8381965: NullPointerException in TypeAnnotationPositions

[lahodaj]

Consider code like this:

import java.lang.annotation.ElementType;
import java.lang.annotation.Target;
import java.util.function.Consumer;
import java.util.List;

class Test {
    static final Consumer<List<@TypeAnno String>> TEST = id((List<@TypeAnno String> arg) -> {});


    private static <T> Consumer<T> id(Consumer<T> t) { return t;}
}

@Target(ElementType.TYPE_USE)
@interface TypeAnno { }

There's an explicit lambda here, (List<@TypeAnno String> arg) -> {}. javac will create a helper block for it in DeferredAttr.attribSpeculativeLambda:

{
    List<@TypeAnno String> arg;
    {}
}

and will then speculative-attribute this block. But, when the parameters are placed into the block, they are still marked/flagged as parameters. And since the fix for https://bugs.openjdk.org/browse/JDK-8371155, the type annotations positions on the local variable type get resolved earlier in the pipeline, and even during the speculative attribution. But when the position for the type annotation is being resolved during this speculative attribution, the variable is interpreted as a parameter, but there's no (meaningful) enclosing lambda. So javac either fails with an exception, or assigns nonsensical position to the type annotation.

The primary proposal in the PR is to avoid resolving type annotations while doing speculative attribution.

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Issue

• JDK-8381965: NullPointerException in TypeAnnotationPositions (Bug - P2)

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