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https://issues.apache.org/jira/browse/GROOVY-12469?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18132232#comment-18132232
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ASF GitHub Bot commented on GROOVY-12469:
-----------------------------------------
paulk-asert merged PR #2999:
URL: https://github.com/apache/groovy/pull/2999
> SC: static compilation inserts wrong cast, derived from generic return type
> when assigned to a variable
> -------------------------------------------------------------------------------------------------------
>
> Key: GROOVY-12469
> URL: https://issues.apache.org/jira/browse/GROOVY-12469
> Project: Groovy
> Issue Type: Bug
> Affects Versions: 2.5.23, 3.0.25, 5.0.3, 4.0.33, 5.1.3, 6.0.0
> Reporter: Björn Kautler
> Priority: Major
>
> Given the following snippet:
> {code:groovy}
> import java.lang.annotation.Annotation
> import java.lang.annotation.Retention
> import java.lang.annotation.Target
> import groovy.transform.CompileStatic
> @CompileStatic
> <T extends Annotation> T getRetention(Class<T> clazz) {
> Target.getAnnotation(Target)
> }
> @CompileStatic
> def foo() {
> Annotation x = getRetention(Retention) /*as Annotation*/
> }
> foo().toString()
> {code}
> This compiles fine under all versions, but fails with a
> {{GroovyCastException}} in all versions.
>
> The generated byte-code under SC has a cast on {{Retention}} in this, even
> though the variable is of type {{Annotation}} explicitly.
> Commenting in the {{as Annotation}} cast makes it work.
> Removing the {{Annotation x =}} also makes it work.
> Removing the {{@CompileStatic}} or replacing it by {{@TypeChecked}} of course
> also makes it work.
>
> I'd say static-compilation should here not insert an unnecessary cast to
> {{{}Retention{}}}, but at most a cast to {{Annotation}} as that is, what the
> variable needs and which should be consistent with JVM type-erasure, and also
> with the variant without the variable. Even with the method returning
> {{Annotation}} instead of {{def}} it works just fine. Just if the method
> declares to return {{Retention}} explicitly, the cast exception comes, but
> then rightfully.
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