1 //===----------------------------------------------------------------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 // UNSUPPORTED: c++98, c++03, c++11, c++14, c++17 10 11 // <functional> 12 // 13 // reference_wrapper 14 // 15 // template <class... ArgTypes> 16 // std::invoke_result_t<T&, ArgTypes...> 17 // operator()(ArgTypes&&... args) const; 18 // 19 // Requires T to be a complete type (since C++20). 20 21 #include <functional> 22 23 24 struct Foo; 25 Foo& get_foo(); 26 27 void test() { 28 std::reference_wrapper<Foo> ref = get_foo(); 29 ref(0); // incomplete at the point of call 30 } 31 32 struct Foo { void operator()(int) const { } }; 33 Foo& get_foo() { static Foo foo; return foo; } 34 35 int main() { 36 test(); 37 } 38