[clang] [lit] Are all RUN lines skipped in windows cmd? (PR #65242)

[Joel E. Denny via cfe-commits]

jdenny-ornl wrote:

Thanks for everyone's comments so far.

This PR is not ready to land.  As discussed, it doesn't fully fix support for windows `cmd` as a lit external shell.  Given how long that use case has been broken (apparently since April, 2022), it seems that's a use case no one cares about anymore.

Possible next steps include:

1. Fix windows `cmd` support.  That looks straight-forward.  If we're going to do that, then we probably should also apply changes that PR #65267 applied for sh-like external shells, and there [might still be further changes along those lines as well](https://discourse.llvm.org/t/rfc-improving-lits-debug-output/72839/44?u=jdenny-ornl).  But I don't see a reason to go down this path if no one actually cares.
2. Land a patch to raise a python exception when lit encounters its code path to use windows `cmd` as an external shell.  If no one complains for a few weeks, then we drop support.
3. Rewrite this PR's title and commit log to explain what it does do: clean up the `%dbg` expansion implementation, and make `--per-test-coverage` work for lit's internal shell.

Please let me know if you have opinions on this.  When I have some more time, I'm thinking of pursuing 1 and 3.




https://github.com/llvm/llvm-project/pull/65242