$ for v in 5.8.9 5.10t 5.12t 5.14t 5.16t 5.18t 5.20t; do
   echo $v
   $v/bin/perl -le'print ref( qr/x/ )'
done
5.8.9
Regexp
5.10t
Regexp
5.12t
Regexp
5.14t
Regexp
5.16t
Regexp
5.18t
Regexp
5.20t
Regexp