git submodule “--reference” parameter

Question

In the git submodule documentation for git submodule add , it shows that there is a --reference parameter. Presumably, this works the same way the --reference parameter for git clone works, by copying objects from it, instead of the remote repository. After executing with this parameter, if I look inside .git/modules/<submodule>/objects/info , there is an alternates file, containing the path to the reference repo.

However, git clone also has a --dissociate parameter, to essentially do this for only the initial clone. Is there a way to the same thing for a submodule repository?

Answer 1

Apparently the only way to do this is to run git repack -a -d in the submodule directory after cloning it with --reference .

I guess a future Git version might add direct support for --dissociate to git submodule {add,update} itself, but it doesn't exist in the latest (2.15) version yet.

Answer 2

" git submodule update " and " git submodule add " supported the " --reference " option to borrow objects from a neighbouring local repository like " git clone " does, but lacked the more recent invention " --dissociate ".

That is no longer the case with Git 2.18 (Q2 2018)

submodule: add --dissociate option to add/update commands

Add --dissociate option to add and update commands, both clone helper commands that already have the --reference option --dissociate pairs with.

The documentation now adds:

 --dissociate:: 

This option is only valid for add and update commands.
These commands sometimes need to clone a remote repository. In this case, this option will be passed to the git clone command.