Merge/diff tool that can show authors (supports blame or annotate) in files under version control - version-control

Question

When merging files it will be helpful (as for me) to show an author of each line. Is there any diff or merge tool supporting that?

Answer 1

The bundled gitk tool is not really a merge tool, but it shows conflicted lines with red and blue and "+"'s in front, and you can Rightclick->"Show origin of this line" on any of them, to go to the commit which introduced the line:
You can run your mergetool, or just a text editor with diffmarks in parallel

Answer 2

So what you really want is a tool that can easily identify your changes
relative to other's changes in a merge conflict, rather actually identify
the author of each line (which would be a mean to achieve that), right?
If I understood you correctly, I have some relatively good news: It
can be done with git + kdiff3. For merging you can just use git mergetool
(which you can configure to use kdiff3). But it is not supported natively
if you get a merge conflict when doing interactive rebase, so for that
some manual scripting is required.
Instead of making up my own simple merge conflict example, I will use
http://www.gitguys.com/topics/merging-with-a-conflict-conflicts-and-resolutions/
as an basis. Follow that page to git merge test. From after the merge
command I diverge a bit from that example by running different commands
(but basically doing the same job). I'll do all the manuall steps first.
So we have a merge conflict and git has inserted content from both
contributing sources into the file in this <<<<<<<...>>>>>>> format,
which I really do not like at all and never consider even looking at it.
Instead I use my favourite merge tool, kdiff3.
First we need to find which versions that are involved.
$ git ls-files -u
100644 b0ed415d15862ac5582b51e4de65528e86934cd2 1 README
100644 56300e3ac4e4521c3500618a301bb2ab2d6a52f5 2 README
100644 9585db7d9c2d9ca05075f67a878f2554886d7b1a 3 README
$
Basted that information we can perform a three way merge:
$ git cat-file blob b0ed415d15862ac5582b51e4de65528e86934cd2 > v1
$ git cat-file blob 56300e3ac4e4521c3500618a301bb2ab2d6a52f5 > v2
$ git cat-file blob 9585db7d9c2d9ca05075f67a878f2554886d7b1a > v3
$ kdiff3 -o merge_result v1 v2 v3 &
[2] 18394
$
Which gives the following view where you can select from which ancestor
you want to merge from.
Afterwords (if you are satisfied with the merge result)
you need to
$ rm v1 v2 v3
$ mv merge_result README
$ git add README
All the manual steps above are done automatically with git mergetool.
So why showing all that then? Well, because if you get a corresponding
conflict during git rebase -i, then it has to be done that way (before running git rebase --continue).
In this small example there is only one conflict
line, so it does not show the more typical case where a lot of lines
are automatically resolved, leaving you to just manually resolve the
ones that was not done automatically.
A more real life example might look more like the following:
Notice that in the merge result you now clearly see the origin of the C lines that
were automatically resolved. I think this is sort of what you were asking for when asking for getting the author for each line, right?
That information is completely absent in the <<<<<<<...>>>>>>> text (and it is difficult/impossible to spot that you should update the printed string in the hello function).
I cannot recommend kdiff3 highly enough. Using a graphical merge tool like that compared to some lines from both sources mixed inline in the file is like using an excavator versus a spade.

Answer 3

No. And, I think, never will be - when we merge, we think about content, not authorship