Recursively checkout submodules

Having found some Git time recently i started to tackle the next major issue on my agenda to improve submodule experience: Check out the matching versions of populated submodules when doing a checkout in the superproject (without having to do an explicit "git submodule update").

So here is what i came up with so far: The first two patches lay the groundwork by introducing a new function checkout_submodule() in submodule.c and calling it from checkout_entry(). The new "ignore_submodules" flags added to "struct checkout" and "struct unpack_trees_options" can be used to prevent that (and default to true, which is the old behavior then changed by the following patches). The next two patches teach "git checkout" and "git checkout-index" to default to checking out submodules too unless the new option "--ignore-subodules" is used.

What's working:
* Changing branches and specific revisions update the submodules accordingly
* "Revert changes" in "git gui" resets submodules now

What's missing:
* Test cases
* I think "git fetch" should recurse into populated submodules too, otherwise the commits to check out there might be missing

Opinions?

Jens Lehmann (4):
Prepare checkout_entry() for recursive checkout of submodules Add "ignore_submodules" member to "struct unpack_trees_options" Teach checkout to recursively checkout submodules Teach checkout-index to recursively checkout submodules

 Documentation/git-checkout-index.txt |    9 ++++++++-
 Documentation/git-checkout.txt       |    7 +++++++
 archive.c                            |    1 +
 builtin/apply.c                      |    1 +
 builtin/checkout-index.c             |    5 ++++-
 builtin/checkout.c                   |    6 ++++++
 builtin/clone.c                      |    1 +
 builtin/commit.c                     |    1 +
 builtin/merge.c                      |    2 ++
 builtin/read-tree.c                  |    1 +
 builtin/reset.c                      |    1 +
 cache.h                              |    3 ++-
 diff-lib.c                           |    2 ++
 entry.c                              |    9 ++++++---
 merge-recursive.c                    |    1 +
 submodule.c                          |   32 ++++++++++++++++++++++++++++++++
 submodule.h                          |    1 +
 t/t2013-checkout-submodule.sh        |   14 ++++++++++++--
 unpack-trees.c                       |    1 +
 unpack-trees.h                       |    3 ++-
 20 files changed, 92 insertions(+), 9 deletions(-)