Re: [PATCH] blame: add the ability to ignore commits

From: Barret Rhoden <brho@google.com>
Date: Jan 14, 2019, 15:19 UTC
Message-ID: <20190114101956.2b899d0e@brho.roam.corp.google.com>
In-Reply-To: <xmqq1s5k16zj.fsf@gitster-ct.c.googlers.com>

On 2019-01-10 at 14:29 Junio C Hamano <gitster@pobox.com> wrote:

Show 21 quoted lines

> > For instance, commit X does this:
> >
> > -foo(x,y);
> > +foo(x,y,z);
> >
> > Then commit Y comes along to reformat it:
> >
> > -foo(x,y,z);
> > +foo(x, y, z);
> >
> > And the history / rev-list for the file looks like:
> >
> > ---O---A---X---B---C---D---Y---E---F
> >
> > I want to ignore/skip Y and see X in the blame output.    
> 
> If you skip Y, the altered history would have "foo(x, y, z)" in E,
> "foo(x,y,z)" in X, and "foo(x,y)" in A.  If you start blaming from
> F, you'd get E as the commit that explains the latest state.  If you
> do not skip Y, you'd get Y.  I am not sure how you'd get X in either
> case.

The way to do it is to let the blames get passed to Y - don't yank it from the graph. Then when trying to pass the blames from Y to its parent, when we get a diff chunk that Y is responsible for, instead of keeping it on Y's suspect list, we hand the blame_entry to D. That blame_entry will get passed all the way back to X, which also has a diff that touches that line.

Basically we do the same blame processing as usual, but just don't let any blames stick to Y.

Barret