test/std/strings/basic.string/string.capacity/max_size.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: no-exceptions

// After changing the alignment of the allocated pointer from 16 to 8, the exception
// thrown is no longer `bad_alloc` but instead length_error on systems using new
// headers but a dylib that doesn't contain 04ce0ba.
//
// XFAIL: using-built-library-before-llvm-19

// <string>

// size_type max_size() const; // constexpr since C++20

// NOTE: asan and msan will fail for one of two reasons
// 1. If allocator_may_return_null=0 then they will fail because the allocation
//    returns null.
// 2. If allocator_may_return_null=1 then they will fail because the allocation
//    is too large to succeed.
// UNSUPPORTED: sanitizer-new-delete

#include <string>
#include <cassert>
#include <new>

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

template <class S>
TEST_CONSTEXPR_CXX20 void test_resize_max_size_minus_1(const S& s) {
  S s2(s);
  const std::size_t sz = s2.max_size() - 1;
  try {
    s2.resize(sz, 'x');
  } catch (const std::bad_alloc&) {
    return;
  }
  assert(s2.size() == sz);
}

template <class S>
TEST_CONSTEXPR_CXX20 void test_resize_max_size(const S& s) {
  S s2(s);
  const std::size_t sz = s2.max_size();
  try {
    s2.resize(sz, 'x');
  } catch (const std::bad_alloc&) {
    return;
  }
  assert(s.size() == sz);
}

template <class S>
TEST_CONSTEXPR_CXX20 void test_string() {
  {
    S s;
    assert(s.max_size() >= s.size());
    assert(s.max_size() > 0);
    if (!TEST_IS_CONSTANT_EVALUATED) {
      test_resize_max_size_minus_1(s);
      test_resize_max_size(s);
    }
  }
  {
    S s("123");
    assert(s.max_size() >= s.size());
    assert(s.max_size() > 0);
    if (!TEST_IS_CONSTANT_EVALUATED) {
      test_resize_max_size_minus_1(s);
      test_resize_max_size(s);
    }
  }
  {
    S s("12345678901234567890123456789012345678901234567890");
    assert(s.max_size() >= s.size());
    assert(s.max_size() > 0);
    if (!TEST_IS_CONSTANT_EVALUATED) {
      test_resize_max_size_minus_1(s);
      test_resize_max_size(s);
    }
  }
}

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

  return true;
}

int main(int, char**) {
  test();
#if TEST_STD_VER >= 20
  static_assert(test());
#endif

  return 0;
}