git rebase - difference between rebasing against develop and origin/develop?

Question

This is odd. There's apparently some difference between rebasing against my local develop branch, and the remote develop branch. Here are some details:

So let's say I have a feature branch, feat, which I've been rebasing from time to time:

git pull --rebase origin develop

This is working fine. But now I'm done and ready to squash my commits and I noticed a big difference between:

git rebase -i origin develop

and

git rebase -i develop

The former brings up my editor with a HUGE list of commits from develop, none of them are my changes on feat. It also switches me to the develop branch. The latter brings up my editor with just my commits on feat and does not switch me to my local develop branch.

Is git rebase -i origin develop actually switching me to my local develop and then rebasing against the remote? Am I supposed to git checkout develop; git pull first, then git checkout feat; git rebase -i develop?

Answer 1

git rebase -i origin develop

is not the right syntax to use for rebase.

git rebase -i develop
# or this, for the remote-tracking branch
git rebase -i origin/develop

are the correct syntaxes.

The official Linux Kernel Git documentation for git rebase says that this is the general syntax (omitting some options for clarity):

git rebase [-i] [<upstream>] [<branch>]

where <upstream> is a branch:

<upstream>

Upstream branch to compare against. May be any valid commit, not just an existing branch name. Defaults to the configured upstream for the current branch.

When you use git rebase -i origin develop, origin is the name of your remote, not a branch. If you wanted to rebase against origin/develop, you need to use the path separator /:

git rebase -i origin/develop

As for your question:

Is git rebase -i origin develop actually switching me to my local develop and then rebasing against the remote?

It might be switching to your local develop, but since the syntax isn't even valid, I'm not 100% sure. The reason I say maybe is because the behavior of rebase when you pass a valid upstream branch and another branch is to checkout the second branch before rebasing against the first:

If <branch> is specified, git rebase will perform an automatic git checkout <branch> before doing anything else. Otherwise it remains on the current branch.

Finally, git rebase -i develop and git rebase -i origin/develop could be different if your local develop isn't update-to-date with your remote-tracking branch origin/develop, like if you git fetch and never merge updates into your local develop.