fsck.c: add an fsck_set_msg_type() API that takes enums

Change code I added in acf9de4c94 (mktag: use fsck instead of custom
verify_tag(), 2021-01-05) to make use of a new API function that takes
the fsck_msg_{id,type} types, instead of arbitrary strings that
we'll (hopefully) parse into those types.

At the time that the fsck_set_msg_type() API was introduced in
0282f4dced (fsck: offer a function to demote fsck errors to warnings,
2015-06-22) it was only intended to be used to parse user-supplied
data.

For things that are purely internal to the C code it makes sense to
have the compiler check these arguments, and to skip the sanity
checking of the data in fsck_set_msg_type() which is redundant to
checks we get from the compiler.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/mktag.c

@@ -88,7 +88,8 @@ int cmd_mktag(int argc, const char **argv, const char *prefix)
 		die_errno(_("could not read from stdin"));
 
 	fsck_options.error_func = mktag_fsck_error_func;
-	fsck_set_msg_type(&fsck_options, "extraheaderentry", "warn");
+	fsck_set_msg_type_from_ids(&fsck_options, FSCK_MSG_EXTRA_HEADER_ENTRY,
+				   FSCK_WARN);
 	/* config might set fsck.extraHeaderEntry=* again */
 	git_config(git_fsck_config, &fsck_options);
 	if (fsck_tag_standalone(NULL, buf.buf, buf.len, &fsck_options,

fsck.c

@@ -132,6 +132,22 @@ int is_valid_msg_type(const char *msg_id, const char *msg_type)
 	return 1;
 }
 
+void fsck_set_msg_type_from_ids(struct fsck_options *options,
+				enum fsck_msg_id msg_id,
+				enum fsck_msg_type msg_type)
+{
+	if (!options->msg_type) {
+		int i;
+		enum fsck_msg_type *severity;
+		ALLOC_ARRAY(severity, FSCK_MSG_MAX);
+		for (i = 0; i < FSCK_MSG_MAX; i++)
+			severity[i] = fsck_msg_type(i, options);
+		options->msg_type = severity;
+	}
+
+	options->msg_type[msg_id] = msg_type;
+}
+
 void fsck_set_msg_type(struct fsck_options *options,
 		       const char *msg_id_str, const char *msg_type_str)
 {
@@ -144,16 +160,7 @@ void fsck_set_msg_type(struct fsck_options *options,
 	if (msg_type != FSCK_ERROR && msg_id_info[msg_id].msg_type == FSCK_FATAL)
 		die("Cannot demote %s to %s", msg_id_str, msg_type_str);
 
-	if (!options->msg_type) {
-		int i;
-		enum fsck_msg_type *severity;
-		ALLOC_ARRAY(severity, FSCK_MSG_MAX);
-		for (i = 0; i < FSCK_MSG_MAX; i++)
-			severity[i] = fsck_msg_type(i, options);
-		options->msg_type = severity;
-	}
-
-	options->msg_type[msg_id] = msg_type;
+	fsck_set_msg_type_from_ids(options, msg_id, msg_type);
 }
 
 void fsck_set_msg_types(struct fsck_options *options, const char *values)

fsck.h

@@ -82,6 +82,9 @@ enum fsck_msg_id {
 struct fsck_options;
 struct object;
 
+void fsck_set_msg_type_from_ids(struct fsck_options *options,
+				enum fsck_msg_id msg_id,
+				enum fsck_msg_type msg_type);
 void fsck_set_msg_type(struct fsck_options *options,
 		       const char *msg_id, const char *msg_type);
 void fsck_set_msg_types(struct fsck_options *options, const char *values);