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https://issues.apache.org/jira/browse/GROOVY-12106?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Eric Milles updated GROOVY-12106:
---------------------------------
    Language: groovy

> STC cannot resolve inherited static trait method from sub-trait body
> --------------------------------------------------------------------
>
>                 Key: GROOVY-12106
>                 URL: https://issues.apache.org/jira/browse/GROOVY-12106
>             Project: Groovy
>          Issue Type: Bug
>          Components: Static Type Checker
>    Affects Versions: 5.0.7
>            Reporter: James Fredley
>            Priority: Major
>              Labels: static-method, sts, traits
>
> h2. Summary
> Groovy 5 static type checking does not resolve a static method declared by a 
> parent trait when the method is called from a sub-trait body.
> This is independent of Grails and can be reproduced with plain Groovy traits 
> under @CompileStatic.
> This was re-tested on Groovy 5.0.7-SNAPSHOT. Both an unqualified call and a 
> qualified call fail static type checking:
> {code:groovy}
> inheritedStaticMethod(value)
> {code}
> {code:groovy}
> ParentTrait.inheritedStaticMethod(value)
> {code}
> The failure is distinct from GROOVY-11985, which fixed 
> static-override-via-this. This issue is about resolving a parent trait's 
> static method from a sub-trait body.
> h2. Standalone reproducer
> {code:groovy}
> import groovy.transform.CompileStatic
> @CompileStatic
> trait ParentTrait {
>     static void configure(Closure closure, Object target) {
>         if (closure != null) {
>             closure.delegate = target
>             closure.resolveStrategy = Closure.DELEGATE_ONLY
>             closure.call()
>         }
>     }
> }
> @CompileStatic
> trait ChildTrait extends ParentTrait {
>     void applyConfig(Closure closure, Object target) {
>         configure(closure, target)
>     }
> }
> @CompileStatic
> class Example implements ChildTrait {
> }
> {code}
> h2. Expected result
> The code should pass static type checking. A sub-trait should be able to 
> resolve a static method declared by a parent trait.
> h2. Actual result
> Static type checking fails on the call from the sub-trait body:
> {code}
> Cannot find matching method ChildTrait#configure(groovy.lang.Closure, 
> java.lang.Object)
> {code}
> Using a qualified call also fails:
> {code:groovy}
> ParentTrait.configure(closure, target)
> {code}
> h2. Real-world use case
> Apache Grails has the same pattern in the GraphQL DSL helper traits.
> Parent trait method:
> {code}
> grails-data-graphql/core/src/main/groovy/org/grails/gorm/graphql/entity/dsl/helpers/ExecutesClosures.groovy
> line 34
> {code}
> {code:groovy}
> @CompileStatic
> trait ExecutesClosures {
>     static void withDelegate(@DelegatesTo(strategy = Closure.DELEGATE_ONLY) 
> Closure closure, Object delegate) {
>         ...
>     }
> }
> {code}
> Sub-traits that should be able to call the inherited helper:
> {code}
> grails-data-graphql/core/src/main/groovy/org/grails/gorm/graphql/entity/dsl/helpers/Arguable.groovy
> grails-data-graphql/core/src/main/groovy/org/grails/gorm/graphql/entity/dsl/helpers/ComplexTyped.groovy
> {code}
> Grails currently works around this by inlining the parent trait helper body 
> into each sub-trait. Once this Groovy STC issue is fixed, that inline 
> workaround can be removed.
> h2. Workaround
> Inline the static helper body in each sub-trait, or avoid calling the 
> inherited static trait method from the sub-trait.



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