.rb
@@ -206,7 +206,7 @@ module Paludis
         def test_add_bad_tree
             assert_raise TypeError do
                 dl.add(env[Selection::BestVersionOnly.new(Generator::Matches.new(
-                    pda, []))].last.build_dependencies_key.value, dd)
+                    pda, nil, []))].last.build_dependencies_key.value, dd)
             end
         end
 
diff --git a/ruby/environment_TEST.rb b/ruby/environment_TEST.rb
index 22ac5c4c1..dd76c4d5c 100644
--- a/ruby/environment_TEST.rb
+++ b/ruby/environment_TEST.rb
@@ -2,7 +2,7 @@
 # vim: set sw=4 sts=4 et tw=80 :
 
 #
-# Copyright (c) 2006, 2007, 2008, 2009, 2010 Ciaran McCreesh
+# Copyright (c) 2006, 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
 # Copyright (c) 2007, 2008 Richard Brown
 #
 # This file is part of the Paludis package manager. Paludis is free software;
@@ -80,7 +80,7 @@ module Paludis
 
         def pid
             env[Selection::RequireExactlyOne.new(Generator::Matches.new(
-                Paludis::parse_user_package_dep_spec('=foo/bar-1.0::testrepo', env, []), []))].first
+                Paludis::parse_user_package_dep_spec('=foo/bar-1.0::testrepo', env, []), nil, []))].first
         end
 
         def test_accept_license
@@ -88,7 +88,7 @@ module Paludis
             assert !env.accept_license('Failure', pid)
 
             pid2 = env[Selection::RequireExactlyOne.new(Generator::Matches.new(
-                Paludis::parse_user_package_dep_spec('=foo/baz-1.0::testrepo', env, []), []))].first
+                Paludis::parse_user_package_dep_spec('=foo/baz-1.0::testrepo', env, []), nil, []))].first
             assert env.accept_license('GPL-2', pid2)
             assert env.accept_license('Failure', pid2)
         end
@@ -107,7 +107,7 @@ module Paludis
 
         def pid
             env[Selection::RequireExactlyOne.new(Generator::Matches.new(
-                Paludis::parse_user_package_dep_spec('=foo/bar-1.0::testrepo', env, []), []))].first
+                Paludis::parse_user_package_dep_spec('=foo/bar-1.0::testrepo', env, []), nil, []))].first
         end
 
         def test_accept_keywords
@@ -311,7 +311,7 @@ module Paludis
         end
 
         def test_package_database_query
-            a = env[Selection::AllVersionsSorted.new(Generator::Matches.new(pda, []))]
+            a = env[Selection::AllVersionsSorted.new(Generator::Matches.new(pda, nil, []))]
             assert_kind_of Array, a
             assert_equal 1, a.length
             pid = a.first
@@ -320,7 +320,7 @@ module Paludis
             assert_equal '1.0', pid.version.to_s
             assert_equal 'testrepo', pid.repository_name
 
-            a = env[Selection::AllVersionsSorted.new(Generator::Matches.new(pda, []) | Filter::SupportsAction.new(InstallAction))]
+            a = env[Selection::AllVersionsSorted.new(Generator::Matches.new(pda, nil, []) | Filter::SupportsAction.new(InstallAction))]
             assert_kind_of Array, a
             assert_equal 1, a.length
             pid = a.first
@@ -329,7 +329,7 @@ module Paludis
             assert_equal '1.0', pid.version.to_s
             assert_equal 'testrepo', pid.repository_name
 
-            a = env[Selection::AllVersionsSorted.new(Generator::Matches.new(pda, []))]
+            a = env[Selection::AllVersionsSorted.new(Generator::Matches.new(pda, nil, []))]
             assert_kind_of Array, a
             assert_equal 1, a.length
             pid = a.first
@@ -338,7 +338,7 @@ module Paludis
             assert_equal '1.0', pid.version.to_s
             assert_equal 'testrepo', pid.repository_name
 
-            a = env[Selection::AllVersionsSorted.new(Generator::Matches.new(pda2, []) | Filter::SupportsAction.new(InstallAction))]
+            a = env[Selection::AllVersionsSorted.new(Generator::Matches.new(pda2, nil, []) | Filter::SupportsAction.new(InstallAction))]
             assert_kind_of Array, a
             assert_equal 2, a.length
             pid = a.shift
@@ -368,10 +368,10 @@ module Paludis
 
 
             a = env[Selection::AllVersionsUnsorted.new(Generator::Matches.new(Paludis::parse_user_package_dep_spec(
-                '>=foo/bar-27', env, []), []))]
+                '>=foo/bar-27', env, []), nil, []))]
             assert a.empty?
 
-            a = env[Selection::AllVersionsUnsorted.new(Generator::Matches.new(pda2, []) | Filter::SupportsAction.new(ConfigAction))]
+            a = env[Selection::AllVersionsUnsorted.new(Generator::Matches.new(pda2, nil, []) | Filter::SupportsAction.new(ConfigAction))]
             assert a.empty?
         end
     end
diff --git a/ruby/generator.cc b/ruby/generator.cc
index 16631b992..5d6f753eb 100644
--- a/ruby/generator.cc
+++ b/ruby/generator.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2008, 2009 Ciaran McCreesh
+ * Copyright (c) 2008, 2009, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -110,14 +110,15 @@ namespace
     }
 
     VALUE
-    generator_matches_new(VALUE self, VALUE spec_v, VALUE options_v)
+    generator_matches_new(VALUE self, VALUE spec_v, VALUE id_v, VALUE options_v)
     {
         Generator * ptr(0);
         try
         {
             std::shared_ptr<const PackageDepSpec> spec(value_to_package_dep_spec(spec_v));
+            std::shared_ptr<const PackageID> id(value_to_package_id(id_v, true));
             MatchPackageOptions options(value_to_match_package_options(options_v));
-            ptr = new generator::Matches(*spec, options);
+            ptr = new generator::Matches(*spec, id, options);
             VALUE data(Data_Wrap_Struct(self, 0, &Common<Generator>::free, ptr));
             rb_obj_call_init(data, 2, &spec_v);
             return data;
@@ -300,7 +301,7 @@ namespace
          * Generate matching packages.
          */
         c_generator_matches = rb_define_class_under(c_generator_module, "Matches", c_generator);
-        rb_define_singleton_method(c_generator_matches, "new", RUBY_FUNC_CAST(&generator_matches_new), 2);
+        rb_define_singleton_method(c_generator_matches, "new", RUBY_FUNC_CAST(&generator_matches_new), 3);
 
         /*
          * Document-class: Paludis::Generator::Intersection
diff --git a/ruby/generator_TEST.rb b/ruby/generator_TEST.rb
index e4dd336a5..7b91c0820 100644
--- a/ruby/generator_TEST.rb
+++ b/ruby/generator_TEST.rb
@@ -2,7 +2,7 @@
 # vim: set sw=4 sts=4 et tw=80 :
 
 #
-# Copyright (c) 2008 Ciaran McCreesh
+# Copyright (c) 2008, 2011 Ciaran McCreesh
 #
 # This file is part of the Paludis package manager. Paludis is free software;
 # you can redistribute it and/or modify it under the terms of the GNU General
@@ -51,15 +51,15 @@ module Paludis
 
         def test_create
             assert_nothing_raised do
-                Generator::Matches.new(Paludis::parse_user_package_dep_spec("a/b", env, []), [])
+                Generator::Matches.new(Paludis::parse_user_package_dep_spec("a/b", env, []), nil, [])
             end
         end
 
         def test_to_s
-            assert_equal Generator::Matches.new(Paludis::parse_user_package_dep_spec("a/b", env, []), []).to_s,
+            assert_equal Generator::Matches.new(Paludis::parse_user_package_dep_spec("a/b", env, []), nil, []).to_s,
                 "packages matching a/b"
             assert_equal Generator::Matches.new(Paludis::parse_user_package_dep_spec("a/b", env, []),
-                                               [:ignore_additional_requirements]).to_s,
+                                               nil, [:ignore_additional_requirements]).to_s,
                 "packages matching a/b (ignoring additional requirements)"
         end
     end
diff --git a/ruby/package_id.cc b/ruby/package_id.cc
index 71dab061f..e7ba44b8e 100644
--- a/ruby/package_id.cc
+++ b/ruby/package_id.cc
@@ -576,8 +576,11 @@ paludis::ruby::package_id_to_value(std::shared_ptr<const PackageID> m)
 }
 
