cat-file: fix remaining usage bugs

With the migration of --batch-all-objects to OPT_CMDMODE() in the
preceding commit one bug with combining it and other OPT_CMDMODE()
options was solved, but we were still left with e.g. --buffer silently
being discarded when not in batch mode.

Fix all those bugs, and in addition emit errors telling the user
specifically what options can't be combined with what other options,
before this we'd usually just emit the cryptic usage text and leave
the users to work it out by themselves.

This change is rather large, because to do so we need to untangle the
options processing so that we can not only error out, but emit
sensible errors, and e.g. emit errors about options before errors
about stray argc elements (as they might become valid if the option
were removed).

Some of the output changes ("error:" to "fatal:" with
usage_msg_opt[f]()), but none of the exit codes change, except in
those cases where we silently accepted bad option combinations before,
now we'll error out.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 63 insertions, 32 deletions

diff --git a/builtin/cat-file.c b/builtin/cat-file.c
index 8735620813..895292074a 100644
--- a/builtin/cat-file.c
+++ b/builtin/cat-file.c
@@ -648,6 +648,8 @@ static int batch_option_callback(const struct option *opt,
 int cmd_cat_file(int argc, const char **argv, const char *prefix)
 {
 	int opt = 0;
+	int opt_cw = 0;
+	int opt_epts = 0;
 	const char *exp_type = NULL, *obj_name = NULL;
 	struct batch_options batch = {0};
 	int unknown_type = 0;
@@ -701,45 +703,74 @@ int cmd_cat_file(int argc, const char **argv, const char *prefix)
 	batch.buffer_output = -1;
 
 	argc = parse_options(argc, argv, prefix, options, usage, 0);
-	if (argc && batch.enabled)
-		usage_with_options(usage, options);
-	if (opt == 'b') {
-		batch.all_objects = 1;
-	} else if (opt) {
-		if (batch.enabled && (opt == 'c' || opt == 'w'))
-			batch.cmdmode = opt;
-		else if (argc == 1)
-			obj_name = argv[0];
-		else
-			usage_with_options(usage, options);
-	} else if (!opt && !batch.enabled) {
-		if (argc == 2) {
-			exp_type = argv[0];
-			obj_name = argv[1];
-		} else
-			usage_with_options(usage, options);
-	} else if (batch.enabled && batch.cmdmode != opt)
-		usage_with_options(usage, options);
+	opt_cw = (opt == 'c' || opt == 'w');
+	opt_epts = (opt == 'e' || opt == 'p' || opt == 't' || opt == 's');
 
-	if ((batch.follow_symlinks || batch.all_objects) && !batch.enabled) {
-		usage_with_options(usage, options);
-	}
-
-	if (force_path && opt != 'c' && opt != 'w') {
-		error("--path=<path> needs --textconv or --filters");
-		usage_with_options(usage, options);
-	}
+	/* --batch-all-objects? */
+	if (opt == 'b')
+		batch.all_objects = 1;
 
-	if (force_path && batch.enabled) {
-		error("--path=<path> incompatible with --batch");
-		usage_with_options(usage, options);
-	}
+	/* Option compatibility */
+	if (force_path && !opt_cw)
+		usage_msg_optf(_("'%s=<%s>' needs '%s' or '%s'"),
+			       usage, options,
+			       "--path", _("path|tree-ish"), "--filters",
+			       "--textconv");
 
+	/* Option compatibility with batch mode */
+	if (batch.enabled)
+		;
+	else if (batch.follow_symlinks)
+		usage_msg_optf(_("'%s' requires a batch mode"), usage, options,
+			       "--follow_symlinks");
+	else if (batch.buffer_output >= 0)
+		usage_msg_optf(_("'%s' requires a batch mode"), usage, options,
+			       "--buffer");
+	else if (batch.all_objects)
+		usage_msg_optf(_("'%s' requires a batch mode"), usage, options,
+			       "--batch-all-objects");
+
+	/* Batch defaults */
 	if (batch.buffer_output < 0)
 		batch.buffer_output = batch.all_objects;
 
-	if (batch.enabled)
+	/* Return early if we're in batch mode? */
+	if (batch.enabled) {
+		if (opt_cw)
+			batch.cmdmode = opt;
+		else if (opt && opt != 'b')
+			usage_msg_optf(_("'-%c' is incompatible with batch mode"),
+				       usage, options, opt);
+		else if (argc)
+			usage_msg_opt(_("batch modes take no arguments"), usage,
+				      options);
+
 		return batch_objects(&batch);
+	}
+
+	if (opt) {
+		if (!argc && opt == 'c')
+			usage_msg_optf(_("<rev> required with '%s'"),
+				       usage, options, "--textconv");
+		else if (!argc && opt == 'w')
+			usage_msg_optf(_("<rev> required with '%s'"),
+				       usage, options, "--filters");
+		else if (!argc && opt_epts)
+			usage_msg_optf(_("<object> required with '-%c'"),
+				       usage, options, opt);
+		else if (argc == 1)
+			obj_name = argv[0];
+		else
+			usage_msg_opt(_("too many arguments"), usage, options);
+	} else if (!argc) {
+		usage_with_options(usage, options);
+	} else if (argc != 2) {
+		usage_msg_optf(_("only two arguments allowed in <type> <object> mode, not %d"),
+			      usage, options, argc);
+	} else if (argc) {
+		exp_type = argv[0];
+		obj_name = argv[1];
+	}
 
 	if (unknown_type && opt != 't' && opt != 's')
 		die("git cat-file --allow-unknown-type: use with -s or -t");