This only surfaced as a regression after 2.36 release, but the
breakage was already there with us for at least a year.
The diff_free() call is to be used after we completely finished with
a diffopt structure. After "git diff A B" finishes producing
output, calling it before process exit is fine. But there are
commands that prepares diff_options struct once, compares two sets
of paths, releases resources that were used to do the comparison,
then reuses the same diff_option struct to go on to compare the next
two sets of paths, like "git log -p".
After "git log -p" finishes showing a single commit, calling it
before it goes on to the next commit is NOT fine. There is a
mechanism, the .no_free member in diff_options struct, to help "git
log" to avoid calling diff_free() after showing each commit and
instead call it just one. When the mechanism was introduced in
e900d494 (diff: add an API for deferred freeing, 2021-02-11),
however, we forgot to do the same to "diff-tree --stdin", which *is*
a moral equivalent to "git log".
During 2.36 release cycle, we started clearing the pathspec in
diff_free(), so programs like gitk that runs
git diff-tree --stdin -- <pathspec>
downstream of a pipe, processing one commit after another, started
showing irrelevant comparison outside the given <pathspec> from the
second commit. The same commit, by forgetting to teach the .no_free
mechanism, broke "diff-tree --stdin -I<regexp>" and nobody noticed
it for over a year, presumably because it is so seldom used an
option.
But <pathspec> is a different story. The breakage was very
prominently visible and was reported immediately after 2.36 was
released.
Fix this breakage by mimicking how "git log" utilizes the .no_free
member so that "diff-tree --stdin" behaves more similarly to "log".
Protect the fix with a few new tests.
Reported-by: Matthias Aßhauer <mha1993@xxxxxxx>
Helped-by: René Scharfe <l.s.r@xxxxxx>
Helped-by: Phillip Wood <phillip.wood123@xxxxxxxxx>
Signed-off-by: Junio C Hamano <gitster@xxxxxxxxx>
---
* I feel MUCH better with this than the revert, now Phillip helped
me to get the root cause straight. Addition of clear_pathspec()
to diff_tree() was *not* a mistake but is quite reasonable thing
to do. Not using the .no_free hack in a code path that needed it
was.
builtin/diff-tree.c | 3 +++
log-tree.c | 1 +
t/t4013-diff-various.sh | 14 ++++++++++++++
3 files changed, 18 insertions(+)
diff --git a/builtin/diff-tree.c b/builtin/diff-tree.c
index 0e0ac1f167..116097a404 100644
--- a/builtin/diff-tree.c
+++ b/builtin/diff-tree.c
@@ -195,6 +195,7 @@ int cmd_diff_tree(int argc, const char **argv, const char *prefix)
int saved_dcctc = 0;
opt->diffopt.rotate_to_strict = 0;
+ opt->diffopt.no_free = 1;
if (opt->diffopt.detect_rename) {
if (!the_index.cache)
repo_read_index(the_repository);
@@ -217,6 +218,8 @@ int cmd_diff_tree(int argc, const char **argv, const char *prefix)
}
opt->diffopt.degraded_cc_to_c = saved_dcctc;
opt->diffopt.needed_rename_limit = saved_nrl;
+ opt->diffopt.no_free = 0;
+ diff_free(&opt->diffopt);
}
return diff_result_code(&opt->diffopt, 0);
diff --git a/log-tree.c b/log-tree.c
index 25165e2a91..f8c18fd8b9 100644
--- a/log-tree.c
+++ b/log-tree.c
@@ -1098,6 +1098,7 @@ int log_tree_commit(struct rev_info *opt, struct commit *commit)
opt->loginfo = &log;
opt->diffopt.no_free = 1;
+ /* NEEDSWORK: no restoring of no_free? Why? */
if (opt->line_level_traverse)
return line_log_print(opt, commit);
diff --git a/t/t4013-diff-various.sh b/t/t4013-diff-various.sh
index 750aee17ea..628b01f355 100755
--- a/t/t4013-diff-various.sh
+++ b/t/t4013-diff-various.sh
@@ -542,6 +542,20 @@ test_expect_success 'diff-tree --stdin with log formatting' '
test_cmp expect actual
'
+test_expect_success 'diff-tree --stdin with pathspec' '
+ cat >expect <<-EOF &&
+ Third
+
+ dir/sub
+ Second
+
+ dir/sub
+ EOF
+ git rev-list master^ |
+ git diff-tree -r --stdin --name-only --format=%s dir >actual &&
+ test_cmp expect actual
+'
+
test_expect_success 'diff -I<regex>: setup' '
git checkout master &&
test_seq 50 >file0 &&
--
2.36.0-202-g319c44b8f9
