Where does my commit goes if I checkout tag and commit?

Question

In GIT, if I checkout a tag I'll get my working copy to that tag's reference, i.e. the code will represent what I had at that time. I'm I correct?

Now, if I do that, and modify my code and commit. Where is that commit going? Will it sort of 'auto-merge'? Meaning that if I push my commit, someone that clones the repo will also get the fix I did from the tag? Or otherwise, if I switch back to master, will I have the code modification available there?

Answer 1

The commit is still only stored locally. Only you have a reference to the modified version. If you want to make it available to others, you will also have to do a git push of your code to the given branch.

Your commits are branch-specific, meaning if you change branches after committing, your changes will not carry over. However, when you change back to the branch, the commit will still be there.

Answer 2

It will not "auto-merge". It is stored in the repository, referenced by HEAD directly. Usually the reference HEAD (the small file in .git, named HEAD) contains the name of the branch, which top-commit reference is updated with every commit. In you case it is a so called "detached HEAD".

You can always save the detached HEAD in a real branch reference: git branch something. Or just checkout another branch and forget about the commits, they will be cleaned up eventually.