[PATCH v10 0/8] set-head/fetch remote/HEAD updates

[PATCH v10 0/8] set-head/fetch remote/HEAD updates

[Bence Ferdinandy]

Sorry for sending a v10 so soon after v9 without really waiting for feedback,
but as I started digging into
https://lore.kernel.org/git/D4ZAELFWJMKN.S88LJ6YK31LZ@ferdinandy.com/ I
realized that the root cause is in fetch and not remote add, so the solution
belongs to this series. I'll leave my overall comments for v9 in here for
clarity.

v10: added a new patch (8/8) on top of v9 to handle HEAD in mirrored bare
repositories, rest of the patches are unchanged

v9:
the two most notable changes are
- the new patch 1/7 which address
  https://lore.kernel.org/git/Zw8IKyPkG0Hr6%2F5t@nand.local/, but see
  https://lore.kernel.org/git/D4ZAELFWJMKN.S88LJ6YK31LZ@ferdinandy.com/
- the refs_update_symref -> refs_update_symref_extended change in 2/7,
  reflecting on Phillip's comments (see
  https://lore.kernel.org/git/a7cb48e5-d8ba-44c1-9dbe-d1e8f8a63e3c@gmail.com/)

Hopefully with 1/7 the series is ready to move back to seen :)

Best,
Bence

Bence Ferdinandy (8):
  t/t5505-remote: set default branch to main
  refs: atomically record overwritten ref in update_symref
  remote set-head: refactor for readability
  remote set-head: better output for --auto
  refs: add TRANSACTION_CREATE_EXISTS error
  refs: add create_only option to refs_update_symref_extended
  fetch: set remote/HEAD if it does not exist
  fetch set_head: handle mirrored bare repositories

 builtin/fetch.c                  |  90 ++++++++++++
 builtin/remote.c                 |  52 +++++--
 refs.c                           |  41 +++++-
 refs.h                           |   8 +-
 refs/files-backend.c             |  24 ++--
 refs/reftable-backend.c          |   6 +-
 t/t4207-log-decoration-colors.sh |   3 +-
 t/t5505-remote.sh                |  83 ++++++++++-
 t/t5510-fetch.sh                 | 229 ++++++++++++++++---------------
 t/t5512-ls-remote.sh             |   2 +
 t/t5514-fetch-multiple.sh        |  17 ++-
 t/t5516-fetch-push.sh            |   3 +-
 t/t5527-fetch-odd-refs.sh        |   3 +-
 t/t7900-maintenance.sh           |   3 +-
 t/t9210-scalar.sh                |   5 +-
 t/t9211-scalar-clone.sh          |   6 +-
 t/t9902-completion.sh            |  65 +++++++++
 17 files changed, 486 insertions(+), 154 deletions(-)

-- 
2.47.0.94.g8861098b6d

[PATCH v10 1/8] t/t5505-remote: set default branch to main

[Bence Ferdinandy]

Consider the bare repository called "mirror" in the test.  Running `git
remote add --mirror -f origin ../one` will not change HEAD, consequently
if init.defaultBranch is not the same as what HEAD in the remote
("one"), HEAD in "mirror" will be pointing to a non-existent reference.
Hence if "mirror" is used as a remote by yet another repository,
ls-remote will not show HEAD. On the other hand, if init.defaultBranch
happens to match HEAD in "one", then ls-remote will show HEAD.

Since the CI globally exports GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main,
there's a drift between how the test repositories are set up in the CI
and during local testing. This issue does not manifest currently, as the
test does not do any remote HEAD manipulation where this would come up,
but should such things be added, a locally passing test would break the
CI vice-versa.

Set GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main in the test to be
consistent with the CI.
---

Notes:
    v9: - new patch
        - a bandaid for the CI issue noticed by Taylor (cf:
          https://lore.kernel.org/git/Zw8IKyPkG0Hr6%2F5t@nand.local/), but
          see
          https://lore.kernel.org/git/D4ZAELFWJMKN.S88LJ6YK31LZ@ferdinandy.com/ for the root cause in detail
    
    v10: no change

 t/t5505-remote.sh | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/t/t5505-remote.sh b/t/t5505-remote.sh
index 532035933f..9b50276646 100755
--- a/t/t5505-remote.sh
+++ b/t/t5505-remote.sh
@@ -2,6 +2,9 @@
 
 test_description='git remote porcelain-ish'
 
+GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
+export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
+
 TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
-- 
2.47.0.94.g8861098b6d

[PATCH v10 2/8] refs: atomically record overwritten ref in update_symref

[Bence Ferdinandy]

When updating a symref with update_symref it's currently not possible to
know for sure what was the previous value that was overwritten. Extend
refs_update_symref under a new function name, to record the value after
the ref has been locked if the caller of refs_update_symref_extended
requests it via a new variable in the function call. Keep the original
refs_update_symref function with the same signature, but now as
a wrapper around refs_update_symref_extended.

Signed-off-by: Bence Ferdinandy <bence@ferdinandy.com>
---

Notes:
    v4: new patch
    
    v5: - added before_target to reftables backend
        - added an extra safety check for transaction's existence in refs.c
    
    v6: - no change
    
    v7: - remove the whole before_target concept from the backends and
          handle checking it in refs.c instead (thanks Karthik)
        - rename the before_target to referent which is how the same concept
          is called in the backends
        - change commit prefix to be more in line with project standards
    
    v8: no change
    
    v9: - instead of adding parameters to refs_update_symref, rename what
          was in v8 as refs_update_symref_extended and make refs_update_symref
          a wrapper for that. This significantly reduces the number of files
          that need to be touched, and avoids adding a lot of dummy NULL-s
          in unrelated places.
    
    v10: no change

 refs.c | 19 ++++++++++++++++---
 refs.h |  4 ++++
 2 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/refs.c b/refs.c
index 5f729ed412..24a4172cd2 100644
--- a/refs.c
+++ b/refs.c
@@ -2115,6 +2115,13 @@ int peel_iterated_oid(struct repository *r, const struct object_id *base, struct
 
 int refs_update_symref(struct ref_store *refs, const char *ref,
 		       const char *target, const char *logmsg)
+{
+	return refs_update_symref_extended(refs, ref, target, logmsg, NULL);
+}
+
+int refs_update_symref_extended(struct ref_store *refs, const char *ref,
+		       const char *target, const char *logmsg,
+		       struct strbuf *referent)
 {
 	struct ref_transaction *transaction;
 	struct strbuf err = STRBUF_INIT;
@@ -2122,13 +2129,20 @@ int refs_update_symref(struct ref_store *refs, const char *ref,
 
 	transaction = ref_store_transaction_begin(refs, &err);
 	if (!transaction ||
-	    ref_transaction_update(transaction, ref, NULL, NULL,
+		ref_transaction_update(transaction, ref, NULL, NULL,
 				   target, NULL, REF_NO_DEREF,
 				   logmsg, &err) ||
-	    ref_transaction_commit(transaction, &err)) {
+		ref_transaction_prepare(transaction, &err)) {
 		ret = error("%s", err.buf);
+		goto cleanup;
 	}
+	if (referent)
+		refs_read_symbolic_ref(refs, ref, referent);
 
+	if (ref_transaction_commit(transaction, &err))
+		ret = error("%s", err.buf);
+
+cleanup:
 	strbuf_release(&err);
 	if (transaction)
 		ref_transaction_free(transaction);
@@ -2948,4 +2962,3 @@ int ref_update_expects_existing_old_ref(struct ref_update *update)
 	return (update->flags & REF_HAVE_OLD) &&
 		(!is_null_oid(&update->old_oid) || update->old_target);
 }
-
diff --git a/refs.h b/refs.h
index 108dfc93b3..259191a485 100644
--- a/refs.h
+++ b/refs.h
@@ -573,6 +573,10 @@ int refs_copy_existing_ref(struct ref_store *refs, const char *oldref,
 int refs_update_symref(struct ref_store *refs, const char *refname,
 		       const char *target, const char *logmsg);
 
+int refs_update_symref_extended(struct ref_store *refs, const char *refname,
+		       const char *target, const char *logmsg,
+		       struct strbuf *referent);
+
 enum action_on_err {
 	UPDATE_REFS_MSG_ON_ERR,
 	UPDATE_REFS_DIE_ON_ERR,
-- 
2.47.0.94.g8861098b6d

[PATCH v10 3/8] remote set-head: refactor for readability

[Bence Ferdinandy]

Rename buf and buf2 to something more explanatory.

Instead of calling get_main_ref_store(the_repository) multiple times,
call it once and store in a new refs variable. Although this change
probably offers some performance benefits, the main purpose is to
shorten the line lengths of function calls using this variable.

Signed-off-by: Bence Ferdinandy <bence@ferdinandy.com>
---

Notes:
    v5: new patch (split from the next patch as a preparatory step)
    
    v6: no change
    
    v7: - change commit prefix to be more in line with project standards
    
    v8: no change
    
    v9: - further improve readability by renaming buf, and buf2 consistently
          with how patch 6 was already done
    
    v10: no change

 builtin/remote.c | 23 ++++++++++++-----------
 1 file changed, 12 insertions(+), 11 deletions(-)

diff --git a/builtin/remote.c b/builtin/remote.c
index 76670ddd8b..1d68c5b2ba 100644
--- a/builtin/remote.c
+++ b/builtin/remote.c
@@ -1402,8 +1402,9 @@ static int show(int argc, const char **argv, const char *prefix)
 static int set_head(int argc, const char **argv, const char *prefix)
 {
 	int i, opt_a = 0, opt_d = 0, result = 0;
-	struct strbuf buf = STRBUF_INIT, buf2 = STRBUF_INIT;
+	struct strbuf b_head = STRBUF_INIT, b_remote_head = STRBUF_INIT;
 	char *head_name = NULL;
+	struct ref_store *refs = get_main_ref_store(the_repository);
 
 	struct option options[] = {
 		OPT_BOOL('a', "auto", &opt_a,
@@ -1415,7 +1416,7 @@ static int set_head(int argc, const char **argv, const char *prefix)
 	argc = parse_options(argc, argv, prefix, options,
 			     builtin_remote_sethead_usage, 0);
 	if (argc)
-		strbuf_addf(&buf, "refs/remotes/%s/HEAD", argv[0]);
+		strbuf_addf(&b_head, "refs/remotes/%s/HEAD", argv[0]);
 
 	if (!opt_a && !opt_d && argc == 2) {
 		head_name = xstrdup(argv[1]);
@@ -1434,25 +1435,25 @@ static int set_head(int argc, const char **argv, const char *prefix)
 			head_name = xstrdup(states.heads.items[0].string);
 		free_remote_ref_states(&states);
 	} else if (opt_d && !opt_a && argc == 1) {
-		if (refs_delete_ref(get_main_ref_store(the_repository), NULL, buf.buf, NULL, REF_NO_DEREF))
-			result |= error(_("Could not delete %s"), buf.buf);
+		if (refs_delete_ref(refs, NULL, b_head.buf, NULL, REF_NO_DEREF))
+			result |= error(_("Could not delete %s"), b_head.buf);
 	} else
 		usage_with_options(builtin_remote_sethead_usage, options);
 
 	if (head_name) {
-		strbuf_addf(&buf2, "refs/remotes/%s/%s", argv[0], head_name);
+		strbuf_addf(&b_remote_head, "refs/remotes/%s/%s", argv[0], head_name);
 		/* make sure it's valid */
-		if (!refs_ref_exists(get_main_ref_store(the_repository), buf2.buf))
-			result |= error(_("Not a valid ref: %s"), buf2.buf);
-		else if (refs_update_symref(get_main_ref_store(the_repository), buf.buf, buf2.buf, "remote set-head"))
-			result |= error(_("Could not setup %s"), buf.buf);
+		if (!refs_ref_exists(refs, b_remote_head.buf))
+			result |= error(_("Not a valid ref: %s"), b_remote_head.buf);
+		else if (refs_update_symref(refs, b_head.buf, b_remote_head.buf, "remote set-head"))
+			result |= error(_("Could not setup %s"), b_head.buf);
 		else if (opt_a)
 			printf("%s/HEAD set to %s\n", argv[0], head_name);
 		free(head_name);
 	}
 
-	strbuf_release(&buf);
-	strbuf_release(&buf2);
+	strbuf_release(&b_head);
+	strbuf_release(&b_remote_head);
 	return result;
 }
 
-- 
2.47.0.94.g8861098b6d

[PATCH v10 4/8] remote set-head: better output for --auto

[Bence Ferdinandy]

Currently, set-head --auto will print a message saying "remote/HEAD set
to branch", which implies something was changed.

