RFC: Subprojects

Hello,

one thing that I have been missing so far in all SCM systems apart from CVS (and there it's just coincidence) is the ability to include a project as part of a bigger project. Developing software for embedded systems, I need that feature fairly often, for example the source tree for a particular device almost always contains one or more Linux trees, some binutils, gcc and gdb stuff and so on.

The changes necessary here would be fairly simple: "tree" objects would point to a "commit" or a "tag" object when a subproject is used.

In the working directory, this would be represented by a .git directory that contains a symref to the embedding project instead of the objects directory. Head pointers are only required if you intend to push changes upstream to the maintainer of the embedded project. Each subproject has its own index.

Would such a feature make sense, and what behaviour would make the most sense for the various operations (e.g. shall commits in the inner project propagate to the outer?)?

    Simon