[PATCH v3 0/4] Fix git-last-modified(1) bug triggered when passing a tree-ish

Recently there was a bug reported[1] passing a tree OID triggers a BUG:

    $ git last-modified fb06ce04173d47aaaa498385621cba8b8dfd7584
    BUG: builtin/last-modified.c:456: paths remaining beyond boundary in last-modified
    [1]    690163 IOT instruction (core dumped)  git last-modified

    `fb06ce04173d47aaaa498385621cba8b8dfd7584` is the tree commit id of web_src. I
    suppose this should've returned a nice error message or blank output.

Fix this bug by checking the revision argument.

[1]: https://lore.kernel.org/git/03f96860-29fc-42a7-a220-c3ec65eb8516@codeberg.org/

---
Changes in v3:
- Split the change to plug the leak into a separate commit.
- Small changes to commit messages.
- Link to v2: https://patch.msgid.link/20260114-toon-last-modified-tree-v2-0-ba3b1860898f@iotcl.com

Changes in v2:
- Prepend the change with a commit that modifies the error message
  when more than one revision is given.
- Prepend another commit that removes double error message.
- Add test to ensure the command works with annotated tags too.
- Link to v1: https://patch.msgid.link/20260112-toon-last-modified-tree-v1-1-ecbc78341f76@iotcl.com

---
Toon Claes (4):
      last-modified: rewrite error message when more than one revision given
      last-modified: fix memory leak when more than one revision is given
      last-modified: remove double error message
      last-modified: verify revision argument is a commit-ish

 builtin/last-modified.c  | 19 ++++++++++++++-----
 t/t8020-last-modified.sh | 15 ++++++++++++++-
 2 files changed, 28 insertions(+), 6 deletions(-)

Range-diff versus v2:

-:  ---------- > 1:  053c119ab1 last-modified: rewrite error message when more than one revision given
1:  5c9936500b ! 2:  827b1500fe last-modified: rewrite error message when more than one revision given
    @@ Metadata
     Author: Toon Claes <toon@iotcl.com>
     
      ## Commit message ##
    -    last-modified: rewrite error message when more than one revision given
    +    last-modified: fix memory leak when more than one revision is given
     
    -    When more than one revision is passed to the git-last-modified(1)
    -    command, this error message was printed:
    -
    -        error: last-modified can only operate on one tree at a time
    -
    -    Calling these a "tree" is technically not correct. git-last-modified(1)
    -    expects revisions that peel to a commit.
    -
    -    Rephrase the error message to:
    -
    -        error: last-modified can only operate on one revision at a time
    -
    -    While at it, also fix a memory leak that remained uncovered so far.
    +    When more than one revision is given, the function
    +    populate_paths_from_revs() leaks a `struct pathspec`. Plug it.
     
         Signed-off-by: Toon Claes <toon@iotcl.com>
     
    @@ builtin/last-modified.c: static int populate_paths_from_revs(struct last_modifie
      			continue;
      
     -		if (num_interesting++)
    --			return error(_("last-modified can only operate on one tree at a time"));
    +-			return error(_("last-modified can only operate on one revision at a time"));
     +		if (num_interesting++) {
     +			ret = error(_("last-modified can only operate on one revision at a time"));
     +			goto out;
    @@ builtin/last-modified.c: static int populate_paths_from_revs(struct last_modifie
      }
      
      static void last_modified_emit(struct last_modified *lm,
    -
    - ## t/t8020-last-modified.sh ##
    -@@ t/t8020-last-modified.sh: test_expect_success 'setup' '
    - 	test_commit 3 a/b/file
    - '
    - 
    --test_expect_success 'cannot run last-modified on two trees' '
    -+test_expect_success 'cannot run last-modified on two revision' '
    - 	test_must_fail git last-modified HEAD HEAD~1
    - '
    - 
2:  5c964488fd = 3:  7748574724 last-modified: remove double error message
3:  cb6ff40853 ! 4:  6846722750 last-modified: verify revision argument is a commit-ish
    @@ Commit message
             git last-modified HEAD^{tree}
             BUG: builtin/last-modified.c:456: paths remaining beyond boundary in last-modified
     
    -    Fix this error by verifying the parsed revision peels to a commit-ish.
    -
    -    While at it, also fix a memory leak in populate_paths_from_revs().
    +    Fix this error by verifying the parsed revision is a commit-ish.
     
         Reported-by: Gusted <gusted@codeberg.org>
         Signed-off-by: Toon Claes <toon@iotcl.com>

--- base-commit: 7264e61d87e58b9d0f5e6424c47c11e9657dfb75 change-id: 20260112-toon-last-modified-tree-fdd96b2feaf7