Change the output of --auto, so the output actually reflects what was
done: a) set a previously unset HEAD, b) change HEAD because remote
changed or c) no updates. As a fourth output, if HEAD is changed from
a previous value that was not a remote branch, explicitly call attention
to this fact.

Signed-off-by: Bence Ferdinandy <bence@ferdinandy.com>
---

Notes:
    v1-v2:
    
        was RFC in https://lore.kernel.org/git/20240910203835.2288291-1-bence@ferdinandy.com/
    
    v3:
    
        This patch was originally sent along when I thought set-head was
        going to be invoked by fetch, but the discussion on the RFC
        concluded that it should be not. This opened the possibility to make
        it more explicit.
    
        Note: although I feel both things the patch does are really just
        cosmetic, an argument could be made for breaking it into two, one
        for the no-op part and one for the --auto print update.
    
        Was sent in:
        https://lore.kernel.org/git/20240915221055.904107-1-bence@ferdinandy.com/
    
    v4:
        - changes are now handled atomically via the ref update transaction
        - outputs have changed along the lines of Junio's suggestion
        - minor refactor to set_head for improved legibility
    
    v5: - the minor refactor has been split out into its own patch
    
    v6: - fixed uninitialized prev_head
        - fixed case of unusual previous target
        - fixed a test that would have been actually broken at this patch
          (the output was only correct with the later update to fetch)
        - added 4 tests for the 4 output cases
    
    v7: - change commit prefix to be more in line with project standards
        - fixed tests to also work with the reftable backend
        - renamed report function, fixed style issue with checking buf len
        - fixed not releasing an strbuf
    
    v8: no change
    
    v9: - mark output strings in report_set_head_auto as translatable
        - rename buf_prev to b_local_head for consistency
        - use ${SQ} in tests instead of '\''
    
    v10: no change

 builtin/remote.c  | 33 +++++++++++++++++++++++++++---
 t/t5505-remote.sh | 51 ++++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 80 insertions(+), 4 deletions(-)

diff --git a/builtin/remote.c b/builtin/remote.c
index 1d68c5b2ba..108f1271d3 100644
--- a/builtin/remote.c
+++ b/builtin/remote.c
@@ -1399,10 +1399,35 @@ static int show(int argc, const char **argv, const char *prefix)
 	return result;
 }
 
+static void report_set_head_auto(const char *remote, const char *head_name,
+			struct strbuf *b_local_head) {
+	struct strbuf buf_prefix = STRBUF_INIT;
+	const char *prev_head = NULL;
+
+	strbuf_addf(&buf_prefix, "refs/remotes/%s/", remote);
+	skip_prefix(b_local_head->buf, buf_prefix.buf, &prev_head);
+
+	if (prev_head && !strcmp(prev_head, head_name))
+		printf(_("'%s/HEAD' is unchanged and points to '%s'\n"),
+			remote, head_name);
+	else if (prev_head)
+		printf(_("'%s/HEAD' has changed from '%s' and now points to '%s'\n"),
+			remote, prev_head, head_name);
+	else if (!b_local_head->len)
+		printf(_("'%s/HEAD' is now created and points to '%s'\n"),
+			remote, head_name);
+	else
+		printf(_("'%s/HEAD' used to point to '%s' "
+			"(which is not a remote branch), but now points to '%s'\n"),
+			remote, b_local_head->buf, head_name);
+	strbuf_release(&buf_prefix);
+}
+
 static int set_head(int argc, const char **argv, const char *prefix)
 {
 	int i, opt_a = 0, opt_d = 0, result = 0;
-	struct strbuf b_head = STRBUF_INIT, b_remote_head = STRBUF_INIT;
+	struct strbuf b_head = STRBUF_INIT, b_remote_head = STRBUF_INIT,
+		b_local_head = STRBUF_INIT;
 	char *head_name = NULL;
 	struct ref_store *refs = get_main_ref_store(the_repository);
 
@@ -1445,15 +1470,17 @@ static int set_head(int argc, const char **argv, const char *prefix)
 		/* make sure it's valid */
 		if (!refs_ref_exists(refs, b_remote_head.buf))
 			result |= error(_("Not a valid ref: %s"), b_remote_head.buf);
-		else if (refs_update_symref(refs, b_head.buf, b_remote_head.buf, "remote set-head"))
+		else if (refs_update_symref_extended(refs, b_head.buf, b_remote_head.buf,
+					"remote set-head", &b_local_head))
 			result |= error(_("Could not setup %s"), b_head.buf);
 		else if (opt_a)
-			printf("%s/HEAD set to %s\n", argv[0], head_name);
+			report_set_head_auto(argv[0], head_name, &b_local_head);
 		free(head_name);
 	}
 
 	strbuf_release(&b_head);
 	strbuf_release(&b_remote_head);
+	strbuf_release(&b_local_head);
 	return result;
 }
 
diff --git a/t/t5505-remote.sh b/t/t5505-remote.sh
index 9b50276646..0ea86d51a4 100755
--- a/t/t5505-remote.sh
+++ b/t/t5505-remote.sh
@@ -432,12 +432,51 @@ test_expect_success 'set-head --auto' '
 	)
 '
 
+test_expect_success 'set-head --auto detects creation' '
+	(
+		cd test &&
+		git symbolic-ref -d refs/remotes/origin/HEAD &&
+		git remote set-head --auto origin >output &&
+		echo "${SQ}origin/HEAD${SQ} is now created and points to ${SQ}main${SQ}" >expect &&
+		test_cmp expect output
+	)
+'
+
+test_expect_success 'set-head --auto detects no change' '
+	(
+		cd test &&
+		git remote set-head --auto origin >output &&
+		echo "${SQ}origin/HEAD${SQ} is unchanged and points to ${SQ}main${SQ}" >expect &&
+		test_cmp expect output
+	)
+'
+
+test_expect_success 'set-head --auto detects change' '
+	(
+		cd test &&
+		git symbolic-ref refs/remotes/origin/HEAD refs/remotes/origin/ahead &&
+		git remote set-head --auto origin >output &&
+		echo "${SQ}origin/HEAD${SQ} has changed from ${SQ}ahead${SQ} and now points to ${SQ}main${SQ}" >expect &&
+		test_cmp expect output
+	)
+'
+
+test_expect_success 'set-head --auto detects strange ref' '
+	(
+		cd test &&
+		git symbolic-ref refs/remotes/origin/HEAD refs/heads/main &&
+		git remote set-head --auto origin >output &&
+		echo "${SQ}origin/HEAD${SQ} used to point to ${SQ}refs/heads/main${SQ} (which is not a remote branch), but now points to ${SQ}main${SQ}" >expect &&
+		test_cmp expect output
+	)
+'
+
 test_expect_success 'set-head --auto has no problem w/multiple HEADs' '
 	(
 		cd test &&
 		git fetch two "refs/heads/*:refs/remotes/two/*" &&
 		git remote set-head --auto two >output 2>&1 &&
-		echo "two/HEAD set to main" >expect &&
+		echo "${SQ}two/HEAD${SQ} is now created and points to ${SQ}main${SQ}" >expect &&
 		test_cmp expect output
 	)
 '
@@ -456,6 +495,16 @@ test_expect_success 'set-head explicit' '
 	)
 '
 
+test_expect_success 'set-head --auto reports change' '
+	(
+		cd test &&
+		git remote set-head origin side2 &&
+		git remote set-head --auto origin >output 2>&1 &&
+		echo "${SQ}origin/HEAD${SQ} has changed from ${SQ}side2${SQ} and now points to ${SQ}main${SQ}" >expect &&
+		test_cmp expect output
+	)
+'
+
 cat >test/expect <<EOF
 Pruning origin
 URL: $(pwd)/one
-- 
2.47.0.94.g8861098b6d

[PATCH v10 5/8] refs: add TRANSACTION_CREATE_EXISTS error

[Bence Ferdinandy]

Currently there is only one special error for transaction, for when
there is a naming conflict, all other errors are dumped under a generic
error. Add a new special error case for when the caller requests the
reference to be updated only when it does not yet exist and the
reference actually does exist.

Signed-off-by: Bence Ferdinandy <bence@ferdinandy.com>
---

Notes:
    v4: new patch
    v5: no change
    v6: no change
    
    v7: - change commit prefix to be more in line with project standards
        - changed error checking to Karthik's suggestion
    
    v8: no change
    
    v9: - no change
    
    v10: no change

 refs.h                  |  4 +++-
 refs/files-backend.c    | 24 ++++++++++++++++--------
 refs/reftable-backend.c |  6 ++++--
 3 files changed, 23 insertions(+), 11 deletions(-)

diff --git a/refs.h b/refs.h
index 259191a485..a5bc25442b 100644
--- a/refs.h
+++ b/refs.h
@@ -762,8 +762,10 @@ int ref_transaction_verify(struct ref_transaction *transaction,
 
 /* Naming conflict (for example, the ref names A and A/B conflict). */
 #define TRANSACTION_NAME_CONFLICT -1
+/* When only creation was requested, but the ref already exists. */
+#define TRANSACTION_CREATE_EXISTS -2
 /* All other errors. */
-#define TRANSACTION_GENERIC_ERROR -2
+#define TRANSACTION_GENERIC_ERROR -3
 
 /*
  * Perform the preparatory stages of committing `transaction`. Acquire
diff --git a/refs/files-backend.c b/refs/files-backend.c
index 0824c0b8a9..e743ec44b5 100644
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -2502,14 +2502,18 @@ static int split_symref_update(struct ref_update *update,
 static int check_old_oid(struct ref_update *update, struct object_id *oid,
 			 struct strbuf *err)
 {
+	int ret = TRANSACTION_GENERIC_ERROR;
+
 	if (!(update->flags & REF_HAVE_OLD) ||
 		   oideq(oid, &update->old_oid))
 		return 0;
 
-	if (is_null_oid(&update->old_oid))
+	if (is_null_oid(&update->old_oid)) {
 		strbuf_addf(err, "cannot lock ref '%s': "
 			    "reference already exists",
 			    ref_update_original_update_refname(update));
+		ret = TRANSACTION_CREATE_EXISTS;
+	}
 	else if (is_null_oid(oid))
 		strbuf_addf(err, "cannot lock ref '%s': "
 			    "reference is missing but expected %s",
@@ -2522,7 +2526,7 @@ static int check_old_oid(struct ref_update *update, struct object_id *oid,
 			    oid_to_hex(oid),
 			    oid_to_hex(&update->old_oid));
 
-	return -1;
+	return ret;
 }
 
 /*
@@ -2602,9 +2606,11 @@ static int lock_ref_for_update(struct files_ref_store *refs,
 					ret = TRANSACTION_GENERIC_ERROR;
 					goto out;
 				}
-			} else if  (check_old_oid(update, &lock->old_oid, err)) {
-				ret = TRANSACTION_GENERIC_ERROR;
-				goto out;
+			} else {
+				ret = check_old_oid(update, &lock->old_oid, err);
+				if  (ret) {
+					goto out;
+				}
 			}
 		} else {
 			/*
@@ -2635,9 +2641,11 @@ static int lock_ref_for_update(struct files_ref_store *refs,
 				    update->old_target);
 			ret = TRANSACTION_GENERIC_ERROR;
 			goto out;
-		} else if  (check_old_oid(update, &lock->old_oid, err)) {
-			ret = TRANSACTION_GENERIC_ERROR;
-			goto out;
+		} else {
+			ret = check_old_oid(update, &lock->old_oid, err);
+			if  (ret) {
+				goto out;
+			}
 		}
 
 		/*
diff --git a/refs/reftable-backend.c b/refs/reftable-backend.c
index 3c6107c7ce..b3b5ce77dd 100644
--- a/refs/reftable-backend.c
+++ b/refs/reftable-backend.c
@@ -1206,10 +1206,13 @@ static int reftable_be_transaction_prepare(struct ref_store *ref_store,
 				goto done;
 			}
 		} else if ((u->flags & REF_HAVE_OLD) && !oideq(&current_oid, &u->old_oid)) {
-			if (is_null_oid(&u->old_oid))
+			ret = TRANSACTION_NAME_CONFLICT;
+			if (is_null_oid(&u->old_oid)) {
 				strbuf_addf(err, _("cannot lock ref '%s': "
 						   "reference already exists"),
 					    ref_update_original_update_refname(u));
+				ret = TRANSACTION_CREATE_EXISTS;
+			}
 			else if (is_null_oid(&current_oid))
 				strbuf_addf(err, _("cannot lock ref '%s': "
 						   "reference is missing but expected %s"),
@@ -1221,7 +1224,6 @@ static int reftable_be_transaction_prepare(struct ref_store *ref_store,
 					    ref_update_original_update_refname(u),
 					    oid_to_hex(&current_oid),
 					    oid_to_hex(&u->old_oid));
-			ret = -1;
 			goto done;
 		}
 
-- 
2.47.0.94.g8861098b6d

[PATCH v10 6/8] refs: add create_only option to refs_update_symref_extended

[Bence Ferdinandy]

Allow the caller to specify that it only wants to update the symref if
it does not already exist. Silently ignore the error from the
transaction API if the symref already exists.

