describe: teach --match to accept multiple patterns

Teach `--match` to be accepted multiple times, accumulating a list of
patterns to match into a string list. Each pattern is inclusive, such
that a tag need only match one of the provided patterns to be
considered for matching.

This extension is useful as it enables more flexibility in what tags
match, and may avoid the need to run the describe command multiple
times to get the same result.

Add tests and update the documentation for this change.

Signed-off-by: Jacob Keller <jacob.keller@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-describe.txt

@@ -83,7 +83,10 @@ OPTIONS
 --match <pattern>::
 	Only consider tags matching the given `glob(7)` pattern,
 	excluding the "refs/tags/" prefix.  This can be used to avoid
-	leaking private tags from the repository.
+	leaking private tags from the repository. If given multiple times, a
+	list of patterns will be accumulated, and tags matching any of the
+	patterns will be considered. Use `--no-match` to clear and reset the
+	list of patterns.
 
 --always::
 	Show uniquely abbreviated commit object as fallback.

builtin/describe.c

@@ -28,7 +28,7 @@ static int abbrev = -1; /* unspecified */
 static int max_candidates = 10;
 static struct hashmap names;
 static int have_util;
-static const char *pattern;
+static struct string_list patterns = STRING_LIST_INIT_NODUP;
 static int always;
 static const char *dirty;
 
@@ -129,9 +129,24 @@ static int get_name(const char *path, const struct object_id *oid, int flag, voi
 	if (!all && !is_tag)
 		return 0;
 
-	/* Accept only tags that match the pattern, if given */
-	if (pattern && (!is_tag || wildmatch(pattern, path + 10, 0, NULL)))
-		return 0;
+	/*
+	 * If we're given patterns, accept only tags which match at least one
+	 * pattern.
+	 */
+	if (patterns.nr) {
+		struct string_list_item *item;
+
+		if (!is_tag)
+			return 0;
+
+		for_each_string_list_item(item, &patterns) {
+			if (!wildmatch(item->string, path + 10, 0, NULL))
+				break;
+
+			/* If we get here, no pattern matched. */
+			return 0;
+		}
+	}
 
 	/* Is it annotated? */
 	if (!peel_ref(path, peeled.hash)) {
@@ -404,7 +419,7 @@ int cmd_describe(int argc, const char **argv, const char *prefix)
 			    N_("only output exact matches"), 0),
 		OPT_INTEGER(0, "candidates", &max_candidates,
 			    N_("consider <n> most recent tags (default: 10)")),
-		OPT_STRING(0, "match",       &pattern, N_("pattern"),
+		OPT_STRING_LIST(0, "match", &patterns, N_("pattern"),
 			   N_("only consider tags matching <pattern>")),
 		OPT_BOOL(0, "always",        &always,
 			N_("show abbreviated commit object as fallback")),
@@ -430,6 +445,7 @@ int cmd_describe(int argc, const char **argv, const char *prefix)
 		die(_("--long is incompatible with --abbrev=0"));
 
 	if (contains) {
+		struct string_list_item *item;
 		struct argv_array args;
 
 		argv_array_init(&args);
@@ -440,8 +456,8 @@ int cmd_describe(int argc, const char **argv, const char *prefix)
 			argv_array_push(&args, "--always");
 		if (!all) {
 			argv_array_push(&args, "--tags");
-			if (pattern)
-				argv_array_pushf(&args, "--refs=refs/tags/%s", pattern);
+			for_each_string_list_item(item, &patterns)
+				argv_array_pushf(&args, "--refs=refs/tags/%s", item->string);
 		}
 		if (argc)
 			argv_array_pushv(&args, argv);

t/t6120-describe.sh

@@ -182,6 +182,10 @@ check_describe "test2-lightweight-*" --tags --match="test2-*"
 
 check_describe "test2-lightweight-*" --long --tags --match="test2-*" HEAD^
 
+check_describe "test1-lightweight-*" --long --tags --match="test1-*" --match="test2-*" HEAD^
+
+check_describe "test2-lightweight-*" --long --tags --match="test1-*" --no-match --match="test2-*" HEAD^
+
 test_expect_success 'name-rev with exact tags' '
 	echo A >expect &&
 	tag_object=$(git rev-parse refs/tags/A) &&
@@ -206,4 +210,19 @@ test_expect_success 'describe --contains with the exact tags' '
 	test_cmp expect actual
 '
 
+test_expect_success 'describe --contains and --match' '
+	echo "A^0" >expect &&
+	tagged_commit=$(git rev-parse "refs/tags/A^0") &&
+	test_must_fail git describe --contains --match="B" $tagged_commit &&
+	git describe --contains --match="B" --match="A" $tagged_commit >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'describe --contains and --no-match' '
+	echo "A^0" >expect &&
+	tagged_commit=$(git rev-parse "refs/tags/A^0") &&
+	git describe --contains --match="B" --no-match $tagged_commit >actual &&
+	test_cmp expect actual
+'
+
 test_done