[PATCH] D48946: [Preamble] Check system dependencies in preamble too

[Sam McCall via Phabricator via cfe-commits]

sammccall accepted this revision.
sammccall added a comment.
This revision is now accepted and ready to land.

This seems like it might be a nontrivial performance hit (it's going to result in `stat`ing all these files, right?).
Agreed it's important for correctness, it's possible someone wants the performance/correctness tradeoff though.



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Comment at: lib/Frontend/PrecompiledPreamble.cpp:71
+ // but there is no way to distinguish between those and the ones that can be
+ // spuriously added by '-isystem' (e.g. to avoid errors from those headers).
+ bool needSystemDependencies() override { return true; }
----------------
avoid errors --> suppress warnings?


Repository:
  rC Clang

https://reviews.llvm.org/D48946