Signed-off-by: Bence Ferdinandy <bence@ferdinandy.com>
---

Notes:
    v4: new patch
    v5: no change
    
    v6: - switched from bool to int for create_only
        - refactored logic in refs_update_symref with goto as layed out by
          Junio
    
    v7: - change commit prefix to be more in line with project standards
        - refactored code to accommodate changes in the first patch, but
          otherwise no change
    
    v8: no change
    
    v9: - no change (except for following through the
          refs_update_symref_extended refactoring)
    
    v10: no change

 builtin/remote.c |  2 +-
 refs.c           | 32 +++++++++++++++++++++++---------
 refs.h           |  2 +-
 3 files changed, 25 insertions(+), 11 deletions(-)

diff --git a/builtin/remote.c b/builtin/remote.c
index 108f1271d3..b1eba75a2b 100644
--- a/builtin/remote.c
+++ b/builtin/remote.c
@@ -1471,7 +1471,7 @@ static int set_head(int argc, const char **argv, const char *prefix)
 		if (!refs_ref_exists(refs, b_remote_head.buf))
 			result |= error(_("Not a valid ref: %s"), b_remote_head.buf);
 		else if (refs_update_symref_extended(refs, b_head.buf, b_remote_head.buf,
-					"remote set-head", &b_local_head))
+					"remote set-head", &b_local_head, 0))
 			result |= error(_("Could not setup %s"), b_head.buf);
 		else if (opt_a)
 			report_set_head_auto(argv[0], head_name, &b_local_head);
diff --git a/refs.c b/refs.c
index 24a4172cd2..093ee11ab0 100644
--- a/refs.c
+++ b/refs.c
@@ -2116,31 +2116,45 @@ int peel_iterated_oid(struct repository *r, const struct object_id *base, struct
 int refs_update_symref(struct ref_store *refs, const char *ref,
 		       const char *target, const char *logmsg)
 {
-	return refs_update_symref_extended(refs, ref, target, logmsg, NULL);
+	return refs_update_symref_extended(refs, ref, target, logmsg, NULL, 0);
 }
 
 int refs_update_symref_extended(struct ref_store *refs, const char *ref,
 		       const char *target, const char *logmsg,
-		       struct strbuf *referent)
+		       struct strbuf *referent, int create_only)
 {
 	struct ref_transaction *transaction;
 	struct strbuf err = STRBUF_INIT;
-	int ret = 0;
+	int ret = 0, prepret = 0;
 
 	transaction = ref_store_transaction_begin(refs, &err);
-	if (!transaction ||
-		ref_transaction_update(transaction, ref, NULL, NULL,
-				   target, NULL, REF_NO_DEREF,
-				   logmsg, &err) ||
-		ref_transaction_prepare(transaction, &err)) {
+	if (!transaction) {
+	error_return:
 		ret = error("%s", err.buf);
 		goto cleanup;
 	}
+	if (create_only) {
+		if (ref_transaction_create(transaction, ref, NULL, target,
+					   REF_NO_DEREF, logmsg, &err))
+			goto error_return;
+		prepret = ref_transaction_prepare(transaction, &err);
+		if (prepret && prepret != TRANSACTION_CREATE_EXISTS)
+			goto error_return;
+	} else {
+		if (ref_transaction_update(transaction, ref, NULL, NULL,
+					   target, NULL, REF_NO_DEREF,
+					   logmsg, &err) ||
+			ref_transaction_prepare(transaction, &err))
+			goto error_return;
+	}
+
 	if (referent)
 		refs_read_symbolic_ref(refs, ref, referent);
 
+	if (prepret == TRANSACTION_CREATE_EXISTS)
+		goto cleanup;
 	if (ref_transaction_commit(transaction, &err))
-		ret = error("%s", err.buf);
+		goto error_return;
 
 cleanup:
 	strbuf_release(&err);
diff --git a/refs.h b/refs.h
index a5bc25442b..458582ebcf 100644
--- a/refs.h
+++ b/refs.h
@@ -575,7 +575,7 @@ int refs_update_symref(struct ref_store *refs, const char *refname,
 
 int refs_update_symref_extended(struct ref_store *refs, const char *refname,
 		       const char *target, const char *logmsg,
-		       struct strbuf *referent);
+		       struct strbuf *referent, int create_only);
 
 enum action_on_err {
 	UPDATE_REFS_MSG_ON_ERR,
-- 
2.47.0.94.g8861098b6d

[PATCH v10 7/8] fetch: set remote/HEAD if it does not exist

[Bence Ferdinandy]

If the user has remote/HEAD set already and it looks like it has changed
on the server, then print a message, otherwise set it if we can.
Silently pass if the user already has the same remote/HEAD set as
reported by the server or if we encounter any errors along the way.

Signed-off-by: Bence Ferdinandy <bence@ferdinandy.com>
---

Notes:
    v3: - does not rely on remote set-head anymore so it only authenticates
        once
        - uses the new REF_CREATE_ONLY to atomically check if the ref exists
          and only write it if it doesn't
        - in all other cases the maximum it does is print a warning
    
    v4: - instead of the discarded REF_CREATE_ONLY, it uses the existing,
          but updated transaction api to request a silent create only
        - it now uses the atomic before_target to determine reporting
        - refactored for legibility
    
    v5: - instead of printing a not too useful message, it now fails
          silently, this in line with the objective to only set up
          remote/HEAD automatically if the right thing is trivial, for
          everything else there is remote set-head
        - fixed all failing tests
        - added two new tests, one for checking if remote/HEAD is set to the
          correct one, and one to test that we do not override remote/HEAD
          if it has changed on the server from what we have locally
    
    v6: - fixed style issues and unintended extra empty line
        - updated function call with bool to int from previous patch's
          change
        - removed calls to error(...) inherited from builtin/remote.c so we
          actually fail silently
        - set the test for remote set-head --auto to the correct value here,
          which was previously erronously set in the remote set-head patch
    
    v7: - no change
    
    v8: - changed logmsg in call to refs_update_symref from "remote
          set-head" to "fetch"
    
    v9: - follow through with refs_update_symref_extended
        - fix test errors uncovered by the new patch
    
    v10: no change

 builtin/fetch.c                  |  82 +++++++++++
 t/t4207-log-decoration-colors.sh |   3 +-
 t/t5505-remote.sh                |  21 ++-
 t/t5510-fetch.sh                 | 229 ++++++++++++++++---------------
 t/t5512-ls-remote.sh             |   2 +
 t/t5514-fetch-multiple.sh        |  17 ++-
 t/t5516-fetch-push.sh            |   3 +-
 t/t5527-fetch-odd-refs.sh        |   3 +-
 t/t7900-maintenance.sh           |   3 +-
 t/t9210-scalar.sh                |   5 +-
 t/t9211-scalar-clone.sh          |   6 +-
 t/t9902-completion.sh            |  65 +++++++++
 12 files changed, 315 insertions(+), 124 deletions(-)

diff --git a/builtin/fetch.c b/builtin/fetch.c
index d9027e4dc9..31edc67447 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -1578,6 +1578,80 @@ static int backfill_tags(struct display_state *display_state,
 	return retcode;
 }
 
+static void report_set_head(const char *remote, const char *head_name,
+			struct strbuf *buf_prev) {
+	struct strbuf buf_prefix = STRBUF_INIT;
+	const char *prev_head = NULL;
+
+	strbuf_addf(&buf_prefix, "refs/remotes/%s/", remote);
+	skip_prefix(buf_prev->buf, buf_prefix.buf, &prev_head);
+
+	if (prev_head && strcmp(prev_head, head_name)) {
+		printf("'HEAD' at '%s' has changed from '%s' to '%s'\n",
+			remote, prev_head, head_name);
+		printf("Run 'git remote set-head %s %s' to follow the change.\n",
+			remote, head_name);
+	}
+}
+
+static const char *strip_refshead(const char *name){
+	skip_prefix(name, "refs/heads/", &name);
+	return name;
+}
+
+static int set_head(const struct ref *remote_refs)
+{
+	int result = 0;
+	struct strbuf b_head = STRBUF_INIT, b_remote_head = STRBUF_INIT,
+		b_local_head = STRBUF_INIT;
+	const char *remote = gtransport->remote->name;
+	char *head_name = NULL;
+	struct ref *ref, *matches;
+	struct ref *fetch_map = NULL, **fetch_map_tail = &fetch_map;
+	struct refspec_item refspec = {
+		.force = 0,
+		.pattern = 1,
+		.src = (char *) "refs/heads/*",
+		.dst = (char *) "refs/heads/*",
+	};
+	struct string_list heads = STRING_LIST_INIT_DUP;
+	struct ref_store *refs = get_main_ref_store(the_repository);
+
+	get_fetch_map(remote_refs, &refspec, &fetch_map_tail, 0);
+	matches = guess_remote_head(find_ref_by_name(remote_refs, "HEAD"),
+				    fetch_map, 1);
+	for (ref = matches; ref; ref = ref->next) {
+		string_list_append(&heads, strip_refshead(ref->name));
+	}
+
+
+	if (!heads.nr)
+		result = 1;
+	else if (heads.nr > 1)
+		result = 1;
+	else
+		head_name = xstrdup(heads.items[0].string);
+	if (head_name) {
+		strbuf_addf(&b_head, "refs/remotes/%s/HEAD", remote);
+		strbuf_addf(&b_remote_head, "refs/remotes/%s/%s", remote, head_name);
+		/* make sure it's valid */
+		if (!refs_ref_exists(refs, b_remote_head.buf))
+			result = 1;
+		else if (refs_update_symref_extended(refs, b_head.buf, b_remote_head.buf,
+					"fetch", &b_local_head, 1))
+			result = 1;
+		else
+			report_set_head(remote, head_name, &b_local_head);
+
+		free(head_name);
+	}
+
+	strbuf_release(&b_head);
+	strbuf_release(&b_local_head);
+	strbuf_release(&b_remote_head);
+	return result;
+}
+
 static int do_fetch(struct transport *transport,
 		    struct refspec *rs,
 		    const struct fetch_config *config)
@@ -1647,6 +1721,8 @@ static int do_fetch(struct transport *transport,
 				    "refs/tags/");
 	}
 
