Subject: [PATCH v2 04/10] backfill: die on incompatible filter options

From: "Derrick Stolee via GitGitGadget" <[email-masked]>
Date: Mon, 04 May 2026 20:21:13 +0000

From: Derrick Stolee <[email-masked]>

The 'git backfill' command uses the path-walk API in a critical way: it
uses the objects output from the command to find the batches of missing
objects that should be requested from the server. Unlike 'git
pack-objects', we cannot fall back to another mechanism.

The previous change added the path_walk_filter_compatible() method that
we can reuse here. Use it during argument validation in cmd_backfill().

Signed-off-by: Derrick Stolee <[email-masked]>
---
 builtin/backfill.c  | 5 ++---
 t/t5620-backfill.sh | 8 ++++++++
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/builtin/backfill.c b/builtin/backfill.c
index 7ffab2ea74..b80f9ebe69 100644
--- a/builtin/backfill.c
+++ b/builtin/backfill.c
@@ -96,9 +96,8 @@ static void reject_unsupported_rev_list_options(struct rev_info *revs)
 	if (revs->explicit_diff_merges)
 		die(_("'%s' cannot be used with 'git backfill'"),
 		    "--diff-merges");
-	if (revs->filter.choice)
-		die(_("'%s' cannot be used with 'git backfill'"),
-		    "--filter");
+	if (!path_walk_filter_compatible(&revs->filter))
+		die(_("cannot backfill with these filter options"));
 }
 
 static int do_backfill(struct backfill_context *ctx)
diff --git a/t/t5620-backfill.sh b/t/t5620-backfill.sh
index 94f35ce190..ede89f8c33 100755
--- a/t/t5620-backfill.sh
+++ b/t/t5620-backfill.sh
@@ -15,6 +15,14 @@ test_expect_success 'backfill rejects unexpected arguments' '
 	test_grep "unrecognized argument: --unexpected-arg" err
 '
 
+test_expect_success 'backfill rejects incompatible filter options' '
+	test_must_fail git backfill --objects --filter=tree:1 2>err &&
+	test_grep "cannot backfill with these filter options" err &&
+
+	test_must_fail git backfill --objects --filter=blob:limit=10m 2>err &&
+	test_grep "cannot backfill with these filter options" err
+'
+
 # We create objects in the 'src' repo.
 test_expect_success 'setup repo for object creation' '
 	echo "{print \$1}" >print_1.awk &&
-- 
gitgitgadget