libcxx/test/std/utilities/optional/optional.syn/optional_nullopt_t.fail.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>

// A program that necessitates the instantiation of template optional for
// (possibly cv-qualified) nullopt_t is ill-formed.

#include <optional>

int main()
{
    using std::optional;
    using std::nullopt_t;
    using std::nullopt;

    optional<nullopt_t> opt; // expected-note 1 {{requested here}}
    optional<const nullopt_t> opt1; // expected-note 1 {{requested here}}
    optional<nullopt_t &> opt2; // expected-note 1 {{requested here}}
    optional<nullopt_t &&> opt3; // expected-note 1 {{requested here}}
    // expected-error@optional:* 4 {{instantiation of optional with nullopt_t is ill-formed}}
}