RFR: 6983726: Reimplement MethodHandleProxies.asInterfaceInstance [v16]

[Mandy Chung]

On Wed, 31 May 2023 12:38:14 GMT, Johannes Kuhn <jkuhn at openjdk.org> wrote:

>>> Then we still need to obtain the implemented interface and original method handle information every time they are queried. Having these information (or the method handle providing access) computed early is more convenient.
>> 
>> I was thinking the wrapper instance class still implements some private methods to get the implemented interface and original method handle which can be accessed only `java.base` via deep reflection.
>
>> It should not trigger `checkPackageAccess` if it does not implement the interface AFAICT.
> 
> `checkPackageAccess` is also called by the application class loader:
> https://github.com/openjdk/jdk/blob/master/src/java.base/share/classes/jdk/internal/loader/ClassLoaders.java#L174-L189
> 
> It should make it impossible to reference for example `sun.misc.Unsafe`.

I'm referring to the private `ClassLoader.checkPackageAccess(Class<?> cls, ProtectionDomain pd)` method that is only invoked by the VM.

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PR Review Comment: https://git.openjdk.org/jdk/pull/13197#discussion_r1211956537