[PATCH] D58784: [FileCheck]Remove assertions that prevent matching an empty string at file start before CHECK-NEXT/SAME

[Thomas Preud'homme via Phabricator via llvm-commits]

thopre added a comment.

In D58784#1424297 <https://reviews.llvm.org/D58784#1424297>, @jhenderson wrote:

> I think `CHECK-FIRSTLINE: {{^$}}` would be a natural consequence of not wanting to change the permitted uses of other check directives, although I definitely agree it's not ideal. I'm not sure how else it would work if CHECK-SAME remained illegal as the first CHECK, and if we don't want to change CHECK-EMPTY's semantics. I suppose we could special-case CHECK-EMPTY's behaviour when it is the first check in the file to match the first line. This would certainly be intuitive, but it means that CHECK-EMPTY would no longer mean the same as CHECK-NEXT (except matching an empty line) in all cases. Thus CHECK-EMPTY becomes "Checks if the NEXT line in the input is completely empty. If it is the first specified CHECK, it checks that the first line matches is empty." I think this would be nicer than a new directive for this specific case, or to force regular expressions etc.


I think I can be convinced that it is ok to make an initial CHECK-NEXT match the first line of input if an explicit mention to this case is added to the existing documentation for CHECK-NEXT and perhaps also reword the current text slightly to indicate that CHECK-NEXT checks for a match in the next line of input (so that the explicit mention of CHECK-NEXT as first directive feels natural to whoever is reading).


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  rL LLVM

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  https://reviews.llvm.org/D58784/new/

https://reviews.llvm.org/D58784