[perl #133762] Quanthashes should be parameterizable

# New Ticket Created by  Lars Dɪᴇᴄᴋᴏᴡ 迪拉斯 
# Please include the string:  [perl #133762]
# in the subject line of all future correspondence about this issue. 
# <URL: https://rt.perl.org/Ticket/Display.html?id=133762 >


› rpm -qi rakudo | rg Version
Version     : 2018.12

subset Foo of Str where .chars > 0;
my SetHash of Foo %f;
%f.elems.say;

    SetHash cannot be parameterized

subset Foo of Str where .chars > 0;
subset Foo-SetHash of SetHash where $_ ~~ Foo;
my Foo-SetHash $f;
$f.elems.say;

    Invocant of method 'elems' must be an object instance of type 'Setty', not a type object of type 'Foo-SetHash'.  Did you forget a '.new'?

subset Foo of Str where .chars > 0;
subset Foo-SetHash of SetHash where $_ ~~ Foo;
my $f = Foo-SetHash.new;
$f.elems.say;

    You cannot create an instance of this type (Foo-SetHash)