StrictClass

martin@babylon MINGW64 ~/repositories/papierlos/perl6-papierlos (master)
$ perl6 -e 'use StrictClass; role B { has $.foo is required }; class A does B {}; A.new( foo => 1).perl.say;'
A.new(foo => 1)

martin@babylon MINGW64 ~/repositories/papierlos/perl6-papierlos (master)
$ perl6 -e 'use StrictClass; role B { has $.foo is required }; class A does B does StrictClass  {}; A.new( foo => 1).perl.say;'
The attribute '$!foo' is required, but you did not provide a value for it.
  in method new at C:\rakudo\share\perl6\site\sources\9CFA02DF4E647A51F48B1D301294D0DCFA1E8357 (StrictClass) line 9
  in block <unit> at -e line 1

martin@babylon MINGW64 ~/repositories/papierlos/perl6-papierlos (master)
$ perl6 -e 'use StrictClass; role B { has $.foo }; class A does B does StrictClass  {}; A.new( foo => 1).perl.say;'
any(A.new(foo => Any), {:foo(1)})

--------

martin@babylon MINGW64 ~/repositories/papierlos/lib (master)
$ cat A.pm6
use StrictClass;
use B;
class A does B does StrictClass {}

martin@babylon MINGW64 ~/repositories/papierlos/lib (master)
$ cat B.pm6
role B {
        has $.foo is required;
}

martin@babylon MINGW64 ~/repositories/papierlos/lib (master)
$ perl6 -I. -e 'use A; A.new(:foo(1))'
The attribute '$!foo' is required, but you did not provide a value for it.
  in method new at C:\rakudo\share\perl6\site\sources\9CFA02DF4E647A51F48B1D301294D0DCFA1E8357 (StrictClass) line 9
  in block <unit> at -e line 1