//===----------------------------------------------------------------------===//
//
// 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>

// template<class charT, class traits, class Allocator>
//   basic_string<charT,traits,Allocator>
//   operator+(const basic_string<charT,traits,Allocator>& lhs,
//             const basic_string<charT,traits,Allocator>& rhs); // constexpr since C++20

// template<class charT, class traits, class Allocator>
//   basic_string<charT,traits,Allocator>&&
//   operator+(const basic_string<charT,traits,Allocator>&& lhs,
//             const basic_string<charT,traits,Allocator>& rhs); // constexpr since C++20

// template<class charT, class traits, class Allocator>
//   basic_string<charT,traits,Allocator>&&
//   operator+(const basic_string<charT,traits,Allocator>& lhs,
//             const basic_string<charT,traits,Allocator>&& rhs); // constexpr since C++20

// template<class charT, class traits, class Allocator>
//   basic_string<charT,traits,Allocator>&&
//   operator+(const basic_string<charT,traits,Allocator>&& lhs,
//             const basic_string<charT,traits,Allocator>&& rhs); // constexpr since C++20

#include <string>
#include <utility>
#include <cassert>

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

template <class S>
TEST_CONSTEXPR_CXX20 void test0(const S& lhs, const S& rhs, const S& x) {
  assert(lhs + rhs == x);
  LIBCPP_ASSERT(is_string_asan_correct(lhs + rhs));
}

#if TEST_STD_VER >= 11
template <class S>
TEST_CONSTEXPR_CXX20 void test1(S&& lhs, const S& rhs, const S& x) {
  assert(std::move(lhs) + rhs == x);
}

template <class S>
TEST_CONSTEXPR_CXX20 void test2(const S& lhs, S&& rhs, const S& x) {
  assert(lhs + std::move(rhs) == x);
}

template <class S>
TEST_CONSTEXPR_CXX20 void test3(S&& lhs, S&& rhs, const S& x) {
  assert(std::move(lhs) + std::move(rhs) == x);
}
#endif

template <class S>
TEST_CONSTEXPR_CXX20 void test_string() {
  test0(S(""), S(""), S(""));
  test0(S(""), S("12345"), S("12345"));
  test0(S(""), S("1234567890"), S("1234567890"));
  test0(S(""), S("12345678901234567890"), S("12345678901234567890"));
  test0(S("abcde"), S(""), S("abcde"));
  test0(S("abcde"), S("12345"), S("abcde12345"));
  test0(S("abcde"), S("1234567890"), S("abcde1234567890"));
  test0(S("abcde"), S("12345678901234567890"), S("abcde12345678901234567890"));
  test0(S("abcdefghij"), S(""), S("abcdefghij"));
  test0(S("abcdefghij"), S("12345"), S("abcdefghij12345"));
  test0(S("abcdefghij"), S("1234567890"), S("abcdefghij1234567890"));
  test0(S("abcdefghij"), S("12345678901234567890"), S("abcdefghij12345678901234567890"));
  test0(S("abcdefghijklmnopqrst"), S(""), S("abcdefghijklmnopqrst"));
  test0(S("abcdefghijklmnopqrst"), S("12345"), S("abcdefghijklmnopqrst12345"));
  test0(S("abcdefghijklmnopqrst"), S("1234567890"), S("abcdefghijklmnopqrst1234567890"));
  test0(S("abcdefghijklmnopqrst"), S("12345678901234567890"), S("abcdefghijklmnopqrst12345678901234567890"));
#if TEST_STD_VER >= 11
  test1(S(""), S(""), S(""));
  test1(S(""), S("12345"), S("12345"));
  test1(S(""), S("1234567890"), S("1234567890"));
  test1(S(""), S("12345678901234567890"), S("12345678901234567890"));
  test1(S("abcde"), S(""), S("abcde"));
  test1(S("abcde"), S("12345"), S("abcde12345"));
  test1(S("abcde"), S("1234567890"), S("abcde1234567890"));
  test1(S("abcde"), S("12345678901234567890"), S("abcde12345678901234567890"));
  test1(S("abcdefghij"), S(""), S("abcdefghij"));
  test1(S("abcdefghij"), S("12345"), S("abcdefghij12345"));
  test1(S("abcdefghij"), S("1234567890"), S("abcdefghij1234567890"));
  test1(S("abcdefghij"), S("12345678901234567890"), S("abcdefghij12345678901234567890"));
  test1(S("abcdefghijklmnopqrst"), S(""), S("abcdefghijklmnopqrst"));
  test1(S("abcdefghijklmnopqrst"), S("12345"), S("abcdefghijklmnopqrst12345"));
  test1(S("abcdefghijklmnopqrst"), S("1234567890"), S("abcdefghijklmnopqrst1234567890"));
  test1(S("abcdefghijklmnopqrst"), S("12345678901234567890"), S("abcdefghijklmnopqrst12345678901234567890"));

