libcxx/test/std/containers/views/views.span/span.obs/empty.nodiscard.verify.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-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 // UNSUPPORTED: c++03, c++11, c++14, c++17
   9
  10 // <span>
  11
  12 // [[nodiscard]] constexpr bool empty() const noexcept;
  13
  14 #include <span>
  15
  16 void test() {
  17   std::span<int> s1;
  18   s1.empty(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
  19
  20   int arr[] = {1, 2, 3};
  21   std::span<int, 3> s2{arr};
  22   s2.empty(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
  23 }