+	strvec_push(&transport_ls_refs_options.ref_prefixes, "HEAD");
+
 	if (must_list_refs) {
 		trace2_region_enter("fetch", "remote_refs", the_repository);
 		remote_refs = transport_get_remote_refs(transport,
@@ -1791,6 +1867,12 @@ static int do_fetch(struct transport *transport,
 				  "you need to specify exactly one branch with the --set-upstream option"));
 		}
 	}
+	if (set_head(remote_refs))
+		;
+		/*
+		 * Way too many cases where this can go wrong
+		 * so let's just fail silently for now.
+		 */
 
 cleanup:
 	if (retcode) {
diff --git a/t/t4207-log-decoration-colors.sh b/t/t4207-log-decoration-colors.sh
index 73ea9e5155..d55d22cb2f 100755
--- a/t/t4207-log-decoration-colors.sh
+++ b/t/t4207-log-decoration-colors.sh
@@ -59,7 +59,8 @@ ${c_reset}${c_tag}tag: ${c_reset}${c_tag}v1.0${c_reset}${c_commit}, \
 ${c_reset}${c_tag}tag: ${c_reset}${c_tag}B${c_reset}${c_commit})${c_reset} B
 ${c_commit}COMMIT_ID${c_reset}${c_commit} (${c_reset}\
 ${c_tag}tag: ${c_reset}${c_tag}A1${c_reset}${c_commit}, \
-${c_reset}${c_remoteBranch}other/main${c_reset}${c_commit})${c_reset} A1
+${c_reset}${c_remoteBranch}other/main${c_reset}${c_commit}, \
+${c_reset}${c_remoteBranch}other/HEAD${c_reset}${c_commit})${c_reset} A1
 	${c_commit}COMMIT_ID${c_reset}${c_commit} (${c_reset}\
 ${c_stash}refs/stash${c_reset}${c_commit})${c_reset} On main: Changes to A.t
 	${c_commit}COMMIT_ID${c_reset}${c_commit} (${c_reset}\
diff --git a/t/t5505-remote.sh b/t/t5505-remote.sh
index 0ea86d51a4..4990d00209 100755
--- a/t/t5505-remote.sh
+++ b/t/t5505-remote.sh
@@ -74,7 +74,7 @@ test_expect_success 'add another remote' '
 		cd test &&
 		git remote add -f second ../two &&
 		tokens_match "origin second" "$(git remote)" &&
-		check_tracking_branch second main side another &&
+		check_tracking_branch second main side another HEAD &&
 		git for-each-ref "--format=%(refname)" refs/remotes |
 		sed -e "/^refs\/remotes\/origin\//d" \
 		    -e "/^refs\/remotes\/second\//d" >actual &&
@@ -476,7 +476,7 @@ test_expect_success 'set-head --auto has no problem w/multiple HEADs' '
 		cd test &&
 		git fetch two "refs/heads/*:refs/remotes/two/*" &&
 		git remote set-head --auto two >output 2>&1 &&
-		echo "${SQ}two/HEAD${SQ} is now created and points to ${SQ}main${SQ}" >expect &&
+		echo "${SQ}two/HEAD${SQ} is unchanged and points to ${SQ}main${SQ}" >expect &&
 		test_cmp expect output
 	)
 '
@@ -764,8 +764,10 @@ test_expect_success 'reject --no-no-tags' '
 '
 
 cat >one/expect <<\EOF
+  apis/HEAD -> apis/main
   apis/main
   apis/side
+  drosophila/HEAD -> drosophila/main
   drosophila/another
   drosophila/main
   drosophila/side
@@ -783,11 +785,14 @@ test_expect_success 'update' '
 '
 
 cat >one/expect <<\EOF
+  drosophila/HEAD -> drosophila/main
   drosophila/another
   drosophila/main
   drosophila/side
+  manduca/HEAD -> manduca/main
   manduca/main
   manduca/side
+  megaloprepus/HEAD -> megaloprepus/main
   megaloprepus/main
   megaloprepus/side
 EOF
@@ -795,7 +800,7 @@ EOF
 test_expect_success 'update with arguments' '
 	(
 		cd one &&
-		for b in $(git branch -r)
+		for b in $(git branch -r | grep -v HEAD)
 		do
 		git branch -r -d $b || exit 1
 		done &&
@@ -827,10 +832,13 @@ test_expect_success 'update --prune' '
 '
 
 cat >one/expect <<-\EOF
+  apis/HEAD -> apis/main
   apis/main
   apis/side
+  manduca/HEAD -> manduca/main
   manduca/main
   manduca/side
+  megaloprepus/HEAD -> megaloprepus/main
   megaloprepus/main
   megaloprepus/side
 EOF
@@ -838,7 +846,7 @@ EOF
 test_expect_success 'update default' '
 	(
 		cd one &&
-		for b in $(git branch -r)
+		for b in $(git branch -r | grep -v HEAD)
 		do
 		git branch -r -d $b || exit 1
 		done &&
@@ -850,6 +858,7 @@ test_expect_success 'update default' '
 '
 
 cat >one/expect <<\EOF
+  drosophila/HEAD -> drosophila/main
   drosophila/another
   drosophila/main
   drosophila/side
@@ -858,7 +867,7 @@ EOF
 test_expect_success 'update default (overridden, with funny whitespace)' '
 	(
 		cd one &&
-		for b in $(git branch -r)
+		for b in $(git branch -r | grep -v HEAD)
 		do
 		git branch -r -d $b || exit 1
 		done &&
@@ -872,7 +881,7 @@ test_expect_success 'update default (overridden, with funny whitespace)' '
 test_expect_success 'update (with remotes.default defined)' '
 	(
 		cd one &&
-		for b in $(git branch -r)
+		for b in $(git branch -r | grep -v HEAD)
 		do
 		git branch -r -d $b || exit 1
 		done &&
diff --git a/t/t5510-fetch.sh b/t/t5510-fetch.sh
index 0890b9f61c..dfc8d748ba 100755
--- a/t/t5510-fetch.sh
+++ b/t/t5510-fetch.sh
@@ -75,6 +75,30 @@ test_expect_success "fetch test for-merge" '
 	cut -f -2 .git/FETCH_HEAD >actual &&
 	test_cmp expected actual'
 
+test_expect_success "fetch test remote HEAD" '
+	cd "$D" &&
+	cd two &&
+	git fetch &&
+	git rev-parse --verify refs/remotes/origin/HEAD &&
+	git rev-parse --verify refs/remotes/origin/main &&
+	head=$(git rev-parse refs/remotes/origin/HEAD) &&
+	branch=$(git rev-parse refs/remotes/origin/main) &&
+	test "z$head" = "z$branch"'
+
+test_expect_success "fetch test remote HEAD change" '
+	cd "$D" &&
+	cd two &&
+	git switch -c other &&
+	git push -u origin other &&
+	git rev-parse --verify refs/remotes/origin/HEAD &&
+	git rev-parse --verify refs/remotes/origin/main &&
+	git rev-parse --verify refs/remotes/origin/other &&
+	git remote set-head origin other &&
+	git fetch &&
+	head=$(git rev-parse refs/remotes/origin/HEAD) &&
+	branch=$(git rev-parse refs/remotes/origin/other) &&
+	test "z$head" = "z$branch"'
+
 test_expect_success 'fetch --prune on its own works as expected' '
 	cd "$D" &&
 	git clone . prune &&
@@ -478,7 +502,6 @@ test_expect_success 'unbundle 1' '
 	test_must_fail git fetch "$D/bundle1" main:main
 '
 
-
 test_expect_success 'bundle 1 has only 3 files ' '
 	cd "$D" &&
 	test_bundle_object_count bundle1 3
@@ -819,7 +842,7 @@ test_expect_success 'fetch from multiple configured URLs in single remote' '
 
 # configured prune tests
 
-set_config_tristate () {
+set_config_tristate() {
 	# var=$1 val=$2
 	case "$2" in
 	unset)
@@ -833,12 +856,12 @@ set_config_tristate () {
 	esac
 }
 
-test_configured_prune () {
+test_configured_prune() {
 	test_configured_prune_type "$@" "name"
 	test_configured_prune_type "$@" "link"
 }
 
-test_configured_prune_type () {
+test_configured_prune_type() {
 	fetch_prune=$1
 	remote_origin_prune=$2
 	fetch_prune_tags=$3
@@ -848,8 +871,7 @@ test_configured_prune_type () {
 	cmdline=$7
 	mode=$8
 
-	if test -z "$cmdline_setup"
-	then
+	if test -z "$cmdline_setup"; then
 		test_expect_success 'setup cmdline_setup variable for subsequent test' '
 			remote_url="file://$(git -C one config remote.origin.url)" &&
 			remote_fetch="$(git -C one config remote.origin.fetch)" &&
@@ -857,12 +879,10 @@ test_configured_prune_type () {
 		'
 	fi
 
-	if test "$mode" = 'link'
-	then
+	if test "$mode" = 'link'; then
 		new_cmdline=""
 
-		if test "$cmdline" = ""
-		then
+		if test "$cmdline" = ""; then
 			new_cmdline=$cmdline_setup
 		else
 			new_cmdline=$(perl -e '
@@ -873,10 +893,8 @@ test_configured_prune_type () {
 		fi
 
 		if test "$fetch_prune_tags" = 'true' ||
-		   test "$remote_origin_prune_tags" = 'true'
-		then
-			if ! printf '%s' "$cmdline\n" | grep -q refs/remotes/origin/
-			then
+			test "$remote_origin_prune_tags" = 'true'; then
+			if ! printf '%s' "$cmdline\n" | grep -q refs/remotes/origin/; then
 				new_cmdline="$new_cmdline refs/tags/*:refs/tags/*"
 			fi
 		fi
@@ -946,100 +964,100 @@ test_configured_prune_type () {
 # $7 git-fetch $cmdline:
 #
 #                     $1    $2    $3    $4    $5     $6     $7
-test_configured_prune unset unset unset unset kept   kept   ""
-test_configured_prune unset unset unset unset kept   kept   "--no-prune"
-test_configured_prune unset unset unset unset pruned kept   "--prune"
-test_configured_prune unset unset unset unset kept   pruned \
+test_configured_prune unset unset unset unset kept kept ""
+test_configured_prune unset unset unset unset kept kept "--no-prune"
+test_configured_prune unset unset unset unset pruned kept "--prune"
+test_configured_prune unset unset unset unset kept pruned \
 	"--prune origin refs/tags/*:refs/tags/*"
 test_configured_prune unset unset unset unset pruned pruned \
 	"--prune origin refs/tags/*:refs/tags/* +refs/heads/*:refs/remotes/origin/*"
 
-test_configured_prune false unset unset unset kept   kept   ""
-test_configured_prune false unset unset unset kept   kept   "--no-prune"
-test_configured_prune false unset unset unset pruned kept   "--prune"
+test_configured_prune false unset unset unset kept kept ""
+test_configured_prune false unset unset unset kept kept "--no-prune"
+test_configured_prune false unset unset unset pruned kept "--prune"
 
-test_configured_prune true  unset unset unset pruned kept   ""
-test_configured_prune true  unset unset unset pruned kept   "--prune"
-test_configured_prune true  unset unset unset kept   kept   "--no-prune"
+test_configured_prune true unset unset unset pruned kept ""
+test_configured_prune true unset unset unset pruned kept "--prune"
+test_configured_prune true unset unset unset kept kept "--no-prune"
 
-test_configured_prune unset false unset unset kept   kept   ""
-test_configured_prune unset false unset unset kept   kept   "--no-prune"
-test_configured_prune unset false unset unset pruned kept   "--prune"
+test_configured_prune unset false unset unset kept kept ""
+test_configured_prune unset false unset unset kept kept "--no-prune"
+test_configured_prune unset false unset unset pruned kept "--prune"
 
-test_configured_prune false false unset unset kept   kept   ""
-test_configured_prune false false unset unset kept   kept   "--no-prune"
-test_configured_prune false false unset unset pruned kept   "--prune"
-test_configured_prune false false unset unset kept   pruned \
+test_configured_prune false false unset unset kept kept ""
+test_configured_prune false false unset unset kept kept "--no-prune"
+test_configured_prune false false unset unset pruned kept "--prune"
+test_configured_prune false false unset unset kept pruned \
 	"--prune origin refs/tags/*:refs/tags/*"
 test_configured_prune false false unset unset pruned pruned \
 	"--prune origin refs/tags/*:refs/tags/* +refs/heads/*:refs/remotes/origin/*"
 
-test_configured_prune true  false unset unset kept   kept   ""
-test_configured_prune true  false unset unset pruned kept   "--prune"
-test_configured_prune true  false unset unset kept   kept   "--no-prune"
+test_configured_prune true false unset unset kept kept ""
+test_configured_prune true false unset unset pruned kept "--prune"
+test_configured_prune true false unset unset kept kept "--no-prune"
 
-test_configured_prune unset true  unset unset pruned kept   ""
-test_configured_prune unset true  unset unset kept   kept   "--no-prune"
-test_configured_prune unset true  unset unset pruned kept   "--prune"
+test_configured_prune unset true unset unset pruned kept ""
+test_configured_prune unset true unset unset kept kept "--no-prune"
+test_configured_prune unset true unset unset pruned kept "--prune"
 
