[libcxx-commits] [libcxx] [libcxxabi] [libc++] Split the monolithic __threading_support header (PR #79654)

[Louis Dionne via libcxx-commits]

ldionne wrote:

> This requires updating libcxx and libcxxabi at the same time.
> 
> Any opposition to replacing the includes in libcxxabi with
> 
> ```
> #if __has_include(<__thread/support.h>)
> #include <__thread/support.h>
> #else
> #include <__threading_support>
> #endif
> ```
> 
> for a while, so that projects can keep rolling libcxxabi and libcxx independently? (We have an autoroller for libcxxabi that has been working without issues for years up to this change, and we have one for libcxx that's broken pretty frequently due to libcxx changes, including right now. It'd be nice if libcxxabi could keep rolling.)

We can do that... but what I don't understand is how you build libc++abi. We require building libc++ and libc++abi at the same time, so how do you manage to roll both libraries independently?

https://github.com/llvm/llvm-project/pull/79654