[PATCH 0/3] Teach git-diff-tree(1) option --max-depth

[Toon Claes <toon@iotcl.com>]

Please consider these patches authored by Peff. They add option
`--max-depth` to the diff machinery.

During the process to upstream the git-blame-tree(1), later named
git-last-modified(1), various times[1][2][3] the topic was raised to add
option `--max-depth` to the diff machinery. In this patch series this
change is added as a separate patch series.

The patches were originally written by Peff[4] and I'm crediting him as
the author. I've taken the patches almost verbatim from his fork on
GitHub, with some minor tweaks in the commit messages. Because only tiny
changes were made, I've kept his Signed-off-by trailers, but I can
remove if disagreed on.

The goal of the option `--max-depth` is to stop recursively traversing
the tree if the given depth is reached from the pathspec.

These patches add `max_depth` and `max_depth_valid` to `struct
diff_options`. This is different from what git-grep(1) does, which uses
`max_depth` on `struct pathspec` instead. At the moment I'm on the fence
whether this is an issue: while it probably makes sense to consolidate
them into the same structs, it does not really make sense to reuse these
the struct fields if they are used in two separate code paths.

[1]: https://lore.kernel.org/git/20130318121243.GC14789@sigill.intra.peff.net/
[2]: https://lore.kernel.org/git/20160831054201.ldlwptlmcndjmfwu@sigill.intra.peff.net/
[3]: https://lore.kernel.org/git/Y+%2FmnnJUz75yfWCN@coredump.intra.peff.net/
[4]: https://github.com/peff/git/tree/jk/diff-max-depth

---
Jeff King (3):
      combine-diff: zero memory used for callback filepairs
      within_depth: fix return for empty path
      diff: teach tree-diff a max-depth parameter

 Documentation/diff-options.adoc |  28 +++++++++++
 combine-diff.c                  |   2 +-
 diff-lib.c                      |   5 ++
 diff.c                          |  19 +++++++
 diff.h                          |   9 ++++
 dir.c                           |   2 +-
 t/meson.build                   |   1 +
 t/t4072-diff-max-depth.sh       | 109 ++++++++++++++++++++++++++++++++++++++++
 tree-diff.c                     |  78 ++++++++++++++++++++++++++--
 9 files changed, 248 insertions(+), 5 deletions(-)
---



---

base-commit: e813a0200a7121b97fec535f0d0b460b0a33356c
change-id: 20250724-toon-max-depth-25d3c19e2607

Thanks
--
Toon