[libcxx-commits] [libcxx] [libc++][format] Handle range-underlying-spec (PR #81914)

[Mark de Wever via libcxx-commits]

https://github.com/mordante commented:

Thanks for working on this. Since the patch is a draft I mainly glanced over it.

I'm curious, why did you add `__has_range_underlying_spec_` instead of using `__use_range_fill_`?

https://github.com/llvm/llvm-project/pull/81914