libcxx/test/std/utilities/expected/expected.void/equality/equality.other_expected.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 // template<class T2, class E2> requires (is_void_v<T2>)
  12 //   friend constexpr bool operator==(const expected& x, const expected<T2, E2>& y);
  13
  14 #include <cassert>
  15 #include <concepts>
  16 #include <expected>
  17 #include <type_traits>
  18 #include <utility>
  19
  20 #include "test_macros.h"
  21
  22 // Test constraint
  23 template <class T1, class T2>
  24 concept CanCompare = requires(T1 t1, T2 t2) { t1 == t2; };
  25
  26 struct Foo{};
  27 static_assert(!CanCompare<Foo, Foo>);
  28
  29 static_assert(CanCompare<std::expected<void, int>, std::expected<void, int>>);
  30 static_assert(CanCompare<std::expected<void, int>, std::expected<void, short>>);
  31
  32 // Note this is true because other overloads in expected<non-void> are unconstrained
  33 static_assert(CanCompare<std::expected<void, int>, std::expected<int, int>>);
  34
  35 constexpr bool test() {
  36   // x.has_value() && y.has_value()
  37   {
  38     const std::expected<void, int> e1;
  39     const std::expected<void, int> e2;
  40     assert(e1 == e2);
  41   }
  42
  43   // !x.has_value() && y.has_value()
  44   {
  45     const std::expected<void, int> e1(std::unexpect, 5);
  46     const std::expected<void, int> e2;
  47     assert(e1 != e2);
  48   }
  49
  50   // x.has_value() && !y.has_value()
  51   {
  52     const std::expected<void, int> e1;
  53     const std::expected<void, int> e2(std::unexpect, 10);
  54     const std::expected<void, int> e3(std::unexpect, 5);
  55     assert(e1 != e2);
  56     assert(e1 != e3);
  57   }
  58
  59   // !x.has_value() && !y.has_value()
  60   {
  61     const std::expected<void, int> e1(std::unexpect, 5);
  62     const std::expected<void, int> e2(std::unexpect, 10);
  63     const std::expected<void, int> e3(std::unexpect, 5);
  64     assert(e1 != e2);
  65     assert(e1 == e3);
  66   }
  67
  68   return true;
  69 }
  70
  71 int main(int, char**) {
  72   test();
  73   static_assert(test());
  74   return 0;
  75 }