Merge branch 'kh/you-still-use-whatchanged-fix' into maint-2.51

The "do you still use it?" message given by a command that is
deeply deprecated and allow us to suggest alternatives has been
updated.

* kh/you-still-use-whatchanged-fix:
  BreakingChanges: remove claim about whatchanged reports
  whatchanged: remove not-even-shorter clause
  whatchanged: hint about git-log(1) and aliasing
  you-still-use-that??: help the user help themselves
  t0014: test shadowing of aliases for a sample of builtins
  git: allow alias-shadowing deprecated builtins
  git: move seen-alias bookkeeping into handle_alias(...)
  git: add `deprecated` category to --list-cmds
  Makefile: don’t add whatchanged after it has been removed

Author: gitster

Documentation/BreakingChanges.adoc

@@ -235,7 +235,7 @@ These features will be removed.
   equivalent `git log --raw`.  We have nominated the command for
   removal, have changed the command to refuse to work unless the
   `--i-still-use-this` option is given, and asked the users to report
-  when they do so.  So far there hasn't been a single complaint.
+  when they do so.
 +
 The command will be removed.
 

Documentation/config/alias.adoc

@@ -3,7 +3,8 @@ alias.*::
 	after defining `alias.last = cat-file commit HEAD`, the invocation
 	`git last` is equivalent to `git cat-file commit HEAD`. To avoid
 	confusion and troubles with script usage, aliases that
-	hide existing Git commands are ignored. Arguments are split by
+	hide existing Git commands are ignored except for deprecated
+	commands.  Arguments are split by
 	spaces, the usual shell quoting and escaping are supported.
 	A quote pair or a backslash can be used to quote them.
 +

Documentation/git-whatchanged.adoc

@@ -15,7 +15,7 @@ WARNING
 -------
 `git whatchanged` has been deprecated and is scheduled for removal in
 a future version of Git, as it is merely `git log` with different
-default; `whatchanged` is not even shorter to type than `log --raw`.
+defaults.
 
 DESCRIPTION
 -----------
@@ -24,7 +24,11 @@ Shows commit logs and diff output each commit introduces.
 
 New users are encouraged to use linkgit:git-log[1] instead.  The
 `whatchanged` command is essentially the same as linkgit:git-log[1]
-but defaults to showing the raw format diff output and skipping merges.
+but defaults to showing the raw format diff output and skipping merges:
+
+----
+git log --raw --no-merges
+----
 
 The command is primarily kept for historical reasons; fingers of
 many people who learned Git long before `git log` was invented by

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

Makefile

@@ -883,7 +883,9 @@ BUILT_INS += git-stage$X
 BUILT_INS += git-status$X
 BUILT_INS += git-switch$X
 BUILT_INS += git-version$X
+ifndef WITH_BREAKING_CHANGES
 BUILT_INS += git-whatchanged$X
+endif
 
 # what 'all' will build but not install in gitexecdir
 OTHER_PROGRAMS += git$X

builtin/log.c

@@ -543,7 +543,13 @@ int cmd_whatchanged(int argc,
 	cmd_log_init(argc, argv, prefix, &rev, &opt, &cfg);
 
 	if (!cfg.i_still_use_this)
-		you_still_use_that("git whatchanged");
+		you_still_use_that("git whatchanged",
+				   _("\n"
+				     "hint: You can replace 'git whatchanged <opts>' with:\n"
+				     "hint:\tgit log <opts> --raw --no-merges\n"
+				     "hint: Or make an alias:\n"
+				     "hint:\tgit config set --global alias.whatchanged 'log --raw --no-merges'\n"
+				     "\n"));
 
 	if (!rev.diffopt.output_format)
 		rev.diffopt.output_format = DIFF_FORMAT_RAW;

builtin/pack-redundant.c

@@ -626,7 +626,7 @@ int cmd_pack_redundant(int argc, const char **argv, const char *prefix UNUSED, s
 	}
 
 	if (!i_still_use_this)
-		you_still_use_that("git pack-redundant");
+		you_still_use_that("git pack-redundant", NULL);
 
 	if (load_all_packs)
 		load_all();

git-compat-util.h

@@ -460,7 +460,7 @@ void warning_errno(const char *err, ...) __attribute__((format (printf, 1, 2)));
 
 void show_usage_if_asked(int ac, const char **av, const char *err);
 
