Re: git rerere and diff3

From: Junio C Hamano <gitster@pobox.com>
Date: Jun 26, 2018, 19:05 UTC
Message-ID: <xmqq1sctl676.fsf@gitster-ct.c.googlers.com>
In-Reply-To: <CAP71WjzHffLRCDbjvF7qpexjXDMFcJkaPpEn=AtbSMCJd6QkBQ@mail.gmail.com>

Nicolas Dechesne <nicolas.dechesne@linaro.org> writes:

Show 10 quoted lines

> i have noticed that merge.conflictstyle has an impact on the rerere
> resolution. looking briefly at the source code, it seems that git
> tries to discard the common ancestor diff3 bits, but what I am seeing
> is that if i do the following then it fails:
>
> 1. from a clean rr-cache state, with merge.conflictsytle=diff3, git
> merge <branch with conflict>, resolve the conflicts, then commit
> 2. undo the previous merge, remove merge.conflictstyle=diff3 (disable
> diff3) and merge the *same* branch, then rerere won't fix the
> conflicts

It is possible that the conflict left when making the same merge are actually different when using these two conflict styles. IOW, if the merge produces

	<<<
	side A
	|||
	common
	===
	side B
	>>>

when diff3 style is chosen, but if the same merge results in

	<<<
	side A'
	===
	side B'
	>>>

where side A' is not identical to side A (or B' and B are not identical), then we will fail to find the previously recorded resolution.