Is it necessary to run `git stash push` before `git checkout`

Question

git checkout by default leaves alone the uncommitted changes in the working tree directory. Then is it necessary to run git stash push before git checkout (and then run git stash pop at some later point after git checkout)? Or when is it necessary, and when is it not?

My question comes from https://stackoverflow.com/a/48156644/156458 and is more general.

Answer 1

If there are uncommitted changes that will be overwritten by git checkout the command will complain and abort. In that case git commit or git stash is necessary.

If there are uncommitted changes that will not be overwritten by git checkout the command succeeds and the changes spilled into the new branch. If you don't want to see these changes in the new branch use git commit or git stash before git checkout.

Unlike other commands (like git pull and git rebase) git checkout doesn't have option --autostash because it's meaningless: in most cases you don't want to automatically do git stash pop when switching to a new branch.