Re: [PATCH] range-diff: optionally include merge commits' diffs in the analysis

From: Junio C Hamano <gitster@pobox.com>
Date: Nov 8, 2024, 11:56 UTC
Message-ID: <xmqq5xoyndkp.fsf@gitster.g>
In-Reply-To: <abc2453b-f7df-4601-8834-595881f9ceca@kdbg.org>

Johannes Sixt <j6t@kdbg.org> writes:

Show 13 quoted lines

> Am 07.11.24 um 18:20 schrieb Johannes Schindelin via GitGitGadget:
>> +--diff-merges=<format>::
>> +	Instead of ignoring merge commits, generate diffs for them using the
>> +	corresponding `--diff-merges=<format>` option of linkgit:git-log[1],
>> +	and include them in the comparison.
>> ++
>> +Note: Some of the formats supported by linkgit:git-log[1] make less sense in
>> +the context of the `range-diff` command than other formats, so choose wisely!
>
> Can we please be a bit more specific which options are usable or which
> are not usable? Perhaps you even mean to say that 'first-parent' is the
> only one that makes sense? At a minimum, we should mention that it is
> the one that makes most sense (if that is the case).

Good suggestion.

I am curious to see how well things like "--cc" and "--remerge-diff" fare in this use case. I suspect that in a case where the original round forgot to make necessary semantic conflict resolutions (aka "evil merge") that the new round has, all of them (including the "--first-parent") would essentially show the same change, but what is shown in such a case would be more readable with "--first-parent" by treating a merge as if it were just a single parent commit making a lot of changes, iow, merely one among other commits with equal footing.