I simply moved the external1/MySub directory to external2/MySub
Move as in mv (unix command), or git mv (git command)?
You need to move the special entry of the index representing the submodule for the parent repo.
Normally, (reading git mv), this should have been enough:
git mv external1/MySub external2/MySub
Moving a submodule using a gitfile (which means they were cloned with a Git version 1.7.8 or newer) will update the gitfile and core.worktree setting to make the submodule work in the new location.
It also will attempt to update the submodule.<name>.path setting in the gitmodules file and stage that file (unless -n is used).
That works best with the latest 1.8.5 git (like msysgit for Windows, or latest package for Unix)
Suseika adds in the comments
If you get message
fatal: renaming '%submodule%' failed: No such file or directory
it is probably because you're adding a directory level, e.g. moving submodule "math" to "libs/math".
git mv doesn't create missing [intermediate] directories, you should mkdir them yourself.
git 2.9 (June 2016) will improve git mv for submodule:
See commit a127331 (19 Apr 2016) by Stefan Beller (stefanbeller).
(Merged by Junio C Hamano -- gitster -- in commit 9cb50a3, 29 Apr 2016)
mv: allow moving nested submodules
"git mv old new" did not adjust the path for a submodule that lives as a subdirectory inside old/ directory correctly.
submodules however need to update their link to the git directory as
well as updates to the .gitmodules file.
Git 2.12 (Q1 2017) offers to move nested submodules to the parent repo:
There is a new submodule helper "git submodule absorbgitdirs" to make it easier to move embedded .git/ directory for submodules in a
superproject to .git/modules/ (and point the latter with the former
that is turned into a "gitdir:" file) has been added.
See commit 7c4be45 (27 Dec 2016), commit f6f8586, commit 47e83eb, commit 1a248cf (12 Dec 2016), and commit 6f94351, commit 89c8626, commit 90c0011, commit 6f94351, commit 89c8626, commit 90c0011 (08 Dec 2016) by Stefan Beller (stefanbeller).
(Merged by Junio C Hamano -- gitster -- in commit da2b74e, 10 Jan 2017)
submodule: add absorb-git-dir function
When a submodule has its git dir inside the working dir, the submodule
support for checkout that we plan to add in a later patch will fail.
Add functionality to migrate the git directory to be absorbed
into the superprojects git directory.
The newly added code in this patch is structured such that other areas of
Git can also make use of it. The code in the submodule--helper is a mere
wrapper and option parser for the function absorb_git_dir_into_superproject, that takes care of embedding the
submodules git directory into the superprojects git dir. That function
makes use of the more abstract function for this use case
relocate_gitdir, which can be used by e.g. the worktree code eventually
to move around a git directory.
Note: there is still (Git 2.14.x/2.15, Q4 2017) a bug linked to submodule moving: see "Git: moving submodules recursively (nested submodules)".
Git 2.15.x/2.16 (Q1 2018) will make moving submodule more robust, since "git fetch --recurse-submodules" now knows that submodules can be
moved around in the superproject in addition to getting updated,
and finds the ones that need to be fetched accordingly.
See commit 4b4aced, commit c68f837 (16 Oct 2017), and commit 01ce122 (06 Oct 2017) by Heiko Voigt (hvoigt).
(Merged by Junio C Hamano -- gitster -- in commit b4d658b, 06 Nov 2017)
implement fetching of moved submodules
We store the changed submodules paths to calculate which submodule needs
fetching. This does not work for moved submodules since their paths do
not stay the same in case of a moved submodules.
In case of new submodules we do not have a path in the current checkout, since they just appeared in this fetch.
It is more general to collect the submodule names for changes instead of
their paths to include the above cases. If we do not have a
configuration for a gitlink we rely on constructing a default name from
the path if a git repository can be found at its path. We skip
non-configured gitlinks whose default name collides with a configured
one.
Note that, before Git 2.19 (Q3 2018), the code to try seeing if a fetch is necessary in a submodule during a fetch with --recurse-submodules got confused when the path to the submodule was changed in the range of commits in the
superproject, sometimes showing "(null)".
This has been corrected.
See commit c3749f6, commit 5fc8475 (14 Jun 2018) by Stefan Beller (stefanbeller).
(Merged by Junio C Hamano -- gitster -- in commit 085d2ab, 28 Jun 2018)
submodule: fix NULL correctness in renamed broken submodules
When fetching with recursing into submodules, the fetch logic inspects
the superproject which submodules actually need to be fetched.
This is tricky for submodules that were renamed in the fetched range of commits.
This was implemented in c68f837 (implement fetching of moved
submodules, 2017-10-16, Git v2.16.0), and this patch fixes a mistake in the logic
there.
