//===----------------------------------------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//

// <string>

// basic_string<charT,traits,Allocator>&
//   append(const basic_string<charT,traits>& str); // constexpr since C++20

#include <string>
#include <cassert>

#include "test_macros.h"
#include "min_allocator.h"

template <class S>
TEST_CONSTEXPR_CXX20 void
test(S s, S str, S expected)
{
    s.append(str);
    LIBCPP_ASSERT(s.__invariants());
    assert(s == expected);
}

template <class S>
TEST_CONSTEXPR_CXX20 void test_string() {
  test(S(), S(), S());
  test(S(), S("12345"), S("12345"));
  test(S(), S("1234567890"), S("1234567890"));
  test(S(), S("12345678901234567890"), S("12345678901234567890"));

  test(S("12345"), S(), S("12345"));
  test(S("12345"), S("12345"), S("1234512345"));
  test(S("12345"), S("1234567890"), S("123451234567890"));
  test(S("12345"), S("12345678901234567890"), S("1234512345678901234567890"));

  test(S("1234567890"), S(), S("1234567890"));
  test(S("1234567890"), S("12345"), S("123456789012345"));
  test(S("1234567890"), S("1234567890"), S("12345678901234567890"));
  test(S("1234567890"), S("12345678901234567890"), S("123456789012345678901234567890"));

  test(S("12345678901234567890"), S(), S("12345678901234567890"));
  test(S("12345678901234567890"), S("12345"), S("1234567890123456789012345"));
  test(S("12345678901234567890"), S("1234567890"), S("123456789012345678901234567890"));
  test(S("12345678901234567890"), S("12345678901234567890"),
        S("1234567890123456789012345678901234567890"));
}

TEST_CONSTEXPR_CXX20 bool test() {
  test_string<std::string>();
#if TEST_STD_VER >= 11
  test_string<std::basic_string<char, std::char_traits<char>, min_allocator<char>>>();
#endif

#if TEST_STD_VER >= 11
  {   // LWG 2946
    std::string s;
    s.append({"abc", 1});
    assert(s.size() == 1);
    assert(s == "a");
  }
#endif

  return true;
}

int main(int, char**)
{
  test();
#if TEST_STD_VER > 17
  static_assert(test());
#endif

  return 0;
}