Bogus(?) Error when is required an attribute of CStruct repr

[zoffixznet]

If you mark an attribute as is required on a class with CStruct repr, then you get an error about CStruct representation attribute. Is that an accurate error? Sounds like it's saying an attribute with CStruct repr isn't supported, which isn't what the code is trying to use:

$ perl6 -e 'use NativeCall; class B is repr("CStruct") { has uint32 $.b } ; B.new(:1b)'


$ perl6 -e 'use NativeCall; class B is repr("CStruct") { has uint32 $.b is required} ; B.new(:1b)'
CStruct representation attribute not yet fully implemented
  in submethod BUILDALL at -e line 1
  in block <unit> at -e line 1

This is Rakudo version 2018.05-54-g148d7c5 built on MoarVM version 2018.05-57-g89dee3b
implementing Perl 6.c.

Looks like it comes from here, but I'm unsure if the error should be changed to say the trait is not supported or if there is actually a way to check if an attribute has been initialized and that should be implemented instead of throwing an error.