Re: git-diff-tree does not use alternate objects for submodules

> Orgad and Raizel Shaneh <orgads@gmail.com> writes:
> 
> > I have a project with a submodule. Both have objects/info/alternate
> > (different ones).
> >
> > After running 'git gc', running gitk on the superproject results in:
> > ?? Submodule sub 227e2b5...d8597e2 (commits not present)
> 
> When "--submodule" option was implemented in 752c0c, it was done with an
> premature and incomplete optimization, and I think you are seeing an
> unfortunate side effect of it. The code attempts to link the object store
> of the submodule repository into the in-core representation of the object
> store of the superproject (in submodule.c::add_submodule_odb()), but does
> not do a good job of it.  It does not take alternates into account, and
> who knows what else is missing.  Sigh...
> 
> The right approach to implement this feature would have been to fork a
> child process and perform the submodule operation inside the child, which
> will chdir into the submodule and treat as if it is a freestanding git
> repository, without contaminating the superproject process.
> 
> For now, an easiest workaround would be to rephrase the error message to
> "commits not present" to "commit not present or missing", or something.