GNU bug report logs - #75884
29.4; Dash character "-" appears as diff when it is the leading character in a line in a patch

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Message #11 received at 75884 <at> debbugs.gnu.org (full text, mbox):

From: Sean Whitton <spwhitton <at> spwhitton.name>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: Husain Alshehhi <husain <at> alshehhi.io>, Dmitry Gutov <dmitry <at> gutov.dev>,
 75884 <at> debbugs.gnu.org, Juri Linkov <juri <at> linkov.net>
Subject: Re: bug#75884: 29.4; Dash character "-" appears as diff when it is
 the leading character in a line in a patch
Date: Sat, 08 Feb 2025 12:28:42 +0000

Hello,

On Sat 08 Feb 2025 at 11:32am +02, Eli Zaretskii wrote:

>> Date: Sun, 26 Jan 2025 21:39:35 -0600
>> From: Husain Alshehhi <husain <at> alshehhi.io>
>>
>> diff-mode does not handle a patch very well. In particular, if a patch
>> contains the commit message, and if the commit message contains a dash
>> character "-" at the beginning of a line, diff-mode interprets this as a
>> diff rather than part of the commit message.
>>
>> To replicate this bug: copy the following in a file (e.g. test.patch),
>> open it in diff-mode, and you will see that the line "- unordered lists"
>> shows up in `diff-indicator-removed' face:
>
> I also see the final "--" line in that face, FWIW.
>
> Dmitry, Juri, Sean: any comments or suggestions?

For patches generated by git, indeed, anything before the first hunk
should not be fontified as though it were a patch.

Similarly we should look for a "-- " line at the end of the message and
treat it as an e-mail signature.

But one question I immediately have is how much of this is Git-specific.
Is there some specification of the unified diff format anywhere?

Could there be non-Git unidifed diffs this would break?

-- 
Sean Whitton

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