git-diff across branches?

I was wondering if there was a way to make a git-diff across (local) branches.

Something like:

$ git-diff --branch test1 HEAD --branch test2 HEAD file.cpp (would show a diff for file.cpp between test1 HEAD and test2 HEAD)

On Tue, Jan 08, 2008 at 05:44:14AM -0300, Gonzalo Garramuño wrote:

I think you are mistaken about how HEAD works; it is a pointer to a particular branch. So there is no "HEAD" for test1; there is simply test1, and from time to time your repository's HEAD points to test1.

However, that makes things easier. You can simply do this:

  git-diff test1 test2 file.cpp

Unless you mean that you have two separate repositories, test1 and test2. In which case each _does_ have its own HEAD, and you will have to fetch from one repo into the other to get your answer:

  # go into one of the repos
  cd test1
  # fetch the 'master' ref from the other repo and store it in this repo
  # using the name 'test2'
  git fetch ../test2 master:test2
  # now we can diff between them
  git diff HEAD test2 file.cpp

-Peff

Jeff King <peff@peff.net> writes:

Canonically it is

  # git diff test1 test2 -- file.cpp

but you can also use (for example if file was renamed)

  # git diff test1:file.cpp test2:file.cpp
 

[cut]

Not necessary. If those two repositories are on the same local filesystem, you can use trick from GitTips:

  http://git.or.cz/gitwiki/GitTips#head-9f79516c05f0c1b51945b848adb3dd1c5a2bf016

  (assuming we are in test1, and ../test2 is relative path to test2)
  # GIT_ALTERNATE_OBJECT_DIRECTORIES=../test2/.git/objects git diff-tree \
     $(GIT_DIR=../test2/.git git rev-parse --verify HEAD) HEAD