RFR 6388543: improve accuracy of source positions for AnnotationValue param of Messager.printMessage

[Liam Miller-Cushon]

Any more thoughts on this? I'm happy to revise the approach if there's a
better way to use the hint.

On Tue, Jan 3, 2017 at 10:28 PM, Liam Miller-Cushon <cushon at google.com>
wrote:

> Thanks for the feedback,
>
> On Tue, Jan 3, 2017 at 9:00 PM, Jonathan Gibbons <
> jonathan.gibbons at oracle.com> wrote:
>
>> I guess I am slightly surprised by the proposed solution, as regards the
>> choice of what it means to find a match. I have always assumed that any
>> implementation would iterate over the element values of the annotation,
>> looking for a value that is .equals to the given value, for some
>> appropriate definition of AnnotationValue.equals.  It does not seem obvious
>> to me that you should be searching within the individual element values for
>> the match. I am also surprised that you might match for @B + 2; I would
>> expect the annotation mirror to only match at the top level.   For example,
>> assuming a "first one wins" policy, I would have expected @B + 2 to match
>> the second annotation in the pair of annotations `@A(x = {1}, y = @B(2))
>> @B(2)`
>
>
> I thought the proposed approach was consistent with the existing handling
> of AnnotationMirror. The overloads of matchAnnoToTree use reference
> equality to find a matching AnnotationMirror, which could be either a
> top-level or nested annotation on the element. So given `@A(x = {1}, y =
> @B(2)) @B(2)`, passing an AnnotationMirror for @B to printMessage(...,
> Element, AnnotationMirror) could match either appearance of @B depending on
> which instance the argument was.
>
> Is there a definition of AnnotationValue.equals that would be more
> appropriate than reference equality? Value equality would be ambiguous for
> e.g. `@A(x=1, y=1, z=1)` and @A + 1.
>
> The motivation for supporting array elements was the same one mentioned in
> the bug [1], which I've heard repeated elsewhere: for annotations
> containing large array initializers it'd be helpful to place the caret at a
> specific element instead of the start of the array.
>
> Liam
>
> [1] https://bugs.openjdk.java.net/browse/JDK-6388543?
> focusedCommentId=12267020&page=com.atlassian.jira.
> plugin.system.issuetabpanels:comment-tabpanel#comment-12267020
>
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