[PATCH] D30882: Add a callback for __has_include and use it for dependency scanning

[Duncan P. N. Exon Smith via Phabricator via cfe-commits]

dexonsmith added a comment.

In https://reviews.llvm.org/D30882#1075589, @dexonsmith wrote:

> In https://reviews.llvm.org/D30882#1075576, @pete wrote:
>
> > Would it be ok to turn this on by default, without a flag, only in the case of the path actually existing, and only the found path being the one we add to the .d?
>
>
> I think that pessimizes some incremental builds:
>
> - You have a `__has_include("missing.h")`, but don't include missing.h.
> - Change "missing.h" (but don't delete it).
> - An incremental build now has to rebuild the object file, even though nothing will have changed.
>
>   However, it's fixing an actual bug, so it makes sense to me to be more conservative.


To be clear, I meant "yes" by that!


https://reviews.llvm.org/D30882