libcxx/test/std/utilities/expected/expected.bad/error.member.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, c++17, c++20
  10
  11 // E& error() & noexcept;
  12 // const E& error() const & noexcept;
  13 // E&& error() && noexcept;
  14 // const E&& error() const && noexcept;
  15
  16 #include <cassert>
  17 #include <concepts>
  18 #include <expected>
  19 #include <utility>
  20
  21 template <class T>
  22 concept ErrorNoexcept =
  23     requires(T&& t) {
  24       { std::forward<T>(t).error() } noexcept;
  25     };
  26
  27 static_assert(!ErrorNoexcept<int>);
  28 static_assert(ErrorNoexcept<std::bad_expected_access<int>&>);
  29 static_assert(ErrorNoexcept<std::bad_expected_access<int> const&>);
  30 static_assert(ErrorNoexcept<std::bad_expected_access<int>&&>);
  31 static_assert(ErrorNoexcept<std::bad_expected_access<int> const&&>);
  32
  33 void test() {
  34   // &
  35   {
  36     std::bad_expected_access<int> e(5);
  37     decltype(auto) i = e.error();
  38     static_assert(std::same_as<decltype(i), int&>);
  39     assert(i == 5);
  40   }
  41
  42   // const &
  43   {
  44     const std::bad_expected_access<int> e(5);
  45     decltype(auto) i = e.error();
  46     static_assert(std::same_as<decltype(i), const int&>);
  47     assert(i == 5);
  48   }
  49
  50   // &&
  51   {
  52     std::bad_expected_access<int> e(5);
  53     decltype(auto) i = std::move(e).error();
  54     static_assert(std::same_as<decltype(i), int&&>);
  55     assert(i == 5);
  56   }
  57
  58   // const &&
  59   {
  60     const std::bad_expected_access<int> e(5);
  61     decltype(auto) i = std::move(e).error();
  62     static_assert(std::same_as<decltype(i), const int&&>);
  63     assert(i == 5);
  64   }
  65 }
  66
  67 int main(int, char**) {
  68   test();
  69   return 0;
  70 }