On 16/10/19 10:43 +0100, Jonathan Wakely wrote:
On 16/10/19 10:42 +0100, Jonathan Wakely wrote:
On 12/10/19 18:15 +0200, Romain Geissler wrote:
Le sam. 12 oct. 2019 à 17:44, Romain Geissler
<romain.geiss...@gmail.com> a écrit :
It looks like this creates the following error when I try to bootstrap
clang 9.0.0 using the latest gcc and libstdc++ from trunk. Note that
with g++, there is no problem, however it looks like clang++ has some
problem with the new header. I don't know if this is an issue on
libstdc++ side or clang++ side.
__is_same_as is not implemented as a compiler builtin in clang++
Sigh, I guess that explains why we weren't using it already.
unlike g++, thus the error on clang 9.0.0 side. It looks like current
clang trunk doesn't define __is_same_as either. Until clang implements
this support (if it ever will), usage of __is_same_as in libstdc++
shall be conditional, only when __has_builtin(__is_same_as) is true
(however that would require that gcc implements __has_builtin, as
implemented here:
https://gcc.gnu.org/ml/gcc-patches/2019-10/msg00062.html )
No, we don't need GCC to support __has_builtin, because we know GCC
supports __is_same_as so there's no need to check for it.
So something like this would work fine:
#if __GNUC__ >= 10
# define _GLIBCXX_HAVE__IS_SAME_AS
#elif defined(__has_builtin)
# if __has_builtin(__is_same_as)
# define _GLIBCXX_HAVE__IS_SAME_AS
# endif
#endif
It looks like Clang provides __is_same instead.
I'll commit a fix today.
This is what I've committed to trunk, after testing on x86_64-linux,
and checking it with Clang.
Thanks for testing and reporting the problem.
commit 98afe2e1a9ee322885ce526f3df6ee612566da96
Author: Jonathan Wakely <jwak...@redhat.com>
Date: Wed Oct 16 11:00:17 2019 +0100
Only use GCC-specific __is_same_as built-in conditionally
Clang doesn't support __is_same_as but provides __is_same instead.
Restore the original implementation (pre r276891) when neither of those
built-ins is available.
* include/bits/c++config (_GLIBCXX_BUILTIN_IS_SAME_AS): Define to
one of __is_same_as or __is_same when available.
* include/std/concepts (__detail::__same_as): Use std::is_same_v.
* include/std/type_traits (is_same) [_GLIBCXX_BUILTIN_IS_SAME_AS]:
Use new macro instead of __is_same_as.
(is_same) [!_GLIBCXX_BUILTIN_IS_SAME_AS]: Restore partial
specialization.
(is_same_v) [_GLIBCXX_BUILTIN_IS_SAME_AS]: Use new macro.
(is_same_v) [!_GLIBCXX_BUILTIN_IS_SAME_AS]: Use std::is_same.
diff --git a/libstdc++-v3/include/bits/c++config b/libstdc++-v3/include/bits/c++config
index c8e099aaadd..32db60f39e5 100644
--- a/libstdc++-v3/include/bits/c++config
+++ b/libstdc++-v3/include/bits/c++config
@@ -633,6 +633,7 @@ namespace std
# define _GLIBCXX_HAVE_BUILTIN_HAS_UNIQ_OBJ_REP 1
# define _GLIBCXX_HAVE_BUILTIN_IS_AGGREGATE 1
# define _GLIBCXX_HAVE_BUILTIN_LAUNDER 1
+# define _GLIBCXX_BUILTIN_IS_SAME_AS(T, U) __is_same_as(T, U)
# if __GNUC__ >= 9
# define _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED 1
# endif
@@ -650,6 +651,9 @@ namespace std
# if __has_builtin(__builtin_is_constant_evaluated)
# define _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED 1
# endif
+# if ! __is_identifier(__is_same)
+# define _GLIBCXX_BUILTIN_IS_SAME_AS(T, U) __is_same(T, U)
+# endif
#endif // GCC
// PSTL configuration
diff --git a/libstdc++-v3/include/std/concepts b/libstdc++-v3/include/std/concepts
index 6b1150a32d2..6d740eb663c 100644
--- a/libstdc++-v3/include/std/concepts
+++ b/libstdc++-v3/include/std/concepts
@@ -23,7 +23,7 @@
// <http://www.gnu.org/licenses/>.
/** @file include/concepts
- * This is __a Standard C++ Library header.
+ * This is a Standard C++ Library header.
* @ingroup concepts
*/
@@ -54,7 +54,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
namespace __detail
{
template<typename _Tp, typename _Up>
- concept __same_as = __is_same_as(_Tp, _Up);
+ concept __same_as = std::is_same_v<_Tp, _Up>;
} // namespace __detail
/// [concept.same], concept same_as
diff --git a/libstdc++-v3/include/std/type_traits b/libstdc++-v3/include/std/type_traits
index 4de5daa9f06..8e787a994c3 100644
--- a/libstdc++-v3/include/std/type_traits
+++ b/libstdc++-v3/include/std/type_traits
@@ -1390,9 +1390,20 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
/// is_same
template<typename _Tp, typename _Up>
struct is_same
- : public integral_constant<bool, __is_same_as(_Tp, _Up)>
+#ifdef _GLIBCXX_BUILTIN_IS_SAME_AS
+ : public integral_constant<bool, _GLIBCXX_BUILTIN_IS_SAME_AS(_Tp, _Up)>
+#else
+ : public false_type
+#endif
{ };
+#ifndef _GLIBCXX_BUILTIN_IS_SAME_AS
+ template<typename _Tp>
+ struct is_same<_Tp, _Tp>
+ : public true_type
+ { };
+#endif
+
/// is_base_of
template<typename _Base, typename _Derived>
struct is_base_of
@@ -3154,8 +3165,13 @@ template <typename _Tp>
inline constexpr size_t rank_v = rank<_Tp>::value;
template <typename _Tp, unsigned _Idx = 0>
inline constexpr size_t extent_v = extent<_Tp, _Idx>::value;
+#ifdef _GLIBCXX_BUILTIN_IS_SAME_AS
template <typename _Tp, typename _Up>
- inline constexpr bool is_same_v = __is_same_as(_Tp, _Up);
+ inline constexpr bool is_same_v = _GLIBCXX_BUILTIN_IS_SAME_AS(_Tp, _Up);
+#else
+template <typename _Tp, typename _Up>
+ inline constexpr bool is_same_v = std::is_same<_Tp, _Up>::value;
+#endif
template <typename _Base, typename _Derived>
inline constexpr bool is_base_of_v = is_base_of<_Base, _Derived>::value;
template <typename _From, typename _To>
