libcxx/test/std/utilities/optional/optional.object/optional.object.observe/value_const.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
  11 // XFAIL: availability-bad_optional_access-missing && !no-exceptions
  12
  13 // <optional>
  14
  15 // constexpr const T& optional<T>::value() const &;
  16
  17 #include <optional>
  18 #include <type_traits>
  19 #include <cassert>
  20
  21 #include "test_macros.h"
  22
  23 using std::optional;
  24 using std::in_place_t;
  25 using std::in_place;
  26 using std::bad_optional_access;
  27
  28 struct X
  29 {
  30     X() = default;
  31     X(const X&) = delete;
  32     constexpr int test() const & {return 3;}
  33     int test() & {return 4;}
  34     constexpr int test() const && {return 5;}
  35     int test() && {return 6;}
  36 };
  37
  38 int main(int, char**)
  39 {
  40     {
  41         const optional<X> opt; ((void)opt);
  42         ASSERT_NOT_NOEXCEPT(opt.value());
  43         ASSERT_SAME_TYPE(decltype(opt.value()), X const&);
  44     }
  45     {
  46         constexpr optional<X> opt(in_place);
  47         static_assert(opt.value().test() == 3, "");
  48     }
  49     {
  50         const optional<X> opt(in_place);
  51         assert(opt.value().test() == 3);
  52     }
  53 #ifndef TEST_HAS_NO_EXCEPTIONS
  54     {
  55         const optional<X> opt;
  56         try
  57         {
  58             (void)opt.value();
  59             assert(false);
  60         }
  61         catch (const bad_optional_access&)
  62         {
  63         }
  64     }
  65 #endif
  66
  67   return 0;
  68 }