[PATCH] D139653: [clang] Set ShowInSystemHeader for module-build and module-import remarks

[Dave Lee via Phabricator via cfe-commits]

kastiglione added a comment.

> Also, do you think this should be configurable on the command line?

Do you have a flag in mind? I have worked around the current behavior with `-Wno-system-header`, but there are two problems with that: first, it's not obvious that it's needed (I had to debug clang to figure out why diagnostics were missing, most people wouldn't do that), and second it can result in many many warnings, which – if you are only interested in module remarks, represents a bunch of noise.

> I'm thinking about users that are trying to debug their own modular code, but don't really care what happens in the SDK.

My first question is how many of those users are there? It seems to me that the module remarks are more for tooling developers than end users. Speaking as someone working on tools, I think I would always want all module-build remarks, since – correct me if I'm wrong – they're relevant only to performance, and for performance I want to see all the builds.

For module-import remarks, I could see it being more interesting to developers, but I don't know how many developers know about and use `-Rmodule-import`. If we want to proactively support those users, maybe the solution is two flags, say `-Rmodule-import` and `-Rmodule-import-all` (I can't think of a better spelling).

For relevant comparisons, the only thing I can think about is the `-H` flag, which shows all header includes, it does not exclude system headers. Speaking of which, an equivalent for modules might be helpful.


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  https://reviews.llvm.org/D139653/new/

https://reviews.llvm.org/D139653