-test_configured_prune false true  unset unset pruned kept   ""
-test_configured_prune false true  unset unset kept   kept   "--no-prune"
-test_configured_prune false true  unset unset pruned kept   "--prune"
+test_configured_prune false true unset unset pruned kept ""
+test_configured_prune false true unset unset kept kept "--no-prune"
+test_configured_prune false true unset unset pruned kept "--prune"
 
-test_configured_prune true  true  unset unset pruned kept   ""
-test_configured_prune true  true  unset unset pruned kept   "--prune"
-test_configured_prune true  true  unset unset kept   kept   "--no-prune"
-test_configured_prune true  true  unset unset kept   pruned \
+test_configured_prune true true unset unset pruned kept ""
+test_configured_prune true true unset unset pruned kept "--prune"
+test_configured_prune true true unset unset kept kept "--no-prune"
+test_configured_prune true true unset unset kept pruned \
 	"--prune origin refs/tags/*:refs/tags/*"
-test_configured_prune true  true  unset unset pruned pruned \
+test_configured_prune true true unset unset pruned pruned \
 	"--prune origin refs/tags/*:refs/tags/* +refs/heads/*:refs/remotes/origin/*"
 
 # --prune-tags on its own does nothing, needs --prune as well, same
 # for fetch.pruneTags without fetch.prune
-test_configured_prune unset unset unset unset kept kept     "--prune-tags"
-test_configured_prune unset unset true unset  kept kept     ""
-test_configured_prune unset unset unset true  kept kept     ""
+test_configured_prune unset unset unset unset kept kept "--prune-tags"
+test_configured_prune unset unset true unset kept kept ""
+test_configured_prune unset unset unset true kept kept ""
 
 # These will prune the tags
 test_configured_prune unset unset unset unset pruned pruned "--prune --prune-tags"
-test_configured_prune true  unset true  unset pruned pruned ""
-test_configured_prune unset true  unset true  pruned pruned ""
+test_configured_prune true unset true unset pruned pruned ""
+test_configured_prune unset true unset true pruned pruned ""
 
 # remote.<name>.pruneTags overrides fetch.pruneTags, just like
 # remote.<name>.prune overrides fetch.prune if set.
-test_configured_prune true  unset true unset pruned pruned  ""
-test_configured_prune false true  false true  pruned pruned ""
-test_configured_prune true  false true  false kept   kept   ""
+test_configured_prune true unset true unset pruned pruned ""
+test_configured_prune false true false true pruned pruned ""
+test_configured_prune true false true false kept kept ""
 
 # When --prune-tags is supplied it's ignored if an explicit refspec is
 # given, same for the configuration options.
 test_configured_prune unset unset unset unset pruned kept \
 	"--prune --prune-tags origin +refs/heads/*:refs/remotes/origin/*"
-test_configured_prune unset unset true  unset pruned kept \
+test_configured_prune unset unset true unset pruned kept \
 	"--prune origin +refs/heads/*:refs/remotes/origin/*"
-test_configured_prune unset unset unset true pruned  kept \
+test_configured_prune unset unset unset true pruned kept \
 	"--prune origin +refs/heads/*:refs/remotes/origin/*"
 
 # Pruning that also takes place if a file:// url replaces a named
 # remote. However, because there's no implicit
 # +refs/heads/*:refs/remotes/origin/* refspec and supplying it on the
 # command-line negates --prune-tags, the branches will not be pruned.
-test_configured_prune_type unset unset unset unset kept   kept   "origin --prune-tags" "name"
-test_configured_prune_type unset unset unset unset kept   kept   "origin --prune-tags" "link"
+test_configured_prune_type unset unset unset unset kept kept "origin --prune-tags" "name"
+test_configured_prune_type unset unset unset unset kept kept "origin --prune-tags" "link"
 test_configured_prune_type unset unset unset unset pruned pruned "origin --prune --prune-tags" "name"
-test_configured_prune_type unset unset unset unset kept   pruned "origin --prune --prune-tags" "link"
+test_configured_prune_type unset unset unset unset kept pruned "origin --prune --prune-tags" "link"
 test_configured_prune_type unset unset unset unset pruned pruned "--prune --prune-tags origin" "name"
-test_configured_prune_type unset unset unset unset kept   pruned "--prune --prune-tags origin" "link"
-test_configured_prune_type unset unset true  unset pruned pruned "--prune origin" "name"
-test_configured_prune_type unset unset true  unset kept   pruned "--prune origin" "link"
-test_configured_prune_type unset unset unset true  pruned pruned "--prune origin" "name"
-test_configured_prune_type unset unset unset true  kept   pruned "--prune origin" "link"
-test_configured_prune_type true  unset true  unset pruned pruned "origin" "name"
-test_configured_prune_type true  unset true  unset kept   pruned "origin" "link"
-test_configured_prune_type unset  true true  unset pruned pruned "origin" "name"
-test_configured_prune_type unset  true true  unset kept   pruned "origin" "link"
-test_configured_prune_type unset  true unset true  pruned pruned "origin" "name"
-test_configured_prune_type unset  true unset true  kept   pruned "origin" "link"
+test_configured_prune_type unset unset unset unset kept pruned "--prune --prune-tags origin" "link"
+test_configured_prune_type unset unset true unset pruned pruned "--prune origin" "name"
+test_configured_prune_type unset unset true unset kept pruned "--prune origin" "link"
+test_configured_prune_type unset unset unset true pruned pruned "--prune origin" "name"
+test_configured_prune_type unset unset unset true kept pruned "--prune origin" "link"
+test_configured_prune_type true unset true unset pruned pruned "origin" "name"
+test_configured_prune_type true unset true unset kept pruned "origin" "link"
+test_configured_prune_type unset true true unset pruned pruned "origin" "name"
+test_configured_prune_type unset true true unset kept pruned "origin" "link"
+test_configured_prune_type unset true unset true pruned pruned "origin" "name"
+test_configured_prune_type unset true unset true kept pruned "origin" "link"
 
 # When all remote.origin.fetch settings are deleted a --prune
 # --prune-tags still implicitly supplies refs/tags/*:refs/tags/* so
@@ -1137,8 +1155,7 @@ test_expect_success 'fetching with auto-gc does not lock up' '
 	)
 '
 
-for section in fetch transfer
-do
+for section in fetch transfer; do
 	test_expect_success "$section.hideRefs affects connectivity check" '
 		GIT_TRACE="$PWD"/trace git -c $section.hideRefs=refs -c \
 			$section.hideRefs="!refs/tags/" fetch &&
@@ -1157,21 +1174,23 @@ test_expect_success 'prepare source branch' '
 	test 3 -le $(wc -l <actual)
 '
 
-validate_store_type () {
+validate_store_type() {
 	git -C dest count-objects -v >actual &&
-	case "$store_type" in
-	packed)
-		grep "^count: 0$" actual ;;
-	loose)
-		grep "^packs: 0$" actual ;;
-	esac || {
+		case "$store_type" in
+		packed)
+			grep "^count: 0$" actual
+			;;
+		loose)
+			grep "^packs: 0$" actual
+			;;
+		esac || {
 		echo "store_type is $store_type"
 		cat actual
 		false
 	}
 }
 
-test_unpack_limit () {
+test_unpack_limit() {
 	store_type=$1
 
 	case "$store_type" in
@@ -1192,43 +1211,39 @@ test_unpack_limit () {
 test_unpack_limit packed
 test_unpack_limit loose
 
-setup_negotiation_tip () {
+setup_negotiation_tip() {
 	SERVER="$1"
 	URL="$2"
 	USE_PROTOCOL_V2="$3"
 
 	rm -rf "$SERVER" client trace &&
-	git init -b main "$SERVER" &&
-	test_commit -C "$SERVER" alpha_1 &&
-	test_commit -C "$SERVER" alpha_2 &&
-	git -C "$SERVER" checkout --orphan beta &&
-	test_commit -C "$SERVER" beta_1 &&
-	test_commit -C "$SERVER" beta_2 &&
-
-	git clone "$URL" client &&
-
-	if test "$USE_PROTOCOL_V2" -eq 1
-	then
-		git -C "$SERVER" config protocol.version 2 &&
-		git -C client config protocol.version 2
-	fi &&
-
-	test_commit -C "$SERVER" beta_s &&
-	git -C "$SERVER" checkout main &&
-	test_commit -C "$SERVER" alpha_s &&
-	git -C "$SERVER" tag -d alpha_1 alpha_2 beta_1 beta_2
+		git init -b main "$SERVER" &&
+		test_commit -C "$SERVER" alpha_1 &&
+		test_commit -C "$SERVER" alpha_2 &&
+		git -C "$SERVER" checkout --orphan beta &&
+		test_commit -C "$SERVER" beta_1 &&
+		test_commit -C "$SERVER" beta_2 &&
+		git clone "$URL" client &&
+		if test "$USE_PROTOCOL_V2" -eq 1; then
+			git -C "$SERVER" config protocol.version 2 &&
+				git -C client config protocol.version 2
+		fi &&
+		test_commit -C "$SERVER" beta_s &&
+		git -C "$SERVER" checkout main &&
+		test_commit -C "$SERVER" alpha_s &&
+		git -C "$SERVER" tag -d alpha_1 alpha_2 beta_1 beta_2
 }
 
-check_negotiation_tip () {
+check_negotiation_tip() {
 	# Ensure that {alpha,beta}_1 are sent as "have", but not {alpha_beta}_2
 	ALPHA_1=$(git -C client rev-parse alpha_1) &&
-	grep "fetch> have $ALPHA_1" trace &&
-	BETA_1=$(git -C client rev-parse beta_1) &&
-	grep "fetch> have $BETA_1" trace &&
-	ALPHA_2=$(git -C client rev-parse alpha_2) &&
-	! grep "fetch> have $ALPHA_2" trace &&
-	BETA_2=$(git -C client rev-parse beta_2) &&
-	! grep "fetch> have $BETA_2" trace
+		grep "fetch> have $ALPHA_1" trace &&
+		BETA_1=$(git -C client rev-parse beta_1) &&
+		grep "fetch> have $BETA_1" trace &&
+		ALPHA_2=$(git -C client rev-parse alpha_2) &&
+		! grep "fetch> have $ALPHA_2" trace &&
+		BETA_2=$(git -C client rev-parse beta_2) &&
+		! grep "fetch> have $BETA_2" trace
 }
 
 test_expect_success '--negotiation-tip limits "have" lines sent' '
diff --git a/t/t5512-ls-remote.sh b/t/t5512-ls-remote.sh
index 64b3491e4e..1b3865e154 100755
--- a/t/t5512-ls-remote.sh
+++ b/t/t5512-ls-remote.sh
@@ -293,6 +293,8 @@ test_expect_success 'ls-remote with filtered symref (refname)' '
 	cat >expect <<-EOF &&
 	ref: refs/heads/main	HEAD
 	$rev	HEAD
+	ref: refs/remotes/origin/main	refs/remotes/origin/HEAD
+	$rev	refs/remotes/origin/HEAD
 	EOF
 	git ls-remote --symref . HEAD >actual &&
 	test_cmp expect actual
diff --git a/t/t5514-fetch-multiple.sh b/t/t5514-fetch-multiple.sh
index 579872c258..e3482b27b2 100755
--- a/t/t5514-fetch-multiple.sh
+++ b/t/t5514-fetch-multiple.sh
@@ -45,14 +45,17 @@ test_expect_success setup '
 '
 
 cat > test/expect << EOF
+  one/HEAD -> one/main
   one/main
   one/side
   origin/HEAD -> origin/main
   origin/main
   origin/side
+  three/HEAD -> three/main
   three/another
   three/main
   three/side
+  two/HEAD -> two/main
   two/another
   two/main
   two/side
@@ -97,6 +100,7 @@ cat > expect << EOF
   origin/HEAD -> origin/main
   origin/main
   origin/side
+  three/HEAD -> three/main
   three/another
   three/main
   three/side
@@ -112,8 +116,10 @@ test_expect_success 'git fetch --multiple (but only one remote)' '
 '
 
 cat > expect << EOF
+  one/HEAD -> one/main
   one/main
   one/side
+  two/HEAD -> two/main
   two/another
   two/main
   two/side
@@ -141,7 +147,7 @@ test_expect_success 'git fetch --multiple (bad remote names)' '
 
