Command to list commits that point to a given tree.

Hi,

Normally, the natural thing to do is to dereference objects in the following directions:

commit -> tree tag -> commit tag -> other object

However, sometimes it is convenient to look in the other direction. The command git-name-rev satisfies this need partially by listing symbolic names for given commits.

Is there a command that can do this more generally? In particular, I am looking for a command that will return a list of commits that point to a particular tree.

Right now I plan to brute force it. Basically, I will call git-rev-list to list the commits and, for each commit, map it to a tree. Then, I will reverse the map in order to be able to look up a commit based on the tree.

I was thinking, though, that it might be somewhat useful in general to, at least, provide a command for the following:

- Given a blob, list the tree and/or tag objects that reference that
  blob.

- Given a tree, list the tree, commit and/or tag objects that reference
  it.

- Given a commit, list the commit and/or tag objects that reference it.

Carl