Merge branch 'jc/push-follow-tag'

The new "--follow-tags" option tells "git push" to push relevant
annotated tags when pushing branches out.

* jc/push-follow-tag:
  push: --follow-tags
  commit.c: use clear_commit_marks_many() in in_merge_bases_many()
  commit.c: add in_merge_bases_many()
  commit.c: add clear_commit_marks_many()

9 files changed, 218 insertions, 14 deletions

diff --git a/Documentation/git-push.txt b/Documentation/git-push.txt
index 577d201c00..eb2883c94c 100644
--- a/Documentation/git-push.txt
+++ b/Documentation/git-push.txt
@@ -9,7 +9,7 @@ git-push - Update remote refs along with associated objects
 SYNOPSIS
 --------
 [verse]
-'git push' [--all | --mirror | --tags] [-n | --dry-run] [--receive-pack=<git-receive-pack>]
+'git push' [--all | --mirror | --tags] [--follow-tags] [-n | --dry-run] [--receive-pack=<git-receive-pack>]
 	   [--repo=<repository>] [-f | --force] [--prune] [-v | --verbose] [-u | --set-upstream]
 	   [<repository> [<refspec>...]]
 
@@ -117,6 +117,12 @@ already exists on the remote side.
 	addition to refspecs explicitly listed on the command
 	line.
 
+--follow-tags::
+	Push all the refs that would be pushed without this option,
+	and also push annotated tags in `refs/tags` that are missing
+	from the remote but are pointing at committish that are
+	reachable from the refs being pushed.
+
 --receive-pack=<git-receive-pack>::
 --exec=<git-receive-pack>::
 	Path to the 'git-receive-pack' program on the remote
diff --git a/builtin/push.c b/builtin/push.c
index 42b129d36c..5e4a0e958f 100644
--- a/builtin/push.c
+++ b/builtin/push.c
@@ -437,6 +437,8 @@ int cmd_push(int argc, const char **argv, const char *prefix)
 		OPT_BIT(0, "prune", &flags, N_("prune locally removed refs"),
 			TRANSPORT_PUSH_PRUNE),
 		OPT_BIT(0, "no-verify", &flags, N_("bypass pre-push hook"), TRANSPORT_PUSH_NO_HOOK),
+		OPT_BIT(0, "follow-tags", &flags, N_("push missing but relevant tags"),
+			TRANSPORT_PUSH_FOLLOW_TAGS),
 		OPT_END()
 	};
 
diff --git a/commit.c b/commit.c
index e8eb0aec55..b4512ab0b2 100644
--- a/commit.c
+++ b/commit.c
@@ -463,14 +463,23 @@ static void clear_commit_marks_1(struct commit_list **plist,
 	}
 }
 
-void clear_commit_marks(struct commit *commit, unsigned int mark)
+void clear_commit_marks_many(int nr, struct commit **commit, unsigned int mark)
 {
 	struct commit_list *list = NULL;
-	commit_list_insert(commit, &list);
+
+	while (nr--) {
+		commit_list_insert(*commit, &list);
+		commit++;
+	}
 	while (list)
 		clear_commit_marks_1(&list, pop_commit(&list), mark);
 }
 
+void clear_commit_marks(struct commit *commit, unsigned int mark)
+{
+	clear_commit_marks_many(1, &commit, mark);
+}
+
 void clear_commit_marks_for_object_array(struct object_array *a, unsigned mark)
 {
 	struct object *object;
@@ -797,8 +806,7 @@ struct commit_list *get_merge_bases_many(struct commit *one,
 	if (!result || !result->next) {
 		if (cleanup) {
 			clear_commit_marks(one, all_flags);
-			for (i = 0; i < n; i++)
-				clear_commit_marks(twos[i], all_flags);
+			clear_commit_marks_many(n, twos, all_flags);
 		}
 		return result;
 	}
@@ -816,8 +824,7 @@ struct commit_list *get_merge_bases_many(struct commit *one,
 	free_commit_list(result);
 
 	clear_commit_marks(one, all_flags);
-	for (i = 0; i < n; i++)
-		clear_commit_marks(twos[i], all_flags);
+	clear_commit_marks_many(n, twos, all_flags);
 
 	cnt = remove_redundant(rslt, cnt);
 	result = NULL;
@@ -852,25 +859,36 @@ int is_descendant_of(struct commit *commit, struct commit_list *with_commit)
 }
 
