[PATCH] D54769: [FileCheck] New option -warn

[Paul Robinson via Phabricator via llvm-commits]

probinson added a comment.

In D54769#1308872 <https://reviews.llvm.org/D54769#1308872>, @SjoerdMeijer wrote:

> I am unsure about 3), i.e. I can't remember/am unsure if we can avoid false positives. I will look into this again, or if someone can remind me that's fine too :-). But I thought this was the motivating case for emitting a diagnostic: if a false positive cannot be easily be avoided, an opt-in warning is the best we can do at the moment. The use case would indeed be to enable this while developing new tests.


Someone had a use-case for label-only check prefixes, which was when the labels were the same across several runs but the checks between the labels would vary.  I think it had to do with instructions emitted for different subtargets.  Thus, if a given prefix had only labels, and we diagnosed that, it would be a false positive.
Now, if the only directives ever seen were labels, that's different, and suggests a misunderstanding of LABEL.  But it also will not lead to tests that do the wrong thing.  So, I'm not convinced that we can have a diagnostic for your case 3 that would really be meaningful and useful.


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  https://reviews.llvm.org/D54769/new/

https://reviews.llvm.org/D54769