Fix two test failures caused by Windows mangling of function types.

On Windows the function template `template <class T> void test()` has
the same mangled name when instantiated with the distinct types `void()`
and `void() noexcept`. When this occurs Clang emits an error. This error
was causing two type-traits tests to fail.

However this can be worked around by using class templates instead of
function templates, which is what this patch does to fix the errors.

llvm-svn: 302380

2 files changed, 21 insertions, 15 deletions

diff --git a/libcxx/test/std/utilities/meta/meta.unary/meta.unary.cat/is_function.pass.cpp b/libcxx/test/std/utilities/meta/meta.unary/meta.unary.cat/is_function.pass.cpp
index c340ba69cda..4e875fa9452 100644
--- a/libcxx/test/std/utilities/meta/meta.unary/meta.unary.cat/is_function.pass.cpp
+++ b/libcxx/test/std/utilities/meta/meta.unary/meta.unary.cat/is_function.pass.cpp
@@ -16,9 +16,13 @@
 
 #include "test_macros.h"
 
+// NOTE: On Windows the function `test_is_function<void()>` and
+// `test_is_function<void() noexcept> has the same mangled despite being
+// a distinct instantiation. This causes Clang to emit an error. However
+// structs do not have this problem.
+
 template <class T>
-void test_is_function()
-{
+struct test_is_function {
     static_assert( std::is_function<T>::value, "");
     static_assert( std::is_function<const T>::value, "");
     static_assert( std::is_function<volatile T>::value, "");
@@ -29,11 +33,10 @@ void test_is_function()
     static_assert( std::is_function_v<volatile T>, "");
     static_assert( std::is_function_v<const volatile T>, "");
 #endif
-}
+};
 
 template <class T>
-void test_is_not_function()
-{
+struct test_is_not_function {
     static_assert(!std::is_function<T>::value, "");
     static_assert(!std::is_function<const T>::value, "");
     static_assert(!std::is_function<volatile T>::value, "");
@@ -44,7 +47,7 @@ void test_is_not_function()
     static_assert(!std::is_function_v<volatile T>, "");
     static_assert(!std::is_function_v<const volatile T>, "");
 #endif
-}
+};
 
 class Empty
 {
diff --git a/libcxx/test/std/utilities/meta/meta.unary/meta.unary.cat/member_function_pointer.pass.cpp b/libcxx/test/std/utilities/meta/meta.unary/meta.unary.cat/member_function_pointer.pass.cpp
index 691c549b5e7..f685d71eebd 100644
--- a/libcxx/test/std/utilities/meta/meta.unary/meta.unary.cat/member_function_pointer.pass.cpp
+++ b/libcxx/test/std/utilities/meta/meta.unary/meta.unary.cat/member_function_pointer.pass.cpp
@@ -14,9 +14,12 @@
 #include <type_traits>
 #include "test_macros.h"
 
+// NOTE: On Windows the function `test_is_member_function<void()>` and
+// `test_is_member_function<void() noexcept> has the same mangled despite being
+// a distinct instantiation. This causes Clang to emit an error. However
+// structs do not have this problem.
 template <class T>
-void test_member_function_pointer_imp()
-{
+struct test_member_function_pointer_imp {
     static_assert(!std::is_void<T>::value, "");
 #if TEST_STD_VER > 11
     static_assert(!std::is_null_pointer<T>::value, "");
@@ -33,16 +36,16 @@ void test_member_function_pointer_imp()
     static_assert(!std::is_union<T>::value, "");
     static_assert(!std::is_class<T>::value, "");
     static_assert(!std::is_function<T>::value, "");
-}
+};
 
 template <class T>
-void test_member_function_pointer()
+struct test_member_function_pointer :
+    test_member_function_pointer_imp<T>,
+    test_member_function_pointer_imp<const T>,
+    test_member_function_pointer_imp<volatile T>,
+    test_member_function_pointer_imp<const volatile T>
 {
-    test_member_function_pointer_imp<T>();
-    test_member_function_pointer_imp<const T>();
-    test_member_function_pointer_imp<volatile T>();
-    test_member_function_pointer_imp<const volatile T>();
-}
+};
 
 class Class
 {