Re: git and appending merge commits

["Shawn O. Pearce" <spearce@spearce.org>]

Adam Majer <adamm@zombino.com> wrote:
...
>   5. append master merge changeset
> 
> #5 results in "messsed up" diffs
> 
> For an example of such a mess up please see,
> 
> http://git.debian.org/?p=collab-maint/mrtg.git;a=commitdiff;h=a8bc78ffd6d51ab09a791fa97e25f57b60eecd06
> 
> It appears that the tool generates a patch to a patch and displays that
> instead of the appended merge diff which is what I would have expected..
> 
> Is current output by design?

Yes, it is by design.  This is a feature of Git that very few
(if any) other systems have.

What you are seeing here is a combined diff.  It is a diff of the
final output of the merge against its two parents (the two branches
that were merged together).  Places where both a "++" or "--" prefix
a line indicate a place where the merge commit adds something that
is not in either parent.  This is stuff that the merge author edited
himself/herself during the merge.

If you had not amended the merge, you would have seen a less
interesting diff here, as the combined diff output tries to
avoid showing trivial changes.

-- 
Shawn.