----- Mail original ----- > De: "Brian Goetz" <brian.go...@oracle.com> > À: "Remi Forax" <fo...@univ-mlv.fr> > Cc: "amber-spec-experts" <amber-spec-experts@openjdk.java.net> > Envoyé: Jeudi 2 Avril 2020 16:19:15 > Objet: Re: Semantics of an empty PermittedSubtypes attribute for the VM
> At the language level, we won’t let you define a class with an empty set of > permitted types; you should define a final class instead. > > But, having the VM treat an empty PS attribute as if it were not there seems > wrong; I would think an empty PS attribute would be a class file error. For comparison, i believe the VM also allows attribute NestMembers or BootstrapMethods to be empty. Rémi > >> On Apr 2, 2020, at 7:58 AM, Remi Forax <fo...@univ-mlv.fr> wrote: >> >> Hi all, >> With my ASM hat, >> from the JVMS POV, javac can not generate an empty list of permitted subtypes >> and the implementation in Hotspot ignores the attribute PermittedSubtypes if >> there is no subtype listed. >> >> So currently, ASM doesn't allow you to create an attribute PermittedSubtypes >> with an empty number of subtypes. >> I believe this is the correct semantics, i just want to be sure that i've not >> overlook something. >> >> regards, >> Rémi
