parse-options: exit 0 on -h

The standard philosophy for Unix software when a help option (such as
--help) is specified is that the software should exit 0, printing the
help output to standard output, since the standard output is for
user-requested output and the program performed the requested task
successfully.  If the user specifies an incorrect option, then the help
output should be printed to standard error (since the user has made a
mistake) and it should exit unsuccessfully.

Most of our commands currently exit 129 on receiving the -h option to
print the short help, which does not line up with the standard
philosophy above.  Let's change that to exit 0 instead.

This requires changes to a variety of tests which previously wanted the
129 exit code, so update them.  Note that because git diff does its own
option parsing, it still exits with 129, so update some of the tests to
expect either exit status.

Some commands also now pass with -h but not --help-all, so handle those
cases differently for those commands.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: bk2204

builtin/blame.c

@@ -1013,6 +1013,7 @@ int cmd_blame(int argc,
 		case PARSE_OPT_UNKNOWN:
 			break;
 		case PARSE_OPT_HELP:
+			exit(0);
 		case PARSE_OPT_HELP_ERROR:
 		case PARSE_OPT_ERROR:
 		case PARSE_OPT_SUBCOMMAND:

builtin/shortlog.c

@@ -433,6 +433,7 @@ int cmd_shortlog(int argc,
 		case PARSE_OPT_UNKNOWN:
 			break;
 		case PARSE_OPT_HELP:
+			exit(0);
 		case PARSE_OPT_HELP_ERROR:
 		case PARSE_OPT_ERROR:
 		case PARSE_OPT_SUBCOMMAND:

builtin/update-index.c

@@ -1133,6 +1133,7 @@ int cmd_update_index(int argc,
 			break;
 		switch (parseopt_state) {
 		case PARSE_OPT_HELP:
+			exit(0);
 		case PARSE_OPT_HELP_ERROR:
 		case PARSE_OPT_ERROR:
 			exit(129);

contrib/subtree/t/t7900-subtree.sh

@@ -99,7 +99,7 @@ test_create_subtree_add () {
 }
 
 test_expect_success 'shows short help text for -h' '
-	test_expect_code 129 git subtree -h >out 2>err &&
+	git subtree -h >out 2>err &&
 	test_must_be_empty err &&
 	grep -e "^ *or: git subtree pull" out &&
 	grep -F -e "--[no-]annotate" out

parse-options.c

@@ -1135,8 +1135,9 @@ enum parse_opt_result parse_options_step(struct parse_opt_ctx_t *ctx,
 		case PARSE_OPT_UNKNOWN:
 			goto unknown;
 		case PARSE_OPT_HELP:
-		case PARSE_OPT_HELP_ERROR:
 			goto show_usage;
+		case PARSE_OPT_HELP_ERROR:
+			goto show_usage_stderr;
 		case PARSE_OPT_NON_OPTION:
 		case PARSE_OPT_SUBCOMMAND:
 		case PARSE_OPT_COMPLETE:
@@ -1170,6 +1171,9 @@ enum parse_opt_result parse_options_step(struct parse_opt_ctx_t *ctx,
  show_usage:
 	return usage_with_options_internal(ctx, usagestr, options,
 					   USAGE_NORMAL, USAGE_TO_STDOUT);
+ show_usage_stderr:
+	return usage_with_options_internal(ctx, usagestr, options,
+					   USAGE_NORMAL, USAGE_TO_STDERR);
 }
 
 int parse_options_end(struct parse_opt_ctx_t *ctx)
@@ -1201,6 +1205,7 @@ int parse_options(int argc, const char **argv,
 	parse_options_start_1(&ctx, argc, argv, prefix, options, flags);
 	switch (parse_options_step(&ctx, options, usagestr)) {
 	case PARSE_OPT_HELP:
+		exit(0);
 	case PARSE_OPT_HELP_ERROR:
 	case PARSE_OPT_ERROR:
 		exit(129);
@@ -1500,11 +1505,11 @@ void show_usage_with_options_if_asked(int ac, const char **av,
 		if (!strcmp(av[1], "-h")) {
 			usage_with_options_internal(NULL, usagestr, opts,
 						    USAGE_NORMAL, USAGE_TO_STDOUT);
-			exit(129);
+			exit(0);
 		} else if (!strcmp(av[1], "--help-all")) {
 			usage_with_options_internal(NULL, usagestr, opts,
 						    USAGE_FULL, USAGE_TO_STDOUT);
-			exit(129);
+			exit(0);
 		}
 	}
 }

t/for-each-ref-tests.sh

@@ -522,7 +522,7 @@ test_expect_success 'Verify descending sort' '
 '
 
 test_expect_success 'Give help even with invalid sort atoms' '
-	test_expect_code 129 ${git_for_each_ref} --sort=bogus -h >actual 2>&1 &&
+	${git_for_each_ref} --sort=bogus -h >actual 2>&1 &&
 	grep "^usage: ${git_for_each_ref}" actual
 '
 

t/t0012-help.sh

@@ -260,7 +260,7 @@ do
 		(
 			GIT_CEILING_DIRECTORIES=$(pwd) &&
 			export GIT_CEILING_DIRECTORIES &&
-			test_expect_code 129 git -C sub $builtin -h >output 2>err
+			git -C sub $builtin -h >output 2>err
 		) &&
 		test_must_be_empty err &&
 		test_grep usage output

t/t0040-parse-options.sh

@@ -68,7 +68,7 @@ Alias
 EOF
 
 test_expect_success 'test help' '
-	test_must_fail test-tool parse-options -h >output 2>output.err &&
+	test-tool parse-options -h >output 2>output.err &&
 	test_must_be_empty output.err &&
 	test_cmp expect output
 '

t/t0450-txt-doc-vs-help.sh

@@ -29,7 +29,7 @@ help_to_synopsis () {
 		return 0
 	fi &&
 	mkdir -p "$out_dir" &&
-	test_expect_code 129 git $builtin -h >"$out.raw" 2>&1 &&
+	test_might_fail git $builtin -h >"$out.raw" 2>&1 &&
 	sed -n \
 		-e '1,/^$/ {
 			/^$/d;

t/t0610-reftable-basics.sh

@@ -15,9 +15,9 @@ export GIT_TEST_DEFAULT_REF_FORMAT
 INVALID_OID=$(test_oid 001)
 
 test_expect_success 'pack-refs does not crash with -h' '
-	test_expect_code 129 git pack-refs -h >usage &&
+	git pack-refs -h >usage &&
 	test_grep "[Uu]sage: git pack-refs " usage &&
-	test_expect_code 129 nongit git pack-refs -h >usage &&
+	nongit git pack-refs -h >usage &&
 	test_grep "[Uu]sage: git pack-refs " usage
 '