On Mon, Jan 07, 2013 at 07:59:53AM +0100, Jens Lehmann wrote:
> Am 07.01.2013 02:39, schrieb Jonathan Nieder:
> > (just cc-ing Jens and Peter, who might be interested)
> 
> I´m currently working on teaching mv to move submodules and intend
> to send those patches to the list after finishing submodule deinit.
> Please see
>   https://github.com/jlehmann/git-submod-enhancements/commits/mv-submodules
> for the current state of this series.

Thinking about this a bit more, I'm not clear on how out-of-tree
updates (i.e. worktree in .git/modules/*/config) propogated during
branch checkouts (merges, rebases, etc.).  I just got a broken rebase
trying to move a trivial patch back before the submodule move, and Git
was confused about what had happened to the submodules.  Here's a
simple script that illustrates the problem:

  #!/bin/sh
  rm -rf a b c
  mkdir a
  (cd a
   git init
   echo a > README
   git add README
   git commit -am 'a'
  )
  git clone a b
  (cd b
   git submodule add ../a submod-1
   git commit -am 'add submodule at submod-1'
  )
  git clone b c
  (cd c
   git submodule update --init
  )
  (cd b
   git-submodule-mv.sh submod-1 submod-2
   git commit -am 'move submodule from submod-1 to submod-2'
  )
  (cd c
   git pull
   ls -d .git/modules/*
   cat .git/modules/submod-1/config
   ls -a submod*
  )

The end result is that `c` gets the `.gitmodules` path updates and new
gitlinked directory from the submodule move in `b` (using my
git-submodule-mv.sh posted earlier in this thread), but `submod-1` is
left lying around (because Git doesn't know that it can remove
submod-1/.git and submod-1/README).  The Git directory for the
submodule stays in .git/modules/submod-1/ (good), but the worktree in
.git/modules/submod-1/config still points to ../../../submod-1 (bad).

This means that submodule moves are possible, but anyone trying to
share them between several repositories (or trying to rebase across
the move within their own repository) is in for a world of suffering
;).  I'm not sure how this should be addressed, but I didn't see
anything handling it in Jens' new series.

Thanks,
Trevor

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