Subject: Re: sudmodule.<name>.recurse ignored

From: "Michael S. Tsirkin" <[email-masked]>
Date: Wed, 12 Oct 2022 17:49:18 -0400

On Wed, Oct 12, 2022 at 09:56:45AM -0700, Glen Choo wrote:
> "Michael S. Tsirkin" <[email-masked]> writes:
> 
> > Fundamentally the problem we encounter regularly is this:
> > 	qemu is superproject, ui/keycodemapdb is subproject.
> >
> >
> > 	I have a change on master setting the submodule commit:
> >
> > 	qemu$ git show master | grep +Sub
> > 	+Subproject commit 7381b9bfadd31c4c9e9a10b5bb5032f9189d4352
> >
> > 	and check it out:
> >
> > 	qemu$ git submodule update --init ui/keycodemapdb
> > 	Submodule 'ui/keycodemapdb' (https://gitlab.com/qemu-project/keycodemapdb.git) registered for path 'ui/keycodemapdb'
> > 	Submodule path 'ui/keycodemapdb': checked out '7381b9bfadd31c4c9e9a10b5bb5032f9189d4352'
> >
> >
> > 	In another branch I have a different commit:
> >
> > 	qemu$ git show sub-foo  | grep +Sub
> > 	+Subproject commit 57ba70da5312170883a3d622cd2aa3fd0e2ec7ae
> >
> >
> > 	Now I switch branches and nothing happens, the submodule
> > 	is marked as dirty:
> >
> > 	qemu$ git checkout sub-foo
> > 	M       ui/keycodemapdb
> > 	Switched to branch 'sub-foo'
> >
> > 	qemu$ (cd ui/keycodemapdb && git show | head -1)
> > 	commit 7381b9bfadd31c4c9e9a10b5bb5032f9189d4352
> >
> >
> > it is now very easy to generate incorrect code:
> > - git commit -a  will commit the change to submodule
> > - any build will use a mix of super and subproject that
> >   is completely untested
> >
> >
> > As a result people are basically saying avoid using submodules
> > but I am wondering whether git can be tweaked to do the
> > right thing by default.
> >
> 
> It sounds like you want submodule.recurse [1] :)

yes. unfortuntely there is no way to set it by default
for cloned repos. users have to remember to set it.

> With that enabled, your
> "git checkout" should behave like "git checkout --recurse-submodules",
> which should make ui/keycodemapdb check out the correct commit as long
> as the submodule commit is present locally. If is is _not_ present
> locally, you will have to run "git submodule update".
> 
> Unfortunately, you typically won't know whether the commit is present
> before running the command. This is yet another of those things that are
> painful with submodules.
> 
> [1] https://git-scm.com/docs/git-config#Documentation/git-config.txt-submodulerecurse
> 
> > I understand we can work around it by asking everyone to
> > create a correct config, but can't we make it DTRT by default
> > to reduce friction?
> 
> You might be interested in the proposed 'new' Submodule UX [2]; one of
> the goals is to make manual submodule management via "git submodule"
> unnecessary.
> 
> As a part of that, you should be able to set "submodule.recurse = true"
> and have high confidence that all necessary submodules and submodule
> commits are present.

Hmm. How about only doing this for active submodules? Possible?

> Work on that is still ongoing, but this situation
> should have improved as of [3].
> 
> [2] https://lore.kernel.org/git/[email-masked]/
> [3] https://lore.kernel.org/git/[email-masked]/
> 
> >
> >
> > -- 
> > MST