Make swap_noexcept.pass.cpp tests more portable. Patch from STL@microsoft.com.

See D21820 for more information (https://reviews.llvm.org/D21820).

llvm-svn: 276590

1 files changed, 6 insertions, 9 deletions

diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/string.special/swap_noexcept.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/string.special/swap_noexcept.pass.cpp
index 4ac13d10e67..757d5eeb2dc 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/string.special/swap_noexcept.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/string.special/swap_noexcept.pass.cpp
@@ -22,6 +22,7 @@
 // This tests a conforming extension
 
 #include <string>
+#include <utility>
 #include <cassert>
 
 #include "test_macros.h"
@@ -56,30 +57,26 @@ int main()
 {
     {
         typedef std::string C;
-        C c1, c2;
-        static_assert(noexcept(swap(c1, c2)), "");
+        static_assert(noexcept(swap(std::declval<C&>(), std::declval<C&>())), "");
     }
     {
         typedef std::basic_string<char, std::char_traits<char>, test_allocator<char>> C;
-        C c1, c2;
-        static_assert(noexcept(swap(c1, c2)), "");
+        LIBCPP_STATIC_ASSERT(noexcept(swap(std::declval<C&>(), std::declval<C&>())), "");
     }
     {
         typedef std::basic_string<char, std::char_traits<char>, some_alloc<char>> C;
-        C c1, c2;
 #if TEST_STD_VER >= 14
     //  In c++14, if POCS is set, swapping the allocator is required not to throw
-        static_assert( noexcept(swap(c1, c2)), "");
+        static_assert( noexcept(swap(std::declval<C&>(), std::declval<C&>())), "");
 #else
-        static_assert(!noexcept(swap(c1, c2)), "");
+        static_assert(!noexcept(swap(std::declval<C&>(), std::declval<C&>())), "");
 #endif
     }
 #if TEST_STD_VER >= 14
     {
         typedef std::basic_string<char, std::char_traits<char>, some_alloc2<char>> C;
-        C c1, c2;
     //  if the allocators are always equal, then the swap can be noexcept
-        static_assert( noexcept(swap(c1, c2)), "");
+        static_assert( noexcept(swap(std::declval<C&>(), std::declval<C&>())), "");
     }
 #endif
 }