parse-options: catch likely typo in presense of aggregated options.

If options are aggregated, and that the whole token is an exact
prefix of a long option that is longer than 2 letters, reject
it.  This is to prevent a common typo:

	$ git commit -amend

to get interpreted as "commit all with message 'end'".

The typo check isn't performed if there is no aggregation,
because the stuck form is the recommended one.  If we have `-o`
being a valid short option that takes an argument, and --option
a long one, then we _MUST_ accept -option as "'o' option with
argument 'ption'", which is our official recommended form.

Signed-off-by: Pierre Habouzit <madcoder@debian.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 28 insertions, 2 deletions

diff --git a/parse-options.c b/parse-options.c
index 7a08a0c64..d9562ba50 100644
--- a/parse-options.c
+++ b/parse-options.c
@@ -216,6 +216,26 @@ is_abbreviated:
 	return error("unknown option `%s'", arg);
 }
 
+void check_typos(const char *arg, const struct option *options)
+{
+	if (strlen(arg) < 3)
+		return;
+
+	if (!prefixcmp(arg, "no-")) {
+		error ("did you mean `--%s` (with two dashes ?)", arg);
+		exit(129);
+	}
+
+	for (; options->type != OPTION_END; options++) {
+		if (!options->long_name)
+			continue;
+		if (!prefixcmp(options->long_name, arg)) {
+			error ("did you mean `--%s` (with two dashes ?)", arg);
+			exit(129);
+		}
+	}
+}
+
 static NORETURN void usage_with_options_internal(const char * const *,
                                                  const struct option *, int);
 
@@ -235,12 +255,18 @@ int parse_options(int argc, const char **argv, const struct option *options,
 
 		if (arg[1] != '-') {
 			args.opt = arg + 1;
-			do {
+			if (*args.opt == 'h')
+				usage_with_options(usagestr, options);
+			if (parse_short_opt(&args, options) < 0)
+				usage_with_options(usagestr, options);
+			if (args.opt)
+				check_typos(arg + 1, options);
+			while (args.opt) {
 				if (*args.opt == 'h')
 					usage_with_options(usagestr, options);
 				if (parse_short_opt(&args, options) < 0)
 					usage_with_options(usagestr, options);
-			} while (args.opt);
+			}
 			continue;
 		}