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 // <functional> 10 11 // reference_wrapper 12 13 // template <ObjectType T> reference_wrapper<T> ref(reference_wrapper<T> t); 14 // LWG 3146 "Excessive unwrapping in std::ref/cref" 15 16 #include <functional> 17 #include <cassert> 18 19 #include "test_macros.h" 20 test()21TEST_CONSTEXPR_CXX20 bool test() 22 { 23 { 24 int i = 0; 25 std::reference_wrapper<int> ri(i); 26 std::reference_wrapper<std::reference_wrapper<int> > rri(ri); 27 auto rrj = std::ref(rri); 28 ASSERT_SAME_TYPE(decltype(rrj), std::reference_wrapper<std::reference_wrapper<int> >); 29 assert(&rrj.get() == &ri); 30 } 31 { 32 int i = 0; 33 std::reference_wrapper<int> ri(i); 34 std::reference_wrapper<const std::reference_wrapper<int> > rri(ri); 35 auto rrj = std::ref(rri); 36 ASSERT_SAME_TYPE(decltype(rrj), std::reference_wrapper<const std::reference_wrapper<int> >); 37 assert(&rrj.get() == &ri); 38 } 39 { 40 int i = 0; 41 std::reference_wrapper<int> ri(i); 42 std::reference_wrapper<std::reference_wrapper<int> > rri(ri); 43 auto rrj = std::cref(rri); 44 ASSERT_SAME_TYPE(decltype(rrj), std::reference_wrapper<const std::reference_wrapper<int> >); 45 assert(&rrj.get() == &ri); 46 } 47 { 48 int i = 0; 49 std::reference_wrapper<int> ri(i); 50 std::reference_wrapper<const std::reference_wrapper<int> > rri(ri); 51 auto rrj = std::cref(rri); 52 ASSERT_SAME_TYPE(decltype(rrj), std::reference_wrapper<const std::reference_wrapper<int> >); 53 assert(&rrj.get() == &ri); 54 } 55 return true; 56 } 57 main(int,char **)58int main(int, char**) 59 { 60 test(); 61 #if TEST_STD_VER > 17 62 static_assert(test()); 63 #endif 64 65 return 0; 66 } 67