test/std/utilities/optional/optional.object/optional.object.observe/has_value.pass.cpp

//===----------------------------------------------------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is dual licensed under the MIT and the University of Illinois Open
// Source Licenses. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

// UNSUPPORTED: c++98, c++03, c++11, c++14
// <optional>

// constexpr bool optional<T>::has_value() const noexcept;

#include <optional>
#include <type_traits>
#include <cassert>

#include "test_macros.h"

int main()
{
    using std::optional;
    {
        const optional<int> opt; ((void)opt);
        ASSERT_NOEXCEPT(opt.has_value());
        ASSERT_SAME_TYPE(decltype(opt.has_value()), bool);
    }
    {
        constexpr optional<int> opt;
        static_assert(!opt.has_value(), "");
    }
    {
        constexpr optional<int> opt(0);
        static_assert(opt.has_value(), "");
    }
}