= Description This series teaches "git clone --recurse-submodules" and "git submodule update" to understand "submodule.propagateBranches" (see Further Reading for context), i.e. if the superproject has a branch checked out and a submodule is cloned, the submodule will have the same branch checked out. To do this, "git submodule update" checks if "submodule.propagateBranches" is true, and if so, gets the current superproject branch and updates the submodule by running "git checkout -b my-superproject-branch". Since "git clone --recurse-submodules" is implemented using "git submodule update", it also learns this trick. The main challenges with this approach are: * If the remote HEAD points to a branch, "git clone" always creates that branch in the clone. But with "submodule.propagateBranches", we want submodules to use the branch names of their superproject, not their upstream. This is solved by adding a new flag to "git clone", "--detach", which detaches the clone's HEAD at the branch and does not create it. * When "git submodule update" recurses into submodules, the parent process has to propagate the value of "submodule.propagateBranches" to child processes, otherwise the behavior will be inconsistent if the submodule has the config unset. This is solved by adding an internal GIT_* environment variable and passing it down via prepare_submodule_repo_env(). This is cleaner than passing "-c submodule.propagateBranches=true", but an even cleaner solution would be for submodules to read "submodule.propagateBranches" from their superproject config. This would also be useful for "submodule.alternateLocation" and "submodule.alternateErrorStrategy", as we wouldn't have to set those values in newly-cloned submodules. This requires teaching Git to treat submodules differently, which was the subject of some WIP in [1]. That topic has stalled, but I don't mind restarting it if others prefer that. [1] https://lore.kernel.org/git/20220310004423.2627181-1-emilyshaffer@xxxxxxxxxx/ = Patch organization * Patch 1/6 adds "--detach" to "git clone" * Patch 2/6 creates the environment variable and repository setting for "submodule.propagateBranches" * Patches 3-5/6 are prep work, and 6/6 adds the actual "submodule.propagateBranches" behavior = Future work * Patch 4, which refactors resolve_gitlink_ref(), notes that a better interface would be to return the refname instead of using an "out" parameter, but we use an "out" parameter so that any new callers trying to use the old function signature will get stopped by the compiler. The refactor can be finished at a later time. = Further reading Submodule branching RFC: https://lore.kernel.org/git/kl6lv912uvjv.fsf@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/ Original Submodule UX RFC/Discussion: https://lore.kernel.org/git/YHofmWcIAidkvJiD@xxxxxxxxxx/ Contributor Summit submodules Notes: https://lore.kernel.org/git/nycvar.QRO.7.76.6.2110211148060.56@xxxxxxxxxxxxxxxxx/ Submodule UX overhaul updates: https://lore.kernel.org/git/?q=Submodule+UX+overhaul+update "git branch --recurse-submodules": https://lore.kernel.org/git/20220129000446.99261-1-chooglen@xxxxxxxxxx/ Glen Choo (6): clone: teach --detach option repo-settings: add submodule_propagate_branches t5617: drop references to remote-tracking branches submodule: return target of submodule symref submodule--helper: refactor up-to-date criterion clone, submodule update: check out branches Documentation/git-clone.txt | 7 +++- builtin/branch.c | 11 ++---- builtin/clone.c | 12 ++++-- builtin/submodule--helper.c | 37 +++++++++++++++++-- builtin/update-index.c | 4 +- cache.h | 1 + combine-diff.c | 3 +- diff-lib.c | 2 +- dir.c | 2 +- object-file.c | 2 +- read-cache.c | 4 +- refs.c | 10 +++-- refs.h | 5 ++- repo-settings.c | 11 +++--- repository.h | 1 + submodule.c | 2 + t/t5601-clone.sh | 22 +++++++++++ ...es-remote.sh => t5617-clone-submodules.sh} | 36 +++++++++++++++++- t/t7406-submodule-update.sh | 22 +++++++++++ unpack-trees.c | 3 +- 20 files changed, 161 insertions(+), 36 deletions(-) rename t/{t5617-clone-submodules-remote.sh => t5617-clone-submodules.sh} (72%) base-commit: 9bf691b78cf906751e65d65ba0c6ffdcd9a5a12c Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-1321%2Fchooglen%2Fsubmodule%2Fclone-recursive-with-branch-v1 Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-1321/chooglen/submodule/clone-recursive-with-branch-v1 Pull-Request: https://github.com/git/git/pull/1321 -- gitgitgadget
