[libcxx-commits] [libcxx] [libc++] Implement the public invoke API in terms of the libc++-internal API (PR #146334)

[Nikolas Klauser via libcxx-commits]

================
@@ -352,75 +315,78 @@ inline const bool __is_invocable_r_v = __invokable_r<_Ret, _Func, _Args...>::val
 template <class _Func, class... _Args>
 inline const bool __is_nothrow_invocable_v = __nothrow_invokable<_Func, _Args...>::value;
 
+template <class _Ret, class _Func, class... _Args>
+inline const bool __is_nothrow_invocable_r_v = __nothrow_invokable_r<_Ret, _Fn, _Args...>::value;
+
 template <class _Func, class... _Args>
 struct __invoke_result
     : enable_if<__is_invocable_v<_Func, _Args...>, typename __invokable_r<void, _Func, _Args...>::_Result> {};
 
 template <class _Func, class... _Args>
 using __invoke_result_t _LIBCPP_NODEBUG = typename __invoke_result<_Func, _Args...>::type;
 
-#  if _LIBCPP_STD_VER >= 17
+#endif // __has_builtin(__builtin_invoke_r)
+
+template <class _Ret, bool = is_void<_Ret>::value>
+struct __invoke_void_return_wrapper {
+  template <class... _Args>
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 static _Ret __call(_Args&&... __args) {
+    return std::__invoke(std::forward<_Args>(__args)...);
+  }
+};
+
+template <class _Ret>
+struct __invoke_void_return_wrapper<_Ret, true> {
+  template <class... _Args>
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 static void __call(_Args&&... __args) {
+    std::__invoke(std::forward<_Args>(__args)...);
+  }
+};
+
+template <class _Ret, class... _Args>
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _Ret __invoke_r(_Args&&... __args) {
+  return __invoke_void_return_wrapper<_Ret>::__call(std::forward<_Args>(__args)...);
+}
+
+#if _LIBCPP_STD_VER >= 17
 
 // is_invocable
 
 template <class _Fn, class... _Args>
-struct _LIBCPP_NO_SPECIALIZATIONS is_invocable : bool_constant<__is_invocable_v<_Fn, _Args...>> {};
+struct _LIBCPP_NO_SPECIALIZATIONS is_invocable : bool_constant<__is_invocable_v<_Fn, _Args...> > {};
 
 template <class _Ret, class _Fn, class... _Args>
 struct _LIBCPP_NO_SPECIALIZATIONS is_invocable_r : bool_constant<__is_invocable_r_v<_Ret, _Fn, _Args...>> {};
 
 template <class _Fn, class... _Args>
 _LIBCPP_NO_SPECIALIZATIONS inline constexpr bool is_invocable_v = __is_invocable_v<_Fn, _Args...>;
 
-template <class _Ret, class _Fn, class... _Args>
----------------
philnik777 wrote:

There is none. I'm not sure how it happened, probably copy-pasted something wrong.

https://github.com/llvm/llvm-project/pull/146334