[libcxx-commits] [libcxx] WIP: [libc++][string] P2587R3: `to_string` or not `to_string` (PR #78100)

[Hristo Hristov via libcxx-commits]

H-G-Hristov wrote:

Some notes:
- the code is in the dylib. Removing that breaks Apple backdeployment. (The dylib is always built with the same C++ version).
- `std::format's implementation of `long double` is incorrect. Our `to_chars` implementation is donated by the MSVC team. On Windows `long double` and `double` use the same underlying type. So the output accuracy of `long double` is not correct on platforms where taht is not the case.

https://github.com/llvm/llvm-project/pull/78100