23 lines · cpp
1//===----------------------------------------------------------------------===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8 9// <iterator>10 11// <iterator>12// template <class C> constexpr auto empty(const C& c) -> decltype(c.empty());13 14// UNSUPPORTED: c++03, c++11, c++14, c++1715 16#include <vector>17#include <iterator>18 19void f() {20 std::vector<int> c;21 std::empty(c); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}22}23