-NORETURN void you_still_use_that(const char *command_name);
+NORETURN void you_still_use_that(const char *command_name, const char *hint);
 
 #ifndef NO_OPENSSL
 #ifdef APPLE_COMMON_CRYPTO

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);
@@ -360,7 +365,7 @@ static int handle_options(const char ***argv, int *argc, int *envchanged)
 	return (*argv) - orig_argv;
 }
 
-static int handle_alias(struct strvec *args)
+static int handle_alias(struct strvec *args, struct string_list *expanded_aliases)
 {
 	int envchanged = 0, ret = 0, saved_errno = errno;
 	int count, option_count;
@@ -371,6 +376,8 @@ static int handle_alias(struct strvec *args)
 	alias_command = args->v[0];
 	alias_string = alias_lookup(alias_command);
 	if (alias_string) {
+		struct string_list_item *seen;
+
 		if (args->nr == 2 && !strcmp(args->v[1], "-h"))
 			fprintf_ln(stderr, _("'%s' is aliased to '%s'"),
 				   alias_command, alias_string);
@@ -418,6 +425,25 @@ static int handle_alias(struct strvec *args)
 		if (!strcmp(alias_command, new_argv[0]))
 			die(_("recursive alias: %s"), alias_command);
 
+		string_list_append(expanded_aliases, alias_command);
+		seen = unsorted_string_list_lookup(expanded_aliases,
+						   new_argv[0]);
+
+		if (seen) {
+			struct strbuf sb = STRBUF_INIT;
+			for (size_t i = 0; i < expanded_aliases->nr; i++) {
+				struct string_list_item *item = &expanded_aliases->items[i];
+
+				strbuf_addf(&sb, "\n  %s", item->string);
+				if (item == seen)
+					strbuf_addstr(&sb, " <==");
+				else if (i == expanded_aliases->nr - 1)
+					strbuf_addstr(&sb, " ==>");
+			}
+			die(_("alias loop detected: expansion of '%s' does"
+			      " not terminate:%s"), expanded_aliases->items[0].string, sb.buf);
+		}
+
 		trace_argv_printf(new_argv,
 				  "trace: alias expansion: %s =>",
 				  alias_command);
@@ -590,7 +616,7 @@ 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 +673,7 @@ 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 +694,16 @@ 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);
 	}
@@ -793,13 +824,29 @@ static void execv_dashed_external(const char **argv)
 		exit(128);
 }
 
+static int is_deprecated_command(const char *cmd)
+{
+	struct cmd_struct *builtin = get_builtin(cmd);
+	return builtin && (builtin->option & DEPRECATED);
+}
+
 static int run_argv(struct strvec *args)
 {
 	int done_alias = 0;
-	struct string_list cmd_list = STRING_LIST_INIT_DUP;
-	struct string_list_item *seen;
+	struct string_list expanded_aliases = STRING_LIST_INIT_DUP;
 
 	while (1) {
+		/*
+		 * Allow deprecated commands to be overridden by aliases. This
+		 * creates a seamless path forward for people who want to keep
+		 * using the name after it is gone, but want to skip the
+		 * deprecation complaint in the meantime.
+		 */
+		if (is_deprecated_command(args->v[0]) &&
+		    handle_alias(args, &expanded_aliases)) {
+			done_alias = 1;
+			continue;
+		}
 		/*
 		 * If we tried alias and futzed with our environment,
 		 * it no longer is safe to invoke builtins directly in
@@ -849,35 +896,17 @@ static int run_argv(struct strvec *args)
 		/* .. then try the external ones */
 		execv_dashed_external(args->v);
 
