config: use an enum for type

The --type=<X> option for 'git config' has previously been defined using
macros, but using a typed enum is better for tracking the possible
values.

Move the definition up to make sure it is defined before a macro uses
some of its terms.

Update the initializer for config_display_options to explicitly set
'type' to TYPE_NONE even though this is implied by a zero value.

This assists in knowing that the switch statement added in the previous
change has a complete set of cases for a properly-valued enum.

Signed-off-by: Derrick Stolee <stolee@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/config.c

@@ -86,6 +86,17 @@ struct config_location_options {
 	.respect_includes_opt = -1, \
 }
 
+enum config_type {
+	TYPE_NONE = 0,
+	TYPE_BOOL,
+	TYPE_INT,
+	TYPE_BOOL_OR_INT,
+	TYPE_PATH,
+	TYPE_EXPIRY_DATE,
+	TYPE_COLOR,
+	TYPE_BOOL_OR_STR,
+};
+
 #define CONFIG_TYPE_OPTIONS(type) \
 	OPT_GROUP(N_("Type")), \
 	OPT_CALLBACK('t', "type", &type, N_("type"), N_("value is given this type"), option_parse_type), \
@@ -111,7 +122,7 @@ struct config_display_options {
 	int show_origin;
 	int show_scope;
 	int show_keys;
-	int type;
+	enum config_type type;
 	char *default_value;
 	/* Populated via `display_options_init()`. */
 	int term;
@@ -122,17 +133,9 @@ struct config_display_options {
 	.term = '\n', \
 	.delim = '=', \
 	.key_delim = ' ', \
+	.type = TYPE_NONE, \
 }
 
-#define TYPE_NONE		0
-#define TYPE_BOOL		1
-#define TYPE_INT		2
-#define TYPE_BOOL_OR_INT	3
-#define TYPE_PATH		4
-#define TYPE_EXPIRY_DATE	5
-#define TYPE_COLOR		6
-#define TYPE_BOOL_OR_STR	7
-
 #define OPT_CALLBACK_VALUE(s, l, v, h, i) { \
 	.type = OPTION_CALLBACK, \
 	.short_name = (s), \