//===----------------------------------------------------------------------===//
//
// 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
// UNSUPPORTED: libcpp-no-concepts
// UNSUPPORTED: gcc-10

// std::ranges::ssize

#include <ranges>

#include <cassert>
#include "test_macros.h"
#include "test_iterators.h"

using RangeSSizeT = decltype(std::ranges::ssize);

static_assert(!std::is_invocable_v<RangeSSizeT, int[]>);
static_assert( std::is_invocable_v<RangeSSizeT, int[1]>);
static_assert( std::is_invocable_v<RangeSSizeT, int (&&)[1]>);
static_assert( std::is_invocable_v<RangeSSizeT, int (&)[1]>);

static_assert(std::semiregular<std::remove_cv_t<RangeSSizeT>>);

struct SizeMember {
  constexpr size_t size() { return 42; }
};

static_assert(!std::is_invocable_v<RangeSSizeT, const SizeMember>);

struct SizeFunction {
  friend constexpr size_t size(SizeFunction) { return 42; }
};

struct SizeFunctionSigned {
  friend constexpr std::ptrdiff_t size(SizeFunctionSigned) { return 42; }
};

struct sentinel {
  bool operator==(std::input_or_output_iterator auto) const { return true; }
};

struct RandomAccesslRange {
  constexpr random_access_iterator<int*> begin() { return {}; }
  constexpr sentinel end() { return {}; }
};

constexpr std::ptrdiff_t operator-(const sentinel, const random_access_iterator<int*>) { return 2; }
constexpr std::ptrdiff_t operator-(const random_access_iterator<int*>, const sentinel) { return 2; }

struct ShortUnsignedReturnType {
  constexpr unsigned short size() { return 42; }
};

// size_t changes depending on the platform.
using SignedSizeT = std::make_signed_t<size_t>;

constexpr bool test() {
  int a[4];

  assert(std::ranges::ssize(a) == 4);
  ASSERT_SAME_TYPE(decltype(std::ranges::ssize(a)), SignedSizeT);

  assert(std::ranges::ssize(SizeMember()) == 42);
  ASSERT_SAME_TYPE(decltype(std::ranges::ssize(SizeMember())), SignedSizeT);

  assert(std::ranges::ssize(SizeFunction()) == 42);
  ASSERT_SAME_TYPE(decltype(std::ranges::ssize(SizeFunction())), SignedSizeT);

  assert(std::ranges::ssize(SizeFunctionSigned()) == 42);
  ASSERT_SAME_TYPE(decltype(std::ranges::ssize(SizeFunctionSigned())), std::ptrdiff_t);

  RandomAccesslRange b;
  assert(std::ranges::ssize(b) == 2);
  ASSERT_SAME_TYPE(decltype(std::ranges::ssize(b)), std::ptrdiff_t);

  // This gets converted to ptrdiff_t because it's wider.
  ShortUnsignedReturnType c;
  assert(std::ranges::ssize(c) == 42);
  ASSERT_SAME_TYPE(decltype(std::ranges::ssize(c)), ptrdiff_t);

  return true;
}

int main(int, char**) {
  test();
  static_assert(test());

  return 0;
}