Allow is_swappable to SFINAE on deleted/ambiguous swap functions

llvm-svn: 275094

1 files changed, 21 insertions, 0 deletions

diff --git a/libcxx/test/std/utilities/meta/meta.unary/meta.unary.prop/is_swappable.pass.cpp b/libcxx/test/std/utilities/meta/meta.unary/meta.unary.prop/is_swappable.pass.cpp
index 9d01128379a..b17ca76fd58 100644
--- a/libcxx/test/std/utilities/meta/meta.unary/meta.unary.prop/is_swappable.pass.cpp
+++ b/libcxx/test/std/utilities/meta/meta.unary/meta.unary.prop/is_swappable.pass.cpp
@@ -49,8 +49,21 @@ struct M {
 
 void swap(M&&, M&&) {}
 
+struct DeletedSwap {
+  friend void swap(DeletedSwap&, DeletedSwap&) = delete;
+};
+
 } // namespace MyNS
 
+namespace MyNS2 {
+
+struct AmbiguousSwap {};
+
+template <class T>
+void swap(T&, T&) {}
+
+} // end namespace MyNS2
+
 int main()
 {
     using namespace MyNS;
@@ -70,6 +83,14 @@ int main()
         static_assert(!std::is_swappable<int() &>::value, "");
     }
     {
+        // test that a deleted swap is correctly handled.
+        static_assert(!std::is_swappable<DeletedSwap>::value, "");
+    }
+    {
+        // test that a swap with ambiguous overloads is handled correctly.
+        static_assert(!std::is_swappable<MyNS2::AmbiguousSwap>::value, "");
+    }
+    {
         // test for presence of is_swappable_v
         static_assert(std::is_swappable_v<int>, "");
         static_assert(!std::is_swappable_v<M>, "");