Subject: [PATCH -v3 3/8] fast-import: allow tags to be identified by mark labels

From: Elijah Newren <[email-masked]>
Date: Thu, 3 Oct 2019 13:27:04 -0700

Mark identifiers are used in fast-export and fast-import to provide a
label to refer to earlier content.  Blobs are given labels because they
need to be referenced in the commits where they first appear with a
given filename, and commits are given labels because they can be the
parents of other commits.  Tags were never given labels, probably
because they were viewed as unnecessary, but that presents two problems:

   1. It leaves us without a way of referring to previous tags if we
      want to create a tag of a tag (or higher nestings).
   2. It leaves us with no way of recording that a tag has already been
      imported when using --export-marks and --import-marks.

Fix these problems by allowing an optional mark label for tags.

Signed-off-by: Elijah Newren <[email-masked]>
---
 Documentation/git-fast-import.txt |  1 +
 fast-import.c                     |  3 ++-
 t/t9300-fast-import.sh            | 19 +++++++++++++++++++
 3 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/Documentation/git-fast-import.txt b/Documentation/git-fast-import.txt
index 0bb276269e..4977869465 100644
--- a/Documentation/git-fast-import.txt
+++ b/Documentation/git-fast-import.txt
@@ -774,6 +774,7 @@ lightweight (non-annotated) tags see the `reset` command below.
 
 ....
 	'tag' SP <name> LF
+	mark?
 	'from' SP <commit-ish> LF
 	original-oid?
 	'tagger' (SP <name>)? SP LT <email> GT SP <when> LF
diff --git a/fast-import.c b/fast-import.c
index caae0819f5..5b9e9e3b02 100644
--- a/fast-import.c
+++ b/fast-import.c
@@ -2713,6 +2713,7 @@ static void parse_new_tag(const char *arg)
 		first_tag = t;
 	last_tag = t;
 	read_next_command();
+	parse_mark();
 
 	/* from ... */
 	if (!skip_prefix(command_buf.buf, "from ", &from))
@@ -2769,7 +2770,7 @@ static void parse_new_tag(const char *arg)
 	strbuf_addbuf(&new_data, &msg);
 	free(tagger);
 
-	if (store_object(OBJ_TAG, &new_data, NULL, &t->oid, 0))
+	if (store_object(OBJ_TAG, &new_data, NULL, &t->oid, next_mark))
 		t->pack_id = MAX_PACK_ID;
 	else
 		t->pack_id = pack_id;
diff --git a/t/t9300-fast-import.sh b/t/t9300-fast-import.sh
index 74bc41333b..3ad2b2f1ba 100755
--- a/t/t9300-fast-import.sh
+++ b/t/t9300-fast-import.sh
@@ -94,6 +94,23 @@ test_expect_success 'A: create pack from stdin' '
 	reset refs/tags/to-be-deleted
 	from 0000000000000000000000000000000000000000
 
+	tag nested
+	mark :6
+	from :4
+	data <<EOF
+	Tag of our lovely commit
+	EOF
+
+	reset refs/tags/nested
+	from 0000000000000000000000000000000000000000
+
+	tag nested
+	mark :7
+	from :6
+	data <<EOF
+	Tag of tag of our lovely commit
+	EOF
+
 	INPUT_END
 	git fast-import --export-marks=marks.out <input &&
 	git whatchanged master
@@ -176,6 +193,8 @@ test_expect_success 'A: verify marks output' '
 	:3 $(git rev-parse --verify master:file3)
 	:4 $(git rev-parse --verify master:file4)
 	:5 $(git rev-parse --verify master^0)
+	:6 $(git cat-file tag nested | grep object | cut -d" " -f 2)
+	:7 $(git rev-parse --verify nested)
 	EOF
 	test_cmp expect marks.out
 '
-- 
2.23.0.264.g3b9f7f2fc6