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[PATCH v3 6/6] send-pack: advise splitting incomplete shallow pushes

From
Elijah Newren via GitGitGadget <gitgitgadget@gmail.com>
Date
Sep 6, 2026, 07:25 UTC
Message-ID
<ae821ce0784286486fe76117b90bce78610ea37f.1788679500.git.gitgitgadget@gmail.com>
In-Reply-To
<pull.2208.v3.git.1788679500.gitgitgadget@gmail.com>
From: Elijah Newren <newren@gmail.com>

When several refs share a pack, an omitted shallow boundary reached from one ref can exclude an object needed by another. Pushing each ref separately recomputes the pack and avoids that interaction.

When such a multi-ref push fails after excluding a boundary, suggest separate pushes. Gate the message on advice.pushShallowBoundary.

Assisted-by: Claude Opus 4.8
Signed-off-by: Elijah Newren <newren@gmail.com>
---
 Documentation/config/advice.adoc |  5 +++++
 advice.c                         |  1 +
 advice.h                         |  1 +
 send-pack.c                      | 26 ++++++++++++++++++++++----
 t/t5538-push-shallow.sh          | 31 +++++++++++++++++++++++++++++++
 5 files changed, 60 insertions(+), 4 deletions(-)
diff --git a/Documentation/config/advice.adoc b/Documentation/config/advice.adoc
index 81f80a9274..6bb6955246 100644
--- a/Documentation/config/advice.adoc
+++ b/Documentation/config/advice.adoc
@@ -99,6 +99,11 @@ all advice messages.
 		a configured remote but looks like a `<remote>/<branch>` ref,
 		suggesting that the remote and branch be given as separate
 		arguments.
+	pushShallowBoundary::
+		Shown when a push from a shallow clone is rejected because
+		the remote could not unpack the pack, hinting that a shallow
+		boundary may have omitted objects and suggesting the refs be
+		pushed one at a time.
 	pushUnqualifiedRefname::
 		Shown when linkgit:git-push[1] gives up trying to
 		guess based on the source and destination refs what
diff --git a/advice.c b/advice.c
index 63bf8b0c5f..3701672048 100644
--- a/advice.c
+++ b/advice.c
@@ -70,6 +70,7 @@ static struct {
 	[ADVICE_PUSH_NON_FF_MATCHING]			= { "pushNonFFMatching" },
 	[ADVICE_PUSH_REF_NEEDS_UPDATE]			= { "pushRefNeedsUpdate" },
 	[ADVICE_PUSH_REPO_LOOKS_LIKE_REF]		= { "pushRepoLooksLikeRef" },
+	[ADVICE_PUSH_SHALLOW_BOUNDARY]			= { "pushShallowBoundary" },
 	[ADVICE_PUSH_UNQUALIFIED_REF_NAME]		= { "pushUnqualifiedRefName" },
 	[ADVICE_PUSH_UPDATE_REJECTED]			= { "pushUpdateRejected" },
 	[ADVICE_PUSH_UPDATE_REJECTED_ALIAS]		= { "pushNonFastForward" }, /* backwards compatibility */
diff --git a/advice.h b/advice.h
index 66f6cd6a77..b2e281baa5 100644
--- a/advice.h
+++ b/advice.h
@@ -37,6 +37,7 @@ enum advice_type {
 	ADVICE_PUSH_NON_FF_MATCHING,
 	ADVICE_PUSH_REF_NEEDS_UPDATE,
 	ADVICE_PUSH_REPO_LOOKS_LIKE_REF,
+	ADVICE_PUSH_SHALLOW_BOUNDARY,
 	ADVICE_PUSH_UNQUALIFIED_REF_NAME,
 	ADVICE_PUSH_UPDATE_REJECTED,
 	ADVICE_PUSH_UPDATE_REJECTED_ALIAS,
diff --git a/send-pack.c b/send-pack.c
index 8a7cedf65a..4fa17810a7 100644
--- a/send-pack.c
+++ b/send-pack.c
@@ -1,4 +1,5 @@
 #include "git-compat-util.h"
+#include "advice.h"
 #include "config.h"
 #include "commit.h"
 #include "date.h"
@@ -161,7 +162,8 @@ static int append_reachable_shallow_grafts(struct repository *r,
 static int pack_objects(struct repository *r,
 			int fd, struct ref *refs, struct oid_array *advertised,
 			struct oid_array *negotiated,
-			struct send_pack_args *args)
+			struct send_pack_args *args,
+			int *excluded_boundary)
 {
 	struct odb_generate_pack_options opts = ODB_GENERATE_PACK_OPTIONS_INIT;
 	struct odb_pack_generator *generator;
@@ -191,7 +193,8 @@ static int pack_objects(struct repository *r,
 	/* Exclude reachable shallow boundaries from the pack. */
 	if (is_repository_shallow(r) &&
 	    get_exclude_boundary_mode(r) == EXCLUDE_BOUNDARY_YES)
-		append_reachable_shallow_grafts(r, refs, advertised,
+		*excluded_boundary = append_reachable_shallow_grafts(
+						r, refs, advertised,
 						negotiated, args,
 						&opts.haves);
 
