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https://issues.apache.org/jira/browse/GROOVY-9908?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Eric Milles closed GROOVY-9908.
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Resolution: Cannot Reproduce
> STC disregards type witnesses
> -----------------------------
>
> Key: GROOVY-9908
> URL: https://issues.apache.org/jira/browse/GROOVY-9908
> Project: Groovy
> Issue Type: Bug
> Components: Static Type Checker
> Affects Versions: 3.0.7
> Reporter: Christopher Smith
> Priority: Major
>
> In trying to work around some generics bugs that I think have patches for
> upcoming versions, I discovered a more basic problem with the STC. I'm having
> trouble with a standalone reproduction, but I can repro in situ.
> I'm putting together a Gremlin traversal (pretty generics-heavy). Gremlin
> defines this method, with no constraints on {{A}}:
> {code:java}
> public static <A> GraphTraversal<A, A> start()
> {code}
> I am trying to feed this to a custom method defined on a Java interface:
> {code:java}
> <A extends Element, E2> GraphTraversal<A, Map<Object, E2>>
> selectProperties(GraphTraversal<A, Vertex> gt);
> {code}
> The solution is that the first {{A}} is {{Vertex}}. However, the simple
> invocation
> {code:groovy}
> p.selectProperties(__.start())
> {code}
> triggers the STC error
> {code}
> Cannot call <A extends org.apache.tinkerpop.gremlin.structure.Element,E2>
> com.example.Projector#selectProperties(org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.GraphTraversal
> <A, org.apache.tinkerpop.gremlin.structure.Vertex>) with arguments
> [org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.GraphTraversal <A
> extends java.lang.Object, A extends java.lang.Object>]
> {code}
> This is a bug but I think already in fixing. The problem I am reporting is
> that even an explicit type witness, which should tell the STC what it needs,
> is ignored:
> {code:groovy}
> p.selectProperties(__.<Vertex,Vertex>start())
> {code}
> This produces the same error as above, specifically including the unbound {{A
> extends Object}} instead of the explicit {{Vertex}}.
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