interactions between type annotations and language model APIs.

[Joe Darcy]

Hello,

On 5/5/2014 1:48 PM, Alex Buckley wrote:
> On 5/5/2014 12:52 PM, Jonathan Gibbons wrote:
>> In particular, TypeMirror is now an AnnotatedConstruct, and various
>> methods in javax.lang.model.util.Types return computed TypeMirrors --
>> for example, capture(TypeMirror), directSupertypes(TypeMirror),
>> erasure(TypeMirror), etc.
>
> Right, because jx.l.m.t.TypeMirror always represented the use of a 
> type at a particular location in source - which can now usually be 
> annotated.
>
>> In cases where the argument has type annotations, what type annotations
>> (if any) should appear on the return value?
>>
>> It would help to see clarification added to the specifications, either
>> generally, or on a case-by-case basis for the affected methods.
>
> To be specific, the "generator" methods in jx.l.m.u.Types are these ten:
>
> asMemberOf
> boxedClass
> capture
> directSupertypes
> erasure
> getArrayType
> getDeclaredType x2
> getWildcardType
> unboxedType
>
> Generally, the "correct" thing to do would be to inspect the 
> TypeMirror argument and thread its type annotations into the 
> TypeMirror result. But not always: just because '@Foo String' appears 
> in source does not mean that calling directSupertypes on its mirror 
> should return '@Foo Object'. There is also a limitation of the API for 
> wildcard annotations: getWildcardType could produce a mirror for '? 
> extends @Foo ...' and '? super @Foo ...' but not '@Foo ? extends ...' 
> or '@Foo ? super ...'.
>
> Joe, what is your view on retrofitting type annotations into Types?
>

Hmm.

My first reaction here is that these methods should by default ignore 
annotations and we should add another utility method or two like:

<T extends TypeMirror> T withAnnotations(T typeMirror, List<? extends 
AnnotationMirror> annotations)

<T extends TypeMirror> T withAnnotations(T typeMirror, 
AnnotatedConstruct annotationHost)

to allow the annotations savvy user to perform whatever annotation 
passing along or computation is appropriate for the problem domain.

-Joe