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  1. JDK
  2. JDK-8246790

LambdaMetafactory fails to support invokespecial method handle with hidden class

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    Details

    • Type: Bug
    • Status: Resolved
    • Priority: P3
    • Resolution: Duplicate
    • Affects Version/s: 15
    • Fix Version/s: None
    • Component/s: core-libs
    • Labels:
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      Description

      Prior to hidden classes, lambda proxy classes are defined as VM anonymous classes. VM anonymous class has special access - same access as its host class. Hence LambdaMetafactory is able to support invokespecial method handle to invoke a member of a superclass or superinterface of the target class even if the lambda proxy class is not a subtype of the method handle being invoked.

      When LMF was converted to use hidden classes, LMF will convert `invokespecial` to access a member of its nestmate to `invokevirtual` or `invokeinterface` for binary compatibility.

      But `invokespecial` invocation on a superclass would crash with `VerifyError`. It's a regression. Since javac generates a bridge method, this issue may not expose in the wild.

      The possible solution is:
      a) change/clarify the contract of LambdaMetafactory (only certain invokeSpecial method handles are supported) or
      b) fall back in those cases to direct MethodHandle invocation

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              Assignee:
              dlsmith Dan Smith
              Reporter:
              mchung Mandy Chung
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