 /*
- * Is "commit" an ancestor of (i.e. reachable from) the "reference"?
+ * Is "commit" an ancestor of one of the "references"?
  */
-int in_merge_bases(struct commit *commit, struct commit *reference)
+int in_merge_bases_many(struct commit *commit, int nr_reference, struct commit **reference)
 {
 	struct commit_list *bases;
-	int ret = 0;
+	int ret = 0, i;
 
-	if (parse_commit(commit) || parse_commit(reference))
+	if (parse_commit(commit))
 		return ret;
+	for (i = 0; i < nr_reference; i++)
+		if (parse_commit(reference[i]))
+			return ret;
 
-	bases = paint_down_to_common(commit, 1, &reference);
+	bases = paint_down_to_common(commit, nr_reference, reference);
 	if (commit->object.flags & PARENT2)
 		ret = 1;
 	clear_commit_marks(commit, all_flags);
-	clear_commit_marks(reference, all_flags);
+	clear_commit_marks_many(nr_reference, reference, all_flags);
 	free_commit_list(bases);
 	return ret;
 }
 
+/*
+ * Is "commit" an ancestor of (i.e. reachable from) the "reference"?
+ */
+int in_merge_bases(struct commit *commit, struct commit *reference)
+{
+	return in_merge_bases_many(commit, 1, &reference);
+}
+
 struct commit_list *reduce_heads(struct commit_list *heads)
 {
 	struct commit_list *p;
diff --git a/commit.h b/commit.h
index 4138bb4c08..2d90d9c27c 100644
--- a/commit.h
+++ b/commit.h
@@ -137,6 +137,7 @@ struct commit *pop_most_recent_commit(struct commit_list **list,
 struct commit *pop_commit(struct commit_list **stack);
 
 void clear_commit_marks(struct commit *commit, unsigned int mark);
+void clear_commit_marks_many(int nr, struct commit **commit, unsigned int mark);
 void clear_commit_marks_for_object_array(struct object_array *a, unsigned mark);
 
 /*
@@ -176,6 +177,7 @@ extern struct commit_list *get_shallow_commits(struct object_array *heads,
 
 int is_descendant_of(struct commit *, struct commit_list *);
 int in_merge_bases(struct commit *, struct commit *);
+int in_merge_bases_many(struct commit *, int, struct commit **);
 
 extern int interactive_add(int argc, const char **argv, const char *prefix, int patch);
 extern int run_add_interactive(const char *revision, const char *patch_mode,
diff --git a/remote.c b/remote.c
index 174e48eb74..57f36e14da 100644
--- a/remote.c
+++ b/remote.c
@@ -1195,6 +1195,101 @@ static struct ref **tail_ref(struct ref **head)
 	return tail;
 }
 
