ENH: Added KWSYS_CXX_HAS_ARGUMENT_DEPENDENT_LOOKUP try-compile to KWSys. ...

ENH: Added KWSYS_CXX_HAS_ARGUMENT_DEPENDENT_LOOKUP try-compile to KWSys.  Needed to optionally bring hash table comparison operators into the global namespace when argument dependent lookup is not supported.

CMakeLists.txt

@@ -205,6 +205,8 @@ KWSYS_PLATFORM_CXX_TEST(KWSYS_CXX_HAS_MEMBER_TEMPLATES
   "Checking for member template support" DIRECT)
 KWSYS_PLATFORM_CXX_TEST(KWSYS_CXX_HAS_FULL_SPECIALIZATION
   "Checking for standard template specialization syntax" DIRECT)
+KWSYS_PLATFORM_CXX_TEST(KWSYS_CXX_HAS_ARGUMENT_DEPENDENT_LOOKUP
+  "Checking whether argument dependent lookup is supported" DIRECT)
 
 IF(UNIX)
   KWSYS_PLATFORM_CXX_TEST(KWSYS_STAT_HAS_ST_MTIM

Configure.hxx.in

@@ -76,6 +76,9 @@
 /* Whether the compiler supports member templates.  */
 #define @KWSYS_NAMESPACE@_CXX_HAS_MEMBER_TEMPLATES @KWSYS_CXX_HAS_MEMBER_TEMPLATES@
 
+/* Whether the compiler supports argument dependent lookup.  */
+#define @KWSYS_NAMESPACE@_CXX_HAS_ARGUMENT_DEPENDENT_LOOKUP @KWSYS_CXX_HAS_ARGUMENT_DEPENDENT_LOOKUP@
+
 /* Whether the compiler supports standard full specialization syntax.  */
 #define @KWSYS_NAMESPACE@_CXX_HAS_FULL_SPECIALIZATION @KWSYS_CXX_HAS_FULL_SPECIALIZATION@
 
@@ -128,6 +131,7 @@
 # define KWSYS_CXX_DECL_TYPENAME        @KWSYS_NAMESPACE@_CXX_DECL_TYPENAME
 # define KWSYS_STL_HAS_ALLOCATOR_REBIND @KWSYS_NAMESPACE@_STL_HAS_ALLOCATOR_REBIND
 # define KWSYS_STL_HAS_ALLOCATOR_MAX_SIZE_ARGUMENT @KWSYS_NAMESPACE@_STL_HAS_ALLOCATOR_MAX_SIZE_ARGUMENT
+# define KWSYS_CXX_HAS_ARGUMENT_DEPENDENT_LOOKUP @KWSYS_NAMESPACE@_CXX_HAS_ARGUMENT_DEPENDENT_LOOKUP
 #endif
 
 #endif

hashtable.hxx.in

@@ -1087,6 +1087,14 @@ void hashtable<_Val,_Key,_HF,_Ex,_Eq,_All>
 
 } // namespace @KWSYS_NAMESPACE@
 
+// Normally the comparison operators should be found in the @KWSYS_NAMESPACE@
+// namespace by argument dependent lookup.  For compilers that do not
+// support it we must bring them into the global namespace now.
+#if !@KWSYS_NAMESPACE@_CXX_HAS_ARGUMENT_DEPENDENT_LOOKUP
+using @KWSYS_NAMESPACE@::operator==;
+using @KWSYS_NAMESPACE@::operator!=;
+#endif
+
 #if defined(_MSC_VER)
 # pragma warning (pop)
 #endif

kwsysPlatformCxxTests.cxx

@@ -108,6 +108,20 @@ template <> struct A<int*>
 int main() { return A<int*>::f(); }
 #endif
 
+#ifdef TEST_KWSYS_CXX_HAS_ARGUMENT_DEPENDENT_LOOKUP
+namespace N
+{
+  class A {};
+  int f(A*) { return 0; }
+}
+void f(void*);
+int main()
+{
+  N::A* a = 0;
+  return f(a);
+}
+#endif
+
 #ifdef TEST_KWSYS_STL_HAS_ALLOCATOR_REBIND
 #include <memory>
 template <class T, class Alloc>