[PATCH] D69778: Make -fmodules-codegen and -fmodules-debuginfo work also with precompiled headers

Wed Dec 11 00:49:39 PST 2019

llunak added a comment.

In D69778#1776472 <https://reviews.llvm.org/D69778#1776472>, @dblaikie wrote:

> I guess one aspect is that -building-pch-with-obj seems like it duplicates the fmodules-codegen concept (both basically are a flag passed during pcm/pch build time that says "I promise to build an object file from this pcm/pch, so rely on that assumption when building other things that depend on the pcm/pch) - if I'd noticed the -building-pch-with-obj going in I would've made the point then.

Is that described somewhere? There's no mention of modules codegen anywhere under clang/docs. I was under the impression that modules created the codegen part directly in the .pcm in ELF (or whatever) format.

> But yeah, that's out of scope for this patch, but might be something that'd be good to look into to try to merge these features/codepaths more.

Note that AFAICT the -building-pch-with-obj flag is pretty much internal, used only by the MSVC-like PCH creation, so presumably this could be still unified more without any real harm. And I think I could do the work if it'd be agreed that this would be a good thing.

As for this patch itself, could you please also review https://reviews.llvm.org/D69585 and https://reviews.llvm.org/D69779 ? I have not really tried this patch without the first one, so I'm a bit hesitant to merge it alone, and I quickly ran into the problem fixed by the second patch, so I'd prefer to merge them all three together if possible.

Repository:
  rC Clang

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https://reviews.llvm.org/D69778