 std::shared_ptr<const PackageID>
-paludis::ruby::value_to_package_id(VALUE v)
+paludis::ruby::value_to_package_id(VALUE v, bool nil_ok)
 {
+    if (nil_ok && rb_obj_is_kind_of(v, rb_cNilClass))
+        return std::shared_ptr<const PackageID>();
+
     if (rb_obj_is_kind_of(v, c_package_id))
     {
         std::shared_ptr<const PackageID> * v_ptr;
diff --git a/ruby/paludis_ruby.cc b/ruby/paludis_ruby.cc
index 95d68140b..661c62d60 100644
--- a/ruby/paludis_ruby.cc
+++ b/ruby/paludis_ruby.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2006, 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2006, 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  * Copyright (c) 2006, 2007, 2008 Richard Brown
  *
  * This file is part of the Paludis package manager. Paludis is free software;
@@ -79,20 +79,21 @@ namespace
      * Document-method: match_package
      *
      * call-seq:
-     *     match_package(environment, package_dep_spec, package_id, options) -> true or false
+     *     match_package(environment, package_dep_spec, package_id, from_package_id, options) -> true or false
      *
      * Return whether the specified PackageID matches the specified PackageDepSpec.
      *
      */
-    VALUE paludis_match_package(VALUE, VALUE en, VALUE a, VALUE t, VALUE o)
+    VALUE paludis_match_package(VALUE, VALUE en, VALUE a, VALUE t, VALUE f, VALUE o)
     {
         try
         {
             std::shared_ptr<Environment> env = value_to_environment(en);
             std::shared_ptr<const PackageDepSpec> spec = value_to_package_dep_spec(a);
             std::shared_ptr<const PackageID> target = value_to_package_id(t);
+            std::shared_ptr<const PackageID> from_package_id = value_to_package_id(f, true);
             MatchPackageOptions options(value_to_match_package_options(o));
-            return match_package(*env, *spec, target, options) ? Qtrue : Qfalse;
+            return match_package(*env, *spec, target, from_package_id, options) ? Qtrue : Qfalse;
         }
         catch (const std::exception & e)
         {
@@ -427,7 +428,7 @@ void PALUDIS_VISIBLE paludis::ruby::init()
      */
     c_bad_version_operator_error = rb_define_class_under(c_paludis_module, "BadVersionOperatorError", rb_eRuntimeError);
 
-    rb_define_module_function(c_paludis_module, "match_package", RUBY_FUNC_CAST(&paludis_match_package), 4);
+    rb_define_module_function(c_paludis_module, "match_package", RUBY_FUNC_CAST(&paludis_match_package), 5);
     rb_define_module_function(c_paludis_module, "match_package_in_set", RUBY_FUNC_CAST(&paludis_match_package_in_set), 4);
     rb_define_module_function(c_paludis_module, "version_spec_comparator", RUBY_FUNC_CAST(&paludis_version_spec_comparator), 3);
 
diff --git a/ruby/paludis_ruby.hh b/ruby/paludis_ruby.hh
index 8ac703083..bb86a76c9 100644
--- a/ruby/paludis_ruby.hh
+++ b/ruby/paludis_ruby.hh
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2006, 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2006, 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  * Copyright (c) 2006, 2007, 2008 Richard Brown
  *
  * This file is part of the Paludis package manager. Paludis is free software;
@@ -110,7 +110,7 @@ namespace paludis
         VALUE bool_to_value(bool b);
 
         VersionSpec value_to_version_spec(VALUE v);
-        std::shared_ptr<const PackageID> value_to_package_id(VALUE);
+        std::shared_ptr<const PackageID> value_to_package_id(VALUE, bool nil_ok = false);
         std::shared_ptr<const PackageDepSpec> value_to_package_dep_spec(VALUE v);
         std::shared_ptr<const DependenciesLabelsDepSpec> value_to_dependencies_labels_dep_spec(VALUE v);
         std::shared_ptr<const DepSpec> value_to_dep_spec(VALUE v);
diff --git a/ruby/paludis_ruby_TEST.rb b/ruby/paludis_ruby_TEST.rb
index 8a830fc3e..2bd9d6dd1 100644
--- a/ruby/paludis_ruby_TEST.rb
+++ b/ruby/paludis_ruby_TEST.rb
@@ -2,7 +2,7 @@
 # vim: set sw=4 sts=4 et tw=80 :
 
 #
-# Copyright (c) 2006, 2007, 2008 Ciaran McCreesh
+# Copyright (c) 2006, 2007, 2008, 2011 Ciaran McCreesh
 # Copyright (c) 2008 Richard Brown
 #
 # This file is part of the Paludis package manager. Paludis is free software;
@@ -42,10 +42,10 @@ module Paludis
             spec_good = Paludis::parse_user_package_dep_spec('>=foo/bar-1', env, [])
             spec_bad = Paludis::parse_user_package_dep_spec('>=foo/bar-2', env, [])
             pid = env[Selection::RequireExactlyOne.new(Generator::Matches.new(
-                Paludis::parse_user_package_dep_spec('=foo/bar-1.0::testrepo', env, []), []))].first
+                Paludis::parse_user_package_dep_spec('=foo/bar-1.0::testrepo', env, []), nil, []))].first
 
-            assert Paludis::match_package(env, spec_good, pid, [])
-            assert !Paludis::match_package(env, spec_bad, pid, [])
+            assert Paludis::match_package(env, spec_good, pid, nil, [])
+            assert !Paludis::match_package(env, spec_bad, pid, nil, [])
 
         end
 
@@ -53,7 +53,7 @@ module Paludis
             env = EnvironmentFactory.instance.create("")
             world = env.set('world')
             pid = env[Selection::RequireExactlyOne.new(Generator::Matches.new(
-                Paludis::parse_user_package_dep_spec('=foo/bar-1.0::testrepo', env, []), []))].first
+                Paludis::parse_user_package_dep_spec('=foo/bar-1.0::testrepo', env, []), nil, []))].first
 
             assert Paludis::match_package_in_set(env, world, pid, [])
         end
@@ -62,14 +62,14 @@ module Paludis
             env = EnvironmentFactory.instance.create("")
             spec = Paludis::parse_user_package_dep_spec('>=foo/bar-1', env, [])
             pid = env[Selection::RequireExactlyOne.new(Generator::Matches.new(
-                Paludis::parse_user_package_dep_spec('=foo/bar-1.0::testrepo', env, []), []))].first
+                Paludis::parse_user_package_dep_spec('=foo/bar-1.0::testrepo', env, []), nil, []))].first
 
             assert_raise TypeError do
-                Paludis::match_package(spec,spec,pid, [])
+                Paludis::match_package(spec,spec,pid, nil, [])
             end
 
             assert_raise TypeError do
-                Paludis::match_package(env,spec,spec, [])
+                Paludis::match_package(env,spec,spec, nil, [])
             end
         end
 
diff --git a/ruby/repository_TEST.rb b/ruby/repository_TEST.rb
index 3e0260817..82aae2678 100644
--- a/ruby/repository_TEST.rb
+++ b/ruby/repository_TEST.rb
@@ -2,7 +2,7 @@
 # vim: set sw=4 sts=4 et tw=80 :
 
 #
-# Copyright (c) 2006, 2007, 2008, 2009, 2010 Ciaran McCreesh
+# Copyright (c) 2006, 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
 # Copyright (c) 2006, 2007, 2008 Richard Brown
 #
 # This file is part of the Paludis package manager. Paludis is free software;
@@ -55,7 +55,7 @@ module Paludis
 
         def p
             env[Selection::RequireExactlyOne.new(Generator::Matches.new(
-                Paludis::parse_user_package_dep_spec('=foo/bar-2.0::testrepo', env, []), []))].first
+                Paludis::parse_user_package_dep_spec('=foo/bar-2.0::testrepo', env, []), nil, []))].first
         end
 
         def installed_pid
@@ -185,7 +185,7 @@ module Paludis
 
         def test_get_environment_variable
             pid = env[Selection::BestVersionOnly.new(Generator::Matches.new(Paludis::parse_user_package_dep_spec(
-                '=foo/bar-1.0', env, []), []))].first;
+                '=foo/bar-1.0', env, []), nil, []))].first;
             assert_equal "hello", repo.get_environment_variable(pid, "TEST_ENV_VAR")
             assert_equal "", repo.get_environment_variable(pid, "TEST_UNSET_ENV_VAR")
         end
diff --git a/src/clients/adjutrix/downgrade_check.cc b/src/clients/adjutrix/downgrade_check.cc
index aeb7dbdae..676fac7cc 100644
--- a/src/clients/adjutrix/downgrade_check.cc
+++ b/src/clients/adjutrix/downgrade_check.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -29,6 +29,7 @@
 #include <paludis/util/safe_ofstream.hh>
 #include <paludis/util/safe_ifstream.hh>
 #include <paludis/util/fs_stat.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/package_id.hh>
 #include <paludis/user_dep_spec.hh>
 #include <paludis/generator.hh>
@@ -119,7 +120,7 @@ namespace
                 part_spec.package(b->first.first);
                 if ("(none)" != b->first.second)
                     part_spec.slot_requirement(std::make_shared<UserSlotExactRequirement>(SlotName(b->first.second)));
-                if (! env[selection::SomeArbitraryVersion(generator::Matches(part_spec, { }))]->empty())
+                if (! env[selection::SomeArbitraryVersion(generator::Matches(part_spec, make_null_shared_ptr(), { }))]->empty())
                 {
                     results.insert(std::make_pair(b->first, stringify(b->second) + " -> nothing on " + desc));
                     exit_status |= 2;
diff --git a/src/clients/adjutrix/find_insecure_packages.cc b/src/clients/adjutrix/find_insecure_packages.cc
index 377e2318e..44da9ba56 100644
--- a/src/clients/adjutrix/find_insecure_packages.cc
+++ b/src/clients/adjutrix/find_insecure_packages.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2006, 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2006, 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -33,6 +33,7 @@
 #include <paludis/selection.hh>
 #include <paludis/util/indirect_iterator-impl.hh>
 #include <paludis/util/accept_visitor.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 
 #include <set>
 #include <map>
@@ -86,7 +87,7 @@ namespace
             void visit(const SetSpecTree::NodeType<PackageDepSpec>::Type & node)
             {
                 std::shared_ptr<const PackageIDSequence> insecure(_env[selection::AllVersionsSorted(
-                            generator::Matches(*node.spec(), { }))]);
+                            generator::Matches(*node.spec(), make_null_shared_ptr(), { }))]);
                 for (PackageIDSequence::ConstIterator i(insecure->begin()),
                         i_end(insecure->end()) ; i != i_end ; ++i)
                     if (node.spec()->tag())
diff --git a/src/clients/adjutrix/find_reverse_deps.cc b/src/clients/adjutrix/find_reverse_deps.cc
index 66c45d1ef..2189a7645 100644
--- a/src/clients/adjutrix/find_reverse_deps.cc
+++ b/src/clients/adjutrix/find_reverse_deps.cc
@@ -28,6 +28,7 @@
 #include <paludis/util/options.hh>
 #include <paludis/util/indirect_iterator-impl.hh>
 #include <paludis/util/accept_visitor.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/dep_spec.hh>
 #include <paludis/user_dep_spec.hh>
 #include <paludis/package_id.hh>
@@ -56,6 +57,7 @@ namespace
     {
         private:
             const Environment * const _env;
+            const std::shared_ptr<const PackageID> _from_id;
             const PackageIDSequence & _entries;
             std::string _depname;
             std::string _p;
@@ -69,10 +71,11 @@ namespace
             std::set<SetName> _recursing_sets;
 
