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2.36 gitk/diff-tree --stdin regression fix

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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@live.de>
Helped-by: René Scharfe <l.s.r@web.de>
Helped-by: Phillip Wood <phillip.wood123@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Junio C Hamano 2022-04-26 09:11:44 -07:00
parent 362f869ff2
commit f8781bfda3
3 changed files with 18 additions and 0 deletions
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3
builtin/diff-tree.c
View File

@ -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);

1
log-tree.c
View File

@ -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);

14
t/t4013-diff-various.sh
View File

@ -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 &&