[PATCH] Define __cpp_lib_is_constant_evaluated

[Jonathan Wakely]

On 11/01/19 16:51 +0100, Jakub Jelinek wrote:
>Hi!
>
>Seems __cpp_lib_is_constant_evaluated should be defined to 201811L
>if std::is_constant_evaluated() is implemented.
>
>Ok for trunk?

OK, thanks.

>2019-01-11  Jakub Jelinek  <jakub@redhat.com>
>
>	* include/std/type_traits (__cpp_lib_is_constant_evaluated): Define.
>	* include/std/version (__cpp_lib_is_constant_evaluated): Define.
>
>--- libstdc++-v3/include/std/type_traits.jj	2019-01-01 12:45:50.842546655 +0100
>+++ libstdc++-v3/include/std/type_traits	2019-01-11 16:44:39.546916488 +0100
>@@ -3030,6 +3030,9 @@ template <typename _From, typename _To>
>     using unwrap_ref_decay_t = typename unwrap_ref_decay<_Tp>::type;
>
> #ifdef _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED
>+
>+#define __cpp_lib_is_constant_evaluated 201811L 	
>+
>   constexpr inline bool
>   is_constant_evaluated() noexcept
>   { return __builtin_is_constant_evaluated(); }
>--- libstdc++-v3/include/std/version.jj	2019-01-10 16:42:18.081062695 +0100
>+++ libstdc++-v3/include/std/version	2019-01-11 16:48:35.944119391 +0100
>@@ -142,6 +142,9 @@
>
> #if __cplusplus > 201703L
> // c++2a
>+#ifdef _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED
>+# define __cpp_lib_is_constant_evaluated 201811L
>+#endif
> #define __cpp_lib_list_remove_return_type 201806L
> #endif // C++2a
> #endif // C++17
>
>	Jakub