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libcxx_old/test/std/utilities/optional/optional.object/optional.object.observe/dereference_const.pass.cpp

71 lines
1.8 KiB
C++

//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
// UNSUPPORTED: c++98, c++03, c++11, c++14
// <optional>
// constexpr const T& optional<T>::operator*() const &;
#ifdef _LIBCPP_DEBUG
#define _LIBCPP_ASSERT(x, m) ((x) ? (void)0 : std::exit(0))
#endif
#include <optional>
#include <type_traits>
#include <cassert>
#include "test_macros.h"
using std::optional;
struct X
{
constexpr int test() const& {return 3;}
int test() & {return 4;}
constexpr int test() const&& {return 5;}
int test() && {return 6;}
};
struct Y
{
int test() const {return 2;}
};
int main(int, char**)
{
{
const optional<X> opt; ((void)opt);
ASSERT_SAME_TYPE(decltype(*opt), X const&);
// ASSERT_NOT_NOEXCEPT(*opt);
// FIXME: This assertion fails with GCC because it can see that
// (A) operator*() is constexpr, and
// (B) there is no path through the function that throws.
// It's arguable if this is the correct behavior for the noexcept
// operator.
// Regardless this function should still be noexcept(false) because
// it has a narrow contract.
}
{
constexpr optional<X> opt(X{});
static_assert((*opt).test() == 3, "");
}
{
constexpr optional<Y> opt(Y{});
assert((*opt).test() == 2);
}
#ifdef _LIBCPP_DEBUG
{
const optional<X> opt;
assert((*opt).test() == 3);
assert(false);
}
#endif // _LIBCPP_DEBUG
return 0;
}