Should I use past or present tense in git commit messages?

I wrote a fuller description on 365git.

The use of the imperative, present tense is one that takes a little getting used to. When I started mentioning it, it was met with resistance. Usually along the lines of “The commit message records what I have done”. But, Git is a distributed version control system where there are potentially many places to get changes from. Rather than writing messages that say what you’ve done; consider these messages as the instructions for what applying the commit will do. Rather than having a commit with the title:

Renamed the iVars and removed the common prefix.

Have one like this:

Rename the iVars to remove the common prefix

Which tells someone what applying the commit will do, rather than what you did. Also, if you look at your repository history you will see that the Git generated messages are written in this tense as well - “Merge” not “Merged”, “Rebase” not “Rebased” so writing in the same tense keeps things consistent. It feels strange at first but it does make sense (testimonials available upon application) and eventually becomes natural.

Having said all that - it’s your code, your repository: so set up your own guidelines and stick to them.

If, however, you do decide to go this way then git rebase -i with the reword option would be a good thing to look into.

The preference for present-tense, imperative-style commit messages comes from Git itself. From Documentation/SubmittingPatches in the Git repo:

Describe your changes in imperative mood, e.g. "make xyzzy do frotz" instead of "[This patch] makes xyzzy do frotz" or "[I] changed xyzzy to do frotz", as if you are giving orders to the codebase to change its behavior.

So you'll see a lot of Git commit messages written in that style. If you're working on a team or on open source software, it is helpful if everyone sticks to that style for consistency. Even if you're working on a private project, and you're the only one who will ever see your git history, it's helpful to use the imperative mood because it establishes good habits that will be appreciated when you're working with others.

Your project should almost always use the past tense. In any case, the project should always use the same tense for consistency and clarity.

I understand some of the other arguments arguing to use the present tense, but they usually don't apply. The following bullet points are common arguments for writing in the present tense, and my response.

• Writing in the present tense tells someone what applying the commit will do, rather than what you did.

This is the most correct reason one would want to use the present tense, but only with the right style of project. This manner of thinking considers all commits as optional improvements or features, and you are free to decide which commits to keep and which to reject in your particular repository.

This argument works if you are dealing with a truly distributed project. If you are dealing with a distributed project, you are probably working on an open source project. And it is probably a very large project if it is really distributed. In fact, it's probably either the Linux kernel or Git. Since Linux is likely what caused Git to spread and gain in popularity, it's easy to understand why people would consider its style the authority. Yes, the style makes sense with those two projects. Or, in general, it works with large, open source, distributed projects.

That being said, most projects in source control do not work like this. It is usually incorrect for most repositories. It's a modern way of thinking about a commits: Subversion (SVN) and CVS repositories could barely support this style of repository check-ins. Usually an integration branch handled filtering bad check-ins, but those generally weren't considered "optional" or "nice-to-have features".

In most scenarios, when you are making commits to a source repository, you are writing a journal entry which describes what changed with this update, to make it easier for others in the future to understand why a change was made. It generally isn't an optional change - other people in the project are required to either merge or rebase on it. You don't write a diary entry such as "Dear diary, today I meet a boy and he says hello to me.", but instead you write "I met a boy and he said hello to me."

Finally, for such non-distributed projects, 99.99% of the time a person will be reading a commit message is for reading history - history is read in the past tense. 0.01% of the time it will be deciding whether or not they should apply this commit or integrate it into their branch/repository.

• Consistency. That's how it is in many projects (including git itself). Also git tools that generate commits (like git merge or git revert) do it.

No, I guarantee you that the majority of projects ever logged in a version control system have had their history in the past tense (I don't have references, but it's probably right, considering the present tense argument is new since Git). "Revision" messages or commit messages in the present tense only started making sense in truly distributed projects - see the first point above.

• People not only read history to know "what happened to this codebase", but also to answer questions like "what happens when I cherry-pick this commit", or "what kind of new things will happen to my code base because of these commits I may or may not merge in the future".

See the first point. 99.99% of the time a person will be reading a commit message is for reading history - history is read in the past tense. 0.01% of the time it will be deciding whether or not they should apply this commit or integrate it into their branch/repository. 99.99% beats 0.01%.

• It's usually shorter

I've never seen a good argument that says use improper tense/grammar because it's shorter. You'll probably only save 3 characters on average for a standard 50 character message. That being said, the present tense on average will probably be a few characters shorter.

• You can name commits more consistently with titles of tickets in your issue/feature tracker (which don't use past tense, although sometimes future)

Tickets are written as either something that is currently happening (e.g. the app is showing the wrong behavior when I click this button), or something that needs to be done in the future (e.g. the text will need a review by the editor).

History (i.e. commit messages) is written as something that was done in the past (e.g. the problem was fixed).