Re: Removing useless merge commit with "filter-branch"

From: Junio C Hamano <gitster@pobox.com>
Date: Mar 8, 2012, 23:30 UTC
Message-ID: <7v62eebri3.fsf@alter.siamese.dyndns.org>
In-Reply-To: <CAOMFOmWMsXgepY0-ZWFymd9uHSUmbOk66r75qa-Kv5TWx_U=EA@mail.gmail.com>

Anatol Pomozov <anatol.pomozov@gmail.com> writes:

Show 10 quoted lines

> |
> o      - merge commit that previously merged feature X
> |\
> | \
> |  \
> o  |   - real commit
> |   |
> |  /
> |/
> |

It is unclear how many commits are drawn in the above picture and what "feature X" is about in the above picture. Care to redraw the commit DAG to explain what you are trying to do a bit better?

The way I read it is that you start from a history like this (note that when we draw an ascii art history we often write it sideways, time flows from left to right):

    ---A-----B-----M---
        \         /
         C-------D

where a side branch to implement "feature X" that has C and D forked at A, and it was merged at M after somebody else committed B on the mainline. When you filtered out some parts of the tree, it turns out that C and D are totally unintereseting because their changes touch parts outside of your interest, i.e. the history is:

    ---A-----B-----M---
        \         /
         o-------o

where 'o' are now no-op.

Is that what you are talking about?

I think "log --simplify-merges A..M -- path" may already has logic that deals with this, so it may help if you study what it does and how it does what it does.