 test_expect_success 'git fetch --all (skipFetchAll)' '
 	(cd test4 &&
-	 for b in $(git branch -r)
+	 for b in $(git branch -r | grep -v HEAD)
 	 do
 		git branch -r -d $b || exit 1
 	 done &&
@@ -153,11 +159,14 @@ test_expect_success 'git fetch --all (skipFetchAll)' '
 '
 
 cat > expect << EOF
+  one/HEAD -> one/main
   one/main
   one/side
+  three/HEAD -> three/main
   three/another
   three/main
   three/side
+  two/HEAD -> two/main
   two/another
   two/main
   two/side
@@ -165,7 +174,7 @@ EOF
 
 test_expect_success 'git fetch --multiple (ignoring skipFetchAll)' '
 	(cd test4 &&
-	 for b in $(git branch -r)
+	 for b in $(git branch -r | grep -v HEAD)
 	 do
 		git branch -r -d $b || exit 1
 	 done &&
@@ -221,14 +230,17 @@ test_expect_success 'git fetch --multiple --jobs=0 picks a default' '
 
 create_fetch_all_expect () {
 	cat >expect <<-\EOF
+	  one/HEAD -> one/main
 	  one/main
 	  one/side
 	  origin/HEAD -> origin/main
 	  origin/main
 	  origin/side
+	  three/HEAD -> three/main
 	  three/another
 	  three/main
 	  three/side
+	  two/HEAD -> two/main
 	  two/another
 	  two/main
 	  two/side
@@ -265,6 +277,7 @@ test_expect_success 'git fetch (fetch all remotes with fetch.all = true)' '
 
 create_fetch_one_expect () {
 	cat >expect <<-\EOF
+	  one/HEAD -> one/main
 	  one/main
 	  one/side
 	  origin/HEAD -> origin/main
diff --git a/t/t5516-fetch-push.sh b/t/t5516-fetch-push.sh
index 331778bd42..5a051aa0c7 100755
--- a/t/t5516-fetch-push.sh
+++ b/t/t5516-fetch-push.sh
@@ -1395,7 +1395,8 @@ test_expect_success 'fetch follows tags by default' '
 		git tag -m "annotated" tag &&
 		git for-each-ref >tmp1 &&
 		sed -n "p; s|refs/heads/main$|refs/remotes/origin/main|p" tmp1 |
-		sort -k 3 >../expect
+		sed -n "p; s|refs/heads/main$|refs/remotes/origin/HEAD|p"  |
+		sort -k 4 >../expect
 	) &&
 	test_when_finished "rm -rf dst" &&
 	git init dst &&
diff --git a/t/t5527-fetch-odd-refs.sh b/t/t5527-fetch-odd-refs.sh
index 98ece27c6a..d3996af6ee 100755
--- a/t/t5527-fetch-odd-refs.sh
+++ b/t/t5527-fetch-odd-refs.sh
@@ -52,7 +52,8 @@ test_expect_success LONG_REF 'fetch handles extremely long refname' '
 	long
 	main
 	EOF
-	git for-each-ref --format="%(subject)" refs/remotes/long >actual &&
+	git for-each-ref --format="%(subject)" refs/remotes/long \
+		--exclude=refs/remotes/long/HEAD >actual &&
 	test_cmp expect actual
 '
 
diff --git a/t/t7900-maintenance.sh b/t/t7900-maintenance.sh
index a66d0e089d..88331d1ceb 100755
--- a/t/t7900-maintenance.sh
+++ b/t/t7900-maintenance.sh
@@ -329,7 +329,8 @@ test_expect_success 'incremental-repack task' '
 
 	# Delete refs that have not been repacked in these packs.
 	git for-each-ref --format="delete %(refname)" \
-		refs/prefetch refs/tags refs/remotes >refs &&
+		refs/prefetch refs/tags refs/remotes \
+		--exclude=refs/remotes/*/HEAD >refs &&
 	git update-ref --stdin <refs &&
 
 	# Replace the object directory with this pack layout.
diff --git a/t/t9210-scalar.sh b/t/t9210-scalar.sh
index a30b2c9f70..2237844550 100755
--- a/t/t9210-scalar.sh
+++ b/t/t9210-scalar.sh
@@ -151,7 +151,8 @@ test_expect_success 'scalar clone' '
 			"$(pwd)" &&
 
 		git for-each-ref --format="%(refname)" refs/remotes/origin/ >actual &&
-		echo "refs/remotes/origin/parallel" >expect &&
+		echo "refs/remotes/origin/HEAD" >>expect &&
+		echo "refs/remotes/origin/parallel" >>expect &&
 		test_cmp expect actual &&
 
 		test_path_is_missing 1/2 &&
@@ -220,7 +221,7 @@ test_expect_success 'scalar reconfigure --all with includeIf.onbranch' '
 	done
 '
 
- test_expect_success 'scalar reconfigure --all with detached HEADs' '
+test_expect_success 'scalar reconfigure --all with detached HEADs' '
 	repos="two three four" &&
 	for num in $repos
 	do
diff --git a/t/t9211-scalar-clone.sh b/t/t9211-scalar-clone.sh
index c16ea67c1d..d9cb6b9a3e 100755
--- a/t/t9211-scalar-clone.sh
+++ b/t/t9211-scalar-clone.sh
@@ -32,7 +32,7 @@ test_expect_success 'set up repository to clone' '
 	)
 '
 
-cleanup_clone () {
+cleanup_clone() {
 	rm -rf "$1"
 }
 
@@ -128,7 +128,7 @@ test_expect_success '--single-branch clones HEAD only' '
 	(
 		cd $enlistment/src &&
 		git for-each-ref refs/remotes/origin >out &&
-		test_line_count = 1 out &&
+		test_line_count = 2 out &&
 		grep "refs/remotes/origin/base" out
 	) &&
 
@@ -142,7 +142,7 @@ test_expect_success '--no-single-branch clones all branches' '
 	(
 		cd $enlistment/src &&
 		git for-each-ref refs/remotes/origin >out &&
-		test_line_count = 2 out &&
+		test_line_count = 3 out &&
 		grep "refs/remotes/origin/base" out &&
 		grep "refs/remotes/origin/parallel" out
 	) &&
diff --git a/t/t9902-completion.sh b/t/t9902-completion.sh
index cc6aa9f0cd..b663c4609e 100755
--- a/t/t9902-completion.sh
+++ b/t/t9902-completion.sh
@@ -658,6 +658,7 @@ test_expect_success '__git_refs - simple' '
 	HEAD
 	main
 	matching-branch
+	other/HEAD
 	other/branch-in-other
 	other/main-in-other
 	matching-tag
@@ -673,6 +674,7 @@ test_expect_success '__git_refs - full refs' '
 	cat >expected <<-EOF &&
 	refs/heads/main
 	refs/heads/matching-branch
+	refs/remotes/other/HEAD
 	refs/remotes/other/branch-in-other
 	refs/remotes/other/main-in-other
 	refs/tags/matching-tag
@@ -729,6 +731,7 @@ test_expect_success '__git_refs - remote on local file system - full refs' '
 test_expect_success '__git_refs - configured remote' '
 	cat >expected <<-EOF &&
 	HEAD
+	HEAD
 	branch-in-other
 	main-in-other
 	EOF
@@ -756,6 +759,7 @@ test_expect_success '__git_refs - configured remote - full refs' '
 test_expect_success '__git_refs - configured remote - repo given on the command line' '
 	cat >expected <<-EOF &&
 	HEAD
+	HEAD
 	branch-in-other
 	main-in-other
 	EOF
@@ -787,6 +791,7 @@ test_expect_success '__git_refs - configured remote - full refs - repo given on
 test_expect_success '__git_refs - configured remote - remote name matches a directory' '
 	cat >expected <<-EOF &&
 	HEAD
+	HEAD
 	branch-in-other
 	main-in-other
 	EOF
@@ -875,12 +880,14 @@ test_expect_success '__git_refs - unique remote branches for git checkout DWIMer
 	HEAD
 	main
 	matching-branch
+	other/HEAD
 	other/ambiguous
 	other/branch-in-other
 	other/main-in-other
 	remote/ambiguous
 	remote/branch-in-remote
 	matching-tag
+	HEAD
 	branch-in-other
 	branch-in-remote
 	main-in-other
@@ -904,6 +911,7 @@ test_expect_success '__git_refs - after --opt=' '
 	HEAD
 	main
 	matching-branch
+	other/HEAD
 	other/branch-in-other
 	other/main-in-other
 	matching-tag
@@ -919,6 +927,7 @@ test_expect_success '__git_refs - after --opt= - full refs' '
 	cat >expected <<-EOF &&
 	refs/heads/main
 	refs/heads/matching-branch
+	refs/remotes/other/HEAD
 	refs/remotes/other/branch-in-other
 	refs/remotes/other/main-in-other
 	refs/tags/matching-tag
@@ -935,6 +944,7 @@ test_expect_success '__git refs - excluding refs' '
 	^HEAD
 	^main
 	^matching-branch
+	^other/HEAD
 	^other/branch-in-other
 	^other/main-in-other
 	^matching-tag
@@ -950,6 +960,7 @@ test_expect_success '__git refs - excluding full refs' '
 	cat >expected <<-EOF &&
 	^refs/heads/main
 	^refs/heads/matching-branch
+	^refs/remotes/other/HEAD
 	^refs/remotes/other/branch-in-other
 	^refs/remotes/other/main-in-other
 	^refs/tags/matching-tag
@@ -975,6 +986,7 @@ test_expect_success '__git_refs - do not filter refs unless told so' '
 	main
 	matching-branch
 	matching/branch
+	other/HEAD
 	other/branch-in-other
 	other/main-in-other
 	other/matching/branch-in-other
@@ -1095,6 +1107,7 @@ test_expect_success '__git_complete_refs - simple' '
 	HEAD Z
 	main Z
 	matching-branch Z
+	other/HEAD Z
 	other/branch-in-other Z
 	other/main-in-other Z
 	matching-tag Z
@@ -1123,6 +1136,7 @@ test_expect_success '__git_complete_refs - matching' '
 test_expect_success '__git_complete_refs - remote' '
 	sed -e "s/Z$//" >expected <<-EOF &&
 	HEAD Z
+	HEAD Z
 	branch-in-other Z
 	main-in-other Z
 	EOF
@@ -1139,9 +1153,11 @@ test_expect_success '__git_complete_refs - track' '
 	HEAD Z
 	main Z
 	matching-branch Z
+	other/HEAD Z
 	other/branch-in-other Z
 	other/main-in-other Z
 	matching-tag Z
+	HEAD Z
 	branch-in-other Z
 	main-in-other Z
 	EOF
@@ -1184,6 +1200,7 @@ test_expect_success '__git_complete_refs - suffix' '
 	HEAD.
 	main.
 	matching-branch.
+	other/HEAD.
 	other/branch-in-other.
 	other/main-in-other.
 	matching-tag.
@@ -1199,6 +1216,7 @@ test_expect_success '__git_complete_refs - suffix' '
 test_expect_success '__git_complete_fetch_refspecs - simple' '
 	sed -e "s/Z$//" >expected <<-EOF &&
 	HEAD:HEAD Z
+	HEAD:HEAD Z
 	branch-in-other:branch-in-other Z
 	main-in-other:main-in-other Z
 	EOF
@@ -1225,6 +1243,7 @@ test_expect_success '__git_complete_fetch_refspecs - matching' '
 test_expect_success '__git_complete_fetch_refspecs - prefix' '
 	sed -e "s/Z$//" >expected <<-EOF &&
 	+HEAD:HEAD Z
+	+HEAD:HEAD Z
 	+branch-in-other:branch-in-other Z
 	+main-in-other:main-in-other Z
 	EOF
@@ -1289,6 +1308,7 @@ test_expect_success '__git_complete_worktree_paths with -C' '
 
 test_expect_success 'git switch - with no options, complete local branches and unique remote branch names for DWIM logic' '
 	test_completion "git switch " <<-\EOF
+	HEAD Z
 	branch-in-other Z
 	main Z
 	main-in-other Z
@@ -1435,11 +1455,13 @@ test_expect_success 'git-bisect - existing view subcommand is recognized and ena
 test_expect_success 'git checkout - completes refs and unique remote branches for DWIM' '
 	test_completion "git checkout " <<-\EOF
 	HEAD Z
+	HEAD Z
 	branch-in-other Z
 	main Z
 	main-in-other Z
 	matching-branch Z
 	matching-tag Z
+	other/HEAD Z
 	other/branch-in-other Z
 	other/main-in-other Z
 	EOF
@@ -1461,6 +1483,7 @@ test_expect_success 'git switch - with GIT_COMPLETION_CHECKOUT_NO_GUESS=1, compl
 
