Re: Bug in git-diff output

From: Junio C Hamano <gitster@pobox.com>
Date: Apr 3, 2014, 18:10 UTC
Message-ID: <xmqqeh1eqo6s.fsf@gitster.dls.corp.google.com>
In-Reply-To: <vpqmwg4c4q8.fsf@anie.imag.fr>

Matthieu Moy <Matthieu.Moy@grenoble-inp.fr> writes:

Show 16 quoted lines

> "rocketscienc01100101 ." <rocketscienc01100101@gmail.com> writes:
>
>> http://i.imgur.com/BoJSjm9.png
>>
>> Here's a screenshot that shows the problem.
>
> (better cut-and-paste the text than sending a PNG image)
>
>> There's always a misplaced line in the output (most of the time
>> a[href^=tel] { }), no matter where in the file the changes are.
>
> The part after the @@ are ignored by patch tools. They are here just for
> convenience. They are a guess of what the patch hunk belongs to. For
> C/Java/Ada/... programs, it's the function name. Git does not know about
> CSS syntax, so it guesses wrong (last line starting with a letter I
> guess, not sure exactly what happens when Git doesn't know the syntax).

Ask "git grep -A14 'long def_ff' xdiff/" for details ;-)

This was an attempt to be compatible with stock behaviour of GNU diff: a line that begins with an alpha, _ or $.

>> Sometimes it's even in the wrong position, above the @@ numbers.
>
> That is strange. Do you have a way to reproduce this?

That indeed is unusual. If the payload that was identified by the find_func function has a funny escape sequence or something, you may get funkiness like that in the output on the terminal, which we may want to take notice and sanitize in xdl_emit_hunk_hdr(), instead of straight memcpy() there, but I do not see how that would be an issue in a css source.