builtin/rerere: introduce proper usage strings for subcommands

Adapt git-rerere(1) to have proper usage strings for each of the
subcommands.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-rerere.adoc

@@ -8,7 +8,13 @@ git-rerere - Reuse recorded resolution of conflicted merges
 SYNOPSIS
 --------
 [verse]
-'git rerere' [clear | forget <pathspec>... | diff | status | remaining | gc]
+'git rerere' [--[no-]rerere-autoupdate]
+'git rerere' clear
+'git rerere' diff
+'git rerere' forget <pathspec>...
+'git rerere' gc
+'git rerere' remaining
+'git rerere' status
 
 DESCRIPTION
 -----------

builtin/rerere.c

@@ -10,10 +10,13 @@
 #include "xdiff-interface.h"
 #include "pathspec.h"
 
-static const char * const rerere_usage[] = {
-	N_("git rerere [clear | forget <pathspec>... | diff | status | remaining | gc]"),
-	NULL,
-};
+#define RERERE_USAGE N_("git rerere [--[no-]rerere-autoupdate]")
+#define RERERE_CLEAR_USAGE N_("git rerere clear")
+#define RERERE_DIFF_USAGE N_("git rerere diff")
+#define RERERE_FORGET_USAGE N_("git rerere forget <pathspec>...")
+#define RERERE_GC_USAGE N_("git rerere gc")
+#define RERERE_REMAINING_USAGE N_("git rerere remaining")
+#define RERERE_STATUS_USAGE N_("git rerere status")
 
 static int outf(void *dummy UNUSED, mmfile_t *ptr, int nbuf)
 {
@@ -61,9 +64,13 @@ static int cmd_rerere_clear(int argc,
 	struct option options[] = {
 		OPT_END(),
 	};
+	const char * const rerere_clear_usage[] = {
+		RERERE_CLEAR_USAGE,
+		NULL,
+	};
 	struct string_list merge_rr = STRING_LIST_INIT_DUP;
 
-	argc = parse_options(argc, argv, prefix, options, rerere_usage, 0);
+	argc = parse_options(argc, argv, prefix, options, rerere_clear_usage, 0);
 	if (argc)
 		usage(_("too many arguments"));
 
@@ -81,11 +88,15 @@ static int cmd_rerere_diff(int argc,
 	struct option options[] = {
 		OPT_END(),
 	};
+	const char * const rerere_diff_usage[] = {
+		RERERE_DIFF_USAGE,
+		NULL,
+	};
 	struct string_list merge_rr = STRING_LIST_INIT_DUP;
 	struct strbuf buf = STRBUF_INIT;
 	struct rerere_cache cache;
 
-	argc = parse_options(argc, argv, prefix, options, rerere_usage, 0);
+	argc = parse_options(argc, argv, prefix, options, rerere_diff_usage, 0);
 	if (argc)
 		usage(_("too many arguments"));
 
@@ -115,10 +126,14 @@ static int cmd_rerere_forget(int argc,
 	struct option options[] = {
 		OPT_END(),
 	};
+	const char * const rerere_forget_usage[] = {
+		RERERE_FORGET_USAGE,
+		NULL,
+	};
 	struct pathspec pathspec;
 	int ret;
 
-	argc = parse_options(argc, argv, prefix, options, rerere_usage, 0);
+	argc = parse_options(argc, argv, prefix, options, rerere_forget_usage, 0);
 	if (!argc)
 		warning(_("'git rerere forget' without paths is deprecated"));
 	parse_pathspec(&pathspec, 0, PATHSPEC_PREFER_CWD, prefix, argv);
@@ -140,9 +155,13 @@ static int cmd_rerere_gc(int argc,
 				N_("skip gc while another process holds the lock")),
 		OPT_END(),
 	};
+	const char * const rerere_gc_usage[] = {
+		RERERE_GC_USAGE,
+		NULL,
+	};
 	struct string_list merge_rr = STRING_LIST_INIT_DUP;
 
-	argc = parse_options(argc, argv, prefix, options, rerere_usage, 0);
+	argc = parse_options(argc, argv, prefix, options, rerere_gc_usage, 0);
 	if (argc)
 		usage(_("too many arguments"));
 
@@ -164,6 +183,10 @@ static int cmd_rerere_perform(int argc,
 			N_("register clean resolutions in index"), 1),
 		OPT_END(),
 	};
+	const char * const rerere_usage[] = {
+		RERERE_USAGE,
+		NULL,
+	};
 	enum rerere_flags flags = 0;
 
 	argc = parse_options(argc, argv, prefix, options, rerere_usage, 0);
@@ -186,9 +209,13 @@ static int cmd_rerere_remaining(int argc,
 	struct option options[] = {
 		OPT_END(),
 	};
+	const char * const rerere_remaining_usage[] = {
+		RERERE_REMAINING_USAGE,
+		NULL,
+	};
 	struct string_list merge_rr = STRING_LIST_INIT_DUP;
 
-	argc = parse_options(argc, argv, prefix, options, rerere_usage, 0);
+	argc = parse_options(argc, argv, prefix, options, rerere_remaining_usage, 0);
 	if (argc)
 		usage(_("too many arguments"));
 
@@ -214,10 +241,14 @@ static int cmd_rerere_status(int argc,
 	struct option options[] = {
 		OPT_END(),
 	};
+	const char * const rerere_status_usage[] = {
+		RERERE_STATUS_USAGE,
+		NULL,
+	};
 	struct string_list merge_rr = STRING_LIST_INIT_DUP;
 	struct rerere_cache cache;
 
-	argc = parse_options(argc, argv, prefix, options, rerere_usage, 0);
+	argc = parse_options(argc, argv, prefix, options, rerere_status_usage, 0);
 	if (argc)
 		usage(_("too many arguments"));
 
@@ -247,6 +278,16 @@ int cmd_rerere(int argc,
 		OPT_SUBCOMMAND("status", &fn, cmd_rerere_status),
 		OPT_END(),
 	};
+	const char * const rerere_usage[] = {
+		RERERE_USAGE,
+		RERERE_CLEAR_USAGE,
+		RERERE_DIFF_USAGE,
+		RERERE_FORGET_USAGE,
+		RERERE_GC_USAGE,
+		RERERE_REMAINING_USAGE,
+		RERERE_STATUS_USAGE,
+		NULL,
+	};
 
 	argc = parse_options(argc, argv, prefix, options, rerere_usage,
 			     PARSE_OPT_KEEP_UNKNOWN_OPT | PARSE_OPT_SUBCOMMAND_OPTIONAL);