There is an option –allow-unused-prefixes in FileCheck that checks whether prefix specified by
--check-prefixes is used in file, but what I think is missing is some kind of option/config to detect opposite situation - whether prefix in the file is declared in any RUN line.
At the moment we can have lit tests that contain “CHECK” lines that doesn’t check anything because given prefix is not used by any of RUN lines. I don’t think it is an error in itself, but it would be nice to get at least warning info when running lit test that such prefix exists. And this issue can be as I see now due to two reasons:
RUN line has been removed and given prefix is no longer required
Typo in prefix spelling when writing CHECK line
Is it something by design, or do you think it is worth updating?