[RFC v3 0/4] Preferred local submodule branches

From: "W. Trevor King" <wking@tremily.us>

In another branch of the submodule thread Francesco kicked off, I mentioned that we could store the preferred local submodule branch on a per-superbranch level if we used the .git/modules/<submodule-name>/config for local overrides [1]. Here's a patch series that greatly extends my v2 "submodule: Respect requested branch on all clones" series [2] to also support automatic, recursive submodule checkouts, as I outlined here [3]. After this series, I can get through:

  # create the subproject
  mkdir subproject &&
  (
    cd subproject &&
    git init &&
    echo 'Hello, world' > README &&
    git add README &&
    git commit -m 'Subproject v1'
  ) &&
  # create the superproject
  mkdir superproject
  (
    cd superproject &&
    git init &&
    git submodule add ../subproject submod &&
    git config -f .gitmodules submodule.submod.update merge &&
    git commit -am 'Superproject v1' &&
    ( # 'submodule update' doesn't look in .gitmodules (yet [4]) for a
      # default update mode.  Copy submodule.submod.update over to
      # .git/config
      git submodule init
    )
  ) &&
  # start a feature branch on the superproject
  (
    cd superproject &&
    #git checkout -b my-feature --recurse-submodules &&
    ( # 'git submodule checkout --recurse-submodules' doesn't exist yet, so...
      git checkout -b my-feature &&
      git submodule checkout -b --gitmodules
    ) &&
    (
      cd submod &&
      echo 'Add the subproject side of this feature' > my-feature &&
      git add my-feature &&
      git commit -m 'Add my feature to the subproject'
    ) &&
    echo 'Add the superproject side of this feature' > my-feature &&
    git add my-feature &&
    git commit -am 'Add the feature to the superproject'
  ) &&
  # meanwhile, the subproject has been advancing
  (
    cd subproject &&
    echo 'Goodbye, world' >> README &&
    git commit -am 'Subproject v2'
  ) &&
  # we need to get that critical advance into the superproject quick!
  (
    cd superproject &&
    # update the master branch
    #git checkout --recurse-submodules master
    ( # 'git checkout --recurse-submodules' doesn't exist yet [5,6].
      # Even with that patch, 'git checkout' won't respect
      # submodule.<name>.local-branch without further work.
      git checkout master &&
      git submodule checkout
    ) &&
    git submodule update --remote &&
    git commit -am 'Catch submod up with Subproject v2' &&
    # update the my-feature branch
    #git checkout --recurse-submodules my-feature &&
    ( # 'git checkout --recurse-submodules' doesn't exist yet [5,6].
      git checkout my-feature &&
      git submodule checkout
    ) &&
    git submodule update --remote &&
    git commit -am 'Catch submod up with Subproject v2' &&
    # what does the history look like?
    (
      cd submod &&
      git --no-pager log --graph --date-order --oneline --decorate --all
      # *   16d9e3e (HEAD, my-feature) Merge commit 'f5e134d5747ee4a206e96d8c017f92f5b29a07f3' into my-feature
      # |\  
      # | * f5e134d (origin/master, origin/HEAD, master) Subproject v2
      # * | 0a1cd07 Add my feature to the subproject
      # |/  
      # * c2d32ba Subproject v1
    ) &&
    printf 'master: ' &&
    git ls-tree master submod &&
    # master: 160000 commit f5e134d5747ee4a206e96d8c017f92f5b29a07f3  submod
    printf 'my-feature: ' &&
    git ls-tree my-feature submod
    # my-feature: 160000 commit 16d9e3ea2fb57e7a166587203abdb328f90895d1  submod
  )
  git --version
  # git version 1.8.5.2.237.g01c62c6

I think the first three patches are fairly solid. The last one gets through the above script, but I'd need a more thorough test suite before I trusted it. I tried to be detailed in the commit messages, but of course, we'd want some user-facing documentation if we actually merged something like this series. I'm sending it to the list mostly to explain my current views and re-focus debate [1].

[1]: http://article.gmane.org/gmane.comp.version-control.git/240240 [2]: http://article.gmane.org/gmane.comp.version-control.git/239967 [3]: http://article.gmane.org/gmane.comp.version-control.git/240192 [4]: http://article.gmane.org/gmane.comp.version-control.git/239246 [5]: http://thread.gmane.org/gmane.comp.version-control.git/239695 [6]: http://article.gmane.org/gmane.comp.version-control.git/240117

Cheers, Trevor

W. Trevor King (4):
  submodule: Add helpers for configurable local branches
  submodule: Teach 'update' to preserve local branches
  submodule: Teach 'add' about a configurable local-branch
  submodule: Add a new 'checkout' command

 git-submodule.sh | 152 ++++++++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 138 insertions(+), 14 deletions(-)