libcxx/test/std/utilities/optional/optional.object/optional.object.mod/reset.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>

// void reset() noexcept;

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

using std::optional;

struct X
{
    static bool dtor_called;
    ~X() {dtor_called = true;}
};

bool X::dtor_called = false;

int main()
{
    {
        optional<int> opt;
        static_assert(noexcept(opt.reset()) == true, "");
        opt.reset();
        assert(static_cast<bool>(opt) == false);
    }
    {
        optional<int> opt(3);
        opt.reset();
        assert(static_cast<bool>(opt) == false);
    }
    {
        optional<X> opt;
        static_assert(noexcept(opt.reset()) == true, "");
        assert(X::dtor_called == false);
        opt.reset();
        assert(X::dtor_called == false);
        assert(static_cast<bool>(opt) == false);
    }
    assert(X::dtor_called == false); // TRANSITION, Clang/C2 VSO#239997
    {
        optional<X> opt(X{});
        X::dtor_called = false;
        opt.reset();
        assert(X::dtor_called == true);
        assert(static_cast<bool>(opt) == false);
        X::dtor_called = false;
    }
    assert(X::dtor_called == false); // TRANSITION, Clang/C2 VSO#239997
}