         public:
-            ReverseDepChecker(const Environment * const e,
+            ReverseDepChecker(const Environment * const e, const std::shared_ptr<const PackageID> & f,
                     const PackageIDSequence & entries,
                     const std::string & p) :
                 _env(e),
+                _from_id(f),
                 _entries(entries),
                 _depname(""),
                 _p(p),
@@ -159,10 +162,10 @@ namespace
     }
 
     void
-        ReverseDepChecker::visit(const DependencySpecTree::NodeType<PackageDepSpec>::Type & node)
+    ReverseDepChecker::visit(const DependencySpecTree::NodeType<PackageDepSpec>::Type & node)
     {
         std::shared_ptr<const PackageIDSequence> dep_entries((*_env)[selection::AllVersionsSorted(
-                    generator::Matches(*node.spec(), { mpo_ignore_additional_requirements }))]);
+                    generator::Matches(*node.spec(), _from_id, { mpo_ignore_additional_requirements }))]);
         std::shared_ptr<PackageIDSequence> matches(std::make_shared<PackageIDSequence>());
 
         bool header_written = false;
@@ -216,24 +219,24 @@ namespace
 
         bool found_matches(false);
 
-        for (IndirectIterator<PackageIDSequence::ConstIterator> e(p_entries->begin()), e_end(p_entries->end()) ;
+        for (auto e(p_entries->begin()), e_end(p_entries->end()) ;
                 e != e_end ; ++e)
         {
             try
             {
-                ReverseDepChecker checker(&env, entries, stringify(p) + "-" + stringify(e->canonical_form(idcf_version)));
+                ReverseDepChecker checker(&env, *e, entries, stringify(p) + "-" + stringify((*e)->canonical_form(idcf_version)));
 
-                if (e->build_dependencies_key())
-                    checker.check(e->build_dependencies_key()->value(), e->build_dependencies_key()->raw_name());
+                if ((*e)->build_dependencies_key())
+                    checker.check((*e)->build_dependencies_key()->value(), (*e)->build_dependencies_key()->raw_name());
 
-                if (e->run_dependencies_key())
-                    checker.check(e->run_dependencies_key()->value(), e->run_dependencies_key()->raw_name());
+                if ((*e)->run_dependencies_key())
+                    checker.check((*e)->run_dependencies_key()->value(), (*e)->run_dependencies_key()->raw_name());
 
-                if (e->post_dependencies_key())
-                    checker.check(e->post_dependencies_key()->value(), e->post_dependencies_key()->raw_name());
+                if ((*e)->post_dependencies_key())
+                    checker.check((*e)->post_dependencies_key()->value(), (*e)->post_dependencies_key()->raw_name());
 
-                if (e->suggested_dependencies_key())
-                    checker.check(e->suggested_dependencies_key()->value(), e->suggested_dependencies_key()->raw_name());
+                if ((*e)->suggested_dependencies_key())
+                    checker.check((*e)->suggested_dependencies_key()->value(), (*e)->suggested_dependencies_key()->raw_name());
 
                 found_matches |= checker.found_matches();
             }
@@ -304,7 +307,7 @@ int do_find_reverse_deps(NoConfigEnvironment & env)
     }
 
     std::shared_ptr<const PackageIDSequence> entries(env[selection::AllVersionsSorted(generator::Matches(
-                    *spec, { }))]);
+                    *spec, make_null_shared_ptr(), { }))]);
     int ret(0);
 
     if (entries->empty())
diff --git a/src/clients/adjutrix/keywords_graph.cc b/src/clients/adjutrix/keywords_graph.cc
index 581b12787..2d0679f72 100644
--- a/src/clients/adjutrix/keywords_graph.cc
+++ b/src/clients/adjutrix/keywords_graph.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2006, 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2006, 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -27,6 +27,7 @@
 #include <paludis/util/set.hh>
 #include <paludis/util/indirect_iterator-impl.hh>
 #include <paludis/util/log.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/repository.hh>
 #include <paludis/package_database.hh>
 #include <paludis/metadata_key.hh>
@@ -86,7 +87,7 @@ namespace
         FindUnusedPackagesTask task(&e, &repo);
         std::shared_ptr<const PackageIDSequence> packages(e[selection::AllVersionsGroupedBySlot(
                 generator::InRepository(repo.name()) &
-                generator::Matches(make_package_dep_spec({ }).package(package), { }))]);
+                generator::Matches(make_package_dep_spec({ }).package(package), make_null_shared_ptr(), { }))]);
         std::shared_ptr<const PackageIDSequence> unused(task.execute(package));
 
         if (packages->empty())
diff --git a/src/clients/cave/cmd_config.cc b/src/clients/cave/cmd_config.cc
index 6ee0d2f0b..7f19c590a 100644
--- a/src/clients/cave/cmd_config.cc
+++ b/src/clients/cave/cmd_config.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2010 Ciaran McCreesh
+ * Copyright (c) 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -23,6 +23,7 @@
 #include <paludis/args/do_help.hh>
 #include <paludis/util/wrapped_forward_iterator.hh>
 #include <paludis/util/make_named_values.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/environment.hh>
 #include <paludis/package_database.hh>
 #include <paludis/repository.hh>
@@ -95,7 +96,7 @@ ConfigCommand::run(
 
     PackageDepSpec spec(parse_user_package_dep_spec(*cmdline.begin_parameters(), env.get(), { }));
     const std::shared_ptr<const PackageIDSequence> ids((*env)[selection::AllVersionsUnsorted(
-                generator::Matches(spec, { }) | filter::SupportsAction<ConfigAction>())]);
+                generator::Matches(spec, make_null_shared_ptr(), { }) | filter::SupportsAction<ConfigAction>())]);
     if (ids->empty())
         nothing_matching_error(env.get(), *cmdline.begin_parameters(), filter::SupportsAction<ConfigAction>());
     else if (1 != std::distance(ids->begin(), ids->end()))
diff --git a/src/clients/cave/cmd_contents.cc b/src/clients/cave/cmd_contents.cc
index 3758143d7..7eb9ec89d 100644
--- a/src/clients/cave/cmd_contents.cc
+++ b/src/clients/cave/cmd_contents.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -31,6 +31,7 @@
 #include <paludis/util/options.hh>
 #include <paludis/util/sequence.hh>
 #include <paludis/util/stringify.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/filter.hh>
 #include <paludis/generator.hh>
 #include <paludis/filtered_generator.hh>
@@ -129,7 +130,8 @@ ContentsCommand::run(
                 { }, filter::InstalledAtRoot(env->preferred_root_key()->value())));
 
     std::shared_ptr<const PackageIDSequence> entries(
-            (*env)[selection::AllVersionsSorted(generator::Matches(spec, { }) | filter::InstalledAtRoot(env->preferred_root_key()->value()))]);
+            (*env)[selection::AllVersionsSorted(generator::Matches(spec, make_null_shared_ptr(), { })
+                | filter::InstalledAtRoot(env->preferred_root_key()->value()))]);
 
     if (entries->empty())
         nothing_matching_error(env.get(), *cmdline.begin_parameters(), filter::InstalledAtRoot(env->preferred_root_key()->value()));
diff --git a/src/clients/cave/cmd_digest.cc b/src/clients/cave/cmd_digest.cc
index beb26c1b3..c47a153b4 100644
--- a/src/clients/cave/cmd_digest.cc
+++ b/src/clients/cave/cmd_digest.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2010 Ciaran McCreesh
+ * Copyright (c) 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -31,6 +31,7 @@
 #include <paludis/util/map.hh>
 #include <paludis/util/make_named_values.hh>
 #include <paludis/util/return_literal_function.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 
 #include <paludis/name.hh>
 #include <paludis/environment.hh>
@@ -111,7 +112,7 @@ DigestCommand::run(
         throw args::DoHelp("digest takes exactly two parameters");
 
