Re: Can `git blame` show the date that each line was merged?

From: Jeff King <peff@peff.net>
Date: Jun 4, 2013, 17:44 UTC
Message-ID: <20130604174420.GA25318@sigill.intra.peff.net>
In-Reply-To: <7vfvwx9461.fsf@alter.siamese.dyndns.org>

On Tue, Jun 04, 2013 at 10:28:06AM -0700, Junio C Hamano wrote:

Show 6 quoted lines

> > (though I suspect it would interact oddly with the "--reverse" option,
> > and we would want to either declare them mutually exclusive or figure
> > out some sane semantics).
> 
> It is entirely unclear who the first child is, so I tend to think
> that they have to be mutually exclusive.

That's my thinking, too, but I didn't want to rule out somebody thinking of something clever.

Show 16 quoted lines

> > Your problem is not the presence of "--merges" here, but that you forgot
> > the necessary "file" argument. Try "git blame --merges foo.c".
> >
> > However, this suffers from the same problem as --first-parent, in that
> > it is accepted but not respected. Doing so would not be impossible, but
> > it is a little more than the two-liner above.
> 
> What the command does when it "respects" it is unclear to me.
> In a history like this:
> 
> ---A---B---C
>     \       \
>      E---F---G---H
> 
> and starting at H, pretend everything that happened in, B, C, E and
> F since A was done by G?  Who gets the blame for what A or H did?

In general, I would expect "git blame" with revision arguments to behave as if it was fed the history graph (including parent rewriting). So in this case, I would think it would blame everything before G on G (assuming there are no merges before A), and everything in H would be "not yet committed".

That being said, we do not seem to rewrite parents for min/max parent cases even in "git log". I'm not sure why, nor can I seem to provoke it with simplification options. So maybe I am missing something clever.

-Peff