git submodule update - reset instead of checkout?

Hi everyone,

I've been reading up on the current state of git submodules (our customer's customers want to use them, causing a slight groan from our customer).

The usability thing I wonder about - with git submodule update, is it necessary to detach the head to the current (or upstream) head, instead of resetting the current branch to that state?

Primary interest in the question: Seeing 'detached head' scares almost everybody. To brainstorm:

- as we can already use 'submodule update --remote' to update
  to the remote head of a branch, it would be logical to have
  that branch checked out locally (and unfortunately, potentially
  have that branch's name conflict with the remote branch setup).

- when developers more or less accidentally commit on the detached
  head, all is not lost yet (I remember this being differently),
  but if the next 'submodule update' just resets again, the commit
  just made is still dropped, just as in the detached head state.

- So, we'd need to have 'submodule update' act closer to the pull or
  rebase counterparts and refuse to just lose commits (or uncommitted
  changes).

Having a checked-out branch in the submodule would have the advantage that I can 'just' push local commits. At the moment, doing that requires a relatively intricate dance, not at all similar to working in the base (parent) module.

I'm working on hooks that automatically update the submodules after a commit change (merge, pull, checkout) in the parent module, but with the additional feature of (a) keeping a branch checked out and (b) avoid discarding local changes. Probably means I shouldn't invoke 'submodule update' at all, and deal with everyting myself.

Any thoughs/comments/helpful hints?

(Addional complexity: egit/jgit is in use as well, and the work model we will arrive at probabaly needs to work with the current egit.)

- Andreas

On Fri, Mar 9, 2018 at 7:07 AM Andreas Krey <a.krey@gmx.de> wrote:

Try "git checkout --recurse-submodules" or "git reset --recurse-submodules" (there is also the submodule.recurse option in case you don't want to type the option all the time)

I agree on that. That is what we are trying to work out eventually, too.

One idea is to "reattach the submodule branch if it fits" another idea would be a submodule ref store that is (partially) tied to the superproject, such that the HEAD of the submodule is non-existent for most of the time. https://public-inbox.org/git/cover.1512168087.git.jonathantanmy@google.com/

Our plan is to deprecate "git submodule" just like "git remote" is not a well known tool any more. (e.g. Instead of git remote update, use git fetch, that learned about updating the remote tracking branches on its own)

That sounds familiar, we also have JGit/Gerrit in the setup.

Stefan