     RepositoryName repo(*next(cmdline.begin_parameters()));
-    Filter repo_filter(filter::Matches(make_package_dep_spec({ }).in_repository(repo), { }));
+    Filter repo_filter(filter::Matches(make_package_dep_spec({ }).in_repository(repo), make_null_shared_ptr(), { }));
     QualifiedPackageName pkg(std::string::npos == cmdline.begin_parameters()->find('/') ?
             env->package_database()->fetch_unique_qualified_package_name(PackageNamePart(*cmdline.begin_parameters()), repo_filter) :
             QualifiedPackageName(*cmdline.begin_parameters()));
diff --git a/src/clients/cave/cmd_display_resolution.cc b/src/clients/cave/cmd_display_resolution.cc
index 6273c3596..b5aebc52b 100755
--- a/src/clients/cave/cmd_display_resolution.cc
+++ b/src/clients/cave/cmd_display_resolution.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -317,7 +317,7 @@ namespace
     {
         const std::shared_ptr<const PackageID> maybe_id(id_for_decision_or_null(decision));
         if (maybe_id)
-            return match_package(*env, spec, maybe_id, { });
+            return match_package(*env, spec, maybe_id, make_null_shared_ptr(), { });
         else
         {
             /* could also match slot here too */
@@ -1417,8 +1417,8 @@ namespace
                 cout << fuc(fs_unable_unsuitable_did_not_meet(), fv<'s'>(s));
 
                 if ((*c)->spec().if_package() && (*c)->spec().if_package()->additional_requirements_ptr() &&
-                        (! match_package(*env, *(*c)->spec().if_package(), u->package_id(), { })) &&
-                        match_package(*env, *(*c)->spec().if_package(), u->package_id(), { mpo_ignore_additional_requirements }))
+                        (! match_package(*env, *(*c)->spec().if_package(), u->package_id(), (*c)->from_id(), { })) &&
+                        match_package(*env, *(*c)->spec().if_package(), u->package_id(), (*c)->from_id(), { mpo_ignore_additional_requirements }))
                 {
                     for (AdditionalPackageDepSpecRequirements::ConstIterator a((*c)->spec().if_package()->additional_requirements_ptr()->begin()),
                             a_end((*c)->spec().if_package()->additional_requirements_ptr()->end()) ;
diff --git a/src/clients/cave/cmd_execute_resolution.cc b/src/clients/cave/cmd_execute_resolution.cc
index 3f3b682c6..d5d499686 100644
--- a/src/clients/cave/cmd_execute_resolution.cc
+++ b/src/clients/cave/cmd_execute_resolution.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -148,7 +148,7 @@ namespace
             const PackageDepSpec & spec)
     {
         const std::shared_ptr<const PackageIDSequence> ids((*env)[selection::BestVersionOnly(
-                    generator::Matches(spec, { }))]);
+                    generator::Matches(spec, make_null_shared_ptr(), { }))]);
         if (ids->empty())
             return stringify(spec);
         else
@@ -307,7 +307,7 @@ namespace
                 else
                     r.append(", ");
 
-                const auto replacing_ids((*env)[selection::BestVersionOnly(generator::Matches(*i, { }))]);
+                const auto replacing_ids((*env)[selection::BestVersionOnly(generator::Matches(*i, make_null_shared_ptr(), { }))]);
                 if (replacing_ids->empty())
                     r.append(stringify(*i));
                 else if (id_specs->empty() || *id_specs->begin()->package_ptr() != (*replacing_ids->begin())->name())
@@ -332,7 +332,7 @@ namespace
                 if (! r.empty())
                     r.append(", ");
 
-                const auto ids((*env)[selection::BestVersionOnly(generator::Matches(*i, { }))]);
+                const auto ids((*env)[selection::BestVersionOnly(generator::Matches(*i, make_null_shared_ptr(), { }))]);
                 if (ids->empty())
                     r.append(stringify(*i));
                 else
@@ -1591,7 +1591,7 @@ namespace
             std::string r;
             if (! j.replacing_specs()->empty())
             {
-                const auto origin_ids((*env)[selection::BestVersionOnly(generator::Matches(j.origin_id_spec(), { }))]);
+                const auto origin_ids((*env)[selection::BestVersionOnly(generator::Matches(j.origin_id_spec(), make_null_shared_ptr(), { }))]);
 
                 for (auto i(j.replacing_specs()->begin()), i_end(j.replacing_specs()->end()) ;
                         i != i_end ; ++i)
@@ -1601,7 +1601,7 @@ namespace
                     else
                         r.append(", ");
 
-                    const auto ids((*env)[selection::BestVersionOnly(generator::Matches(*i, { }))]);
+                    const auto ids((*env)[selection::BestVersionOnly(generator::Matches(*i, make_null_shared_ptr(), { }))]);
                     if (ids->empty())
                         r.append(stringify(*i));
                     else if (origin_ids->empty() || (*origin_ids->begin())->name() != (*ids->begin())->name())
diff --git a/src/clients/cave/cmd_find_candidates.cc b/src/clients/cave/cmd_find_candidates.cc
index 215b40aa8..e0346a110 100644
--- a/src/clients/cave/cmd_find_candidates.cc
+++ b/src/clients/cave/cmd_find_candidates.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2010 Ciaran McCreesh
+ * Copyright (c) 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -43,6 +43,7 @@
 #include <paludis/util/make_shared_copy.hh>
 #include <paludis/util/indirect_iterator-impl.hh>
 #include <paludis/util/simple_visitor_cast.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 
 #include <cstdlib>
 #include <iostream>
@@ -193,7 +194,7 @@ FindCandidatesCommand::run_hosted(
                 for (auto m(matches.begin()), m_end(matches.end()) ;
                         m != m_end ; ++m)
                     if (match_package(*env, *m, *(*env)[selection::RequireExactlyOne(generator::Matches(
-                                        parse_user_package_dep_spec(*s, env.get(), { }), { }))]->begin(), { }))
+                                        parse_user_package_dep_spec(*s, env.get(), { }), make_null_shared_ptr(), { }))]->begin(), make_null_shared_ptr(), { }))
                     {
                         ok = true;
                         break;
@@ -298,7 +299,7 @@ FindCandidatesCommand::run_hosted(
                 k_end(search_options.a_matching.end_args()) ;
                 k != k_end ; ++k)
         {
-            generator::Matches m(parse_user_package_dep_spec(*k, env.get(), { updso_allow_wildcards }), { });
+            generator::Matches m(parse_user_package_dep_spec(*k, env.get(), { updso_allow_wildcards }), make_null_shared_ptr(), { });
 
             if (match_generator)
                 match_generator = std::make_shared<generator::Union>(*match_generator, m);
diff --git a/src/clients/cave/cmd_has_version.cc b/src/clients/cave/cmd_has_version.cc
index 3015fcbaa..b96bed002 100644
--- a/src/clients/cave/cmd_has_version.cc
+++ b/src/clients/cave/cmd_has_version.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2010 Ciaran McCreesh
+ * Copyright (c) 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -29,6 +29,7 @@
 #include <paludis/util/indirect_iterator-impl.hh>
 #include <paludis/util/simple_visitor_cast.hh>
 #include <paludis/util/map.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/generator.hh>
 #include <paludis/filtered_generator.hh>
 #include <paludis/filter.hh>
@@ -96,7 +97,7 @@ HasVersionCommand::run(
         throw args::DoHelp("has-version takes exactly one parameter");
 
     auto s(parse_user_package_dep_spec(*cmdline.begin_parameters(), env.get(), { }));
-    auto ids((*env)[selection::BestVersionOnly(generator::Matches(s, { }) | filter::InstalledAtRoot(
+    auto ids((*env)[selection::BestVersionOnly(generator::Matches(s, make_null_shared_ptr(), { }) | filter::InstalledAtRoot(
                     env->preferred_root_key()->value()))]);
 
     if (ids->empty())
diff --git a/src/clients/cave/cmd_info.cc b/src/clients/cave/cmd_info.cc
index 3f621dc1f..24056a1d2 100644
--- a/src/clients/cave/cmd_info.cc
+++ b/src/clients/cave/cmd_info.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2010 Ciaran McCreesh
+ * Copyright (c) 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -376,9 +376,9 @@ namespace
         PackageDepSpec spec(parse_user_package_dep_spec(param, env.get(), { }));
 
         const std::shared_ptr<const PackageIDSequence> installed_ids((*env)[selection::AllVersionsSorted(generator::Matches(
-                        spec, { }) | filter::InstalledAtRoot(env->preferred_root_key()->value()))]);
+                        spec, make_null_shared_ptr(), { }) | filter::InstalledAtRoot(env->preferred_root_key()->value()))]);
         const std::shared_ptr<const PackageIDSequence> installable_ids((*env)[selection::BestVersionOnly(generator::Matches(
-                        spec, { }) | filter::SupportsAction<InstallAction>() | filter::NotMasked())]);
+                        spec, make_null_shared_ptr(), { }) | filter::SupportsAction<InstallAction>() | filter::NotMasked())]);
 
