GIT tip : Keep your branch clean with fixup and autosquash

by Florent Lebreton (fle)
in quick tips

tagged git

Who is not tired of committing a "Remove pdb" or a "Fix a typo" few minutes or hours after committing a clean feature ? A few time ago, I discovered two useful options in GIT that work together : git commit --fixup and git rebase --autosquash. With these, you can easily merge little fixes with the original feature and keep your branch clean.

Preferably, you won't use it in a stable or master branch, because rebase rewrites history and can create a big mess, mainly if project counts several developers. It rather can be convenient to clean a development branch before merging it in master.

--fixup & --autosquash

  • git commit --fixup <commit> automatically marks your commit as a fix of a previous commit
  • git rebase -i --autosquash automatically organize merging of these fixup commits and associated normal commits

Example

Take a git repos with a branch dev. You intend to commit features A and B:

$ (dev) git add featureA
$ (dev) git commit -m "Feature A is done"
[dev fb2f677] Feature A is done
$ (dev) git add featureB
$ (dev) git commit -m "Feature B is done"
[dev 733e2ff] Feature B is done

Your work is in progress and you find minor mistakes in Feature A : it's time to use --fixup option !

$ (dev) git add featureA                # you've removed a pdb : shameful commit
$ (dev) git commit --fixup fb2f677
[dev c5069d5] fixup! Feature A is done

Here, you see that GIT automatically retrieved featureA commit message prefixed by fixup!.

All work is done, let's see the log:

$ (dev) git log --oneline
c5069d5 fixup! Feature A is done
733e2ff Feature B is done
fb2f677 Feature A is done
ac5db87 Previous commit

Now, you want to clean your branch before merging it : it's time to use --autosquash option !

$ (dev) git rebase -i --autosquash ac5db87
pick fb2f677 Feature A is done
fixup c5069d5 fixup! Feature A is done
fixup c9e138f fixup! Feature A is done
pick 733e2ff Feature B is done

This command has opened your editor with lines above. Just save & quit and ... :

$ (dev) git log --oneline
ff4de2a Feature B is done
5478cee Feature A is done
ac5db87 Previous commit

Your shameful commit has been merged properly with the original feature. It's just a shorcut for something you could do otherwise but I find it very convenient :).

That's all folks !

EDIT : git rebase i <after-this-commit> must be launched with as argument the last commit you want to retain as-is, not the first one you want to change.

Thanks regilero & SebCorbin for reviewing!

Comments !