[committed] libstdc++: Replace std::result_of with __invoke_result_t [PR114394]

[committed] libstdc++: Replace std::result_of with __invoke_result_t [PR114394]

[Jonathan Wakely]

Tested aarch64-linux. Pushed to trunk.

-- >8 --

Replace std::result_of with std::invoke_result, as specified in the
standard since C++17, to avoid deprecated warnings for std::result_of.

We don't have __invoke_result_t in C++11 mode, so add it as an alias
template for __invoke_result<>::type (which is what std::result_of uses
as its base class, so there's no change in functionality).

This fixes warnings given by Clang 18.

libstdc++-v3/ChangeLog:

	PR libstdc++/114394
	* include/std/functional (bind): Use __invoke_result_t instead
	of result_of::type.
	* include/std/type_traits (__invoke_result_t): New alias
	template.
	* testsuite/20_util/bind/ref_neg.cc: Adjust prune pattern.
---
 libstdc++-v3/include/std/functional            | 2 +-
 libstdc++-v3/include/std/type_traits           | 4 ++++
 libstdc++-v3/testsuite/20_util/bind/ref_neg.cc | 2 +-
 3 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/libstdc++-v3/include/std/functional b/libstdc++-v3/include/std/functional
index e02be00abe5..766558b3ce0 100644
--- a/libstdc++-v3/include/std/functional
+++ b/libstdc++-v3/include/std/functional
@@ -556,7 +556,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
       template<typename _Fn, typename _CallArgs, typename... _BArgs>
 	using _Res_type_impl
-	  = typename result_of< _Fn&(_Mu_type<_BArgs, _CallArgs>&&...) >::type;
+	  = __invoke_result_t<_Fn&, _Mu_type<_BArgs, _CallArgs>&&...>;
 
       template<typename _CallArgs>
 	using _Res_type = _Res_type_impl<_Functor, _CallArgs, _Bound_args...>;
diff --git a/libstdc++-v3/include/std/type_traits b/libstdc++-v3/include/std/type_traits
index 21402fd8c13..b441bf9908f 100644
--- a/libstdc++-v3/include/std/type_traits
+++ b/libstdc++-v3/include/std/type_traits
@@ -2664,6 +2664,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	_Functor, _ArgTypes...
       >::type
     { };
+
+  // __invoke_result_t (std::invoke_result_t for C++11)
+  template<typename _Fn, typename... _Args>
+    using __invoke_result_t = typename __invoke_result<_Fn, _Args...>::type;
   /// @endcond
 
   template<typename _Functor, typename... _ArgTypes>
diff --git a/libstdc++-v3/testsuite/20_util/bind/ref_neg.cc b/libstdc++-v3/testsuite/20_util/bind/ref_neg.cc
index 4a1ed8dda5f..2db9fa8276a 100644
--- a/libstdc++-v3/testsuite/20_util/bind/ref_neg.cc
+++ b/libstdc++-v3/testsuite/20_util/bind/ref_neg.cc
@@ -50,7 +50,7 @@ void test02()
 
 // Ignore the reasons for deduction/substitution failure in the headers.
 // Arrange for the match to work on installed trees as well as build trees.
-// { dg-prune-output "no type named 'type' in 'struct std::result_of" }
+// { dg-prune-output "no type named 'type' in 'struct std::__invoke_result" }
 
 int main()
 {
-- 
2.44.0