[PATCH] D27204: [libcxxabi] Introduce an externally threaded libc++abi variant

[Eric Fiselier via Phabricator via cfe-commits]

EricWF added a comment.

In https://reviews.llvm.org/D27204#613172, @rmaprath wrote:

> In https://reviews.llvm.org/D27204#613122, @EricWF wrote:
>
> > My main issue with this patch (and https://reviews.llvm.org/D27206) is that there are now two different CMake options for building two different external threading libraries. I would much prefer having libc++abi use libc++'s `__threading_support` header and `cxx_external_threads` library.
>
>
> I would like to do that too!
>
> But I always viewed `libcxx` and `libcxxabi` as two independent libraries that should be usable on their own. In this case, binding `libcxxabi` to `__threading_support` from `libcxx` sounded wrong, because `__threading_support` is something internal to `libcxx` (e.g. all the functions there are prefixed with `__libcpp_` - there may be other `libcpp`-isms arising from `__config` in there too).


Ironically I've always viewed `libcxxabi` as fully dependent on `libcxx` (and personally I would like to see the repos merged; Although using libc++ w/o libc++abi would still be supported).

> Is that not a concern? I could give it a shot and try to merge the two APIs into one if not.

It's not a concern. Libc++abi already depends on libc++ internals to build (See the `#include "__refstring" in `stdlib_stdexcept.cpp`).


https://reviews.llvm.org/D27204