         if (installed_ids->empty() && installable_ids->empty())
             nothing_matching_error(env.get(), param, filter::InstalledAtRoot(env->preferred_root_key()->value()));
diff --git a/src/clients/cave/cmd_match.cc b/src/clients/cave/cmd_match.cc
index 058c25150..dfe5b01d7 100644
--- a/src/clients/cave/cmd_match.cc
+++ b/src/clients/cave/cmd_match.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2010 Ciaran McCreesh
+ * Copyright (c) 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -32,6 +32,7 @@
 #include <paludis/util/iterator_funcs.hh>
 #include <paludis/util/singleton-impl.hh>
 #include <paludis/util/accept_visitor.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/generator.hh>
 #include <paludis/filtered_generator.hh>
 #include <paludis/filter.hh>
@@ -409,7 +410,7 @@ MatchCommand::run_hosted(
         const PackageDepSpec & spec)
 {
     const std::shared_ptr<const PackageID> id(*((*env)[selection::RequireExactlyOne(
-                    generator::Matches(spec, { }))])->begin());
+                    generator::Matches(spec, make_null_shared_ptr(), { }))])->begin());
 
     std::list<std::string> texts;
 
diff --git a/src/clients/cave/cmd_perform.cc b/src/clients/cave/cmd_perform.cc
index f8228d93d..2dcdf172c 100644
--- a/src/clients/cave/cmd_perform.cc
+++ b/src/clients/cave/cmd_perform.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -409,7 +409,7 @@ PerformCommand::run(
 
     const auto spec_str(*next(cmdline.begin_parameters()));
     const auto spec(parse_user_package_dep_spec(spec_str, env.get(), { }));
-    const auto ids((*env)[selection::AllVersionsUnsorted(generator::Matches(spec, { }))]);
+    const auto ids((*env)[selection::AllVersionsUnsorted(generator::Matches(spec, make_null_shared_ptr(), { }))]);
     if (ids->empty())
         nothing_matching_error(env.get(), spec_str, filter::All());
     else if (1 != std::distance(ids->begin(), ids->end()))
@@ -429,7 +429,7 @@ PerformCommand::run(
             p != p_end ; ++p)
     {
         PackageDepSpec rspec(parse_user_package_dep_spec(*p, env.get(), { }));
-        const std::shared_ptr<const PackageIDSequence> rids((*env)[selection::AllVersionsUnsorted(generator::Matches(rspec, { }))]);
+        const std::shared_ptr<const PackageIDSequence> rids((*env)[selection::AllVersionsUnsorted(generator::Matches(rspec, make_null_shared_ptr(), { }))]);
         if (rids->empty())
             nothing_matching_error(env.get(), *p, filter::All());
         else if (1 != std::distance(rids->begin(), rids->end()))
diff --git a/src/clients/cave/cmd_print_best_version.cc b/src/clients/cave/cmd_print_best_version.cc
index 5059ebf19..e39489c30 100644
--- a/src/clients/cave/cmd_print_best_version.cc
+++ b/src/clients/cave/cmd_print_best_version.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2010 Ciaran McCreesh
+ * Copyright (c) 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -29,6 +29,7 @@
 #include <paludis/util/indirect_iterator-impl.hh>
 #include <paludis/util/simple_visitor_cast.hh>
 #include <paludis/util/map.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/generator.hh>
 #include <paludis/filtered_generator.hh>
 #include <paludis/filter.hh>
@@ -108,7 +109,7 @@ PrintBestVersionCommand::run(
         throw args::DoHelp("print-best-version takes exactly one parameter");
 
     auto s(parse_user_package_dep_spec(*cmdline.begin_parameters(), env.get(), { }));
-    auto ids((*env)[selection::BestVersionOnly(generator::Matches(s, { }) | filter::InstalledAtRoot(
+    auto ids((*env)[selection::BestVersionOnly(generator::Matches(s, make_null_shared_ptr(), { }) | filter::InstalledAtRoot(
                     env->preferred_root_key()->value()))]);
 
     if (ids->empty())
diff --git a/src/clients/cave/cmd_print_id_actions.cc b/src/clients/cave/cmd_print_id_actions.cc
index 8e696e771..473dfee13 100644
--- a/src/clients/cave/cmd_print_id_actions.cc
+++ b/src/clients/cave/cmd_print_id_actions.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2010 Ciaran McCreesh
+ * Copyright (c) 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -24,6 +24,7 @@
 #include <paludis/util/set.hh>
 #include <paludis/util/iterator_funcs.hh>
 #include <paludis/util/stringify.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/environment.hh>
 #include <paludis/user_dep_spec.hh>
 #include <paludis/filtered_generator.hh>
@@ -107,7 +108,7 @@ PrintIDActionsCommand::run(
     PackageDepSpec spec(parse_user_package_dep_spec(*cmdline.begin_parameters(), env.get(), { updso_allow_wildcards }));
 
     std::shared_ptr<const PackageIDSequence> entries(
-            (*env)[selection::AllVersionsSorted(generator::Matches(spec, { }))]);
+            (*env)[selection::AllVersionsSorted(generator::Matches(spec, make_null_shared_ptr(), { }))]);
 
     if (entries->empty())
         throw NothingMatching(spec);
diff --git a/src/clients/cave/cmd_print_id_contents.cc b/src/clients/cave/cmd_print_id_contents.cc
index 416179245..f60db7c4f 100644
--- a/src/clients/cave/cmd_print_id_contents.cc
+++ b/src/clients/cave/cmd_print_id_contents.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -29,6 +29,7 @@
 #include <paludis/util/iterator_funcs.hh>
 #include <paludis/util/options.hh>
 #include <paludis/util/sequence.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/filter.hh>
 #include <paludis/generator.hh>
 #include <paludis/filtered_generator.hh>
@@ -160,7 +161,8 @@ PrintIDContentsCommand::run(
                 { updso_allow_wildcards }, filter::InstalledAtRoot(env->preferred_root_key()->value())));
 
     std::shared_ptr<const PackageIDSequence> entries(
-            (*env)[selection::AllVersionsSorted(generator::Matches(spec, { }) | filter::InstalledAtRoot(env->preferred_root_key()->value()))]);
+            (*env)[selection::AllVersionsSorted(generator::Matches(spec, make_null_shared_ptr(), { }) |
+                filter::InstalledAtRoot(env->preferred_root_key()->value()))]);
 
     if (entries->empty())
         throw NothingMatching(spec);
diff --git a/src/clients/cave/cmd_print_id_environment_variable.cc b/src/clients/cave/cmd_print_id_environment_variable.cc
index b7c96e94a..9e7b372f6 100644
--- a/src/clients/cave/cmd_print_id_environment_variable.cc
+++ b/src/clients/cave/cmd_print_id_environment_variable.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2008, 2009, 2010, 2011 Ciaran McCreesh
  * Copyright (c) 2010 David Leverton
  *
  * This file is part of the Paludis package manager. Paludis is free software;
@@ -24,6 +24,7 @@
 #include <paludis/args/args.hh>
 #include <paludis/args/do_help.hh>
 #include <paludis/util/map.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/environment.hh>
 #include <paludis/user_dep_spec.hh>
 #include <paludis/filtered_generator.hh>
@@ -134,7 +135,7 @@ PrintIDEnvironmentVariableCommand::run(
     PackageDepSpec spec(parse_user_package_dep_spec(*cmdline.begin_parameters(), env.get(), { updso_allow_wildcards }));
 
     std::shared_ptr<const PackageIDSequence> entries(
-            (*env)[selection::AllVersionsSorted(generator::Matches(spec, { }))]);
+            (*env)[selection::AllVersionsSorted(generator::Matches(spec, make_null_shared_ptr(), { }))]);
 
     if (entries->empty())
         throw NothingMatching(spec);
diff --git a/src/clients/cave/cmd_print_id_masks.cc b/src/clients/cave/cmd_print_id_masks.cc
index 3f509417d..1937eb6aa 100644
--- a/src/clients/cave/cmd_print_id_masks.cc
+++ b/src/clients/cave/cmd_print_id_masks.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2010 Ciaran McCreesh
+ * Copyright (c) 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -186,7 +186,7 @@ PrintIDMasksCommand::run(
     PackageDepSpec spec(parse_user_package_dep_spec(*cmdline.begin_parameters(), env.get(), { updso_allow_wildcards }));
 
     std::shared_ptr<const PackageIDSequence> entries(
-            (*env)[selection::AllVersionsSorted(generator::Matches(spec, { }))]);
+            (*env)[selection::AllVersionsSorted(generator::Matches(spec, make_null_shared_ptr(), { }))]);
 
     if (entries->empty())
         throw NothingMatching(spec);
diff --git a/src/clients/cave/cmd_print_id_metadata.cc b/src/clients/cave/cmd_print_id_metadata.cc
index 2ce293dc0..960742561 100644
--- a/src/clients/cave/cmd_print_id_metadata.cc
+++ b/src/clients/cave/cmd_print_id_metadata.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -26,6 +26,7 @@
 #include <paludis/util/set.hh>
 #include <paludis/util/iterator_funcs.hh>
 #include <paludis/util/options.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/environment.hh>
 #include <paludis/metadata_key.hh>
 #include <paludis/user_dep_spec.hh>
@@ -151,7 +152,7 @@ PrintIDMetadataCommand::run(
     PackageDepSpec spec(parse_user_package_dep_spec(*cmdline.begin_parameters(), env.get(), { updso_allow_wildcards }));
 