+struct tips {
+	struct commit **tip;
+	int nr, alloc;
+};
+
+static void add_to_tips(struct tips *tips, const unsigned char *sha1)
+{
+	struct commit *commit;
+
+	if (is_null_sha1(sha1))
+		return;
+	commit = lookup_commit_reference_gently(sha1, 1);
+	if (!commit || (commit->object.flags & TMP_MARK))
+		return;
+	commit->object.flags |= TMP_MARK;
+	ALLOC_GROW(tips->tip, tips->nr + 1, tips->alloc);
+	tips->tip[tips->nr++] = commit;
+}
+
+static void add_missing_tags(struct ref *src, struct ref **dst, struct ref ***dst_tail)
+{
+	struct string_list dst_tag = STRING_LIST_INIT_NODUP;
+	struct string_list src_tag = STRING_LIST_INIT_NODUP;
+	struct string_list_item *item;
+	struct ref *ref;
+	struct tips sent_tips;
+
+	/*
+	 * Collect everything we know they would have at the end of
+	 * this push, and collect all tags they have.
+	 */
+	memset(&sent_tips, 0, sizeof(sent_tips));
+	for (ref = *dst; ref; ref = ref->next) {
+		if (ref->peer_ref &&
+		    !is_null_sha1(ref->peer_ref->new_sha1))
+			add_to_tips(&sent_tips, ref->peer_ref->new_sha1);
+		else
+			add_to_tips(&sent_tips, ref->old_sha1);
+		if (!prefixcmp(ref->name, "refs/tags/"))
+			string_list_append(&dst_tag, ref->name);
+	}
+	clear_commit_marks_many(sent_tips.nr, sent_tips.tip, TMP_MARK);
+
+	sort_string_list(&dst_tag);
+
+	/* Collect tags they do not have. */
+	for (ref = src; ref; ref = ref->next) {
+		if (prefixcmp(ref->name, "refs/tags/"))
+			continue; /* not a tag */
+		if (string_list_has_string(&dst_tag, ref->name))
+			continue; /* they already have it */
+		if (sha1_object_info(ref->new_sha1, NULL) != OBJ_TAG)
+			continue; /* be conservative */
+		item = string_list_append(&src_tag, ref->name);
+		item->util = ref;
+	}
+	string_list_clear(&dst_tag, 0);
+
+	/*
+	 * At this point, src_tag lists tags that are missing from
+	 * dst, and sent_tips lists the tips we are pushing or those
+	 * that we know they already have. An element in the src_tag
+	 * that is an ancestor of any of the sent_tips needs to be
+	 * sent to the other side.
+	 */
+	if (sent_tips.nr) {
+		for_each_string_list_item(item, &src_tag) {
+			struct ref *ref = item->util;
+			struct ref *dst_ref;
+			struct commit *commit;
+
+			if (is_null_sha1(ref->new_sha1))
+				continue;
+			commit = lookup_commit_reference_gently(ref->new_sha1, 1);
+			if (!commit)
+				/* not pushing a commit, which is not an error */
+				continue;
+
+			/*
+			 * Is this tag, which they do not have, reachable from
+			 * any of the commits we are sending?
+			 */
+			if (!in_merge_bases_many(commit, sent_tips.nr, sent_tips.tip))
+				continue;
+
+			/* Add it in */
+			dst_ref = make_linked_ref(ref->name, dst_tail);
+			hashcpy(dst_ref->new_sha1, ref->new_sha1);
+			dst_ref->peer_ref = copy_ref(ref);
+		}
+	}
+	string_list_clear(&src_tag, 0);
+	free(sent_tips.tip);
+}
+
 /*
  * Given the set of refs the local repository has, the set of refs the
  * remote repository has, and the refspec used for push, determine
@@ -1257,6 +1352,10 @@ int match_push_refs(struct ref *src, struct ref **dst,
 	free_name:
 		free(dst_name);
 	}
+
+	if (flags & MATCH_REFS_FOLLOW_TAGS)
+		add_missing_tags(src, dst, &dst_tail);
+
 	if (send_prune) {
 		/* check for missing refs on the remote */
 		for (ref = *dst; ref; ref = ref->next) {
diff --git a/remote.h b/remote.h
index f7b08f15de..8743d6ef9d 100644
--- a/remote.h
+++ b/remote.h
@@ -149,7 +149,8 @@ enum match_refs_flags {
 	MATCH_REFS_NONE		= 0,
 	MATCH_REFS_ALL 		= (1 << 0),
 	MATCH_REFS_MIRROR	= (1 << 1),
-	MATCH_REFS_PRUNE	= (1 << 2)
+	MATCH_REFS_PRUNE	= (1 << 2),
+	MATCH_REFS_FOLLOW_TAGS	= (1 << 3)
 };
 
