+"foo" =~ /(?{new Hlagh})/;
+----
+[ 'new', 'Hlagh' ]
+####
+"foo" =~ /(?{new $x})/;
+----
+[ 'new', '$x' ]
+####
+"foo" =~ /(?{new $y})/;
+----
+[ 'new', '$y' ]
+####
+"foo" =~ /(??{new Hlagh})/;
+----
+[ 'new', 'Hlagh' ]
+####
+"foo" =~ /(??{new $x})/;
+----
+[ 'new', '$x' ]
+####
+"foo" =~ /(??{new $y})/;
+----
+[ 'new', '$y' ]
+####