[PATCH] D22773: Modules: add command line option fmodules-disable-diagnostic-validation to disable validation of the diagnostic options when loading the module
Manman Ren via cfe-commits
cfe-commits at lists.llvm.org
Mon Jul 25 16:44:50 PDT 2016
manmanren added a comment.
In https://reviews.llvm.org/D22773#495524, @benlangmuir wrote:
> > the pcm could still be rewritten by a compilation that doesn't use a PCH, and then it would be out of date because of the timestamp instead of the diagnostic options
>
> >
>
> > "a compilation that doesn't use a PCH", is that a different project? And we have two projects building in parallel? Just to make sure I understand.
>
>
> Two different projects (or targets, or whatever), but they don't even have to build at the same time. They just have to share a cache. Suppose you have a project A with a PCH and -fmodules-disable-diagnostic-validation. Suppose you have another project B that does not use this flag, and does not have a PCH. With this patch, A and B can share a module cache.
>
> A builds a PCH that depends on some module X -- OK
> B builds with -Werror. Rebuilds X.pcm -- OK
>
> Now suppose we build A again because of some change: it can't build because X.pcm changed, but we haven't rebuilt the PCH.
Got it, I will update the patch!
Manman
https://reviews.llvm.org/D22773
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