C<experimental:re_strict> warning.
See L<'strict' in re|re/'strict' mode>.
+=head2 New "const" subroutine attribute
+
+The "const" attribute can be applied to an anonymous subroutine. It causes
+it to be executed immediately when it is cloned. Its value is captured and
+used to create a new constant subroutine that is returned. This feature is
+experimental. See L<perlsub/Constant Functions>.
+
=head1 Security
XXX Any security-related notices go here. In particular, any security