Re: [PATCH] Fix grep -Fw '' against empty string

[Jim Meyering]

Paolo Bonzini wrote:
> I found this bug while working on the hang.  I thought it could be
> fixed only by almost-rewriting Fexecute, but this doesn't seem true.
>
> Additional pairs of eyes are very welcome.
>
> Paolo Bonzini (2):
>   grep: fix matching the empty string with grep -Fw
>   test: cover just-fixed bug
>
>  NEWS           |    3 +++
>  src/kwsearch.c |    4 +++-
>  tests/empty    |    4 +---
>  3 files changed, 7 insertions(+), 4 deletions(-)
>
> Subject: [PATCH 1/2] grep: fix matching the empty string with grep -Fw
>
> * NEWS: Document fix.
> * src/kwsearch.c (Fexecute): The empty string is a valid match if it is
> a whole word.

Thanks for the patch.
That looks like a correct change.

However, the change in behavior is likely enough to cause trouble
that I preferred to defer it to 2.7.

While uses like grep -Fw '' (explicit empty string) are probably very
rare, using grep -Fw -f KEYWORD_FILE with blank lines in that file is
much more plausible, and this fix would cause a big behavior change.
With the fix, grep will now match all blank lines in the input.

You're welcome to push it now (though please move the NEWS entry "up").