 /* Reporting of tracking info */
diff --git a/t/t5516-fetch-push.sh b/t/t5516-fetch-push.sh
index 6fd125aecf..d3dc5df7b1 100755
--- a/t/t5516-fetch-push.sh
+++ b/t/t5516-fetch-push.sh
@@ -1077,4 +1077,77 @@ test_expect_success 'fetch exact SHA1' '
 	)
 '
 
+test_expect_success 'fetch follows tags by default' '
+	mk_test heads/master &&
+	rm -fr src dst &&
+	git init src &&
+	(
+		cd src &&
+		git pull ../testrepo master &&
+		git tag -m "annotated" tag &&
+		git for-each-ref >tmp1 &&
+		(
+			cat tmp1
+			sed -n "s|refs/heads/master$|refs/remotes/origin/master|p" tmp1
+		) |
+		sort -k 3 >../expect
+	) &&
+	git init dst &&
+	(
+		cd dst &&
+		git remote add origin ../src &&
+		git config branch.master.remote origin &&
+		git config branch.master.merge refs/heads/master &&
+		git pull &&
+		git for-each-ref >../actual
+	) &&
+	test_cmp expect actual
+'
+
+test_expect_success 'push does not follow tags by default' '
+	mk_test heads/master &&
+	rm -fr src dst &&
+	git init src &&
+	git init --bare dst &&
+	(
+		cd src &&
+		git pull ../testrepo master &&
+		git tag -m "annotated" tag &&
+		git checkout -b another &&
+		git commit --allow-empty -m "future commit" &&
+		git tag -m "future" future &&
+		git checkout master &&
+		git for-each-ref refs/heads/master >../expect &&
+		git push ../dst master
+	) &&
+	(
+		cd dst &&
+		git for-each-ref >../actual
+	) &&
+	test_cmp expect actual
+'
+
+test_expect_success 'push --follow-tag only pushes relevant tags' '
+	mk_test heads/master &&
+	rm -fr src dst &&
+	git init src &&
+	git init --bare dst &&
+	(
+		cd src &&
+		git pull ../testrepo master &&
+		git tag -m "annotated" tag &&
+		git checkout -b another &&
+		git commit --allow-empty -m "future commit" &&
+		git tag -m "future" future &&
+		git checkout master &&
+		git for-each-ref refs/heads/master refs/tags/tag >../expect
+		git push --follow-tag ../dst master
+	) &&
+	(
+		cd dst &&
+		git for-each-ref >../actual
+	) &&
+	test_cmp expect actual
+'
+
 test_done
diff --git a/transport.c b/transport.c
index 42a61b30b3..eb9eb33e0f 100644
--- a/transport.c
+++ b/transport.c
@@ -1128,6 +1128,8 @@ int transport_push(struct transport *transport,
 			match_flags |= MATCH_REFS_MIRROR;
 		if (flags & TRANSPORT_PUSH_PRUNE)
 			match_flags |= MATCH_REFS_PRUNE;
+		if (flags & TRANSPORT_PUSH_FOLLOW_TAGS)
+			match_flags |= MATCH_REFS_FOLLOW_TAGS;
 
 		if (match_push_refs(local_refs, &remote_refs,
 				    refspec_nr, refspec, match_flags)) {
diff --git a/transport.h b/transport.h
index a3450e97c0..9354462708 100644
--- a/transport.h
+++ b/transport.h
@@ -105,6 +105,7 @@ struct transport {
 #define TRANSPORT_PUSH_PRUNE 128
 #define TRANSPORT_RECURSE_SUBMODULES_ON_DEMAND 256
 #define TRANSPORT_PUSH_NO_HOOK 512
+#define TRANSPORT_PUSH_FOLLOW_TAGS 1024
 
 #define TRANSPORT_SUMMARY_WIDTH (2 * DEFAULT_ABBREV + 3)
 #define TRANSPORT_SUMMARY(x) (int)(TRANSPORT_SUMMARY_WIDTH + strlen(x) - gettext_width(x)), (x)