fetch-pack: do not lazy-fetch during ref iteration

In order to determine negotiation tips, "fetch-pack" iterates over all
refs and dereferences all annotated tags found. This causes the
existence of targets of refs and annotated tags to be checked. Avoiding
this is especially important when we use "git fetch" (which invokes
"fetch-pack") to perform lazy fetches in a partial clone because a
target of such a ref or annotated tag may need to be itself lazy-fetched
(and otherwise causing an infinite loop).

Therefore, teach "fetch-pack" not to lazy fetch whenever iterating over
refs. This is done by using the raw form of ref iteration and by
dereferencing tags ourselves.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 20 insertions, 0 deletions

diff --git a/t/t5616-partial-clone.sh b/t/t5616-partial-clone.sh
index 8827c2e..b1a7bd1 100755
--- a/t/t5616-partial-clone.sh
+++ b/t/t5616-partial-clone.sh
@@ -417,6 +417,26 @@ test_expect_success 'fetch lazy-fetches only to resolve deltas, protocol v2' '
 	grep "want $(cat hash)" trace
 '
 
+test_expect_success 'fetch does not lazy-fetch missing targets of its refs' '
+	rm -rf server client trace &&
+
+	test_create_repo server &&
+	test_config -C server uploadpack.allowfilter 1 &&
+	test_config -C server uploadpack.allowanysha1inwant 1 &&
+	test_commit -C server foo &&
+
+	git clone --filter=blob:none "file://$(pwd)/server" client &&
+	# Make all refs point to nothing by deleting all objects.
+	rm client/.git/objects/pack/* &&
+
+	test_commit -C server bar &&
+	GIT_TRACE_PACKET="$(pwd)/trace" git -C client fetch \
+		--no-tags --recurse-submodules=no \
+		origin refs/tags/bar &&
+	FOO_HASH=$(git -C server rev-parse foo) &&
+	! grep "want $FOO_HASH" trace
+'
+
 # The following two tests must be in this order. It is important that
 # the srv.bare repository did not have tags during clone, but has tags
 # in the fetch.