bf95a0cd20
Found while running libc++'s test suite with MSVC's STL, where we use both Clang and MSVC's compiler. libc++'s test suite has started using some C++23 Core Language features that MSVC hasn't implemented yet. When avoiding these features costs just a tiny bit of syntax, I would like to ask libc++ to consider making that change in the interest of practical portability, at least until MSVC catches up. If there's no desire to do so, then I could skip the affected tests, but that would make me a slightly sad kitty.
127 lines
3.4 KiB
C++
127 lines
3.4 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
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// <expected>
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// template<class F> constexpr auto transform_error(F&& f) &;
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// template<class F> constexpr auto transform_error(F&& f) const &;
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// template<class F> constexpr auto transform_error(F&& f) &&;
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// template<class F> constexpr auto transform_error(F&& f) const &&;
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#include <expected>
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#include <concepts>
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#include <cassert>
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#include <memory>
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#include <type_traits>
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#include <utility>
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template <class E, class F>
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concept has_transform =
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requires(E&& e, F&& f) {
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{ std::forward<E>(e).transform(std::forward<F>(f)) };
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};
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// [LWG 3877] https://cplusplus.github.io/LWG/issue3877, check constraint failing but not compile error inside the function body.
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static_assert(!has_transform<const std::expected<int, std::unique_ptr<int>>&, int()>);
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static_assert(!has_transform<const std::expected<int, std::unique_ptr<int>>&&, int()>);
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constexpr void test_val_types() {
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// Test & overload
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{
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auto l = []() -> int { return 1; };
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std::expected<void, int> v;
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std::same_as<std::expected<int, int>> decltype(auto) val = v.transform(l);
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assert(val == 1);
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}
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// Test const& overload
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{
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auto l = []() -> int { return 1; };
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const std::expected<void, int> v;
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std::same_as<std::expected<int, int>> decltype(auto) val = v.transform(l);
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assert(val == 1);
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}
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// Test && overload
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{
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auto l = []() -> int { return 1; };
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std::expected<void, int> v;
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std::same_as<std::expected<int, int>> decltype(auto) val = std::move(v).transform(l);
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assert(val == 1);
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}
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// Test const&& overload
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{
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auto l = []() -> int { return 1; };
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const std::expected<void, int> v;
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std::same_as<std::expected<int, int>> decltype(auto) val = std::move(v).transform(l);
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assert(val == 1);
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}
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}
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constexpr void test_fail() {
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// Test & overload
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{
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auto l = []() -> int {
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assert(false);
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return 0;
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};
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std::expected<void, int> v(std::unexpected<int>(5));
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std::same_as<std::expected<int, int>> decltype(auto) val = v.transform(l);
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assert(val.error() == 5);
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}
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// Test const& overload
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{
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auto l = []() -> int {
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assert(false);
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return 0;
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};
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const std::expected<void, int> v(std::unexpected<int>(5));
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std::same_as<std::expected<int, int>> decltype(auto) val = v.transform(l);
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assert(val.error() == 5);
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}
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// Test && overload
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{
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auto l = []() -> int {
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assert(false);
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return 0;
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};
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std::expected<void, int> v(std::unexpected<int>(5));
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std::same_as<std::expected<int, int>> decltype(auto) val = std::move(v).transform(l);
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assert(val.error() == 5);
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}
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// Test const&& overload
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{
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auto l = []() -> int {
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assert(false);
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return 0;
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};
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const std::expected<void, int> v(std::unexpected<int>(5));
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std::same_as<std::expected<int, int>> decltype(auto) val = std::move(v).transform(l);
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assert(val.error() == 5);
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}
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}
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constexpr bool test() {
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test_fail();
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test_val_types();
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return true;
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}
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int main(int, char**) {
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test();
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static_assert(test());
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return 0;
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}
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