RFR: 6983726: Reimplement MethodHandleProxies.asInterfaceInstance [v16]

[Chen Liang]

On Fri, 26 May 2023 22:05:06 GMT, Mandy Chung <mchung at openjdk.org> wrote:

>>> because a conditionally-exported package is considered a non-(unconditionally-)exported package.
>> 
>> OK.  I need to look into the right solution for this.   The Proxy implementation uses null protection domain to define the proxy class whereas this patch uses the protection domain as the interface to define the MHProxy class.  That's why this issue only occurs in this new implementation.
>
> If we can avoid implementing `sun.invoke.WrapperInstance`, this package access check issue would go away.  Do you think you can look into it?

I think we can probably insert a static final field in a wrapper instance class to point to the implemented class and verify with the `PROXY_CLASS_INFOS` ClassValue, much like VarForm field in VarHandle implementations. This should have less reflective impact than the annotation-based approach, and can be cached in a ClassValue as well. Should we cache it though?

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PR Review Comment: https://git.openjdk.org/jdk/pull/13197#discussion_r1207426728