Subject: [PATCH v2] revision: fix --left/right-only use with unrelated histories

From: Matt Hunter <[email-masked]>
Date: Sun, 30 Mar 2025 07:24:06 -0400

This is a similar fix as 023756f4eb (revision walker: --cherry-pick is a
limited operation), but for the --left-only and --right-only options.

When computing a symmetric difference between two unrelated histories,
no suitable merge base exists, and so no boundary commit is flagged as
UNINTERESTING.  Previously, we relied on the presence of such boundary
to trigger limiting and thus consideration of either "revs->left_only"
or "revs->right_only".

A number of other entries in the option parser have started including
overrides for "revs->limited = 1".  Do the same for these options.

Signed-off-by: Matt Hunter <[email-masked]>
---

Range-diff against v1:
1:  1982f14d70 ! 1:  4f5b264b26 revision: fix --left/right-only use with unrelated histories
    @@ t/t6000-rev-list-misc.sh: test_expect_success 'rev-list --unpacked' '
     +	git rev-list --left-only  HEAD...cmp >head &&
     +	git rev-list --right-only HEAD...cmp >cmp  &&
     +
    -+	test $(comm -12 <(sort head) <(sort cmp) | wc -l) = "0"
    ++	sort head >head.sorted &&
    ++	sort cmp >cmp.sorted &&
    ++	comm -12 head.sorted cmp.sorted >actual &&
    ++	test_line_count = 0 actual
     +'
     +
      test_done

base-commit: 683c54c999c301c2cd6f715c411407c413b1d84e

 revision.c               |  2 ++
 t/t6000-rev-list-misc.sh | 15 +++++++++++++++
 2 files changed, 17 insertions(+)

diff --git a/revision.c b/revision.c
index c4390f0938..e045445bc3 100644
--- a/revision.c
+++ b/revision.c
@@ -2488,10 +2488,12 @@ static int handle_revision_opt(struct rev_info *revs, int argc, const char **arg
 			die(_("options '%s' and '%s' cannot be used together"),
 			    "--left-only", "--right-only/--cherry");
 		revs->left_only = 1;
+		revs->limited = 1;
 	} else if (!strcmp(arg, "--right-only")) {
 		if (revs->left_only)
 			die(_("options '%s' and '%s' cannot be used together"), "--right-only", "--left-only");
 		revs->right_only = 1;
+		revs->limited = 1;
 	} else if (!strcmp(arg, "--cherry")) {
 		if (revs->left_only)
 			die(_("options '%s' and '%s' cannot be used together"), "--cherry", "--left-only");
diff --git a/t/t6000-rev-list-misc.sh b/t/t6000-rev-list-misc.sh
index 6289a2e8b0..d338f7ecb4 100755
--- a/t/t6000-rev-list-misc.sh
+++ b/t/t6000-rev-list-misc.sh
@@ -182,4 +182,19 @@ test_expect_success 'rev-list --unpacked' '
 	test_cmp expect actual
 '
 
+test_expect_success 'rev-list one-sided unrelated symmetric diff' '
+	test_tick &&
+	git commit --allow-empty -m xyz &&
+	git branch cmp &&
+	git rebase --force-rebase --root &&
+
+	git rev-list --left-only  HEAD...cmp >head &&
+	git rev-list --right-only HEAD...cmp >cmp  &&
+
+	sort head >head.sorted &&
+	sort cmp >cmp.sorted &&
+	comm -12 head.sorted cmp.sorted >actual &&
+	test_line_count = 0 actual
+'
+
 test_done
-- 
2.49.0