parse-options.c: fix documentation syntax of optional arguments

When an argument for an option is optional, short options don't need a
space between the option and the argument, and long options need a "=".
Otherwise, arguments are misinterpreted.

Signed-off-by: Michele Ballabio <barra_cuda@katamail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

parse-options.c

@@ -344,7 +344,10 @@ void usage_with_options_internal(const char * const *usagestr,
 			break;
 		case OPTION_INTEGER:
 			if (opts->flags & PARSE_OPT_OPTARG)
-				pos += fprintf(stderr, "[<n>]");
+				if (opts->long_name)
+					pos += fprintf(stderr, "[=<n>]");
+				else
+					pos += fprintf(stderr, "[<n>]");
 			else
 				pos += fprintf(stderr, " <n>");
 			break;
@@ -355,12 +358,18 @@ void usage_with_options_internal(const char * const *usagestr,
 		case OPTION_STRING:
 			if (opts->argh) {
 				if (opts->flags & PARSE_OPT_OPTARG)
-					pos += fprintf(stderr, " [<%s>]", opts->argh);
+					if (opts->long_name)
+						pos += fprintf(stderr, "[=<%s>]", opts->argh);
+					else
+						pos += fprintf(stderr, "[<%s>]", opts->argh);
 				else
 					pos += fprintf(stderr, " <%s>", opts->argh);
 			} else {
 				if (opts->flags & PARSE_OPT_OPTARG)
-					pos += fprintf(stderr, " [...]");
+					if (opts->long_name)
+						pos += fprintf(stderr, "[=...]");
+					else
+						pos += fprintf(stderr, "[...]");
 				else
 					pos += fprintf(stderr, " ...");
 			}

t/t1502-rev-parse-parseopt.sh

@@ -13,7 +13,7 @@ usage: some-command [options] <args>...
     --bar ...             some cool option --bar with an argument
 
 An option group Header
-    -C [...]              option C with an optional argument
+    -C[...]               option C with an optional argument
 
 Extras
     --extra1              line above used to cause a segfault but no longer does