silence 'unused local typedef' warning

The local typedef used for type checking is unreferenced, and causes spurious
warning with GCC 4.8.  Use an inline std::enable_if return type munging to elide
template instantiations for unrelated types.

Signed-off-by: Saleem Abdulrasool <compnerd@compnerd.org>

2 files changed, 6 insertions, 18 deletions

diff --git a/paludis/util/visitor_cast-fwd.hh b/paludis/util/visitor_cast-fwd.hh
index 5fdfa29..06ea2e4 100644
--- a/paludis/util/visitor_cast-fwd.hh
+++ b/paludis/util/visitor_cast-fwd.hh
@@ -21,10 +21,12 @@
 #define PALUDIS_GUARD_PALUDIS_UTIL_VISITOR_CAST_FWD_HH 1
 
 #include <paludis/util/attributes.hh>
+#include <type_traits>
 
 namespace paludis
 {
-    template <typename To_, typename From_>
+    template <typename To_, typename From_,
+              typename = typename std::enable_if<std::is_base_of<From_, To_>::value>::type>
     To_ * visitor_cast(From_ &) PALUDIS_ATTRIBUTE((warn_unused_result));
 }
 
diff --git a/paludis/util/visitor_cast.hh b/paludis/util/visitor_cast.hh
index 568de2d..3ef277d 100644
--- a/paludis/util/visitor_cast.hh
+++ b/paludis/util/visitor_cast.hh
@@ -40,17 +40,6 @@ namespace paludis
         }
     };
 
-    template <typename To_, typename From_, bool ok_>
-    struct VerifyVisitorCastType
-    {
-    };
-
-    template <typename To_, typename From_>
-    struct VerifyVisitorCastType<To_, From_, true>
-    {
-        typedef int IsOK;
-    };
-
     template <typename C_, typename T_>
     struct CopyConst
     {
@@ -63,13 +52,10 @@ namespace paludis
         typedef const T_ Type;
     };
 
-    template <typename To_, typename From_>
-    To_ * visitor_cast(From_ & from)
+    template <typename To_, typename From_, typename>
+    To_ *
+    visitor_cast(From_ & from)
     {
-        /* verify that we are attempting to visitor_cast something that
-         * could potentially be true */
-        typedef typename VerifyVisitorCastType<To_, From_, std::is_base_of<From_, To_>::value>::IsOK TypeIsOK;
-
         VisitorCaster<To_, typename CopyConst<From_, typename From_::VisitableBaseClass>::Type> q;
         return from.template accept_returning<To_ *>(q);
     }