parse-options: Allow to hide options from the default usage.

This is useful for backward-compatibility aliases, or very advanced command
line switches introduced for internal git usages and have no real use for a
user.

parse-options still shows them if the user asks for --help-all.

Signed-off-by: Pierre Habouzit <madcoder@debian.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

parse-options.c

diff --git a/parse-options.c b/parse-options.c
index d3e608a..e12b428 100644
--- a/parse-options.c
+++ b/parse-options.c
@@ -216,6 +216,9 @@
 	return error("unknown option `%s'", arg);
 }
 
+static NORETURN void usage_with_options_internal(const char * const *,
+                                                 const struct option *, int);
+
 int parse_options(int argc, const char **argv, const struct option *options,
                   const char * const usagestr[], int flags)
 {
@@ -249,6 +252,8 @@
 			break;
 		}
 
+		if (!strcmp(arg + 2, "help-all"))
+			usage_with_options_internal(usagestr, options, 1);
 		if (!strcmp(arg + 2, "help"))
 			usage_with_options(usagestr, options);
 		if (parse_long_opt(&args, arg + 2, options))
@@ -263,8 +268,8 @@
 #define USAGE_OPTS_WIDTH 24
 #define USAGE_GAP         2
 
-void usage_with_options(const char * const *usagestr,
-                        const struct option *opts)
+void usage_with_options_internal(const char * const *usagestr,
+                                 const struct option *opts, int full)
 {
 	fprintf(stderr, "usage: %s\n", *usagestr++);
 	while (*usagestr && **usagestr)
@@ -285,6 +290,8 @@
 				fprintf(stderr, "%s\n", opts->help);
 			continue;
 		}
+		if (!full && (opts->flags & PARSE_OPT_HIDDEN))
+			continue;
 
 		pos = fprintf(stderr, "    ");
 		if (opts->short_name)
@@ -335,6 +342,12 @@
 	exit(129);
 }
 
+void usage_with_options(const char * const *usagestr,
+                        const struct option *opts)
+{
+	usage_with_options_internal(usagestr, opts, 0);
+}
+
 /*----- some often used options -----*/
 #include "cache.h"
 

parse-options.h

diff --git a/parse-options.h b/parse-options.h
index a8760ac..102ac31 100644
--- a/parse-options.h
+++ b/parse-options.h
@@ -24,6 +24,7 @@
 	PARSE_OPT_OPTARG  = 1,
 	PARSE_OPT_NOARG   = 2,
 	PARSE_OPT_NONEG   = 4,
+	PARSE_OPT_HIDDEN  = 8,
 };
 
 struct option;
@@ -57,6 +58,8 @@
  *   PARSE_OPT_OPTARG: says that the argument is optionnal (not for BOOLEANs)
  *   PARSE_OPT_NOARG: says that this option takes no argument, for CALLBACKs
  *   PARSE_OPT_NONEG: says that this option cannot be negated
+ *   PARSE_OPT_HIDDEN this option is skipped in the default usage, showed in
+ *                    the long one.
  *
  * `callback`::
  *   pointer to the callback to use for OPTION_CALLBACK.