Re: RFR: 8202471: Make type annotations on owner type parameters available [v4]

[Joel Borggrén-Franck]

On Sat, 31 Oct 2020 21:11:15 GMT, Rafael Winterhalter 
<winterhal...@openjdk.org> wrote:

>> A method's or constructor's owner type might carry annotations on its 
>> potential type parameters but is never represented as parameterized type 
>> what makes these parameters inaccessible at runtime, despite the presence of 
>> parameter type annotations.
>
> Rafael Winterhalter has refreshed the contents of this pull request, and 
> previous commits have been removed. The incremental views will show 
> differences compared to the previous content of the PR.

Hi Rafael,

Thanks for your patience and  for the patch, I left a few comments.

src/java.base/share/classes/java/lang/reflect/Constructor.java line 664:

> 662:         Type t;
> 663:         if (o != null || v.length > 0) {
> 664:             t = ParameterizedTypeImpl.make(enclosingClass, v, o);

I think these should be instantiated by a GenericsFactory. Ideally you 
shouldn't have to import the reflective object directly.

src/java.base/share/classes/java/lang/reflect/Constructor.java line 660:

> 658:         }
> 659: 
> 660:         TypeVariable<?>[] v = enclosingClass.getTypeParameters();

Can you push down most or all of this to resolveOwner? It can then either 
return a Class instance or an appropriate Type instance.

src/java.base/share/classes/java/lang/reflect/Executable.java line 699:

> 697:         }
> 698:         Class<?> c = getDeclaringClass();
> 699:         TypeVariable<?>[] v = c.getTypeParameters();

Same here, can this be pushed down to a common method that either returns a 
Class or resolves the appropriate Type instance?

test/jdk/java/lang/annotation/typeAnnotations/TestReceiverTypeParameterizedConstructor.java
 line 52:

> 50:         Inner(TestReceiverTypeParameterizedConstructor<@TypeAnnotation T> 
> TestReceiverTypeParameterizedConstructor.this) { }
> 51:     }
> 52: 

It might be good to add a case where the annotated type variable isn't on the 
immediate outer type like:

    class Inner2 {
        class  TwiceInner {
            TwiceInner(TestReceiverTypeParameterizedConstructor<@TypeAnnotation 
T>.Inner2 TestReceiverTypeParameterizedConstructor.Inner2.this) { }
        }
    }

Same for the method test.

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PR: https://git.openjdk.java.net/jdk/pull/851