empty capture

gistfile1.txt

use v6;

sub somesub(){
        say "i haz a sub";
};

class Foo {
        has @.a is rw;
        method add(&c){ @.a.push(&c) }
        method postcircumfix:<( )>($self: |$c) {
                #since i stripped self into $self, the capture should be empty
                @.a>>.(|$c)
        }
}

my $foo = Foo.new;
$foo.add(&somesub);

$foo();
#> Too many positional parameters passed; got 1 but expected 0
#>  in sub somesub at empty_capture.p6:3