-		seen = unsorted_string_list_lookup(&cmd_list, args->v[0]);
-		if (seen) {
-			struct strbuf sb = STRBUF_INIT;
-			for (size_t i = 0; i < cmd_list.nr; i++) {
-				struct string_list_item *item = &cmd_list.items[i];
-
-				strbuf_addf(&sb, "\n  %s", item->string);
-				if (item == seen)
-					strbuf_addstr(&sb, " <==");
-				else if (i == cmd_list.nr - 1)
-					strbuf_addstr(&sb, " ==>");
-			}
-			die(_("alias loop detected: expansion of '%s' does"
-			      " not terminate:%s"), cmd_list.items[0].string, sb.buf);
-		}
-
-		string_list_append(&cmd_list, args->v[0]);
-
 		/*
 		 * It could be an alias -- this works around the insanity
 		 * of overriding "git log" with "git show" by having
 		 * alias.log = show
 		 */
-		if (!handle_alias(args))
+		if (!handle_alias(args, &expanded_aliases))
 			break;
 		done_alias = 1;
 	}
 
-	string_list_clear(&cmd_list, 0);
+	string_list_clear(&expanded_aliases, 0);
 
 	return done_alias;
 }

t/t0014-alias.sh

@@ -27,6 +27,20 @@ test_expect_success 'looping aliases - internal execution' '
 	test_grep "^fatal: alias loop detected: expansion of" output
 '
 
+test_expect_success 'looping aliases - deprecated builtins' '
+	test_config alias.whatchanged pack-redundant &&
+	test_config alias.pack-redundant whatchanged &&
+	cat >expect <<-EOF &&
+	${SQ}whatchanged${SQ} is aliased to ${SQ}pack-redundant${SQ}
+	${SQ}pack-redundant${SQ} is aliased to ${SQ}whatchanged${SQ}
+	fatal: alias loop detected: expansion of ${SQ}whatchanged${SQ} does not terminate:
+	  whatchanged <==
+	  pack-redundant ==>
+	EOF
+	test_must_fail git whatchanged -h 2>actual &&
+	test_cmp expect actual
+'
+
 # This test is disabled until external loops are fixed, because would block
 # the test suite for a full minute.
 #
@@ -55,4 +69,47 @@ test_expect_success 'tracing a shell alias with arguments shows trace of prepare
 	test_cmp expect actual
 '
 
+can_alias_deprecated_builtin () {
+	cmd="$1" &&
+	# some git(1) commands will fail for `-h` (the case for
+	# git-status as of 2025-09-07)
+	test_might_fail git status -h >expect &&
+	test_file_not_empty expect &&
+	test_might_fail git -c alias."$cmd"=status "$cmd" -h >actual &&
+	test_cmp expect actual
+}
+
+test_expect_success 'can alias-shadow deprecated builtins' '
+	for cmd in $(git --list-cmds=deprecated)
+	do
+		can_alias_deprecated_builtin "$cmd" || return 1
+	done
+'
+
+test_expect_success 'can alias-shadow via two deprecated builtins' '
+	# some git(1) commands will fail... (see above)
+	test_might_fail git status -h >expect &&
+	test_file_not_empty expect &&
+	test_might_fail git -c alias.whatchanged=pack-redundant \
+		-c alias.pack-redundant=status whatchanged -h >actual &&
+	test_cmp expect actual
+'
+
+cannot_alias_regular_builtin () {
+	cmd="$1" &&
+	# some git(1) commands will fail... (see above)
+	test_might_fail git "$cmd" -h >expect &&
+	test_file_not_empty expect &&
+	test_might_fail git -c alias."$cmd"=status "$cmd" -h >actual &&
+	test_cmp expect actual
+}
+
+test_expect_success 'cannot alias-shadow a sample of regular builtins' '
+	for cmd in grep check-ref-format interpret-trailers \
+		checkout-index fast-import diagnose rev-list prune
+	do
+		cannot_alias_regular_builtin "$cmd" || return 1
+	done
+'
+
 test_done