tree 62667c7cfa9b2b5a0f73c309b09a4640c12f3e48
parent 74d4a8b10b198f1d75be587f7720a770186a631c
author Louis Dionne <ldionne@apple.com> 1599682496 -0400
committer Copybara-Service <copybara-worker@google.com> 1604019803 -0700

[libcxx] Simplify back-deployment testing

The needs of back-deployment testing currently require two different
ways of running the test suite: one based on the deployment target,
and one based on the target triple. Since the triple includes all the
information we need, it's better to have just one way of doing things.

Furthermore, `--param platform=XXX` is also supersedded by using the
target triple. Previously, this parameter would serve the purpose of
controling XFAILs for availability markup errors, however it is possible
to achieve the same thing by using with_system_cxx_lib only and using
.verify.cpp tests instead, as explained in the documentation changes.

The motivation for this change is twofold:
1. This part of the Lit config has always been really confusing and
   complicated, and it has been a source of bugs in the past. I have
   simplified it iteratively in the past, but the complexity is still
   there.
2. The deployment-target detection started failing in weird ways in
   recent Clangs, breaking our CI. Instead of band-aid patching the
   issue, I decided to remove the complexity altogether by using target
   triples even on Apple platforms.

A follow-up to this commit will bring the test suite in line with
the recommended way of handling availability markup tests.

GitOrigin-RevId: ec46cfefe80d58cdc7068ad4e4f8efde6d94d835