date_strptime.c: get rid of backtrack explosion

* ext/date/date_strptime.c (date__strptime_internal): unset
  case-insensitive flag for [:alpha:], which already implies both
  cases, to get rid of backtrack explosion.  [ruby-core:58984]
  [Bug #9221]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44126 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,10 @@
+Tue Dec 10 23:58:30 2013  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* ext/date/date_strptime.c (date__strptime_internal): unset
+	  case-insensitive flag for [:alpha:], which already implies both
+	  cases, to get rid of backtrack explosion.  [ruby-core:58984]
+	  [Bug #9221]
+
 Tue Dec 10 23:44:42 2013  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* array.c (rb_ary_hash): add salt to differentiate false and empty

ext/date/date_strptime.c

@@ -567,8 +567,8 @@ date__strptime_internal(const char *str, size_t slen,
 		    static const char pat_source[] =
 			"\\A("
 			"(?:gmt|utc?)?[-+]\\d+(?:[,.:]\\d+(?::\\d+)?)?"
-			"|[[:alpha:].\\s]+(?:standard|daylight)\\s+time\\b"
-			"|[[:alpha:]]+(?:\\s+dst)?\\b"
+			"|(?-i:[[:alpha:].\\s]+)(?:standard|daylight)\\s+time\\b"
+			"|(?-i:[[:alpha:]]+)(?:\\s+dst)?\\b"
 			")";
 		    static VALUE pat = Qnil;
 		    VALUE m, b;