[PATCH] parse-options: abbreviation engine fix.

[Johannes Schindelin <Johannes.Schindelin@gmx.de>]

When an option could be an ambiguous abbreviation of two options, the code 
used to error out.  Even if an exact match would have occured later.

Test and original patch by Pierre Habouzit.

Signed-off-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
---

	On Mon, 5 Nov 2007, Pierre Habouzit wrote:

	> When we had at least two long option then followed by another 
	> one that was a prefix of both of them, then the abbreviation 
	> detector failed.

	Yeah, I assumed that you would never do such a thing, but I agree 
	that with recursing option parsing it is much more likely.

	It took me some time to understand your patch, and that the moving 
	of the UNSET handling was unnecessary.

	IMHO this patch is easier to read.

 parse-options.c          |   33 +++++++++++++++++++++------------
 t/t0040-parse-options.sh |   13 +++++++++++++
 test-parse-options.c     |    1 +
 3 files changed, 35 insertions(+), 12 deletions(-)

diff --git a/parse-options.c b/parse-options.c
index cc09c98..15b32f7 100644
--- a/parse-options.c
+++ b/parse-options.c
@@ -119,8 +119,8 @@ static int parse_long_opt(struct optparse_t *p, const char *arg,
                           const struct option *options)
 {
 	const char *arg_end = strchr(arg, '=');
-	const struct option *abbrev_option = NULL;
-	int abbrev_flags = 0;
+	const struct option *abbrev_option = NULL, *ambiguous_option = NULL;
+	int abbrev_flags = 0, ambiguous_flags = 0;
 
 	if (!arg_end)
 		arg_end = arg + strlen(arg);
@@ -137,16 +137,16 @@ static int parse_long_opt(struct optparse_t *p, const char *arg,
 			/* abbreviated? */
 			if (!strncmp(options->long_name, arg, arg_end - arg)) {
 is_abbreviated:
-				if (abbrev_option)
-					return error("Ambiguous option: %s "
-						"(could be --%s%s or --%s%s)",
-						arg,
-						(flags & OPT_UNSET) ?
-							"no-" : "",
-						options->long_name,
-						(abbrev_flags & OPT_UNSET) ?
-							"no-" : "",
-						abbrev_option->long_name);
+				if (abbrev_option) {
+					/*
+					 * If this is abbreviated, it is
+					 * ambiguous. So when there is no
+					 * exact match later, we need to
+					 * error out.
+					 */
+					ambiguous_option = abbrev_option;
+					ambiguous_flags = abbrev_flags;
+				}
 				if (!(flags & OPT_UNSET) && *arg_end)
 					p->opt = arg_end + 1;
 				abbrev_option = options;
@@ -176,6 +176,15 @@ is_abbreviated:
 		}
 		return get_value(p, options, flags);
 	}
+
+	if (ambiguous_option)
+		return error("Ambiguous option: %s "
+			"(could be --%s%s or --%s%s)",
+			arg,
+			(ambiguous_flags & OPT_UNSET) ?  "no-" : "",
+			ambiguous_option->long_name,
+			(abbrev_flags & OPT_UNSET) ?  "no-" : "",
+			abbrev_option->long_name);
 	if (abbrev_option)
 		return get_value(p, abbrev_option, abbrev_flags);
 	return error("unknown option `%s'", arg);
diff --git a/t/t0040-parse-options.sh b/t/t0040-parse-options.sh
index ae49424..ee758e5 100755
--- a/t/t0040-parse-options.sh
+++ b/t/t0040-parse-options.sh
@@ -18,6 +18,7 @@ string options
     -s, --string <string>
                           get a string
     --string2 <str>       get another string
+    --st <st>             get another string (pervert ordering)
 
 EOF
 
@@ -90,4 +91,16 @@ test_expect_failure 'ambiguously abbreviated option' '
         test $? != 129
 '
 
+cat > expect << EOF
+boolean: 0
+integer: 2
+string: 123
+EOF
+
+test_expect_failure 'non ambiguous option (after two options it abbreviates)' '
+	test-parse-options --st 123 &&
+	test ! -s output.err &&
+	git diff expect output
+'
+
 test_done
diff --git a/test-parse-options.c b/test-parse-options.c
index 277cfe4..4d3e2ec 100644
--- a/test-parse-options.c
+++ b/test-parse-options.c
@@ -18,6 +18,7 @@ int main(int argc, const char **argv)
 		OPT_GROUP("string options"),
 		OPT_STRING('s', "string", &string, "string", "get a string"),
 		OPT_STRING(0, "string2", &string, "str", "get another string"),
+		OPT_STRING(0, "st", &string, "st", "get another string (pervert ordering)"),
 		OPT_END(),
 	};
 	int i;
-- 
1.5.3.5.1549.g91a3