Re: Properties of trees referencing commit objects (mode 160000)?

Josh Triplett [off-list ref] writes:

On Sun, Mar 20, 2016 at 12:18:04AM -0400, Jeff King wrote:

quoted

On Sat, Mar 19, 2016 at 03:13:48PM -0700, Josh Triplett wrote:

quoted

I'm building some tools to track commit objects, and I'm thinking of
using submodule-style references to commit objects in tree objects (mode
160000) to do so.  I'm trying to figure out some of the properties of
that.

Can a commit object referenced that way live in the same repository,
rather than some external repository?

Yes, it can be in the same repository, but...

Will git clone/checkout/etc handle it properly in that case, in the
absence of a .gitmodules file?  Or would it only work with custom tools?

That depends on the definition of "proper".  The default "proper"
way for the core Git for submodules/gitlinks is to create an empty
directory.  If you want to populate a working tree for that, you'd
need "git submodule" support, but because you are writing "some
tools" on your own, there probably is a reason why you do not want
to use "git submodule", so I am guessing that your definition of
"proper" does not match either core Git or "git submodule" considers
"proper"?  In which case you would need to implement your own
semantics (you may not even want to have an empty directory there,
for example).

quoted

No, we do not follow "gitlinks" like this for reachability. Neither for
pruning, nor for object transfer via push/fetch. So you'd need to have a
separate reference to it (or history containing it).

Argh.  If I have a pile of disconnected commits, is there anything git
*would* follow to see them, other than a pile of refs?

No.