[PATCH] D159064: [Modules] Make clang modules for the C standard library headers

[Ian Anderson via Phabricator via cfe-commits]

iana added a comment.

In D159064#4647709 <https://reviews.llvm.org/D159064#4647709>, @vsapsai wrote:

> Still going through the patch and through the discussion. But wanted to ask if there are any complications in reverting this change? For libc++ we've discussed that we don't really know the perf impact of multiple small modules. So I want to make sure we aren't making decisions that make it impossible to revert the change later.

I don't think we can really revert the C stdlib headers each being in their own module; there isn't any other way around the module layering maze. libc++ is a bit different, it's not just the C stdlib headers that are each in their own module, it's every one of the ~1000 headers right now. I have misgivings about that, I made D155141 <https://reviews.llvm.org/D155141> to reduce that closer to 150 modules instead of 1000 but it was poorly received. I might try to address some of the concerns after I get this one worked through.


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https://reviews.llvm.org/D159064