[libcxx-commits] [PATCH] D103947: [libcxx] Fix using the vcruntime ABI with _HAS_EXCEPTIONS=0 defined

Wed Jun 9 10:12:40 PDT 2021

phosek added a comment.

In D103947#2807992 <https://reviews.llvm.org/D103947#2807992>, @ldionne wrote:

> Is this configuration being tested by a bot? Who is it important for?
>
> This looks good to me, except for the principle that we should not attempt to half-support configurations that we don't commit to testing - instead we should clearly state that those are not supported and simplify the library to not even try to support them. I'm 100% fine with this patch and supportive of this if I can get an answer to the questions above.

This is important for us, I'm trying to set up Fuchsia toolchain build for Windows and I ran into this issue in the runtimes build, this manifests when building compiler-rt (libFuzzer) using the just built Clang and libc++. I hope this also answers the question of testing, once this lands I'll (re-)enable the use of libc++ in our Windows toolchain build which is going cover this configuration.

We could also consider setting up Buildkite pipeline for Windows if we want coverage in libc++ presubmit testing although that's probably more work.

> I'm hitting on that nail again because I happened to be looking at some CMake complexity yesterday that was introduced by attempting to port libc++ to Windows a few years back. I wasn't sure what the status was and whether it was still necessary (I suspect not), but it did prevent me from making simplifications to the code. I'm trying to prevent these situations where we feel blocked from making improvements to avoid breaking <some configuration>, without knowing whether it actually even matters.

Understood, I'd like to get to a state where libc++ could be reliably used on Windows to build Clang itself which I think is a good baseline (that is self-hosting).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D103947/new/

https://reviews.llvm.org/D103947