From @gfldex

role R { method Str() {'hidden!'} };
my $i = 1 but R;
sub f(\bound){ put bound };
f($i);
$i++;
f($i);

# OUTPUT«hidden!␤2␤»

From @coke

On Sun Dec 27 15​:43​:56 2015, gfldex wrote​:

role R { method Str() {'hidden!'} };
my $i = 1 but R;
sub f(\bound){ put bound };
f($i);
$i++;
f($i);

# OUTPUT«hidden!␤2␤»

20​:45 < [Coke]> https://rt-archive.perl.org/perl6/Ticket/Display.html?id=127050 - this
  appears to be a DIHWIDT - the role is applied to the literal 1,
  making a new object; when you ++ you're getting a new instance,
  a (fresh) 2. No?
20​:49 < jnthn> [Coke]​: It's correct behavior. The ticket is confused.
20​:49 < jnthn> (So yes, you're correct. :))
20​:50 < [Coke]> jnthn​: ok, I'll reject.

--
Will "Coke" Coleda

The RT System itself - Status changed from 'new' to 'open'

@coke - Status changed from 'open' to 'rejected'

From @coke

20​:51 < jnthn> Just to add a little, $i++ is taking the Scalar container $i and
  changing the value it references.
20​:51 < jnthn> And the role was, like you said, on the value 1, and now it
  contains the value 2.

--
Will "Coke" Coleda