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
116 lines
2.8 KiB
C++
116 lines
2.8 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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// optional<T>& operator=(nullopt_t) noexcept;
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#include <optional>
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#include <type_traits>
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#include <cassert>
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#include "test_macros.h"
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#include "archetypes.h"
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using std::optional;
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using std::nullopt_t;
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using std::nullopt;
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TEST_CONSTEXPR_CXX20 bool test()
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{
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enum class State { inactive, constructed, destroyed };
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State state = State::inactive;
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struct StateTracker {
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TEST_CONSTEXPR_CXX20 StateTracker(State& s)
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: state_(&s)
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{
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s = State::constructed;
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}
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TEST_CONSTEXPR_CXX20 ~StateTracker() { *state_ = State::destroyed; }
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State* state_;
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};
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{
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optional<int> opt;
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static_assert(noexcept(opt = nullopt) == true, "");
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opt = nullopt;
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assert(static_cast<bool>(opt) == false);
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}
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{
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optional<int> opt(3);
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opt = nullopt;
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assert(static_cast<bool>(opt) == false);
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}
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{
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optional<StateTracker> opt;
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opt = nullopt;
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assert(state == State::inactive);
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assert(static_cast<bool>(opt) == false);
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}
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{
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optional<StateTracker> opt(state);
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assert(state == State::constructed);
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opt = nullopt;
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assert(state == State::destroyed);
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assert(static_cast<bool>(opt) == false);
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}
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#if TEST_STD_VER >= 26
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{
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int i = 0;
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optional<int&> o{i};
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ASSERT_NOEXCEPT(o = std::nullopt);
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o = std::nullopt;
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assert(!o.has_value());
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assert(static_cast<bool>(o) == false);
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}
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#endif
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return true;
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}
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int main(int, char**)
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{
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#if TEST_STD_VER > 17
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static_assert(test());
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#endif
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test();
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using TT = TestTypes::TestType;
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TT::reset();
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{
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optional<TT> opt;
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static_assert(noexcept(opt = nullopt) == true, "");
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assert(TT::destroyed == 0);
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opt = nullopt;
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assert(TT::constructed == 0);
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assert(TT::alive == 0);
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assert(TT::destroyed == 0);
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assert(static_cast<bool>(opt) == false);
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}
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assert(TT::alive == 0);
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assert(TT::destroyed == 0);
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TT::reset();
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{
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optional<TT> opt(42);
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assert(TT::destroyed == 0);
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TT::reset_constructors();
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opt = nullopt;
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assert(TT::constructed == 0);
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assert(TT::alive == 0);
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assert(TT::destroyed == 1);
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assert(static_cast<bool>(opt) == false);
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}
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assert(TT::alive == 0);
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assert(TT::destroyed == 1);
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TT::reset();
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return 0;
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}
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