[libcxx] [test] libc++ test changes for CWG 2094

[BillyONeal]

Summary

Update is_trivially_copyable tests with CWG 2094

Clang 5.0 implements these changes here: https://github.com/llvm-mirror/clang/commit/87cd035326a39523eeb1b295ad36cff337141ef9
MSVC++ will implement these changes in the first toolset update to 2017.

[BillyONeal]

test/std/utilities/meta/meta.unary/meta.unary.prop/is_trivially_copyable.pass.cpp

25 ↗

(On Diff #98368)

Whoops, I fat fingered the closing comment. Will change this to just say "compiler version"

[BillyONeal]

Eric asked to just nuke the offending lines.

[BillyONeal]

Bill got confused.

[mclow.lists]

In general, I prefer having the space between static_assert( and the condition.

That makes it easy (at least for me) to see if there's a ! there or not.
Other than that, this LGTM.

FWIW, I think this is a language change that core got wrong, and it has already come back to bite us. (https://bugs.llvm.org/show_bug.cgi?id=28527)

[BillyONeal]

In D33021#750831, @mclow.lists wrote:

FWIW, I think this is a language change that core got wrong, and it has already come back to bite us. (https://bugs.llvm.org/show_bug.cgi?id=28527)

Hmm.... we actually took steps to do the opposite in std::copy -- to use memcpy even in the presence of volatile -- as a result of this change.

It looks like Core wasn't a fan of doing this either, but that the Itanium ABI forced their hand.

[BillyONeal]

In D33021#751145, @BillyONeal wrote:

Hmm.... we actually took steps to do the opposite in std::copy -- to use memcpy even in the presence of volatile -- as a result of this change.

;) http://imgur.com/a/PMKPS

[EricWF]

LGTM. The bots are already failing because I upgraded their compilers.

@BillyONeal Can you commit this soon so I can clean up any fallout?

[BillyONeal]

Added spaces requested by Marshal.

libcxx/trunk/test/std/utilities/meta/meta.unary/meta.unary.prop/is_trivially_copyable.pass.cpp

 #include <cassert>
 #include "test_macros.h"
 
 template <class T>
 void test_is_trivially_copyable()
 {
     static_assert( std::is_trivially_copyable<T>::value, "");
     static_assert( std::is_trivially_copyable<const T>::value, "");
-    static_assert(!std::is_trivially_copyable<volatile T>::value, "");
-    static_assert(!std::is_trivially_copyable<const volatile T>::value, "");
+    static_assert( std::is_trivially_copyable<volatile T>::value, "");
+    static_assert( std::is_trivially_copyable<const volatile T>::value, "");
 #if TEST_STD_VER > 14
     static_assert( std::is_trivially_copyable_v<T>, "");
     static_assert( std::is_trivially_copyable_v<const T>, "");
-    static_assert(!std::is_trivially_copyable_v<volatile T>, "");
-    static_assert(!std::is_trivially_copyable_v<const volatile T>, "");
+    static_assert( std::is_trivially_copyable_v<volatile T>, "");
+    static_assert( std::is_trivially_copyable_v<const volatile T>, "");
 #endif
 }
 
 template <class T>
 void test_is_not_trivially_copyable()
 {
     static_assert(!std::is_trivially_copyable<T>::value, "");
     static_assert(!std::is_trivially_copyable<const T>::value, "");