Record component annotations with target=PARAMETER

[Brian Goetz]

There are several places that a declaration annotation on a record parameter can be "pushed down" to:

  - The record component itself, stored in the Record attribute (if anno has target RECORD_COMPONENT)
  - Parameters of an implicit canonical constructor (for target PARAMETER)
  - An implicit accessor for the component (for target METHOD)
  - The component field (for target FIELD)

If the anno has multiple of these targets, it is pushed down to multiple places.  

> On Dec 17, 2019, at 5:10 AM, Tagir Valeev <amaembo at gmail.com> wrote:
> 
> Hello!
> 
> Current records JLS spec draft [1] says:
> 
> a record component but T is not applicable to record component
> declarations, field declarations, method declarations, or type
> contexts.
> 
> However, javac doesn't fail if the annotation target is parameter:
> 
> import java.lang.annotation.*;
> 
> record Foo(@Anno int x) {}
> @Target(ElementType.PARAMETER)
> @interface Anno {}
> 
> This code compiles and the canonical constructor is annotated with
> Anno. To me, the javac behavior is expected and spec should be updated
> to include "parameters":
> 
> a record component but T is not applicable to record component
> declarations, field declarations, method declarations, parameters, or
> type contexts.
> 
> What do you think? I'm implementing error highlighting for records in
> IntelliJ now. Should I follow the spec or javac behavior?
> 
> With best regards,
> Tagir Valeev.
> 
> http://cr.openjdk.java.net/~gbierman/jep359/jep359-20191125/specs/records-jls.html#jls-9.7.4