RFR: 8270056: Generated lambda class can not access protected static method of target class

[Mandy Chung]

On Thu, 8 Jul 2021 02:32:45 GMT, Yi Yang <yyang at openjdk.org> wrote:

> Generated lambda class can not access protected static method of the target class. The following exception is thrown when executing the attached reproducible program:
> 
> 
> Exception in thread "main" java.lang.IllegalAccessError: class AccessProtectedStaticMethodFromSuper$B$$Lambda$15/0x0000000800b8ea48 tried to access protected method 'void AccessProtectedStaticMethodFromSuper$A.func()' (AccessProtectedStaticMethodFromSuper$B$$Lambda$15/0x0000000800b8ea48 is in unnamed module of loader AccessProtectedStaticMethodFromSuper$1Loader @71dac704; AccessProtectedStaticMethodFromSuper$A is in unnamed module of loader AccessProtectedStaticMethodFromSuper$1Loader @39ed3c8d)
> 	at AccessProtectedStaticMethodFromSuper.main(AccessProtectedStaticMethodFromSuper.java:51)
> 
> 
> This issue is similar to JDK-8254975(#767) with slight differences: generated lambda proxy calls static protected method rather than protected member method.
> 
> The proposed fix 1) tries to use MethodHandle instead of invoking forwardee directly(since the lambda class has no access to the resolved method) and 2) does not force accepting an implClass as the first argument when invoking a static method.
> 
> Testing:
> - test/jdk/java/ with release mode
> - presubmit tests

Good catch.   It should check if the target class (not `implClass`) and the declaring class of the implementation's method handle are in the same package if it's protected.

I prefer to add the new test case in the existing test `test/jdk/java/lang/invoke/lambda/superProtectedMethod/SuperMethodTest.java`.   The test's name may be made clearer to rename to `ProtectedMethodInOtherPackage` (something like that)

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PR: https://git.openjdk.java.net/jdk/pull/4714