9f5efd5d03
Resolves #174350 - Several issues were found in the current implementation of `optional<T&>` - `value()`, `operator*()`, `and_then()`, `transform()`, `operator->()` still provided their ref-qualified versions for rvalues and `const&`. - Using the listed methods on an rvalue `optional<T&>` would cause a compile failure due to a mismatch in return types. - On the latter, `operator*`, `operator->` would return `const` for a `optional<T&>`, which is an incorrect deep const. - A few constructors were missing (`optional<U>&`), and most constructors relevant to `optional<T&>` were missing `noexcept` - Constructors and `emplace` were not correctly constructing a `T&` as specified in _`convert-ref-init-val`_ - Also corrects the behavior of `value_or` which should return `remove_cv_t<T>` (in our case `decay_t<_Tp>`) - Add several test cases to verify behavior, update `value_or` tests
50 lines
1.2 KiB
C++
50 lines
1.2 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
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// <optional>
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// constexpr bool optional<T>::has_value() const noexcept;
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#include <cassert>
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#include <optional>
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#include "test_macros.h"
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int main(int, char**)
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{
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using std::optional;
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{
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const optional<int> opt; ((void)opt);
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ASSERT_NOEXCEPT(opt.has_value());
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ASSERT_SAME_TYPE(decltype(opt.has_value()), bool);
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}
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{
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constexpr optional<int> opt;
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static_assert(!opt.has_value(), "");
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}
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{
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constexpr optional<int> opt(0);
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static_assert(opt.has_value(), "");
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}
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#if TEST_STD_VER >= 26
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{
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static constexpr int i = 0;
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constexpr optional<const int&> opt{i};
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ASSERT_NOEXCEPT(opt.has_value());
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static_assert(opt.has_value());
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}
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{
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constexpr optional<const int&> opt{};
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static_assert(!opt.has_value());
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}
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#endif
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return 0;
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}
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