     std::shared_ptr<const PackageIDSequence> entries(
-            (*env)[selection::AllVersionsSorted(generator::Matches(spec, { }))]);
+            (*env)[selection::AllVersionsSorted(generator::Matches(spec, make_null_shared_ptr(), { }))]);
 
     if (entries->empty())
         throw NothingMatching(spec);
diff --git a/src/clients/cave/cmd_print_ids.cc b/src/clients/cave/cmd_print_ids.cc
index aa1427ba9..daa5d08ee 100644
--- a/src/clients/cave/cmd_print_ids.cc
+++ b/src/clients/cave/cmd_print_ids.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -30,6 +30,7 @@
 #include <paludis/util/indirect_iterator-impl.hh>
 #include <paludis/util/simple_visitor_cast.hh>
 #include <paludis/util/map.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/generator.hh>
 #include <paludis/filtered_generator.hh>
 #include <paludis/filter.hh>
@@ -289,7 +290,7 @@ PrintIDsCommand::run(
                 m != m_end ; ++m)
         {
             PackageDepSpec s(parse_user_package_dep_spec(*m, env.get(), { updso_allow_wildcards }));
-            g = g & generator::Matches(s, { });
+            g = g & generator::Matches(s, make_null_shared_ptr(), { });
         }
     }
 
diff --git a/src/clients/cave/cmd_report.cc b/src/clients/cave/cmd_report.cc
index db8b224c0..8bbc34881 100644
--- a/src/clients/cave/cmd_report.cc
+++ b/src/clients/cave/cmd_report.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2010 Ciaran McCreesh
+ * Copyright (c) 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -110,7 +110,7 @@ namespace
                                     .version_requirement(make_named_values<VersionRequirement>(
                                             n::version_operator() = vo_equal,
                                             n::version_spec() = id->version())),
-                                    { })) |
+                                    make_null_shared_ptr(), { })) |
                             filter::SupportsAction<InstallAction>())]);
 
                 if (! ids->empty())
diff --git a/src/clients/cave/cmd_search.cc b/src/clients/cave/cmd_search.cc
index 8c5d1b16d..de06f763e 100644
--- a/src/clients/cave/cmd_search.cc
+++ b/src/clients/cave/cmd_search.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2010 Ciaran McCreesh
+ * Copyright (c) 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -48,6 +48,7 @@
 #include <paludis/util/wrapped_output_iterator.hh>
 #include <paludis/util/mutex.hh>
 #include <paludis/util/iterator_funcs.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 
 #include <cstdlib>
 #include <iostream>
@@ -113,7 +114,7 @@ namespace
             const PackageDepSpec & spec)
     {
         const std::shared_ptr<const PackageID> id(*((*env)[selection::RequireExactlyOne(
-                        generator::Matches(spec, { }))])->begin());
+                        generator::Matches(spec, make_null_shared_ptr(), { }))])->begin());
         result->insert(id->name());
     }
 
diff --git a/src/clients/cave/cmd_show.cc b/src/clients/cave/cmd_show.cc
index 7f776c7e9..fe838e91b 100644
--- a/src/clients/cave/cmd_show.cc
+++ b/src/clients/cave/cmd_show.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -176,7 +176,7 @@ namespace
 
         void visit(const SetSpecTree::NodeType<PackageDepSpec>::Type & node)
         {
-            out << fuc(select_format_for_spec(env, *node.spec(),
+            out << fuc(select_format_for_spec(env, *node.spec(), make_null_shared_ptr(),
                         fs_set_spec_installed(),
                         fs_set_spec_installable(),
                         fs_set_spec_unavailable()),
@@ -226,7 +226,7 @@ namespace
     {
         cout << fuc(fs_wildcard_heading(), fv<'s'>(stringify(s)));
 
-        const std::shared_ptr<const PackageIDSequence> names((*env)[selection::BestVersionOnly(generator::Matches(s, { }))]);
+        const std::shared_ptr<const PackageIDSequence> names((*env)[selection::BestVersionOnly(generator::Matches(s, make_null_shared_ptr(), { }))]);
         if (names->empty())
             throw NothingMatching(s);
 
@@ -234,7 +234,7 @@ namespace
                 i != i_end ; ++i)
         {
             PackageDepSpec name_spec(make_package_dep_spec({ }).package((*i)->name()));
-            cout << fuc(select_format_for_spec(env, name_spec,
+            cout << fuc(select_format_for_spec(env, name_spec, make_null_shared_ptr(),
                         fs_wildcard_spec_installed(),
                         fs_wildcard_spec_installable(),
                         fs_wildcard_spec_unavailable()
@@ -1259,7 +1259,7 @@ namespace
     {
         cout << fuc(fs_package_heading(), fv<'s'>(stringify(s)));
 
-        auto ids((*env)[selection::AllVersionsGroupedBySlot(generator::Matches(s, { }))]);
+        auto ids((*env)[selection::AllVersionsGroupedBySlot(generator::Matches(s, make_null_shared_ptr(), { }))]);
         if (ids->empty())
             throw NothingMatching(s);
 
@@ -1274,7 +1274,7 @@ namespace
             for (auto r(repos.begin()), r_end(repos.end()) ; r != r_end ; ++r)
             {
                 auto r_ids((*env)[selection::AllVersionsGroupedBySlot(generator::Matches(
-                                PartiallyMadePackageDepSpec(s).in_repository(*r), { }))]);
+                                PartiallyMadePackageDepSpec(s).in_repository(*r), make_null_shared_ptr(), { }))]);
                 if (! r_ids->empty())
                     do_one_package_with_ids(cmdline, env, s, r_ids, cout, rest_out);
             }
@@ -1294,7 +1294,7 @@ namespace
             const PackageDepSpec & s)
     {
         const std::shared_ptr<const PackageIDSequence> ids((*env)[selection::BestVersionOnly(generator::Matches(s,
-                        { }))]);
+                        make_null_shared_ptr(), { }))]);
         if (ids->empty())
             throw NothingMatching(s);
 
diff --git a/src/clients/cave/cmd_uninstall.cc b/src/clients/cave/cmd_uninstall.cc
index d7829fc93..5f5798e7e 100644
--- a/src/clients/cave/cmd_uninstall.cc
+++ b/src/clients/cave/cmd_uninstall.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2010 Ciaran McCreesh
+ * Copyright (c) 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -142,7 +142,7 @@ UninstallCommand::run(
     {
         PackageDepSpec spec(parse_user_package_dep_spec(*p, env.get(), { updso_allow_wildcards }));
         const std::shared_ptr<const PackageIDSequence> ids((*env)[selection::AllVersionsSorted(
-                    generator::Matches(spec, { }) | filter::SupportsAction<UninstallAction>())]);
+                    generator::Matches(spec, make_null_shared_ptr(), { }) | filter::SupportsAction<UninstallAction>())]);
         if (ids->empty())
             nothing_matching_error(env.get(), *p, filter::SupportsAction<UninstallAction>());
         else if ((! cmdline.a_all_versions.specified()) && has_multiple_versions(ids))
diff --git a/src/clients/cave/cmd_verify.cc b/src/clients/cave/cmd_verify.cc
index 8139be2c8..624ee8ef1 100644
--- a/src/clients/cave/cmd_verify.cc
+++ b/src/clients/cave/cmd_verify.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2010 Ciaran McCreesh
+ * Copyright (c) 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -32,6 +32,7 @@
 #include <paludis/util/simple_visitor_cast.hh>
 #include <paludis/util/md5.hh>
 #include <paludis/util/fs_stat.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <paludis/environment.hh>
 #include <paludis/package_database.hh>
 #include <paludis/repository.hh>
@@ -213,7 +214,8 @@ VerifyCommand::run(
                 { updso_allow_wildcards }, filter::InstalledAtRoot(env->preferred_root_key()->value())));
 
     std::shared_ptr<const PackageIDSequence> entries(
-            (*env)[selection::AllVersionsSorted(generator::Matches(spec, { }) | filter::InstalledAtRoot(env->preferred_root_key()->value()))]);
+            (*env)[selection::AllVersionsSorted(generator::Matches(spec, make_null_shared_ptr(), { }) |
+                filter::InstalledAtRoot(env->preferred_root_key()->value()))]);
 
     if (entries->empty())
         nothing_matching_error(env.get(), *cmdline.begin_parameters(), filter::InstalledAtRoot(env->preferred_root_key()->value()));
diff --git a/src/clients/cave/executables_common.cc b/src/clients/cave/executables_common.cc
index a255a29ea..73dd0418a 100644
--- a/src/clients/cave/executables_common.cc
+++ b/src/clients/cave/executables_common.cc
@@ -2,7 +2,7 @@
 
