RFR: JDK-8225056 VM support for sealed classes

[Harold Seigel]

Hi Remi,

Thank you for reviewing the ASM changes.

Harold

On 5/19/2020 4:41 AM, Remi Forax wrote:
>
> ----- Mail original -----
>> De: "David Holmes" <david.holmes at oracle.com>
>> À: "Harold David Seigel" <harold.seigel at oracle.com>, "hotspot-runtime-dev" <hotspot-runtime-dev at openjdk.java.net>,
>> "amber-dev" <amber-dev at openjdk.java.net>, "core-libs-dev" <core-libs-dev at openjdk.java.net>, "serviceability-dev"
>> <serviceability-dev at openjdk.java.net>
>> Envoyé: Mardi 19 Mai 2020 07:26:38
>> Objet: Re: RFR: JDK-8225056 VM support for sealed classes
>> Hi Harold,
>>
>> Adding serviceability-dev for the serviceability related changes.
>>
>> Nit: "VM support for sealed classes"
>>
>> This RFR covers the VM, core-libs, serviceability and even some
>> langtools tests. AFAICS only the javac changes are not included here so
>> when and where will they be reviewed and under what bug id? Ideally
>> there will be a single JBS issue for "Implementation of JEP 360: Sealed
>> types". It's okay to break up the RFRs across different areas, but it
>> should be done under one bug id.
>>
>> Overall this looks good. I've looked at all files and mainly have some
>> style nits in various places. But there are some more significant items
>> below.
>>
>> On 14/05/2020 7:09 am, Harold Seigel wrote:
>>> Hi,
>>>
>>> Please review this patch for JVM and Core-libs support for the JEP 360
>>> Sealed Classes preview feature.  Code changes include the following:
>>>
>>>    * Processing of the new PermittedSubclasses attribute to enforce that
>>>      a class or interface, whose super is a sealed class or interface,
>>>      must be listed in the super's PermittedSubclasses attribute.
>>>    * Disallow redefinition of a sealed class or interface if its
>>>      redefinition would change its PermittedSubclasses attribute.
>>>    * Support API's to determine if a class or interface is sealed and, if
>>>      it's sealed, return a list of its permitted subclasses.
>>>    * asm support for the PermittedSubclasses attribute
>> I assume Remi is providing the upstream support in ASM? :) But also see
>> below ...
>
> Currently the version of ASM used JDK already supports sealed classes but with the attribute named PermittedSubtypes instead of PermittedSubclasses.
> This patch renames the attribute which is the right thing to do.
> Then when JDK 15 will be released, we will release ASM 9 with full support of PermittedSubclasses, with the right method names, docs, etc, that will be then integrated in JDK 16.
>
> So with my ASM hat, the changes to the 3 ASM classes are good.
>
> Rémi