Fix PR26103 - Error calling is_convertible with incomplete type. Patch from Michael Daniels.

llvm-svn: 258852

2 files changed, 9 insertions, 2 deletions

diff --git a/libcxx/include/type_traits b/libcxx/include/type_traits
index f13e29f971b..3c9e8dd9021 100644
--- a/libcxx/include/type_traits
+++ b/libcxx/include/type_traits
@@ -1347,10 +1347,9 @@ struct __is_convertible_test : public false_type {};
 
 template <class _From, class _To>
 struct __is_convertible_test<_From, _To,
-    decltype(__test_convert<_To>(_VSTD::declval<_From>()))> : public true_type
+    decltype(_VSTD::__is_convertible_imp::__test_convert<_To>(_VSTD::declval<_From>()))> : public true_type
 {};
 
-template <class _Tp> __two __test(...);
 #ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
 template <class _Tp> _Tp&& __source();
 #else
diff --git a/libcxx/test/std/utilities/meta/meta.rel/is_convertible.pass.cpp b/libcxx/test/std/utilities/meta/meta.rel/is_convertible.pass.cpp
index 1681c39972d..144c292b84c 100644
--- a/libcxx/test/std/utilities/meta/meta.rel/is_convertible.pass.cpp
+++ b/libcxx/test/std/utilities/meta/meta.rel/is_convertible.pass.cpp
@@ -52,6 +52,11 @@ class NonCopyable {
   NonCopyable(NonCopyable&);
 };
 
+template <typename T>
+class CannotInstantiate {
+  enum { X = T::ThisExpressionWillBlowUp };
+};
+
 int main()
 {
     // void
@@ -206,4 +211,7 @@ int main()
     test_is_not_convertible<NonCopyable&, NonCopyable>();
 #endif
 
+    // Ensure that CannotInstantiate is not instantiated by is_convertible when it is not needed.
+    // For example CannotInstantiate is instatiated as a part of ADL lookup for arguments of type CannotInstantiate*.
+    static_assert((std::is_convertible<CannotInstantiate<int>*, CannotInstantiate<int>*>::value), "");
 }