Re: [RFC PATCH 00/16] Checkout aware of Submodules!

[Xiaodong Qi <e2000s@gmail.com>]

I found this patch on Reddit and personally support this idea to
simplify the submodule update and checkout process. I don't know how
other users handle the submodule update process, I do sometimes forget
to checkout in superprojects with submodules and get a lot of trouble in
using the submodule function. The patch seems aims to making the process
easier than before, although I am not qualified to review the code in
detail. I suggest experts in this area to review the code promptly and
work out the nuts and bolts toward the goal of this patch. Thank you for
listening.

Regards,
Xiaodong Qi

On 11/15/2016 04:06 PM, Stefan Beller wrote:
> When working with submodules, nearly anytime after checking out 
> a different state of the projects, that has submodules changed
> you'd run "git submodule update" with a current version of Git.
> 
> There are two problems with this approach:
> 
> * The "submodule update" command is dangerous as it
>   doesn't check for work that may be lost in the submodule
>   (e.g. a dangling commit).
> * you may forget to run the command as checkout is supposed
>   to do all the work for you.
> 
> Integrate updating the submodules into git checkout, with the same
> safety promises that git-checkout has, i.e. not throw away data unless
> asked to. This is done by first checking if the submodule is at the same
> sha1 as it is recorded in the superproject. If there are changes we stop
> proceeding the checkout just like it is when checking out a file that
> has local changes.
> 
> The integration happens in the code that is also used in other commands
> such that it will be easier in the future to make other commands aware
> of submodule.
> 
> This also solves d/f conflicts in case you replace a file/directory
> with a submodule or vice versa.
> 
> The patches are still a bit rough, but the overall series seems
> promising enough to me that I want to put it out here.
> 
> Any review, specifically on the design level welcome!
> 
> Thanks,
> Stefan
> 
> Stefan Beller (16):
>   submodule.h: add extern keyword to functions, break line before 80
>   submodule: modernize ok_to_remove_submodule to use argv_array
>   submodule: use absolute path for computing relative path connecting
>   update submodules: add is_submodule_populated
>   update submodules: add submodule config parsing
>   update submodules: add a config option to determine if submodules are
>     updated
>   update submodules: introduce submodule_is_interesting
>   update submodules: add depopulate_submodule
>   update submodules: add scheduling to update submodules
>   update submodules: is_submodule_checkout_safe
>   teach unpack_trees() to remove submodule contents
>   entry: write_entry to write populate submodules
>   submodule: teach unpack_trees() to update submodules
>   checkout: recurse into submodules if asked to
>   completion: add '--recurse-submodules' to checkout
>   checkout: add config option to recurse into submodules by default
> 
>  Documentation/config.txt               |   6 +
>  Documentation/git-checkout.txt         |   8 +
>  builtin/checkout.c                     |  31 ++-
>  cache.h                                |   2 +
>  contrib/completion/git-completion.bash |   2 +-
>  entry.c                                |  17 +-
>  submodule-config.c                     |  22 +++
>  submodule-config.h                     |  17 +-
>  submodule.c                            | 246 +++++++++++++++++++++--
>  submodule.h                            |  77 +++++---
>  t/lib-submodule-update.sh              |  10 +-
>  t/t2013-checkout-submodule.sh          | 344 ++++++++++++++++++++++++++++++++-
>  t/t9902-completion.sh                  |   1 +
>  unpack-trees.c                         | 103 ++++++++--
>  unpack-trees.h                         |   1 +
>  wrapper.c                              |   4 +
>  16 files changed, 806 insertions(+), 85 deletions(-)
>