[gcc r16-700] libstdc++: Use __is_invocable/nothrow_invocable builtins more

[Patrick Palka]

https://gcc.gnu.org/g:259154325688cbfe6d3b50e91dbd6b997a969d6d

commit r16-700-g259154325688cbfe6d3b50e91dbd6b997a969d6d
Author: Patrick Palka <ppalka@redhat.com>
Date:   Fri May 16 13:06:04 2025 -0400

    libstdc++: Use __is_invocable/nothrow_invocable builtins more
    
    As a follow-up to r15-1253 and r15-1254 which made us use these builtins
    in the standard std::is_invocable/nothrow_invocable class templates, let's
    also use them directly in the standard variable templates and our internal
    C++11 __is_invocable/nothrow_invocable class templates.
    
    libstdc++-v3/ChangeLog:
    
            * include/std/type_traits (__is_invocable): Define in terms of
            corresponding builtin if available.
            (__is_nothrow_invocable): Likewise.
            (is_invocable_v): Likewise.
            (is_nothrow_invocable_v): Likewise.
    
    Reviewed-by: Jonathan Wakely <jwakely@redhat.com>

Diff:
---
 libstdc++-v3/include/std/type_traits | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/libstdc++-v3/include/std/type_traits b/libstdc++-v3/include/std/type_traits
index 676cdf2d7e66..0601869266c9 100644
--- a/libstdc++-v3/include/std/type_traits
+++ b/libstdc++-v3/include/std/type_traits
@@ -3212,7 +3212,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
   template<typename _Fn, typename... _ArgTypes>
     struct __is_invocable
+#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_invocable)
+    : __bool_constant<__is_invocable(_Fn, _ArgTypes...)>
+#else
     : __is_invocable_impl<__invoke_result<_Fn, _ArgTypes...>, void>::type
+#endif
     { };
 
   template<typename _Fn, typename _Tp, typename... _Args>
@@ -3263,8 +3267,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   // __is_nothrow_invocable (std::is_nothrow_invocable for C++11)
   template<typename _Fn, typename... _Args>
     struct __is_nothrow_invocable
+#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_nothrow_invocable)
+    : __bool_constant<__is_nothrow_invocable(_Fn, _Args...)>
+#else
     : __and_<__is_invocable<_Fn, _Args...>,
              __call_is_nothrow_<_Fn, _Args...>>::type
+#endif
     { };
 
 #pragma GCC diagnostic push
@@ -3704,10 +3712,19 @@ template <typename _From, typename _To>
   inline constexpr bool is_convertible_v = is_convertible<_From, _To>::value;
 #endif
 template<typename _Fn, typename... _Args>
-  inline constexpr bool is_invocable_v = is_invocable<_Fn, _Args...>::value;
+  inline constexpr bool is_invocable_v
+#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_invocable)
+    = __is_invocable(_Fn, _Args...);
+#else
+    = is_invocable<_Fn, _Args...>::value;
+#endif
 template<typename _Fn, typename... _Args>
   inline constexpr bool is_nothrow_invocable_v
+#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_nothrow_invocable)
+    = __is_nothrow_invocable(_Fn, _Args...);
+#else
     = is_nothrow_invocable<_Fn, _Args...>::value;
+#endif
 template<typename _Ret, typename _Fn, typename... _Args>
   inline constexpr bool is_invocable_r_v
     = is_invocable_r<_Ret, _Fn, _Args...>::value;