Re: [PATCH v4 1/3] Add test to describe expectation of blame --reverse with branched history

From: Junio C Hamano <gitster@pobox.com>
Date: Oct 27, 2015, 17:57 UTC
Message-ID: <xmqqk2q8chyb.fsf@gitster.mtv.corp.google.com>
In-Reply-To: <20151027044049.GA18120@wheezy.local>

Max Kirillov <max@max630.net> writes:

Show 25 quoted lines

>> The explanation of the first paragraph needs to be rewritten to make
>> it understandable, but I am not sure what relevance it has with this
>> change.
> ...
> So the history looks rather like (the interesting line is removed
> in B1, line removal is practically more interesting case because
> edits can be found with normal forward blame):
>
>
>  a0--a1-----*a2-*a3-a4...-*a100
>  |\         /   /         /
>  | b0-B1..bN   /         /
>  |\           /         /
>  | c0..   ..cN         /
>  \                    /
>   z0..            ..zN
>
> ...where many of the c-z branches started before a1 and
> contain the older version of line. And, what I usually need
> is the change b0->B1, because I expect to find there the
> person who did it and explanation why that was done.
>
> Now the git blame --reverse a0..a100 may return me zN, and in
> practice it often does return some quite late commit wN
> which was merged to some a90.

That covers a lot of what I meant by "rewritten to make it understandable". Instead of picking any of the random cN thru zN, you are forcing to find a2, because at the initial phase of the search, you are interested in granularity at the topic level. And the --first-parent combined with --reverse is exactly that, and it is a good thing to support it.