[libcxx-commits] [libcxx] [libc++][filesystem] Fix truncation in vformat_string dynamic fallback (PR #203531)

[Zibi Sarbinowski via libcxx-commits]

zibi2 wrote:

Updated per review: resize to `size` and pass `n + 1` to `vsnprintf`, since `std::string` always has room for the null terminator. PR description updated accordingly.

https://github.com/llvm/llvm-project/pull/203531