 /*
  * Copyright (c) 2009 Alexander Færøy
- * Copyright (c) 2010 Ciaran McCreesh
+ * Copyright (c) 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -37,6 +37,7 @@
 #include <paludis/util/system.hh>
 #include <paludis/util/tokeniser.hh>
 #include <paludis/util/accept_visitor.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 
 #include <algorithm>
 #include <set>
@@ -115,7 +116,7 @@ paludis::cave::executables_common(
                 filter::InstalledAtRoot(env->preferred_root_key()->value())));
 
     std::shared_ptr<const PackageIDSequence> entries(
-            (*env)[selection::AllVersionsSorted(generator::Matches(spec, { }) |
+            (*env)[selection::AllVersionsSorted(generator::Matches(spec, make_null_shared_ptr(), { }) |
                 filter::InstalledAtRoot(env->preferred_root_key()->value()))]);
 
     if (entries->empty())
diff --git a/src/clients/cave/resolve_common.cc b/src/clients/cave/resolve_common.cc
index e554495be..210ab4382 100644
--- a/src/clients/cave/resolve_common.cc
+++ b/src/clients/cave/resolve_common.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -791,7 +791,7 @@ paludis::cave::resolve_common(
     for (args::StringSetArg::ConstIterator i(resolution_options.a_preset.begin_args()),
             i_end(resolution_options.a_preset.end_args()) ;
             i != i_end ; ++i)
-        get_initial_constraints_for_helper.add_preset_spec(parse_user_package_dep_spec(*i, env.get(), { updso_allow_wildcards }));
+        get_initial_constraints_for_helper.add_preset_spec(parse_user_package_dep_spec(*i, env.get(), { updso_allow_wildcards }), make_null_shared_ptr());
 
     get_initial_constraints_for_helper.set_reinstall_scm_days(reinstall_scm_days(resolution_options));
 
diff --git a/src/clients/cave/select_format_for_spec.cc b/src/clients/cave/select_format_for_spec.cc
index 94be4a937..5a59b6d73 100644
--- a/src/clients/cave/select_format_for_spec.cc
+++ b/src/clients/cave/select_format_for_spec.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2008, 2010 Ciaran McCreesh
+ * Copyright (c) 2008, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -35,14 +35,15 @@ T_
 paludis::cave::select_format_for_spec(
         const std::shared_ptr<const Environment> & env,
         const PackageDepSpec & spec,
+        const std::shared_ptr<const PackageID> & from_id,
         const T_ & if_installed,
         const T_ & if_installable,
         const T_ & if_unavailable
         )
 {
-    if (! (*env)[selection::SomeArbitraryVersion(generator::Matches(spec, { }) | filter::InstalledAtRoot(env->system_root_key()->value()))]->empty())
+    if (! (*env)[selection::SomeArbitraryVersion(generator::Matches(spec, from_id, { }) | filter::InstalledAtRoot(env->system_root_key()->value()))]->empty())
         return if_installed;
-    if (! (*env)[selection::SomeArbitraryVersion(generator::Matches(spec, { }) | filter::SupportsAction<InstallAction>()
+    if (! (*env)[selection::SomeArbitraryVersion(generator::Matches(spec, from_id, { }) | filter::SupportsAction<InstallAction>()
                 | filter::NotMasked())]->empty())
         return if_installable;
     return if_unavailable;
@@ -51,6 +52,7 @@ paludis::cave::select_format_for_spec(
 template std::string paludis::cave::select_format_for_spec(
         const std::shared_ptr<const Environment> & env,
         const PackageDepSpec & spec,
+        const std::shared_ptr<const PackageID> & from_id,
         const std::string & if_installed,
         const std::string & if_installable,
         const std::string & if_unavailable
@@ -59,6 +61,7 @@ template std::string paludis::cave::select_format_for_spec(
 template FormatString<'i', 's'> paludis::cave::select_format_for_spec(
         const std::shared_ptr<const Environment> & env,
         const PackageDepSpec & spec,
+        const std::shared_ptr<const PackageID> & from_id,
         const FormatString<'i', 's'> & if_installed,
         const FormatString<'i', 's'> & if_installable,
         const FormatString<'i', 's'> & if_unavailable
@@ -67,6 +70,7 @@ template FormatString<'i', 's'> paludis::cave::select_format_for_spec(
 template FormatString<'s'> paludis::cave::select_format_for_spec(
         const std::shared_ptr<const Environment> & env,
         const PackageDepSpec & spec,
+        const std::shared_ptr<const PackageID> & from_id,
         const FormatString<'s'> & if_installed,
         const FormatString<'s'> & if_installable,
         const FormatString<'s'> & if_unavailable
diff --git a/src/clients/cave/select_format_for_spec.hh b/src/clients/cave/select_format_for_spec.hh
index a946e772d..a967607d5 100644
--- a/src/clients/cave/select_format_for_spec.hh
+++ b/src/clients/cave/select_format_for_spec.hh
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2008, 2010 Ciaran McCreesh
+ * Copyright (c) 2008, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -23,7 +23,9 @@
 #include <paludis/util/attributes.hh>
 #include <paludis/environment-fwd.hh>
 #include <paludis/dep_spec-fwd.hh>
+#include <paludis/package_id-fwd.hh>
 #include <string>
+#include <memory>
 
 namespace paludis
 {
@@ -33,6 +35,7 @@ namespace paludis
         T_ select_format_for_spec(
                 const std::shared_ptr<const Environment> &,
                 const PackageDepSpec &,
+                const std::shared_ptr<const PackageID> & from_id,
                 const T_ & if_installed,
                 const T_ & if_installable,
                 const T_ & if_unavailable
diff --git a/src/clients/cave/size_common.cc b/src/clients/cave/size_common.cc
index 9559e01d8..8bcace5b8 100644
--- a/src/clients/cave/size_common.cc
+++ b/src/clients/cave/size_common.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2010 Ciaran McCreesh
+ * Copyright (c) 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -39,6 +39,7 @@
 #include <paludis/util/fs_path.hh>
 #include <paludis/util/fs_stat.hh>
 #include <paludis/util/iterator_funcs.hh>
+#include <paludis/util/make_null_shared_ptr.hh>
 #include <algorithm>
 #include <functional>
 #include <iostream>
@@ -93,7 +94,7 @@ paludis::cave::size_common(
         const bool best)
 {
     PackageDepSpec spec(parse_user_package_dep_spec(q, env.get(), { }));
-    std::shared_ptr<const PackageIDSequence> entries((*env)[selection::AllVersionsSorted(generator::Matches(spec, { }) |
+    std::shared_ptr<const PackageIDSequence> entries((*env)[selection::AllVersionsSorted(generator::Matches(spec, make_null_shared_ptr(), { }) |
                 filter::InstalledAtRoot(env->preferred_root_key()->value()))]);
 
     if (entries->empty())
diff --git a/src/clients/paludis/applets.cc b/src/clients/paludis/applets.cc
index 04982ab42..92a191278 100644
--- a/src/clients/paludis/applets.cc
+++ b/src/clients/paludis/applets.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2006, 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2006, 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -187,7 +187,7 @@ int do_has_version(const std::shared_ptr<Environment> & env)
     std::shared_ptr<PackageDepSpec> spec(std::make_shared<PackageDepSpec>(
                 parse_user_package_dep_spec(query, env.get(), { })));
     std::shared_ptr<const PackageIDSequence> entries((*env)[selection::SomeArbitraryVersion(
-                generator::Matches(*spec, { }) | filter::InstalledAtRoot(env->preferred_root_key()->value()))]);
+                generator::Matches(*spec, make_null_shared_ptr(), { }) | filter::InstalledAtRoot(env->preferred_root_key()->value()))]);
 
     if (entries->empty())
         return_code = 1;
@@ -205,7 +205,7 @@ int do_best_version(const std::shared_ptr<Environment> & env)
     std::shared_ptr<PackageDepSpec> spec(std::make_shared<PackageDepSpec>(
                 parse_user_package_dep_spec(query, env.get(), { })));
     std::shared_ptr<const PackageIDSequence> entries((*env)[selection::AllVersionsSorted(
-                generator::Matches(*spec, { }) | filter::InstalledAtRoot(env->preferred_root_key()->value()))]);
+                generator::Matches(*spec, make_null_shared_ptr(), { }) | filter::InstalledAtRoot(env->preferred_root_key()->value()))]);
 
     /* make built_with_use work for virtuals... icky... */
     while (! entries->empty())
@@ -246,7 +246,7 @@ int do_match(const std::shared_ptr<Environment> & env)
     std::shared_ptr<PackageDepSpec> spec(std::make_shared<PackageDepSpec>(
                 parse_user_package_dep_spec(query, env.get(), { })));
     std::shared_ptr<const PackageIDSequence> entries((*env)[selection::AllVersionsSorted(
-                generator::Matches(*spec, { }) | filter::InstalledAtRoot(env->preferred_root_key()->value()))]);
+                generator::Matches(*spec, make_null_shared_ptr(), { }) | filter::InstalledAtRoot(env->preferred_root_key()->value()))]);
 
     while (! entries->empty())
     {
@@ -291,10 +291,10 @@ int do_environment_variable(const std::shared_ptr<Environment> & env)
                 parse_user_package_dep_spec(spec_str, env.get(), { })));
 
     std::shared_ptr<const PackageIDSequence> entries((*env)[selection::AllVersionsSorted(
-                generator::Matches(*spec, { }) | filter::InstalledAtRoot(env->preferred_root_key()->value()))]);
+                generator::Matches(*spec, make_null_shared_ptr(), { }) | filter::InstalledAtRoot(env->preferred_root_key()->value()))]);
 
     if (entries->empty())
-        entries = (*env)[selection::AllVersionsSorted(generator::Matches(*spec, { }))];
+        entries = (*env)[selection::AllVersionsSorted(generator::Matches(*spec, make_null_shared_ptr(), { }))];
 
