[libcxx-commits] [libcxx] [libc++] Fix basic_string not allowing max_size() elements to be stored (PR #125423)

[Louis Dionne via libcxx-commits]

================

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ldionne wrote:

Refactoring suggestion for this test file:

```c++
template <class CharT, class Allocator>
TEST_CONSTEXPR_CXX20 void test_string() {
  // all the tests here, including those for max_size().
  // you probably need to use MAKE_STRING to handle wide characters
  // This function:
  //     void test(S s, typename S::size_type n, S expected)
  // can become a lambda or you can call it something like check_impl
  // to make it clear it's just a throwaway helper.
  {
    ...
  }

  {
    // still hardcode the allocator here, whatever, it's still easier to understand the test that way
    std::basic_string<CharT, std::char_traits<CharT>, tiny_size_allocator<32, CharT>> str;
  }
 }

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

 #ifndef TEST_HAS_NO_WIDE_CHARACTERS
  test_string<std::wstring>();
 #endif

   return true;
 }


int main(int, char**) {
  test();
#if TEST_STD_VER > 17
  static_assert(test());
#endif
  return 0;
}
```

https://github.com/llvm/llvm-project/pull/125423