78 lines · cpp
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-exception6//7//===----------------------------------------------------------------------===//8 9// UNSUPPORTED: c++03, c++11, c++14, c++1710 11// struct identity;12 13#include <functional>14 15#include <cassert>16#include <concepts>17#include <utility>18 19#include "MoveOnly.h"20 21static_assert(std::semiregular<std::identity>);22static_assert(requires { typename std::identity::is_transparent; });23 24constexpr bool test() {25 std::identity id;26 int i = 42;27 assert(id(i) == 42);28 assert(id(std::move(i)) == 42);29 30 MoveOnly m1 = 2;31 MoveOnly m2 = id(std::move(m1));32 assert(m2.get() == 2);33 34 assert(&id(i) == &i);35 static_assert(&id(id) == &id);36 37 const std::identity idc;38 assert(idc(1) == 1);39 assert(std::move(id)(1) == 1);40 assert(std::move(idc)(1) == 1);41 42 id = idc; // run-time checks assignment43 static_assert(std::is_same_v<decltype(id(i)), int&>);44 static_assert(std::is_same_v<decltype(id(std::declval<int&&>())), int&&>);45 static_assert(46 std::is_same_v<decltype(id(std::declval<int const&>())), int const&>);47 static_assert(48 std::is_same_v<decltype(id(std::declval<int const&&>())), int const&&>);49 static_assert(std::is_same_v<decltype(id(std::declval<int volatile&>())),50 int volatile&>);51 static_assert(std::is_same_v<decltype(id(std::declval<int volatile&&>())),52 int volatile&&>);53 static_assert(54 std::is_same_v<decltype(id(std::declval<int const volatile&>())),55 int const volatile&>);56 static_assert(57 std::is_same_v<decltype(id(std::declval<int const volatile&&>())),58 int const volatile&&>);59 60 struct S {61 constexpr S() = default;62 constexpr S(S&&) noexcept(false) {}63 constexpr S(S const&) noexcept(false) {}64 };65 S x;66 static_assert(noexcept(id(x)));67 static_assert(noexcept(id(S())));68 69 return true;70}71 72int main(int, char**) {73 test();74 static_assert(test());75 76 return 0;77}78