     if (entries->empty())
         throw NoSuchPackageError(spec_str);
diff --git a/src/clients/paludis/do_config.cc b/src/clients/paludis/do_config.cc
index c1d14ee90..d78a31c66 100644
--- a/src/clients/paludis/do_config.cc
+++ b/src/clients/paludis/do_config.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -81,7 +81,8 @@ namespace
                         filter::InstalledAtRoot(env->preferred_root_key()->value()))));
 
         std::shared_ptr<const PackageIDSequence> entries(
-                (*env)[selection::AllVersionsUnsorted(generator::Matches(*spec, { }) | filter::InstalledAtRoot(env->preferred_root_key()->value()))]);
+                (*env)[selection::AllVersionsUnsorted(generator::Matches(*spec, make_null_shared_ptr(), { })
+                    | filter::InstalledAtRoot(env->preferred_root_key()->value()))]);
 
         if (entries->empty())
             throw NoSuchPackageError(target);
diff --git a/src/clients/paludis/do_contents.cc b/src/clients/paludis/do_contents.cc
index e15189e08..3e7c726f2 100644
--- a/src/clients/paludis/do_contents.cc
+++ b/src/clients/paludis/do_contents.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2006, 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2006, 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -87,7 +87,8 @@ do_one_contents(
                     filter::InstalledAtRoot(env->preferred_root_key()->value()))));
 
     std::shared_ptr<const PackageIDSequence> entries(
-            (*env)[selection::AllVersionsSorted(generator::Matches(*spec, { }) | filter::InstalledAtRoot(env->preferred_root_key()->value()))]);
+            (*env)[selection::AllVersionsSorted(generator::Matches(*spec, make_null_shared_ptr(), { })
+                | filter::InstalledAtRoot(env->preferred_root_key()->value()))]);
 
     if (entries->empty())
         throw NoSuchPackageError(q);
diff --git a/src/clients/paludis/do_executables.cc b/src/clients/paludis/do_executables.cc
index 2b94dd8a9..143f1d481 100644
--- a/src/clients/paludis/do_executables.cc
+++ b/src/clients/paludis/do_executables.cc
@@ -139,7 +139,8 @@ do_one_executables(
                     filter::InstalledAtRoot(env->preferred_root_key()->value()))));
 
     std::shared_ptr<const PackageIDSequence> entries(
-            (*env)[selection::AllVersionsSorted(generator::Matches(*spec, { }) | filter::InstalledAtRoot(env->preferred_root_key()->value()))]);
+            (*env)[selection::AllVersionsSorted(generator::Matches(*spec, make_null_shared_ptr(), { })
+                | filter::InstalledAtRoot(env->preferred_root_key()->value()))]);
 
     if (entries->empty())
         throw NoSuchPackageError(q);
diff --git a/src/clients/paludis/info.cc b/src/clients/paludis/info.cc
index 94d37b98a..fd8e02566 100644
--- a/src/clients/paludis/info.cc
+++ b/src/clients/paludis/info.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -239,11 +239,11 @@ int do_one_info(
             std::make_shared<PackageDepSpec>(parse_user_package_dep_spec(q, env.get(), { })));
 
     std::shared_ptr<const PackageIDSequence>
-        entries((*env)[selection::AllVersionsSorted(generator::Matches(*spec, { }))]),
+        entries((*env)[selection::AllVersionsSorted(generator::Matches(*spec, make_null_shared_ptr(), { }))]),
         installed_entries((*env)[selection::AllVersionsSorted(
-                    generator::Matches(*spec, { }) | filter::InstalledAtRoot(env->preferred_root_key()->value()))]),
+                    generator::Matches(*spec, make_null_shared_ptr(), { }) | filter::InstalledAtRoot(env->preferred_root_key()->value()))]),
         installable_entries((*env)[selection::AllVersionsSorted(
-                    generator::Matches(*spec, { }) | filter::SupportsAction<InstallAction>() | filter::NotMasked())]);
+                    generator::Matches(*spec, make_null_shared_ptr(), { }) | filter::SupportsAction<InstallAction>() | filter::NotMasked())]);
 
     std::shared_ptr<PackageIDSequence> to_show_entries(std::make_shared<PackageIDSequence>());
 
diff --git a/src/output/console_install_task.cc b/src/output/console_install_task.cc
index fdcbea2bf..f6d922aa8 100644
--- a/src/output/console_install_task.cc
+++ b/src/output/console_install_task.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2006, 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2006, 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -512,16 +512,16 @@ ConsoleInstallTask::on_display_merge_list_entry(const DepListEntry & d)
 
     std::shared_ptr<const PackageIDSequence> existing_repo((*environment())[selection::AllVersionsSorted(repo ?
                 generator::Matches(make_package_dep_spec({ })
-                    .package(d.package_id()->name()).in_repository(*repo), { }) :
+                    .package(d.package_id()->name()).in_repository(*repo), d.package_id(), { }) :
                 generator::Matches(make_package_dep_spec({ })
-                    .package(d.package_id()->name()), { }) | filter::InstalledAtRoot(environment()->preferred_root_key()->value())
+                    .package(d.package_id()->name()), d.package_id(), { }) | filter::InstalledAtRoot(environment()->preferred_root_key()->value())
                 )]);;
 
     std::shared_ptr<const PackageIDSequence> existing_slot_repo((*environment())[selection::AllVersionsSorted((repo ?
                     generator::Matches(make_package_dep_spec({ })
-                        .package(d.package_id()->name()).in_repository(*repo), { }) :
+                        .package(d.package_id()->name()).in_repository(*repo), d.package_id(), { }) :
                     generator::Matches(make_package_dep_spec({ })
-                        .package(d.package_id()->name()), { }) | filter::InstalledAtRoot(environment()->preferred_root_key()->value()))
+                        .package(d.package_id()->name()), d.package_id(), { }) | filter::InstalledAtRoot(environment()->preferred_root_key()->value()))
                 | filter::SameSlot(d.package_id()))]);
 
     display_merge_list_entry_start(d, m);
@@ -1430,8 +1430,10 @@ ConsoleInstallTask::display_merge_list_entry_package_tags(const DepListEntry & d
 
         std::shared_ptr<const PackageDepSpec> spec(
             std::static_pointer_cast<const DependencyDepTag>(tag->tag())->dependency());
+        std::shared_ptr<const PackageID> id(
+                std::static_pointer_cast<const DependencyDepTag>(tag->tag())->package_id());
         if (d.kind() != dlk_masked && d.kind() != dlk_block && (*environment())[selection::SomeArbitraryVersion(
-                generator::Matches(*spec, { }) |
+                generator::Matches(*spec, id, { }) |
                 filter::InstalledAtRoot(environment()->preferred_root_key()->value()))]->empty())
             unsatisfied_dependents.insert(tag->tag()->short_text());
         else
@@ -1670,7 +1672,7 @@ ConsoleInstallTask::on_all_masked_error(const AllMaskedError & e)
     {
         std::shared_ptr<const PackageIDSequence> p(
                 (*environment())[selection::AllVersionsSorted(
-                    generator::Matches(e.query(), { })
+                    generator::Matches(e.query(), e.from_id(), { })
                     | filter::SupportsAction<InstallAction>())]);
         if (p->empty())
         {
diff --git a/src/output/console_query_task.cc b/src/output/console_query_task.cc
index cbd7628f7..efd5b35f7 100644
--- a/src/output/console_query_task.cc
+++ b/src/output/console_query_task.cc
@@ -1,7 +1,7 @@
 /* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
 /*
- * Copyright (c) 2007, 2008, 2009, 2010 Ciaran McCreesh
+ * Copyright (c) 2007, 2008, 2009, 2010, 2011 Ciaran McCreesh
  *
  * This file is part of the Paludis package manager. Paludis is free software;
  * you can redistribute it and/or modify it under the terms of the GNU General
@@ -94,7 +94,7 @@ ConsoleQueryTask::show(const PackageDepSpec & a, const std::shared_ptr<const Pac
     if (! a.package_ptr())
     {
         std::shared_ptr<const PackageIDSequence> entries(
-                (*_imp->env)[selection::BestVersionOnly(generator::Matches(a, { }))]);
+                (*_imp->env)[selection::BestVersionOnly(generator::Matches(a, display_entry, { }))]);
         if (entries->empty())
             throw NoSuchPackageError(stringify(a));
 
@@ -117,9 +117,9 @@ ConsoleQueryTask::show_one(const PackageDepSpec & a, const std::shared_ptr<const
     /* prefer the best installed version, then the best visible version, then
      * the best version */
     std::shared_ptr<const PackageIDSequence>
-        entries((*_imp->env)[selection::AllVersionsSorted(generator::Matches(a, { }))]),
+        entries((*_imp->env)[selection::AllVersionsSorted(generator::Matches(a, display_entry, { }))]),
         preferred_entries((*_imp->env)[selection::AllVersionsSorted(
-                    generator::Matches(a, { }) | filter::InstalledAtRoot(_imp->env->preferred_root_key()->value()))]);
+                    generator::Matches(a, display_entry, { }) | filter::InstalledAtRoot(_imp->env->preferred_root_key()->value()))]);
     if (entries->empty())
         throw NoSuchPackageError(stringify(a));
     if (preferred_entries->empty())