[libcxx-commits] [libcxx] [libc++] Avoid heap allocation for default-precision double formatting (PR #212502)

[Nikolas Klauser via libcxx-commits]

https://github.com/philnik777 requested changes to this pull request.

This is incorrect. The standard requires that if there is no precision argument given, this is equivalent to `to_chars` without a precision argument, which this patch changes.

P.S. please don't AI-generate commit messages. They are usually verbose and contain little to no relevant information about the patch.

https://github.com/llvm/llvm-project/pull/212502