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https://issues.apache.org/jira/browse/GROOVY-12602?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18140525#comment-18140525
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ASF GitHub Bot commented on GROOVY-12602:
-----------------------------------------
codeconsole commented on PR #3129:
URL: https://github.com/apache/groovy/pull/3129#issuecomment-6717051316
@daniellansun I can't re-run jobs on apache/groovy, so I merged current
master (492ae79db4) to get a fresh run, which also brings in the Windows Gradle
cache fix (#3110). The failed cell was the `lts (17, windows-latest, 1)`
timeout. No code changes; the core test suite (19,691 tests) passes locally on
the merge.
> SC: a lambda in a trait method calling a trait instance method by implicit
> this throws ClassCastException: Class cannot be cast to the trait
> --------------------------------------------------------------------------------------------------------------------------------------------
>
> Key: GROOVY-12602
> URL: https://issues.apache.org/jira/browse/GROOVY-12602
> Project: Groovy
> Issue Type: Bug
> Affects Versions: 4.0.33, 5.0.8, 6.0.0
> Reporter: Scott Murphy Heiberg
> Priority: Major
>
> {code:groovy}
> import java.util.function.Supplier
> @groovy.transform.CompileStatic
> trait U {
> String getUname() { 'u' }
> String a() { Supplier<String> s = () -> getUname(); s.get() }
> }
> class C implements U {}
> assert new C().a() == 'u'
> {code}
> Actual:
> {noformat}
> java.lang.ClassCastException: class java.lang.Class cannot be cast to class U
> at U$Trait$Helper$_a_lambda1.doCall(...)
> {noformat}
> The same happens for a super trait's accessor read as {{uname}} or called as
> {{getUname()}} in a lambda, for a lambda in a lambda, for a closure in a
> lambda and for a lambda in a trait field initializer.
> Expected: the assertion passes, as it does without {{@CompileStatic}}, with
> {{@TypeChecked}}, and with a closure instead of the lambda.
> A closure in a trait method is rehydrated with the trait instance as its this
> object. A statically compiled lambda is not, and the lambda writer passes the
> trait helper class as the lambda's this object because the helper method is
> static. The implicit-this call then casts that class to the trait.
> Seen in 4.0.33, 5.0.8 and 6.0.0.
> PR: https://github.com/apache/groovy/pull/3129
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