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 10 // <functional> 11 12 // template<class R, class T> constexpr unspecified mem_fn(R T::*) noexcept; // constexpr in C++20 13 14 #include <functional> 15 #include <cassert> 16 17 struct A 18 { 19 double data_; 20 }; 21 22 template <class F> 23 void 24 test(F f) 25 { 26 { 27 A a; 28 f(a) = 5; 29 assert(a.data_ == 5); 30 A* ap = &a; 31 f(ap) = 6; 32 assert(a.data_ == 6); 33 const A* cap = ap; 34 assert(f(cap) == f(ap)); 35 f(cap) = 7; 36 } 37 } 38 39 int main(int, char**) 40 { 41 test(std::mem_fn(&A::data_)); 42 43 return 0; 44 } 45