git/contrib/subtree, branch seen

Merge branch 'cs/subtree-split-recursion' into seen

2026-04-17T21:26:32Z

When processing large history graphs on Debian or Ubuntu, "git subtree" can die with a "recursion depth reached" error. Comments? * cs/subtree-split-recursion: contrib/subtree: reduce recursion during split contrib/subtree: functionalize split traversal contrib/subtree: reduce function side-effects

builds: move build scripts into "tools/"

2026-03-19T13:40:09Z

We have a bunch of scripts used by our different build systems that are all located in the top-level directory. Now that we have introduced the new "tools/" directory though we have a better home for them. Move the scripts into the "tools/" directory. Signed-off-by: Patrick Steinhardt Signed-off-by: Junio C Hamano

contrib/subtree: reduce recursion during split

2026-03-06T21:57:48Z

On Debian-alikes, POSIX sh has a hardcoded recursion depth of 1000. This limit operates like bash's `$FUNCNEST` [1], but it does not actually respect `$FUNCNEST`. This is non-standard behavior. On other distros, the sh recursion depth is limited only by the available stack size. With certain history graphs, subtree splits are recursive—with one recursion per commit. Attempting to split complex repos that have thousands of commits, like [2], may fail on these distros. Reduce the amount of recursion required by eagerly discovering the complete range of commits to process. The recursion is a side-effect of the rejoin-finder in `find_existing_splits`. Rejoin mode, as in git subtree split --rejoin -b hax main ... improves the speed of later splits by merging the split history back into `main`. This gives the splitting algorithm a stopping point. The rejoin maps one commit on `main` to one split commit on `hax`. If we encounter this commit, we know that it maps to `hax`. But this is only a single point in the history. Many splits require history from before the rejoin. See patch content for examples. If pre-rejoin history is required, `check_parents` recursively discovers each individual parent, with one recursion per commit. The recursion deepens the entire tree, even if an older rejoin is available. This quickly overwhelms the Debian sh stack. Instead of recursively processing each commit, process *all* the commits back to the next obvious starting point: i.e., either the next-oldest --rejoin or the beginning of history. This is where the recursion is likely to stop anyway. While this still requires recursion, it is *considerably* less recursive. [1]: https://www.gnu.org/software/bash/manual/html_node/Bash-Variables.html#index-FUNCNEST [2]: https://github.com/christian-heusel/aur.git Signed-off-by: Colin Stagner Signed-off-by: Junio C Hamano

contrib/subtree: functionalize split traversal

2026-03-06T21:57:48Z

`git subtree split` requires an ancestor-first history traversal. Refactor the existing rev-list traversal into its own function, `find_commits_to_split`. Pass unrevs via stdin to avoid limits on the maximum length of command-line arguments. Also remove an unnecessary `eval`. Signed-off-by: Colin Stagner Signed-off-by: Junio C Hamano

contrib/subtree: reduce function side-effects

2026-03-06T21:57:48Z

`process_subtree_split_trailer()` communicates its return value to the caller by setting a variable (`sub`) that is also defined by the calling function. This is both unclear and encourages side-effects. Invoke this function in a sub-shell instead. Signed-off-by: Colin Stagner Signed-off-by: Junio C Hamano

Merge branch 'cs/subtree-split-fixes'

2026-03-03T19:08:12Z

An earlier attempt to optimize "git subtree" discarded too much relevant histories, which has been corrected. * cs/subtree-split-fixes: contrib/subtree: process out-of-prefix subtrees contrib/subtree: test history depth contrib/subtree: capture additional test-cases

Merge branch 'ps/validate-prefix-in-subtree-split'

2026-03-03T01:06:51Z

"git subtree split --prefix=P " now checks the prefix P against the tree of the (potentially quite different from the current working tree) given commit. * ps/validate-prefix-in-subtree-split: subtree: validate --prefix against commit in split

contrib/subtree: process out-of-prefix subtrees

2026-02-20T18:15:31Z

`should_ignore_subtree_split_commit` detects subtrees which are outside of the current path --prefix and ignores them. This can speed up splits of repositories that have many subtrees. Since its inception [1], every iteration of this logic [2], [3] incorrectly excludes commits. This alters the split history. The split history and its commit hashes are API contract, so this is not permissible. While a commit from a different subtree may look like it doesn't contribute anything to a split, sometimes it does. Merge commits are a particular hot spot. For these, the pruning logic in `copy_or_skip` performs: 1. a check for "treesame" parents 2. two different common ancestry checks These checks operate on the **split history**, not the input history. The split history omits commits that do not affect the --prefix. This can significantly alter the ancestry of a merge. In order to determine if `copy_or_skip` will skip a merge, it is likely necessary to compute all the split history... which is what `should_ignore_subtree_split_commit` tries to avoid. To make this logic API-preserving, we could gate it behind a new CLI argument. The present implementation is actually a speed penalty in many cases, however, so this is not done here. Remove the `should_ignore_subtree_split_commit` logic. This fixes the regression reported in [4]. [1]: 98ba49ccc2 (subtree: fix split processing with multiple subtrees present, 2023-12-01) [2]: 83f9dad7d6 (contrib/subtree: fix split with squashed subtrees, 2025-09-09) [3]: 28a7e27cff (contrib/subtree: detect rewritten subtree commits, 2026-01-09) [4]: <20251230170719.845029-1-george@mail.dietrich.pub> Reported-by: George Reported-by: Christian Heusel Signed-off-by: Colin Stagner Signed-off-by: Junio C Hamano

contrib/subtree: test history depth

2026-02-20T18:15:31Z

Add history depth checks to some of the subtree unit tests. These checks were previously introduced as part of 28a7e27cff (contrib/subtree: detect rewritten subtree commits, 2026-01-09), which has since been reverted. Signed-off-by: Colin Stagner Signed-off-by: Junio C Hamano

contrib/subtree: capture additional test-cases

2026-02-20T18:15:31Z

Patch series e7b07376e5 (Merge branch 'rs/subtree-fixes', 2018-10-26) corrects several defects in `git subtree split`. The defects affect `split --rejoin` and merge commit processing. There is no test coverage for this, and e7b07376e5 did not introduce any. Convert the minimum working example [1] from the original patch submission [2] into test cases. [1]: https://gist.github.com/FoxFireX/1b794384612b7fd5e7cd157cff96269e [2]: <20180928183540.48968-1-roger.strain@swri.org> Signed-off-by: Colin Stagner Signed-off-by: Junio C Hamano