test/std/re/re.results/re.results.size/empty.fail.cpp

// -*- 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
//
//===----------------------------------------------------------------------===//

// <regex>

// class match_results<BidirectionalIterator, Allocator>
// bool empty() const;

// UNSUPPORTED: c++98, c++03, c++11, c++14, c++17
// UNSUPPORTED: clang-3.3, clang-3.4, clang-3.5, clang-3.6, clang-3.7, clang-3.8

#include <regex>

#include "test_macros.h"

int main(int, char**)
{
    std::match_results<const char*> c;
    c.empty();  // expected-error {{ignoring return value of function declared with 'nodiscard' attribute}}

  return 0;
}