Queries about JDK-8035890

[Jan Lahoda]

Alex,

Thanks a lot for explanations.

Jan

On 03/28/2014 01:09 AM, Alex Buckley wrote:
> Hi Jan,
>
> On 3/27/2014 4:09 PM, Jan Lahoda wrote:
>> I have a few more questions on this. Considering these declarations of
>> annotation types:
>> @Target({ElementType.METHOD, ElementType.CONSTRUCTOR})
>> @interface DA { }
>> @Target(ElementType.TYPE_USE)
>> @interface TA { }
>>
>> Do I understand correctly that these are supposed to be valid:
>> public <T> @DA int foo1() { return 0;}
>> public <T> @DA void foo2() { }
>> public <T> @TA int foo3() { return 0;}
>
> Yes. The @DA and @TA are part of the MethodDeclaration just like they'd
> be if <T> was not present. So, it reduces to the well-known situation of
> an annotation immediately preceding a type in a method declaration -
> where we have a mechanism for determining whether the annotation is a
> type annotation or a declaration annotation. In other words, the type
> parameter section is invisible for the purpose of ascribing meaning to
> annotations.
>
>> These are supposed to be invalid:
>> public class Foo {
>>      <T> @DA Foo() { }
>>      <T> @TA Foo(int i) { }
>> }
>
> Ah, constructor declarations. The EG never discussed allowing
> annotations after the type parameter section there. I guess that was an
> oversight, but as things stand your two ctors are invalid.
>
>> I am unsure about:
>> public <T> @TA void foo4() { return 0;}
>
> Illegal. We remembered to handle this one:
>
> "If an annotation appears before a void method declaration and is deemed
> to apply only to the type which is closest to the annotation, a
> compile-time error occurs."
>
> Since TA is TYPE_USE, @TA is deemed to apply only to the type which is
> closest to the annotation - though it turns out to be 'void', so oops.
> All this would apply is @TA appeared before the 'public', since it's
> always been the case that an annotation and the type it means to apply
> to can be separated by other modifiers.
>
> Alex