 test_expect_success 'git switch - --guess overrides GIT_COMPLETION_CHECKOUT_NO_GUESS=1, complete local branches and unique remote names for DWIM logic' '
 	GIT_COMPLETION_CHECKOUT_NO_GUESS=1 test_completion "git switch --guess " <<-\EOF
+	HEAD Z
 	branch-in-other Z
 	main Z
 	main-in-other Z
@@ -1470,6 +1493,7 @@ test_expect_success 'git switch - --guess overrides GIT_COMPLETION_CHECKOUT_NO_G
 
 test_expect_success 'git switch - a later --guess overrides previous --no-guess, complete local and remote unique branches for DWIM' '
 	test_completion "git switch --no-guess --guess " <<-\EOF
+	HEAD Z
 	branch-in-other Z
 	main Z
 	main-in-other Z
@@ -1490,6 +1514,7 @@ test_expect_success 'git checkout - with GIT_COMPLETION_NO_GUESS=1 only complete
 	main Z
 	matching-branch Z
 	matching-tag Z
+	other/HEAD Z
 	other/branch-in-other Z
 	other/main-in-other Z
 	EOF
@@ -1498,11 +1523,13 @@ test_expect_success 'git checkout - with GIT_COMPLETION_NO_GUESS=1 only complete
 test_expect_success 'git checkout - --guess overrides GIT_COMPLETION_NO_GUESS=1, complete refs and unique remote branches for DWIM' '
 	GIT_COMPLETION_CHECKOUT_NO_GUESS=1 test_completion "git checkout --guess " <<-\EOF
 	HEAD Z
+	HEAD Z
 	branch-in-other Z
 	main Z
 	main-in-other Z
 	matching-branch Z
 	matching-tag Z
+	other/HEAD Z
 	other/branch-in-other Z
 	other/main-in-other Z
 	EOF
@@ -1514,6 +1541,7 @@ test_expect_success 'git checkout - with --no-guess, only completes refs' '
 	main Z
 	matching-branch Z
 	matching-tag Z
+	other/HEAD Z
 	other/branch-in-other Z
 	other/main-in-other Z
 	EOF
@@ -1522,11 +1550,13 @@ test_expect_success 'git checkout - with --no-guess, only completes refs' '
 test_expect_success 'git checkout - a later --guess overrides previous --no-guess, complete refs and unique remote branches for DWIM' '
 	test_completion "git checkout --no-guess --guess " <<-\EOF
 	HEAD Z
+	HEAD Z
 	branch-in-other Z
 	main Z
 	main-in-other Z
 	matching-branch Z
 	matching-tag Z
+	other/HEAD Z
 	other/branch-in-other Z
 	other/main-in-other Z
 	EOF
@@ -1538,6 +1568,7 @@ test_expect_success 'git checkout - a later --no-guess overrides previous --gues
 	main Z
 	matching-branch Z
 	matching-tag Z
+	other/HEAD Z
 	other/branch-in-other Z
 	other/main-in-other Z
 	EOF
@@ -1550,6 +1581,7 @@ test_expect_success 'git checkout - with checkout.guess = false, only completes
 	main Z
 	matching-branch Z
 	matching-tag Z
+	other/HEAD Z
 	other/branch-in-other Z
 	other/main-in-other Z
 	EOF
@@ -1559,11 +1591,13 @@ test_expect_success 'git checkout - with checkout.guess = true, completes refs a
 	test_config checkout.guess true &&
 	test_completion "git checkout " <<-\EOF
 	HEAD Z
+	HEAD Z
 	branch-in-other Z
 	main Z
 	main-in-other Z
 	matching-branch Z
 	matching-tag Z
+	other/HEAD Z
 	other/branch-in-other Z
 	other/main-in-other Z
 	EOF
@@ -1573,11 +1607,13 @@ test_expect_success 'git checkout - a later --guess overrides previous checkout.
 	test_config checkout.guess false &&
 	test_completion "git checkout --guess " <<-\EOF
 	HEAD Z
+	HEAD Z
 	branch-in-other Z
 	main Z
 	main-in-other Z
 	matching-branch Z
 	matching-tag Z
+	other/HEAD Z
 	other/branch-in-other Z
 	other/main-in-other Z
 	EOF
@@ -1590,6 +1626,7 @@ test_expect_success 'git checkout - a later --no-guess overrides previous checko
 	main Z
 	matching-branch Z
 	matching-tag Z
+	other/HEAD Z
 	other/branch-in-other Z
 	other/main-in-other Z
 	EOF
@@ -1601,6 +1638,7 @@ test_expect_success 'git switch - with --detach, complete all references' '
 	main Z
 	matching-branch Z
 	matching-tag Z
+	other/HEAD Z
 	other/branch-in-other Z
 	other/main-in-other Z
 	EOF
@@ -1612,6 +1650,7 @@ test_expect_success 'git checkout - with --detach, complete only references' '
 	main Z
 	matching-branch Z
 	matching-tag Z
+	other/HEAD Z
 	other/branch-in-other Z
 	other/main-in-other Z
 	EOF
@@ -1783,6 +1822,7 @@ test_expect_success 'git switch - with -d, complete all references' '
 	main Z
 	matching-branch Z
 	matching-tag Z
+	other/HEAD Z
 	other/branch-in-other Z
 	other/main-in-other Z
 	EOF
@@ -1794,6 +1834,7 @@ test_expect_success 'git checkout - with -d, complete only references' '
 	main Z
 	matching-branch Z
 	matching-tag Z
+	other/HEAD Z
 	other/branch-in-other Z
 	other/main-in-other Z
 	EOF
@@ -1801,10 +1842,12 @@ test_expect_success 'git checkout - with -d, complete only references' '
 
 test_expect_success 'git switch - with --track, complete only remote branches' '
 	test_completion "git switch --track " <<-\EOF &&
+	other/HEAD Z
 	other/branch-in-other Z
 	other/main-in-other Z
 	EOF
 	test_completion "git switch -t " <<-\EOF
+	other/HEAD Z
 	other/branch-in-other Z
 	other/main-in-other Z
 	EOF
@@ -1812,10 +1855,12 @@ test_expect_success 'git switch - with --track, complete only remote branches' '
 
 test_expect_success 'git checkout - with --track, complete only remote branches' '
 	test_completion "git checkout --track " <<-\EOF &&
+	other/HEAD Z
 	other/branch-in-other Z
 	other/main-in-other Z
 	EOF
 	test_completion "git checkout -t " <<-\EOF
+	other/HEAD Z
 	other/branch-in-other Z
 	other/main-in-other Z
 	EOF
@@ -1834,6 +1879,7 @@ test_expect_success 'git checkout - with --no-track, complete only local referen
 	main Z
 	matching-branch Z
 	matching-tag Z
+	other/HEAD Z
 	other/branch-in-other Z
 	other/main-in-other Z
 	EOF
@@ -1845,6 +1891,7 @@ test_expect_success 'git switch - with -c, complete all references' '
 	main Z
 	matching-branch Z
 	matching-tag Z
+	other/HEAD Z
 	other/branch-in-other Z
 	other/main-in-other Z
 	EOF
@@ -1856,6 +1903,7 @@ test_expect_success 'git switch - with -C, complete all references' '
 	main Z
 	matching-branch Z
 	matching-tag Z
+	other/HEAD Z
 	other/branch-in-other Z
 	other/main-in-other Z
 	EOF
@@ -1867,6 +1915,7 @@ test_expect_success 'git switch - with -c and --track, complete all references'
 	main Z
 	matching-branch Z
 	matching-tag Z
+	other/HEAD Z
 	other/branch-in-other Z
 	other/main-in-other Z
 	EOF
@@ -1878,6 +1927,7 @@ test_expect_success 'git switch - with -C and --track, complete all references'
 	main Z
 	matching-branch Z
 	matching-tag Z
+	other/HEAD Z
 	other/branch-in-other Z
 	other/main-in-other Z
 	EOF
@@ -1889,6 +1939,7 @@ test_expect_success 'git switch - with -c and --no-track, complete all reference
 	main Z
 	matching-branch Z
 	matching-tag Z
+	other/HEAD Z
 	other/branch-in-other Z
 	other/main-in-other Z
 	EOF
@@ -1900,6 +1951,7 @@ test_expect_success 'git switch - with -C and --no-track, complete all reference
 	main Z
 	matching-branch Z
 	matching-tag Z
+	other/HEAD Z
 	other/branch-in-other Z
 	other/main-in-other Z
 	EOF
@@ -1911,6 +1963,7 @@ test_expect_success 'git checkout - with -b, complete all references' '
 	main Z
 	matching-branch Z
 	matching-tag Z
+	other/HEAD Z
 	other/branch-in-other Z
 	other/main-in-other Z
 	EOF
@@ -1922,6 +1975,7 @@ test_expect_success 'git checkout - with -B, complete all references' '
 	main Z
 	matching-branch Z
 	matching-tag Z
+	other/HEAD Z
 	other/branch-in-other Z
 	other/main-in-other Z
 	EOF
@@ -1933,6 +1987,7 @@ test_expect_success 'git checkout - with -b and --track, complete all references
 	main Z
 	matching-branch Z
 	matching-tag Z
+	other/HEAD Z
 	other/branch-in-other Z
 	other/main-in-other Z
 	EOF
@@ -1944,6 +1999,7 @@ test_expect_success 'git checkout - with -B and --track, complete all references
 	main Z
 	matching-branch Z
 	matching-tag Z
+	other/HEAD Z
 	other/branch-in-other Z
 	other/main-in-other Z
 	EOF
@@ -1955,6 +2011,7 @@ test_expect_success 'git checkout - with -b and --no-track, complete all referen
 	main Z
 	matching-branch Z
 	matching-tag Z
+	other/HEAD Z
 	other/branch-in-other Z
 	other/main-in-other Z
 	EOF
@@ -1966,6 +2023,7 @@ test_expect_success 'git checkout - with -B and --no-track, complete all referen
 	main Z
 	matching-branch Z
 	matching-tag Z
+	other/HEAD Z
 	other/branch-in-other Z
 	other/main-in-other Z
 	EOF
@@ -1973,6 +2031,7 @@ test_expect_success 'git checkout - with -B and --no-track, complete all referen
 
 test_expect_success 'git switch - for -c, complete local branches and unique remote branches' '
 	test_completion "git switch -c " <<-\EOF
+	HEAD Z
 	branch-in-other Z
 	main Z
 	main-in-other Z
@@ -1982,6 +2041,7 @@ test_expect_success 'git switch - for -c, complete local branches and unique rem
 
 test_expect_success 'git switch - for -C, complete local branches and unique remote branches' '
 	test_completion "git switch -C " <<-\EOF
+	HEAD Z
 	branch-in-other Z
 	main Z
 	main-in-other Z
@@ -2019,6 +2079,7 @@ test_expect_success 'git switch - for -C with --no-track, complete local branche
 
 test_expect_success 'git checkout - for -b, complete local branches and unique remote branches' '
 	test_completion "git checkout -b " <<-\EOF
+	HEAD Z
 	branch-in-other Z
 	main Z
 	main-in-other Z
@@ -2028,6 +2089,7 @@ test_expect_success 'git checkout - for -b, complete local branches and unique r
 
 test_expect_success 'git checkout - for -B, complete local branches and unique remote branches' '
 	test_completion "git checkout -B " <<-\EOF
+	HEAD Z
 	branch-in-other Z
 	main Z
 	main-in-other Z
@@ -2065,6 +2127,7 @@ test_expect_success 'git checkout - for -B with --no-track, complete local branc
 
 test_expect_success 'git switch - with --orphan completes local branch names and unique remote branch names' '
 	test_completion "git switch --orphan " <<-\EOF
+	HEAD Z
 	branch-in-other Z
 	main Z
 	main-in-other Z
@@ -2080,6 +2143,7 @@ test_expect_success 'git switch - --orphan with branch already provided complete
 
 test_expect_success 'git checkout - with --orphan completes local branch names and unique remote branch names' '
 	test_completion "git checkout --orphan " <<-\EOF
+	HEAD Z
 	branch-in-other Z
 	main Z
 	main-in-other Z
@@ -2093,6 +2157,7 @@ test_expect_success 'git checkout - --orphan with branch already provided comple
 	main Z
 	matching-branch Z
 	matching-tag Z
+	other/HEAD Z
 	other/branch-in-other Z
 	other/main-in-other Z
 	EOF
-- 
2.47.0.94.g8861098b6d

[PATCH v10 8/8] fetch set_head: handle mirrored bare repositories

[Bence Ferdinandy]

When adding a remote to bare repository with "git remote add --mirror",
running fetch will fail to update HEAD to the remote's HEAD, since it
does not know how to handle bare repositories. On the other hand HEAD
already has content, since "git init --bare" has already set HEAD to
whatever is the default branch set for the user. Unless this - by chance
- is the same as the remote's HEAD, HEAD will be pointing to a bad
symref. Teach set_head to handle bare repositories, by overwriting HEAD
so it mirrors the remote's HEAD.

