llvm/libcxx/test/std/utilities/optional/optional.syn/optional_nullopt_t.verify.cpp

//===----------------------------------------------------------------------===//
//
// 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++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>

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