libcxx/test/std/utilities/optional/optional.nullops/less_than.pass.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
   9 // UNSUPPORTED: c++03, c++11, c++14
  10 // <optional>
  11
  12 // template <class T> constexpr bool operator<(const optional<T>& x, nullopt_t) noexcept;
  13 // template <class T> constexpr bool operator<(nullopt_t, const optional<T>& x) noexcept;
  14
  15 #include <optional>
  16
  17 #include "test_macros.h"
  18
  19 int main(int, char**)
  20 {
  21     using std::optional;
  22     using std::nullopt_t;
  23     using std::nullopt;
  24
  25     {
  26     typedef int T;
  27     typedef optional<T> O;
  28
  29     constexpr O o1;     // disengaged
  30     constexpr O o2{1};  // engaged
  31
  32     static_assert ( !(nullopt < o1), "" );
  33     static_assert (  (nullopt < o2), "" );
  34     static_assert ( !(o1 < nullopt), "" );
  35     static_assert ( !(o2 < nullopt), "" );
  36
  37     static_assert (noexcept(nullopt < o1), "");
  38     static_assert (noexcept(o1 < nullopt), "");
  39     }
  40
  41   return 0;
  42 }