date_parse.c: get rid of backtrack explosion

* ext/date/date_parse.c (parse_time): unset case-insensitive flag
  for [:alpha:], which already implies both cases, to get rid of
  backtrack explosion.  [ruby-core:58876] [Bug #9221]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44086 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,9 @@
+Mon Dec  9 11:14:26 2013  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* ext/date/date_parse.c (parse_time): unset case-insensitive flag
+	  for [:alpha:], which already implies both cases, to get rid of
+	  backtrack explosion.  [ruby-core:58876] [Bug #9221]
+
 Mon Dec  9 08:40:40 2013  Eric Hodel  <drbrain@segment7.net>
 
 	* lib/rubygems:  Update to RubyGems master bf37240.  Fixes useless

ext/date/date_parse.c

@@ -765,9 +765,9 @@ parse_time(VALUE str, VALUE hash)
 		   "("
 		     "(?:gmt|utc?)?[-+]\\d+(?:[,.:]\\d+(?::\\d+)?)?"
 		   "|"
-		     "[[:alpha:].\\s]+(?:standard|daylight)\\stime\\b"
+		     "(?-i:[[:alpha:].\\s]+)(?:standard|daylight)\\stime\\b"
 		   "|"
-		     "[[:alpha:]]+(?:\\sdst)?\\b"
+		     "(?-i:[[:alpha:]]+)(?:\\sdst)?\\b"
 		   ")"
 		")?";
     static VALUE pat = Qnil;