From @zoffixznet

m​: use nqp; class Foo is Int { method new ($v) { nqp​::p6bindattrinvres(self.bless, Int, q|$!value|, nqp​::getattr(nqp​::decont($v), Int, q|$!value|)) } }; my Foo $x .= new​: 42; say $x; say $x.WHAT;
rakudo-moar bb4579​: OUTPUT​: «(signal SEGV)»

From @zoffixznet

On Tue, 19 Sep 2017 08​:15​:15 -0700, cpan@​zoffix.com wrote​:

m​: use nqp; class Foo is Int { method new ($v) {
nqp​::p6bindattrinvres(self.bless, Int, q|$!value|,
nqp​::getattr(nqp​::decont($v), Int, q|$!value|)) } }; my Foo $x .=
new​: 42; say $x; say $x.WHAT;
rakudo-moar bb4579​: OUTPUT​: «(signal SEGV)»

timotimo++ fixed this.

  Rakudo fix​: rakudo/rakudo@dff7d9b28a
  NQP fix​: Raku/nqp@4bc6050d6e
  MoarVM fix​: MoarVM/MoarVM@3b4b032984
  Tests​: rakudo/rakudo@0d2ca0d7e1

@zoffixznet - Status changed from 'new' to 'resolved'