@@ -607,6 +610,8 @@ int send_pack(struct repository *r,
 	int push_options_supported = 0;
 	int object_format_supported = 0;
 	unsigned cmds_sent = 0;
+	int excluded_boundary = 0;
+	int pack_contributing_refs = 0;
 	int ret;
 	struct async demux;
 	char *push_cert_nonce = NULL;
@@ -742,8 +747,10 @@ int send_pack(struct repository *r,
 		default:
 			continue;
 		}
-		if (!ref->deletion)
+		if (!ref->deletion) {
 			need_pack_data = 1;
+			pack_contributing_refs++;
+		}
 
 		if (args->dry_run || !status_report)
 			ref->status = REF_STATUS_OK;
@@ -832,7 +839,8 @@ int send_pack(struct repository *r,
 			   PACKET_READ_DIE_ON_ERR_PACKET);
 
 	if (need_pack_data && cmds_sent) {
-		if (pack_objects(r, out, remote_refs, extra_have, &commons, args) < 0) {
+		if (pack_objects(r, out, remote_refs, extra_have, &commons, args,
+				 &excluded_boundary) < 0) {
 			if (args->stateless_rpc)
 				close(out);
 			if (git_connection_is_socket(conn))
@@ -878,6 +886,16 @@ int send_pack(struct repository *r,
 		}
 	}
 
+	/*
+	 * Per-ref pushes prevent one ref's boundary from excluding objects
+	 * needed by another.
+	 */
+	if (ret < 0 && excluded_boundary && pack_contributing_refs > 1)
+		advise_if_enabled(ADVICE_PUSH_SHALLOW_BOUNDARY,
+			_("A shallow boundary may have excluded objects needed by another ref.\n"
+			  "Try pushing the refs one at a time, e.g.:\n"
+			  "  git push <remote> <ref>"));
+
 	if (ret < 0)
 		goto out;
 
diff --git a/t/t5538-push-shallow.sh b/t/t5538-push-shallow.sh
index e52f3e50e2..f2a84eb227 100755
--- a/t/t5538-push-shallow.sh
+++ b/t/t5538-push-shallow.sh
@@ -343,4 +343,35 @@ test_expect_success 'push to a shallowUpdate receiver rejects a rootless snapsho
 	git --git-dir=seed-receiver.git rev-parse --verify seeded
 '
 
+# Splitting a multi-ref push recomputes the pack and avoids exclusions from
+# one ref stripping objects needed by another.
+test_expect_success 'incomplete multi-ref shallow push advises pushing refs separately' '
+	git init hint-origin &&
+	git -C hint-origin checkout -b A &&
+	test_commit -C hint-origin --no-tag has-shared sh shared &&
+	test_commit -C hint-origin --no-tag A1 &&
+	git -C hint-origin switch --orphan B &&
+	test_commit -C hint-origin --no-tag B0 &&
+	test_commit -C hint-origin --no-tag B1 &&
+
+	# Strict checking rejects the incomplete pack before connectivity.
+	git init --bare hint-receiver.git &&
+	git --git-dir=hint-receiver.git config receive.fsckObjects true &&
+	git -C hint-origin push "file://$(pwd)/hint-receiver.git" \
+		B:refs/heads/B B:refs/heads/A &&
+
+	git clone --depth=1 --no-single-branch \
+		"file://$(pwd)/hint-origin" hint-client &&
+
+	git -C hint-client checkout A &&
+	test_commit -C hint-client --no-tag cX &&
+	git -C hint-client checkout -b topic B &&
+	test_commit -C hint-client --no-tag reintroduce sh shared &&
+
+	test_must_fail git -C hint-client \
+		-c push.shallowExcludeBoundary=true \
+		push --force "file://$(pwd)/hint-receiver.git" A topic 2>err &&
+	test_grep "shallow boundary may have excluded objects" err
+'
+
 test_done

-- 
gitgitgadget
Previous: Elijah Newren via GitGitGadget
Message 18 of 18 in “send-pack: avoid sending the whole tree when pushing from a shallow clone”
  1. send-pack: avoid sending the whole tree when pushing from a shallow cloneElijah Newren via GitGitGadget, Aug 21, 2026
  2. Patrick SteinhardtAug 21, 2026
  3. Elijah NewrenAug 21, 2026
  4. Elijah NewrenAug 21, 2026
  5. Patrick SteinhardtAug 24, 2026
  6. Elijah NewrenAug 25, 2026
  7. Derrick StoleeSep 2, 2026
  8. Elijah NewrenSep 2, 2026
  9. send-pack: avoid sending the whole tree when pushing from a shallow cloneElijah Newren via GitGitGadget, Aug 25, 2026
  10. Derrick StoleeSep 2, 2026
  11. Elijah NewrenSep 3, 2026
  12. 0/6 send-pack: avoid sending the whole tree when pushing from a shallow cloneElijah Newren via GitGitGadget, Sep 6, 2026
  13. 1/6 unpack-objects: distinguish missing objects from type mismatchesElijah Newren via GitGitGadget, Sep 6, 2026
  14. 2/6 receive-pack: avoid repeating connectivity errorsElijah Newren via GitGitGadget, Sep 6, 2026
  15. 3/6 shallow: reject missing boundaries without disconnectingElijah Newren via GitGitGadget, Sep 6, 2026
  16. 4/6 send-pack: optionally omit shallow boundariesElijah Newren via GitGitGadget, Sep 6, 2026
  17. 5/6 send-pack: default to excluding shallow boundariesElijah Newren via GitGitGadget, Sep 6, 2026
  18. 6/6 send-pack: advise splitting incomplete shallow pushesElijah Newren via GitGitGadget, Sep 6, 2026

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