  test2(S(""), S(""), S(""));
  test2(S(""), S("12345"), S("12345"));
  test2(S(""), S("1234567890"), S("1234567890"));
  test2(S(""), S("12345678901234567890"), S("12345678901234567890"));
  test2(S("abcde"), S(""), S("abcde"));
  test2(S("abcde"), S("12345"), S("abcde12345"));
  test2(S("abcde"), S("1234567890"), S("abcde1234567890"));
  test2(S("abcde"), S("12345678901234567890"), S("abcde12345678901234567890"));
  test2(S("abcdefghij"), S(""), S("abcdefghij"));
  test2(S("abcdefghij"), S("12345"), S("abcdefghij12345"));
  test2(S("abcdefghij"), S("1234567890"), S("abcdefghij1234567890"));
  test2(S("abcdefghij"), S("12345678901234567890"), S("abcdefghij12345678901234567890"));
  test2(S("abcdefghijklmnopqrst"), S(""), S("abcdefghijklmnopqrst"));
  test2(S("abcdefghijklmnopqrst"), S("12345"), S("abcdefghijklmnopqrst12345"));
  test2(S("abcdefghijklmnopqrst"), S("1234567890"), S("abcdefghijklmnopqrst1234567890"));
  test2(S("abcdefghijklmnopqrst"), S("12345678901234567890"), S("abcdefghijklmnopqrst12345678901234567890"));

  test3(S(""), S(""), S(""));
  test3(S(""), S("12345"), S("12345"));
  test3(S(""), S("1234567890"), S("1234567890"));
  test3(S(""), S("12345678901234567890"), S("12345678901234567890"));
  test3(S("abcde"), S(""), S("abcde"));
  test3(S("abcde"), S("12345"), S("abcde12345"));
  test3(S("abcde"), S("1234567890"), S("abcde1234567890"));
  test3(S("abcde"), S("12345678901234567890"), S("abcde12345678901234567890"));
  test3(S("abcdefghij"), S(""), S("abcdefghij"));
  test3(S("abcdefghij"), S("12345"), S("abcdefghij12345"));
  test3(S("abcdefghij"), S("1234567890"), S("abcdefghij1234567890"));
  test3(S("abcdefghij"), S("12345678901234567890"), S("abcdefghij12345678901234567890"));
  test3(S("abcdefghijklmnopqrst"), S(""), S("abcdefghijklmnopqrst"));
  test3(S("abcdefghijklmnopqrst"), S("12345"), S("abcdefghijklmnopqrst12345"));
  test3(S("abcdefghijklmnopqrst"), S("1234567890"), S("abcdefghijklmnopqrst1234567890"));
  test3(S("abcdefghijklmnopqrst"), S("12345678901234567890"), S("abcdefghijklmnopqrst12345678901234567890"));
#endif
}

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> > >();
  test_string<std::basic_string<char, std::char_traits<char>, safe_allocator<char> > >();
#endif

  return true;
}

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

  return 0;
}