Re: The merge from hell...

[Linus Torvalds <torvalds@osdl.org>]

On Thu, 2 Feb 2006, Aneesh Kumar wrote:
> 
> Ok i tried using --cc. But then as per the man page if the
> optimization makes the all the hunks disapper then commit log is not
> show unless -m is used.

Ahh. You're mis-using git-diff-tree.

git-diff-tree will _never_ show the commit log if the diff ends up being 
empty. That can actually happen even for a regular commit, because we had 
some early bugs that allowed them.

See commit 69d37960b578be0a69383bd71d06c1fcfb86e8b9, for example. Notice 
how

	git-diff-tree --pretty 69d37960

is entirely silent, even though 

	git log 69d37960

clearly shows that the commit exists. I screwed up a commit, and 
effectively applied an empty patch (this was before git-apply would 
notice, and consider it an error - something I fixed very soon 
afterwards ;^).

> Is there a way to get the commit log printed.

Yes. What you should do is to do

	git-rev-list --parents --pretty

which gives the revision _log_ in pretty format. 

The difference between "git-rev-list --pretty" and "git-diff-tree 
--pretty" is really exactly that "git-rev-list" lists every revision, 
while git-diff-tree only lists revisions that _differ_ in the trees.

This, btw, is also really the main difference between doing a "git log" 
and doing a "git whatchanged". A "git log" shows all revisions (and uses 
"git-rev-list --pretty"). While "git whatchanged" shows what _changed_ 
(and uses "git-diff-tree --pretty").

For a revision tool like gitview, you want to use "git-rev-list --pretty".

[ SIDE NOTE! Actually, there's another format that you may find easier to 
  parse automatically: "git-rev-list --header". It uses the raw format, 
  and adds a NUL character between each rev. That makes things like the 
  date etc trivial to parse, and it's also slightly easier to see the end 
  of a commit message vs just a normal end-of-line. 

  So "gitk", for example, really parses the output of

	git-rev-list --header --topo-order --parents

  to generate the revision list. The "--topo-order" part guarantees that 
  all children will always be shown before any parents. ]

Hope that clarifies the issue.

		Linus