help: add "-a --verbose" to list all commands with synopsis

This lists all recognized commands [1] by category. The group order
follows closely git.txt.

[1] We may actually show commands that are not built (e.g. if you set
NO_PERL you don't have git-instaweb but it's still listed here). I
ignore the problem because on Linux a git package could be split
anyway. The "git-core" package may not contain git-instaweb even if
it's built because it may end up in a separate package. We can't know
anyway.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-help.txt

@@ -8,7 +8,7 @@ git-help - Display help information about Git
 SYNOPSIS
 --------
 [verse]
-'git help' [-a|--all] [-g|--guide]
+'git help' [-a|--all [--verbose]] [-g|--guide]
 	   [-i|--info|-m|--man|-w|--web] [COMMAND|GUIDE]
 
 DESCRIPTION
@@ -42,6 +42,8 @@ OPTIONS
 --all::
 	Prints all the available commands on the standard output. This
 	option overrides any given command or guide name.
+	When used with `--verbose` print description for all recognized
+	commands.
 
 -g::
 --guides::

builtin/help.c

@@ -36,6 +36,7 @@ static const char *html_path;
 
 static int show_all = 0;
 static int show_guides = 0;
+static int verbose;
 static unsigned int colopts;
 static enum help_format help_format = HELP_FORMAT_NONE;
 static int exclude_guides;
@@ -48,6 +49,7 @@ static struct option builtin_help_options[] = {
 			HELP_FORMAT_WEB),
 	OPT_SET_INT('i', "info", &help_format, N_("show info page"),
 			HELP_FORMAT_INFO),
+	OPT__VERBOSE(&verbose, N_("print command description")),
 	OPT_END(),
 };
 
@@ -463,6 +465,11 @@ int cmd_help(int argc, const char **argv, const char *prefix)
 
 	if (show_all) {
 		git_config(git_help_config, NULL);
+		if (verbose) {
+			setup_pager();
+			list_all_cmds_help();
+			return 0;
+		}
 		printf(_("usage: %s%s"), _(git_usage_string), "\n\n");
 		load_command_list("git-", &main_cmds, &other_cmds);
 		list_commands(colopts, &main_cmds, &other_cmds);

help.c

@@ -27,6 +27,17 @@ static struct category_description common_categories[] = {
 	{ CAT_remote, N_("collaborate (see also: git help workflows)") },
 	{ 0, NULL }
 };
+static struct category_description main_categories[] = {
+	{ CAT_mainporcelain, N_("Main Porcelain Commands") },
+	{ CAT_ancillarymanipulators, N_("Ancillary Commands / Manipulators") },
+	{ CAT_ancillaryinterrogators, N_("Ancillary Commands / Interrogators") },
+	{ CAT_foreignscminterface, N_("Interacting with Others") },
+	{ CAT_plumbingmanipulators, N_("Low-level Commands / Manipulators") },
+	{ CAT_plumbinginterrogators, N_("Low-level Commands / Interrogators") },
+	{ CAT_synchingrepositories, N_("Low-level Commands / Synching Repositories") },
+	{ CAT_purehelpers, N_("Low-level Commands / Internal Helpers") },
+	{ 0, NULL }
+};
 
 static const char *drop_prefix(const char *name)
 {
@@ -352,6 +363,11 @@ void list_cmds_by_category(struct string_list *list,
 	}
 }
 
+void list_all_cmds_help(void)
+{
+	print_cmd_by_category(main_categories);
+}
+
 int is_in_cmdlist(struct cmdnames *c, const char *s)
 {
 	int i;

help.h

@@ -19,6 +19,8 @@ static inline void mput_char(char c, unsigned int num)
 }
 
 extern void list_common_cmds_help(void);
+extern void list_all_cmds_help(void);
+
 extern void list_all_main_cmds(struct string_list *list);
 extern void list_all_other_cmds(struct string_list *list);
 extern void list_cmds_by_category(struct string_list *list,

t/t0012-help.sh

@@ -25,6 +25,15 @@ test_expect_success "setup" '
 	EOF
 '
 
+# make sure to exercise these code paths, the output is a bit tricky
+# to verify
+test_expect_success 'basic help commands' '
+	git help >/dev/null &&
+	git help -a >/dev/null &&
+	git help -g >/dev/null &&
+	git help -av >/dev/null
+'
+
 test_expect_success "works for commands and guides by default" '
 	configure_help &&
 	git help status &&