javac crash for annotation on lambda formal parameter type

[Werner Dietl]

It looks like nobody ever tested Type Annotations on Lambdas in fields.
test/tools/javac/annotations/typeAnnotations/referenceinfos/Lambda.java
test/tools/javac/annotations/typeAnnotations/newlocations/Lambda.java
contain several lambda tests, but all within methods.

The code that creates the NPE tries to find the owner for a parameter symbol.
The expectation was that a parameter is always within an method. That
is not true for lambdas it seems.
Even for lambdas within a method it is not modifying the correct type:
it modifies the enclosing method's signature instead of modifying the
lambda's signature.

As lambdas do not have an ExecutableType, the right thing is probably
to not modify the enclosing type.
However, I didn't see a way to determine from a parameter symbol
whether it is a lambda parameter or a normal method parameter.

Also, are the expected outputs for the referenceinfos/Lambda.java test correct?
For a lambda within a field, the type annotation is currently lost.
Where should it show up? On the field? In the instance initializer?

I pushed a changeset to type-annotations with an ugly fix for the NPE
and the expanded test cases:

http://hg.openjdk.java.net/type-annotations/type-annotations/langtools/rev/3705299024dc

cu, WMD.



On Thu, Dec 5, 2013 at 7:47 PM, Alex Buckley <alex.buckley at oracle.com> wrote:
> Starting at JDK8 b91, and continuing through b118, this innocuous program
> crashes javac:
>
> --
> import java.lang.annotation.*;
> import java.util.function.*;
>
> @Retention(RetentionPolicy.RUNTIME)
> @Target(ElementType.TYPE_USE)
> @interface TA {}
>
> class LambdaFormal {
>   IntUnaryOperator x = (@TA int y) -> 1;
> }
> --
>
> with:
>
> java.lang.NullPointerException
>         at
> com.sun.tools.javac.code.TypeAnnotations$TypeAnnotationPositions.separateAnnotationsKinds(TypeAnnotations.java:302)
>         at
> com.sun.tools.javac.code.TypeAnnotations$TypeAnnotationPositions.visitLambda(TypeAnnotations.java:1080)
>         at com.sun.tools.javac.tree.JCTree$JCLambda.accept(JCTree.java:1607)
>         at com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
> ...
>
> This is weird because I'm sure I've annotated lambda formals in this fashion
> since b90. It's due to TYPE_USE - if TA's target is PARAMETER, then the
> program rightly compiles, while if TA's target is FIELD, you get the
> expected applicability error.
>
> Before I file a P2 bug for this, can anyone add some color to the situation?
>
> Alex
>
> P.S. With a TA target of TYPE_USE, b90 produces a class file without the
> expected RuntimeVisibleTypeAnnotations attribute for @TA. But that's less of
> a concern right now.
>



-- 
http://www.google.com/profiles/wdietl