[PATCH 0/8] Introduce git-blame-tree(1) command

This is yet another attempt to upstream the builtin command `git-blame-tree(1)`. This command is similar to git-blame(1) and shows the most recent modification to paths in a tree..

The last attempt (I'm aware of) was made by Ævar in 2023[1]. That series was based of patches by Peff written in 2011[2].

In contrary to Ævar's attempt, my series implements the `git-blame-tree(1)` standalone command. Ævar suggested to only implement the blame-tree subsystem, and test it through test-tool. But since the command line options of that test-tool subcommand were very similar to the standalone command we want to land, I decided transfer the test-tool subcommand into a real Git builtin. Also, nowadays if we want to test the blame-tree subsystem independently, we should use clar unit tests instead of test-tool.

This series brings back the --max-depth changes. I know Ævar removed them because there was controversy, but I think they are relevant to include. And I want to open up the conversation again.

Also extra patches from Peff are included to implement pathspec tries. I've taken them from Peff's fork on GitHub[3], but they also have been posted to this mailing list[4].

Other improvements I've made:

* Rebase onto current master.

* Remove the use of USE_THE_REPOSITORY_VARIABLE.

* Fix various memory leaks.

* Moved code from blame-tree.c to pathspec.c, as suggested in Peff's
  last patch on GitHub.

* Updated the benchmark results in the last commit message, although the
  numbers were roughly the same.

I don't expect this code to be deemed ready to merge, but I mainly want to gather as much feedback as possible and use it to iterate toward actually getting it merged.

There are some things I know that are missing, for example `--porcelain`, but those can be added in a follow-up. At the moment there's one test marked `test_expect_failure`, but I was not able yet identify that bug.

So, let me know what you think?

-- Toon

[1]: https://lore.kernel.org/git/patch-1.1-0ea849d900b-20230205T204104Z-avarab@gmail.com/ [2]: https://lore.kernel.org/git/20110302164031.GA18233@sigill.intra.peff.net/ [3]: https://github.com/peff/git/tree/jk/faster-blame-tree-wip [4]: https://lore.kernel.org/git/YN4zKVK7gvuIZ0vK@coredump.intra.peff.net/

---
Jeff King (7):
      combine-diff: zero memory used for callback filepairs
      within_depth: fix return for empty path
      diff: teach tree-diff a max-depth parameter
      pathspec: add optional trie index
      pathspec: turn on tries when appropriate
      tree-diff: use pathspec tries
      blame-tree: narrow pathspec as we traverse

Toon Claes (1):
      blame-tree: introduce new subcommand to blame files

 .gitignore                      |   1 +
 Documentation/diff-options.adoc |  26 +++++
 Makefile                        |   3 +
 blame-tree.c                    | 216 ++++++++++++++++++++++++++++++++++++++++
 blame-tree.h                    |  43 ++++++++
 builtin.h                       |   1 +
 builtin/blame-tree.c            |  67 +++++++++++++
 combine-diff.c                  |   2 +-
 diff-lib.c                      |   5 +
 diff.c                          |  18 ++++
 diff.h                          |   9 ++
 dir.c                           |   2 +-
 git.c                           |   1 +
 meson.build                     |   2 +
 pathspec.c                      | 216 ++++++++++++++++++++++++++++++++++++++++
 pathspec.h                      |  27 +++++
 t/helper/meson.build            |   1 +
 t/helper/test-pathspec.c        |  96 ++++++++++++++++++
 t/helper/test-tool.c            |   1 +
 t/helper/test-tool.h            |   2 +
 t/meson.build                   |   3 +
 t/perf/p4003-diff-pathspec.sh   |  26 +++++
 t/t4071-diff-max-depth.sh       | 109 ++++++++++++++++++++
 t/t6137-pathspec-trie.sh        |  57 +++++++++++
 t/t8020-blame-tree.sh           | 142 ++++++++++++++++++++++++++
 tree-diff.c                     | 176 +++++++++++++++++++++++++++++---
 26 files changed, 1235 insertions(+), 17 deletions(-)
---

---

base-commit: 683c54c999c301c2cd6f715c411407c413b1d84e change-id: 20250326-toon-blame-tree-2ca74d7712ac

Thanks -- Toon