Can a @Target-less (runtime-retained) annotation be applied on a type parameter declaration?

[Alex Buckley]

Thanks Laird and Liam.

In Java 19, this is a javac bug, because JLS19 is clear that a 
@Target-less annotation can be applied to a type parameter declaration:

"If an annotation of type java.lang.annotation.Target is not present on 
the declaration of an annotation interface A, then A is applicable in 
all declaration contexts and in no type contexts."

- 
https://docs.oracle.com/javase/specs/jls/se19/html/jls-9.html#jls-9.6.4.1-400


As Liam implies, there has been some shimmer in this rule. When type 
annotations were introduced in Java 8, an @Target-less annotation could 
not be applied to a type parameter declaration, but this changed in Java 
14. Compare JLS13 with JLS14:

- 
https://docs.oracle.com/javase/specs/jls/se13/html/jls-9.html#jls-9.6.4.1-400

- 
https://docs.oracle.com/javase/specs/jls/se14/html/jls-9.html#jls-9.6.4.1-400

Alex

On 3/7/2023 4:06 PM, Liam Miller-Cushon wrote:
> Hi Laird,
> 
> Nice find. I'm curious whether anyone on the list is remembering details 
> I'm not, but this looks like a bug to me too.
> 
> I went ahead and filed: https://bugs.openjdk.org/browse/JDK-8303784 
> <https://bugs.openjdk.org/browse/JDK-8303784>
> 
> On Tue, Mar 7, 2023 at 3:53 PM Laird Nelson <ljnelson at gmail.com 
> <mailto:ljnelson at gmail.com>> wrote:
> 
>     Using Java 19:
> 
>     @Retention(RetentionPolicy.RUNTIME)
>     public @interface A {}
> 
>     public class B<@A C> {}
> 
>     Why does javac say that A is "not applicable in this type context"? 
>     (I understand that things have changed here in various versions of
>     the JLS and related @Target javadocs over the years so I'm probably
>     misreading something.)
> 
>     (Originally asked on StackOverflow with more detail:
>     https://stackoverflow.com/questions/75667924/a-target-less-annotation-cannot-be-applied-to-a-type-parameter-declaration-in-j <https://stackoverflow.com/questions/75667924/a-target-less-annotation-cannot-be-applied-to-a-type-parameter-declaration-in-j>
> 
>     Thanks,
>     Laird
>