[jira] [Assigned] (GROOVY-10844) STC mis-tracks generics in type hierarchy

["Eric Milles (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/GROOVY-10844?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Eric Milles reassigned GROOVY-10844:
------------------------------------

    Assignee: Eric Milles

> STC mis-tracks generics in type hierarchy
> -----------------------------------------
>
>                 Key: GROOVY-10844
>                 URL: https://issues.apache.org/jira/browse/GROOVY-10844
>             Project: Groovy
>          Issue Type: Bug
>          Components: Static compilation, Static Type Checker
>    Affects Versions: 4.0.6
>            Reporter: Christopher Smith
>            Assignee: Eric Milles
>            Priority: Critical
>
> I have a Vavr {{Try}} pipeline of this form:
> {code:groovy}
> class AttachmentSpec {
>   // fields
>   Attachment toAttachment(Ref ref) { ... }
> }
> Try.success(initialValue)
>   .mapTry { process(it) } // returns a Map
>   .map { convertToRef(it) } // returns a Ref.File extends Ref
>   .recover { new Ref.Uri(it.href) } // Ref.Uri extends Ref
>   .map(spec::toAttachment)
> {code}
> On a failure in {{process}}, this pipeline should enter {{recover}} and supply a {{Ref.Uri}}, then do the final {{map}}. However, this fails with a {{ClassCastException: cannot convert Ref.Uri to Ref.File}}. Apparently, the compiler infers {{Ref.Uri}} as the return value from the first {{map}} (which is legitimate), but then it fails to produce a compile-time error when {{recover}} presents a then-incompatible {{Ref.File}}. The compiler should either (ideally) recognize that the desired type is superclass {{Ref}} or, more simply but at least correctly, produce a compile-time error until a type witness is inserted (and observed).



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