RFR: 8330467: NoClassDefFoundError when lambda is in a hidden class [v3]

[Mandy Chung]

On Wed, 17 Apr 2024 16:08:31 GMT, Adam Sotona <asotona at openjdk.org> wrote:

>> Current implementation of `LambdaMetafactory` does not allow to use lambdas in hidden classes. Invocation throws `NoClassDefFoundError` instead.
>> 
>> This patch includes lambda implementation in a hidden class under the special handling of `useImplMethodHandle`.
>> The patch also fixes `j/l/i/defineHiddenClass/BasicTest::testLambda` to correctly cover this test case.
>> 
>> Please review.
>> 
>> Thanks,
>> Adam
>
> Adam Sotona has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - typo in comment fix
>  - applied suggested changes

Looks fine to me.   A hidden class cannot be resolved by name.   I tweaked the comment to make it clear.

src/java.base/share/classes/java/lang/invoke/InnerClassLambdaMetafactory.java line 182:

> 180:         // live implementation method handle to the proxy class to invoke
> 181:         // directly. (javac prefers to avoid this situation by generating
> 182:         // bridges in the target class)

Suggestion:

        // lambda class has no access to the resolved method, or does
        // 'invokestatic' on a hidden class which cannot be resolved by name.
        // Instead, we need to pass the live implementation method handle to
        // the proxy class to invoke directly. (javac prefers to avoid this
        // situation by generating bridges in the target class)

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Marked as reviewed by mchung (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/18810#pullrequestreview-2007006920
PR Review Comment: https://git.openjdk.org/jdk/pull/18810#discussion_r1569431448