test/std/utilities/function.objects/range.cmp/not_equal_to.pass.cpp

//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

// UNSUPPORTED: c++03, c++11, c++14, c++17

// <functional>

// ranges::not_equal_to

#include <cassert>
#include <functional>
#include <type_traits>
#include <utility>

#include "test_macros.h"
#include "compare_types.h"
#include "MoveOnly.h"
#include "pointer_comparison_test_helper.h"

struct NotEqualityComparable {
  friend bool operator==(const NotEqualityComparable&, const NotEqualityComparable&);
  friend bool operator!=(const NotEqualityComparable&, const NotEqualityComparable&) = delete;
};

static_assert(!std::is_invocable_v<std::ranges::equal_to, NotEqualityComparable, NotEqualityComparable>);
static_assert(!std::is_invocable_v<std::ranges::equal_to, int, MoveOnly>);
static_assert(std::is_invocable_v<std::ranges::equal_to, explicit_operators, explicit_operators>);

static_assert(requires { typename std::ranges::not_equal_to::is_transparent; });

struct PtrAndNotEqOperator {
  constexpr operator void*() const { return nullptr; }
  // We *don't* want operator!= to be picked here.
  friend constexpr bool operator!=(PtrAndNotEqOperator, PtrAndNotEqOperator) { return true; }
};

constexpr bool test() {
  auto fn = std::ranges::not_equal_to();

  assert(fn(MoveOnly(41), MoveOnly(42)));

  // These are the opposite of other tests.
  ForwardingTestObject a;
  ForwardingTestObject b;
  assert(fn(a, b));
  assert(!fn(std::move(a), std::move(b)));

  assert(fn(1, 2));
  assert(!fn(2, 2));
  assert(fn(2, 1));

  assert(fn(2, 1L));

  // Make sure that "ranges::equal_to(x, y) == !ranges::not_equal_to(x, y)", even here.
  assert(!fn(PtrAndNotEqOperator(), PtrAndNotEqOperator()));
  assert(std::ranges::equal_to()(PtrAndNotEqOperator(), PtrAndNotEqOperator()));

  return true;
}

int main(int, char**) {

  test();
  static_assert(test());

  // test total ordering of int* for not_equal_to<int*> and not_equal_to<void>.
  do_pointer_comparison_test(std::ranges::not_equal_to());

  return 0;
}