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wed 2026-10-07 16:24 UTC

[GSoC PATCH v2] backfill: auto-detect sparse-checkout from config

From
Trieu Huynh <vikingtc4@gmail.com>
Date
Apr 4, 2026, 11:15 UTC
Message-ID
<20260404111557.17220-1-viking4@gmail.com>
From: Trieu Huynh <vikingtc4@gmail.com>

Commit 85127bcdea ("backfill: assume --sparse when sparse-checkout is enabled") intended for 'git backfill' to consult the repository configuration when the user does not pass '--sparse' or '--no-sparse' on the command line. It added the sentinel check:

    if (ctx->sparse < 0)
        ctx->sparse = cfg->apply_sparse_checkout;

However, the ctx->sparse field is initialized to 0 instead of -1, so this guard never triggers. Consequently, the repository config (core.sparseCheckout) is never checked, and the command always performs a full backfill even when sparse-checkout is enabled.

Fix this by initializing ctx->sparse to -1, ensuring the existing fallback logic correctly reads the repository configuration when no explicit flags are provided.

Add a test to verify that 'git backfill' automatically respects sparse-checkout settings when no flags are passed.

Signed-off-by: Trieu Huynh <vikingtc4@gmail.com>
---
v2:
  - Update commit message to explicitly point to addressing 85127bcdea.
  - The code change itself is unchanged.
 builtin/backfill.c  |  2 +-
 t/t5620-backfill.sh | 15 +++++++++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)
diff --git a/builtin/backfill.c b/builtin/backfill.c
index e80fc1b694..54acdfe290 100644
--- a/builtin/backfill.c
+++ b/builtin/backfill.c
@@ -120,7 +120,7 @@ int cmd_backfill(int argc, const char **argv, const char *prefix, struct reposit
 		.repo = repo,
 		.current_batch = OID_ARRAY_INIT,
 		.min_batch_size = 50000,
-		.sparse = 0,
+		.sparse = -1,
 	};
 	struct option options[] = {
 		OPT_UNSIGNED(0, "min-batch-size", &ctx.min_batch_size,
diff --git a/t/t5620-backfill.sh b/t/t5620-backfill.sh
index 58c81556e7..bed4987124 100755
--- a/t/t5620-backfill.sh
+++ b/t/t5620-backfill.sh
@@ -119,6 +119,21 @@ test_expect_success 'backfill --sparse' '
 	test_line_count = 0 missing
 '
 
+test_expect_success 'backfill auto-detects sparse-checkout from config' '
+	git clone --sparse --filter=blob:none \
+		--single-branch --branch=main \
+		"file://$(pwd)/srv.bare" backfill-auto-sparse &&
+
+	git -C backfill-auto-sparse rev-list --quiet --objects --missing=print HEAD >missing &&
+	test_line_count = 44 missing &&
+
+	GIT_TRACE2_EVENT="$(pwd)/auto-sparse-trace" git \
+		-C backfill-auto-sparse backfill &&
+
+	test_trace2_data promisor fetch_count 4 <auto-sparse-trace &&
+	test_trace2_data path-walk paths 5 <auto-sparse-trace
+'
+
 test_expect_success 'backfill --sparse without cone mode (positive)' '
 	git clone --no-checkout --filter=blob:none		\
 		--single-branch --branch=main 		\
-- 
2.43.0
Next: Derrick Stolee
Message 1 of 3 in “backfill: auto-detect sparse-checkout from config”
  1. backfill: auto-detect sparse-checkout from configTrieu Huynh, Apr 4, 2026
  2. Derrick StoleeApr 4, 2026
  3. Junio C HamanoApr 6, 2026

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