libcxx/test/std/utilities/optional/optional.object/optional.object.observe/value_rvalue.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 // constexpr T& optional<T>::value() &&;
  13
  14 #include <optional>
  15 #include <type_traits>
  16 #include <cassert>
  17
  18 #include "test_macros.h"
  19
  20 using std::optional;
  21 using std::bad_optional_access;
  22
  23 struct X
  24 {
  25     X() = default;
  26     X(const X&) = delete;
  27     constexpr int test() const & {return 3;}
  28     int test() & {return 4;}
  29     constexpr int test() const && {return 5;}
  30     int test() && {return 6;}
  31 };
  32
  33 struct Y
  34 {
  35     constexpr int test() && {return 7;}
  36 };
  37
  38 constexpr int
  39 test()
  40 {
  41     optional<Y> opt{Y{}};
  42     return std::move(opt).value().test();
  43 }
  44
  45 int main(int, char**)
  46 {
  47     {
  48         optional<X> opt; ((void)opt);
  49         ASSERT_NOT_NOEXCEPT(std::move(opt).value());
  50         ASSERT_SAME_TYPE(decltype(std::move(opt).value()), X&&);
  51     }
  52     {
  53         optional<X> opt;
  54         opt.emplace();
  55         assert(std::move(opt).value().test() == 6);
  56     }
  57 #ifndef TEST_HAS_NO_EXCEPTIONS
  58     {
  59         optional<X> opt;
  60         try
  61         {
  62             (void)std::move(opt).value();
  63             assert(false);
  64         }
  65         catch (const bad_optional_access&)
  66         {
  67         }
  68     }
  69 #endif
  70     static_assert(test() == 7, "");
  71
  72   return 0;
  73 }