git: add `deprecated` category to --list-cmds

With 145 builtin commands (according to `git --list-cmds=builtins`),
users are probably not keeping on top of which ones (if any) are
deprecated.

Let’s expand the experimental `--list-cmds`[1] to allow users and
programs to query for this information.  We will also use this in an
upcoming commit to implement `is_deprecated_command`.

[1]: Using something which is experimental to query for deprecations is
    perhaps not the most ideal approach, but it is simple to implement
    and better than having to scan the documentation

Acked-by: Patrick Steinhardt <ps@pks.im>
Helped-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Kristoffer Haugsbakk <code@khaugsbakk.name>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

2 files changed, 20 insertions, 9 deletions

diff --git a/Documentation/git.adoc b/Documentation/git.adoc
index 743b7b00e4..a2f0838b16 100644
--- a/Documentation/git.adoc
+++ b/Documentation/git.adoc
@@ -219,7 +219,8 @@ If you just want to run git as if it was started in `<path>` then use
 	List commands by group. This is an internal/experimental
 	option and may change or be removed in the future. Supported
 	groups are: builtins, parseopt (builtin commands that use
-	parse-options), main (all commands in libexec directory),
+	parse-options), deprecated (deprecated builtins),
+	main (all commands in libexec directory),
 	others (all other commands in `$PATH` that have git- prefix),
 	list-<category> (see categories in command-list.txt),
 	nohelpers (exclude helper commands), alias and config
diff --git a/git.c b/git.c
index 83eac0aeab..511efdf205 100644
--- a/git.c
+++ b/git.c
@@ -28,6 +28,7 @@
 #define NEED_WORK_TREE		(1<<3)
 #define DELAY_PAGER_CONFIG	(1<<4)
 #define NO_PARSEOPT		(1<<5) /* parse-options is not used */
+#define DEPRECATED		(1<<6)
 
 struct cmd_struct {
 	const char *cmd;
@@ -51,7 +52,9 @@ const char git_more_info_string[] =
 
 static int use_pager = -1;
 
-static void list_builtins(struct string_list *list, unsigned int exclude_option);
+static void list_builtins(struct string_list *list,
+			  unsigned int include_option,
+			  unsigned int exclude_option);
 
 static void exclude_helpers_from_list(struct string_list *list)
 {
@@ -88,7 +91,7 @@ static int list_cmds(const char *spec)
 		int len = sep - spec;
 
 		if (match_token(spec, len, "builtins"))
-			list_builtins(&list, 0);
+			list_builtins(&list, 0, 0);
 		else if (match_token(spec, len, "main"))
 			list_all_main_cmds(&list);
 		else if (match_token(spec, len, "others"))
@@ -99,6 +102,8 @@ static int list_cmds(const char *spec)
 			list_aliases(&list);
 		else if (match_token(spec, len, "config"))
 			list_cmds_by_config(&list);
+		else if (match_token(spec, len, "deprecated"))
+			list_builtins(&list, DEPRECATED, 0);
 		else if (len > 5 && !strncmp(spec, "list-", 5)) {
 			struct strbuf sb = STRBUF_INIT;
 
@@ -322,7 +327,7 @@ static int handle_options(const char ***argv, int *argc, int *envchanged)
 			if (!strcmp(cmd, "parseopt")) {
 				struct string_list list = STRING_LIST_INIT_DUP;
 
-				list_builtins(&list, NO_PARSEOPT);
+				list_builtins(&list, 0, NO_PARSEOPT);
 				for (size_t i = 0; i < list.nr; i++)
 					printf("%s ", list.items[i].string);
 				string_list_clear(&list, 0);
@@ -590,7 +595,7 @@ static struct cmd_struct commands[] = {
 	{ "notes", cmd_notes, RUN_SETUP },
 	{ "pack-objects", cmd_pack_objects, RUN_SETUP },
 #ifndef WITH_BREAKING_CHANGES
-	{ "pack-redundant", cmd_pack_redundant, RUN_SETUP | NO_PARSEOPT },
+	{ "pack-redundant", cmd_pack_redundant, RUN_SETUP | NO_PARSEOPT | DEPRECATED },
 #endif
 	{ "pack-refs", cmd_pack_refs, RUN_SETUP },
 	{ "patch-id", cmd_patch_id, RUN_SETUP_GENTLY | NO_PARSEOPT },
@@ -647,7 +652,7 @@ static struct cmd_struct commands[] = {
 	{ "verify-tag", cmd_verify_tag, RUN_SETUP },
 	{ "version", cmd_version },
 #ifndef WITH_BREAKING_CHANGES
-	{ "whatchanged", cmd_whatchanged, RUN_SETUP },
+	{ "whatchanged", cmd_whatchanged, RUN_SETUP | DEPRECATED },
 #endif
 	{ "worktree", cmd_worktree, RUN_SETUP },
 	{ "write-tree", cmd_write_tree, RUN_SETUP },
@@ -668,11 +673,16 @@ int is_builtin(const char *s)
 	return !!get_builtin(s);
 }
 
-static void list_builtins(struct string_list *out, unsigned int exclude_option)
+static void list_builtins(struct string_list *out,
+			  unsigned int include_option,
+			  unsigned int exclude_option)
 {
+	if (include_option && exclude_option)
+		BUG("'include_option' and 'exclude_option' are mutually exclusive");
 	for (size_t i = 0; i < ARRAY_SIZE(commands); i++) {
-		if (exclude_option &&
-		    (commands[i].option & exclude_option))
+		if (include_option && !(commands[i].option & include_option))
+			continue;
+		if (exclude_option && (commands[i].option & exclude_option))
 			continue;
 		string_list_append(out, commands[i].cmd);
 	}