On 02/08/17 00:05 +0900, Katsuhiko Nishimra wrote:
On Mon, Jul 31, 2017 at 03:53:42PM +0100, Jonathan Wakely wrote:
This __has_bultin check only exists for Clang, so should be replaced
by the correct __is_identifier check, not left there in addition to
it.


I see. Actually I've guessed so, and thank you for clarifying it.
I'm attaching a replacing patch. Please take a look at it.

Thanks, I've committed this to GCC trunk and will backport it to the
gcc-7-branch after the GCC 7.2 release (which is due any day now).

I've also committed the attached patch which changes our feature
detection for a __has_unique_object_representations builtin, as I
expect that will also need to use __is_identifier if/when Clang
supports it.

Tested powerpc64le-linux, and also tested using Clang version 5.0.0
(trunk 307530) to confirm that __is_aggregate is correctly detected
and std::is_aggregate is defined.

From 1b22cc531027832cf1eb50b73354f1730edbba54 Mon Sep 17 00:00:00 2001
From: Katsuhiko Nishimra <ktns...@gmail.com>
Date: Tue, 1 Aug 2017 20:36:58 +0900
Subject: [PATCH] libstdc++: Support std::is_aggregate on clang++

Currently, libstdc++ tries to detect __is_aggregate built-in macro using
__has_builtin, but this fails on clang++ because __has_builtin on
clang++ detects only built-in functions, not built-in macros. This patch
adds a test using __is_identifier. Tested with clang++
6.0.0-svn309616-1~exp1 and g++ 7.1.0-11 on Debian unstable.
---
libstdc++-v3/include/std/type_traits | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libstdc++-v3/include/std/type_traits 
b/libstdc++-v3/include/std/type_traits
index 390b6f40a..ee9c75baf 100644
--- a/libstdc++-v3/include/std/type_traits
+++ b/libstdc++-v3/include/std/type_traits
@@ -2894,9 +2894,9 @@ template <typename _From, typename _To>

#if __GNUC__ >= 7
# define _GLIBCXX_HAVE_BUILTIN_IS_AGGREGATE 1
-#elif defined __has_builtin
+#elif defined(__is_identifier)
// For non-GNU compilers:
-# if __has_builtin(__is_aggregate)
+# if ! __is_identifier(__is_aggregate)
#  define _GLIBCXX_HAVE_BUILTIN_IS_AGGREGATE 1
# endif
#endif
--
2.13.3




commit 1b00aa3825ea05fea071f31d29aafff71a002c53
Author: Jonathan Wakely <jwak...@redhat.com>
Date:   Wed Aug 9 19:07:28 2017 +0100

    Fix test for __has_unique_object_representations support in Clang
    
    	* include/std/type_traits (_GLIBCXX_NO_BUILTIN_HAS_UNIQ_OBJ_REP):
    	Replace with _GLIBCXX_HAVE_BUILTIN_HAS_UNIQ_OBJ_REP and use
    	__is_identifier to set it.

diff --git a/libstdc++-v3/include/std/type_traits b/libstdc++-v3/include/std/type_traits
index ee9c75b..f021c42 100644
--- a/libstdc++-v3/include/std/type_traits
+++ b/libstdc++-v3/include/std/type_traits
@@ -2873,14 +2873,16 @@ template <typename _Base, typename _Derived>
 template <typename _From, typename _To>
   inline constexpr bool is_convertible_v = is_convertible<_From, _To>::value;
 
-#ifdef __has_builtin
-# if !__has_builtin(__has_unique_object_representations)
-// Try not to break non-GNU compilers that don't support the built-in:
-#  define _GLIBCXX_NO_BUILTIN_HAS_UNIQ_OBJ_REP 1
+#if __GNUC__ >= 7
+# define _GLIBCXX_HAVE_BUILTIN_HAS_UNIQ_OBJ_REP 1
+#elif defined(__is_identifier)
+// For non-GNU compilers:
+# if ! __is_identifier(__has_unique_object_representations)
+#  define _GLIBCXX_HAVE_BUILTIN_HAS_UNIQ_OBJ_REP 1
 # endif
 #endif
 
-#ifndef _GLIBCXX_NO_BUILTIN_HAS_UNIQ_OBJ_REP
+#ifdef _GLIBCXX_HAVE_BUILTIN_HAS_UNIQ_OBJ_REP
 # define __cpp_lib_has_unique_object_representations 201606
   /// has_unique_object_representations
   template<typename _Tp>
@@ -2890,7 +2892,7 @@ template <typename _From, typename _To>
       )>
     { };
 #endif
-#undef _GLIBCXX_NO_BUILTIN_HAS_UNIQ_OBJ_REP
+#undef _GLIBCXX_HAVE_BUILTIN_HAS_UNIQ_OBJ_REP
 
 #if __GNUC__ >= 7
 # define _GLIBCXX_HAVE_BUILTIN_IS_AGGREGATE 1

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