Note, that in this case overriding the local HEAD reference is
necessary, since HEAD will exist before fetch can be run, but this
should not be an issue, since the whole purpose of --mirror is to be an
exact mirror of the remote, so following any changes to HEAD makes
sense.

Also note, that although "git remote set-head" also fails when trying to
update the remote's locally tracked HEAD in a mirrored bare repository,
the usage of the command does not make much sense after this patch:
fetch will update the remote HEAD correctly, and setting it manually to
something else is antithetical to the concept of mirroring.

Signed-off-by: Bence Ferdinandy <bence@ferdinandy.com>
---

Notes:
    v10: - new patch
         - handles the issue discovered in
           https://lore.kernel.org/git/D4ZAELFWJMKN.S88LJ6YK31LZ@ferdinandy.com/T/

 builtin/fetch.c   | 16 ++++++++++++----
 t/t5505-remote.sh | 10 ++++++++++
 2 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/builtin/fetch.c b/builtin/fetch.c
index 31edc67447..249556c9c6 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -1632,14 +1632,22 @@ static int set_head(const struct ref *remote_refs)
 	else
 		head_name = xstrdup(heads.items[0].string);
 	if (head_name) {
-		strbuf_addf(&b_head, "refs/remotes/%s/HEAD", remote);
-		strbuf_addf(&b_remote_head, "refs/remotes/%s/%s", remote, head_name);
+		int is_bare = is_bare_repository();
+		if (is_bare) {
+			strbuf_addstr(&b_head, "HEAD");
+			strbuf_addf(&b_remote_head, "refs/heads/%s", head_name);
+		} else {
+			strbuf_addf(&b_head, "refs/remotes/%s/HEAD", remote);
+			strbuf_addf(&b_remote_head, "refs/remotes/%s/%s", remote, head_name);
+		}
 		/* make sure it's valid */
-		if (!refs_ref_exists(refs, b_remote_head.buf))
+		if (!is_bare && !refs_ref_exists(refs, b_remote_head.buf)) {
 			result = 1;
+		}
 		else if (refs_update_symref_extended(refs, b_head.buf, b_remote_head.buf,
-					"fetch", &b_local_head, 1))
+					"fetch", &b_local_head, !is_bare)) {
 			result = 1;
+		}
 		else
 			report_set_head(remote, head_name, &b_local_head);
 
diff --git a/t/t5505-remote.sh b/t/t5505-remote.sh
index 4990d00209..dfa78f3e8d 100755
--- a/t/t5505-remote.sh
+++ b/t/t5505-remote.sh
@@ -545,6 +545,16 @@ test_expect_success 'add --mirror && prune' '
 	)
 '
 
+test_expect_success 'add --mirror setting HEAD' '
+	mkdir headmirror &&
+	(
+		cd headmirror &&
+		git init --bare -b notmain &&
+		git remote add --mirror -f origin ../one &&
+		test "$(git symbolic-ref HEAD)" = "refs/heads/main"
+	)
+'
+
 test_expect_success 'add --mirror=fetch' '
 	mkdir mirror-fetch &&
 	git init -b main mirror-fetch/parent &&
-- 
2.47.0.94.g8861098b6d

Re: [PATCH v10 0/8] set-head/fetch remote/HEAD updates

[Taylor Blau]

On Mon, Oct 21, 2024 at 03:36:57PM +0200, Bence Ferdinandy wrote:
> Sorry for sending a v10 so soon after v9 without really waiting for feedback,
> but as I started digging into
> https://lore.kernel.org/git/D4ZAELFWJMKN.S88LJ6YK31LZ@ferdinandy.com/ I
> realized that the root cause is in fetch and not remote add, so the solution
> belongs to this series. I'll leave my overall comments for v9 in here for
> clarity.
>
> v10: added a new patch (8/8) on top of v9 to handle HEAD in mirrored bare
> repositories, rest of the patches are unchanged

Thanks. For other readers, this is a continuation of the v9 from this
thread:

    https://lore.kernel.org/git/20241019225330.4001477-1-bence@ferdinandy.com/

Thanks,
Taylor

Re: [PATCH v10 0/8] set-head/fetch remote/HEAD updates

[Bence Ferdinandy]

2024. okt. 21. 22:43:38 Taylor Blau <me@ttaylorr.com>:

> On Mon, Oct 21, 2024 at 03:36:57PM +0200, Bence Ferdinandy wrote:
>> Sorry for sending a v10 so soon after v9 without really waiting for 
>> feedback,
>> but as I started digging into
>> https://lore.kernel.org/git/D4ZAELFWJMKN.S88LJ6YK31LZ@ferdinandy.com/ 
>> I
>> realized that the root cause is in fetch and not remote add, so the 
>> solution
>> belongs to this series. I'll leave my overall comments for v9 in here 
>> for
>> clarity.
>>
>> v10: added a new patch (8/8) on top of v9 to handle HEAD in mirrored 
>> bare
>> repositories, rest of the patches are unchanged
>
> Thanks. For other readers, this is a continuation of the v9 from this
> thread:
>
>     
> https://lore.kernel.org/git/20241019225330.4001477-1-bence@ferdinandy.com/

And people may also want to drop the accidental noreply address in Cc 
when replying :) Sorry for the mixup!

Re: [PATCH v10 0/8] set-head/fetch remote/HEAD updates

[Taylor Blau]

On Mon, Oct 21, 2024 at 03:36:57PM +0200, Bence Ferdinandy wrote:
> Bence Ferdinandy (8):
>   t/t5505-remote: set default branch to main
>   refs: atomically record overwritten ref in update_symref
>   remote set-head: refactor for readability
>   remote set-head: better output for --auto
>   refs: add TRANSACTION_CREATE_EXISTS error
>   refs: add create_only option to refs_update_symref_extended
>   fetch: set remote/HEAD if it does not exist
>   fetch set_head: handle mirrored bare repositories

After applying this topic to 'seen', I noticed some new CI breakage that
appears to be caused by this topic:

    https://github.com/git/git/actions/runs/11449483611/job/31855171514#step:4:2506

After dropping the topic locally and building with 'make SANITIZE=leak'
and then running t0410-partial-clone.sh, I was able to resolve the
failures.

Would you mind building with 'SANITIZE=leak' and running that script to
see if you can address the issue? Thanks.

Thanks,
Taylor

Re: [PATCH v10 0/8] set-head/fetch remote/HEAD updates

[Bence Ferdinandy]

On Tue Oct 22, 2024 at 19:39, Taylor Blau <me@ttaylorr.com> wrote:
> On Mon, Oct 21, 2024 at 03:36:57PM +0200, Bence Ferdinandy wrote:
>> Bence Ferdinandy (8):
>>   t/t5505-remote: set default branch to main
>>   refs: atomically record overwritten ref in update_symref
>>   remote set-head: refactor for readability
>>   remote set-head: better output for --auto
>>   refs: add TRANSACTION_CREATE_EXISTS error
>>   refs: add create_only option to refs_update_symref_extended
>>   fetch: set remote/HEAD if it does not exist
>>   fetch set_head: handle mirrored bare repositories
>
> After applying this topic to 'seen', I noticed some new CI breakage that
> appears to be caused by this topic:
>
>     https://github.com/git/git/actions/runs/11449483611/job/31855171514#step:4:2506
>
> After dropping the topic locally and building with 'make SANITIZE=leak'
> and then running t0410-partial-clone.sh, I was able to resolve the
> failures.
>
> Would you mind building with 'SANITIZE=leak' and running that script to
> see if you can address the issue? Thanks.

Thanks, I can reproduce the issue. I'm hoping there are no more tricks to
testing things :D

Let's see how fast I can handle this ...

Best,
Bence

-- 
bence.ferdinandy.com

Re: [PATCH v10 0/8] set-head/fetch remote/HEAD updates

[Taylor Blau]

On Tue, Oct 22, 2024 at 08:33:28PM +0200, Bence Ferdinandy wrote:
>
> On Tue Oct 22, 2024 at 19:39, Taylor Blau <me@ttaylorr.com> wrote:
> > On Mon, Oct 21, 2024 at 03:36:57PM +0200, Bence Ferdinandy wrote:
> >> Bence Ferdinandy (8):
> >>   t/t5505-remote: set default branch to main
> >>   refs: atomically record overwritten ref in update_symref
> >>   remote set-head: refactor for readability
> >>   remote set-head: better output for --auto
> >>   refs: add TRANSACTION_CREATE_EXISTS error
> >>   refs: add create_only option to refs_update_symref_extended
> >>   fetch: set remote/HEAD if it does not exist
> >>   fetch set_head: handle mirrored bare repositories
> >
> > After applying this topic to 'seen', I noticed some new CI breakage that
> > appears to be caused by this topic:
> >
> >     https://github.com/git/git/actions/runs/11449483611/job/31855171514#step:4:2506
> >
> > After dropping the topic locally and building with 'make SANITIZE=leak'
> > and then running t0410-partial-clone.sh, I was able to resolve the
> > failures.
> >
> > Would you mind building with 'SANITIZE=leak' and running that script to
> > see if you can address the issue? Thanks.
>
> Thanks, I can reproduce the issue. I'm hoping there are no more tricks to
> testing things :D

Great, I'm glad that it was easily reproducible on your end. This one
should have minimal differences from the setup in CI, as I think
building with 'SANITIZE=leak' will suffice.

> Let's see how fast I can handle this ...

Thanks for looking.

Thanks,
Taylor

Re: [PATCH v10 0/8] set-head/fetch remote/HEAD updates

[Bence Ferdinandy]

On Tue Oct 22, 2024 at 21:04, Taylor Blau <me@ttaylorr.com> wrote:
> On Tue, Oct 22, 2024 at 08:33:28PM +0200, Bence Ferdinandy wrote:
>>
>> On Tue Oct 22, 2024 at 19:39, Taylor Blau <me@ttaylorr.com> wrote:
>> > On Mon, Oct 21, 2024 at 03:36:57PM +0200, Bence Ferdinandy wrote:
>> >> Bence Ferdinandy (8):
>> >>   t/t5505-remote: set default branch to main
>> >>   refs: atomically record overwritten ref in update_symref
>> >>   remote set-head: refactor for readability
>> >>   remote set-head: better output for --auto
>> >>   refs: add TRANSACTION_CREATE_EXISTS error
>> >>   refs: add create_only option to refs_update_symref_extended
>> >>   fetch: set remote/HEAD if it does not exist
>> >>   fetch set_head: handle mirrored bare repositories
>> >
>> > After applying this topic to 'seen', I noticed some new CI breakage that
>> > appears to be caused by this topic:
>> >
>> >     https://github.com/git/git/actions/runs/11449483611/job/31855171514#step:4:2506
>> >
>> > After dropping the topic locally and building with 'make SANITIZE=leak'
>> > and then running t0410-partial-clone.sh, I was able to resolve the
>> > failures.
>> >
>> > Would you mind building with 'SANITIZE=leak' and running that script to
>> > see if you can address the issue? Thanks.
>>
>> Thanks, I can reproduce the issue. I'm hoping there are no more tricks to
>> testing things :D
>
> Great, I'm glad that it was easily reproducible on your end. This one
> should have minimal differences from the setup in CI, as I think
> building with 'SANITIZE=leak' will suffice.
>
>> Let's see how fast I can handle this ...
>
> Thanks for looking.

I'll send v11 to the correct thread, hopefully with no random companies in Cc :)