[clang] Thread Safety Analysis: Improved pointer handling (PR #127396)

[Marco Elver via cfe-commits]

melver wrote:

Committed!

> Looks good to me, and thanks for the contribution!

Thanks for your review!
Fingers crossed the Linux kernel changes will also land soon.
 
> > Note, I think for now it might be safer to not enable by default yet, but I've made a note (and hinted at in changelog) that we're planning to default enable in future, so that should give folks enough time to deal with new findings without breaking things just yet.
> 
> If it's off by default it won't be used by a lot of people, and just the separate flag should be enough to unbreak the build, should it be necessary. But I'm also fine if you'd rather leave it opt-in for a bit and collect experiences before we include it in `-Wthread-safety`.

We'll be trying this on some internal codebases as well, and we can't yet force the cleanups to happen right away. But I expect in ~3-6 months we can flip it to default on.

https://github.com/llvm/llvm-project/pull/127396