forked from OSchip/llvm-project
54 lines
1.8 KiB
C++
54 lines
1.8 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++98, c++03, c++11, c++14
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// <optional>
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// constexpr optional(const optional<T>&& rhs);
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// C++17 said:
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// If is_trivially_move_constructible_v<T> is true,
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// this constructor shall be a constexpr constructor.
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//
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// P0602 changed this to:
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// If is_trivially_move_constructible_v<T> is true, this constructor is trivial.
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//
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// which means that it can't be constexpr if T is not trivially move-constructible,
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// because you have to do a placement new to get the value into place.
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// Except in the case where it is moving from an empty optional - that could be
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// made to be constexpr (and libstdc++ does so).
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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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struct S {
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constexpr S() : v_(0) {}
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S(int v) : v_(v) {}
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constexpr S(const S &rhs) : v_(rhs.v_) {} // not trivially moveable
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constexpr S( S &&rhs) : v_(rhs.v_) {} // not trivially moveable
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int v_;
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};
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constexpr bool test() // expected-error {{constexpr function never produces a constant expression}}
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{
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std::optional<S> o1{3};
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std::optional<S> o2 = std::move(o1);
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return o2.has_value(); // return -something-
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}
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int main(int, char**)
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{
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static_assert (!std::is_trivially_move_constructible_v<S>, "" );
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static_assert (test(), ""); // expected-error {{static_assert expression is not an integral constant expression}}
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return 0;
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}
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