ref-filter: add `ref_filter_clear()`

We did not bother to clean up at all in `git branch` or `git tag`, and
`git for-each-ref` only cleans up a couple of members.

Add and call `ref_filter_clear()` when cleaning up a `struct
ref_filter`. Running this patch (without any test changes) indicates a
couple of now leak-free tests. This was found by running:

    $ make SANITIZE=leak
    $ make -C t GIT_TEST_PASSING_SANITIZE_LEAK=check GIT_TEST_OPTS=--immediate

(Note that the `reachable_from` and `unreachable_from` lists should be
cleaned as they are used. So this is just covering any case where we
might bail before running the reachability check.)

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/branch.c

@@ -858,6 +858,7 @@ int cmd_branch(int argc, const char **argv, const char *prefix)
 		print_columns(&output, colopts, NULL);
 		string_list_clear(&output, 0);
 		ref_sorting_release(sorting);
+		ref_filter_clear(&filter);
 		return 0;
 	} else if (edit_description) {
 		const char *branch_name;

builtin/for-each-ref.c

@@ -120,8 +120,7 @@ int cmd_for_each_ref(int argc, const char **argv, const char *prefix)
 	strbuf_release(&err);
 	strbuf_release(&output);
 	ref_array_clear(&array);
-	free_commit_list(filter.with_commit);
-	free_commit_list(filter.no_commit);
+	ref_filter_clear(&filter);
 	ref_sorting_release(sorting);
 	strvec_clear(&vec);
 	return 0;

builtin/tag.c

@@ -645,6 +645,7 @@ int cmd_tag(int argc, const char **argv, const char *prefix)
 
 cleanup:
 	ref_sorting_release(sorting);
+	ref_filter_clear(&filter);
 	strbuf_release(&buf);
 	strbuf_release(&ref);
 	strbuf_release(&reflog_msg);

ref-filter.c

@@ -2866,3 +2866,19 @@ int parse_opt_merge_filter(const struct option *opt, const char *arg, int unset)
 
 	return 0;
 }
+
+void ref_filter_init(struct ref_filter *filter)
+{
+	struct ref_filter blank = REF_FILTER_INIT;
+	memcpy(filter, &blank, sizeof(blank));
+}
+
+void ref_filter_clear(struct ref_filter *filter)
+{
+	oid_array_clear(&filter->points_at);
+	free_commit_list(filter->with_commit);
+	free_commit_list(filter->no_commit);
+	free_commit_list(filter->reachable_from);
+	free_commit_list(filter->unreachable_from);
+	ref_filter_init(filter);
+}

ref-filter.h

@@ -170,4 +170,7 @@ void filter_ahead_behind(struct repository *r,
 			 struct ref_format *format,
 			 struct ref_array *array);
 
+void ref_filter_init(struct ref_filter *filter);
+void ref_filter_clear(struct ref_filter *filter);
+
 #endif /*  REF_FILTER_H  */

t/t0041-usage.sh

@@ -5,6 +5,7 @@ test_description='Test commands behavior when given invalid argument value'
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'setup ' '

t/t3402-rebase-merge.sh

@@ -8,6 +8,7 @@ test_description='git rebase --merge test'
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 T="A quick brown fox