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https://issues.apache.org/jira/browse/GROOVY-10758?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17606646#comment-17606646
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Christopher Smith commented on GROOVY-10758:
--------------------------------------------
{{Resource}} is a Java class in a precompiled dependency jar. I was assembling
{{FooResource}} "by hand", approximately this (I've been tweaking as I go
along):
{code}
ClassHelper.makeWithoutCaching(fqcn).tap {
modifiers |= PUBLIC | FINAL
superClass = makeWithoutCaching(resourceBaseClass).tap { genericsTypes =
[attr] as GenericsType }
// add annotations and methods
}
{code}
As the Javadoc on {{ClassNode}} says "A ClassNode should be created using the
methods in ClassHelper", I had naively expected that "make without caching"
(because that's what we do for {{Map}}) meant "get a new instance so I can
customize the generics on it". I eventually found the methods in
{{GenericsUtils}} after your tips on Stack Overflow, but
{{makeClassSafeWithGenerics}} is a rather unenlightening method name and
carries no Javadoc.
> Improve error message when using generic ClassNodes in ASTT
> -----------------------------------------------------------
>
> Key: GROOVY-10758
> URL: https://issues.apache.org/jira/browse/GROOVY-10758
> Project: Groovy
> Issue Type: Improvement
> Components: Compiler
> Affects Versions: 4.0.5
> Reporter: Christopher Smith
> Priority: Minor
>
> When mistakenly using a shared instance of a {{ClassNode}} that has generics
> applied, the compiler (helpfully!) produces this error:
> {code}
> transform used a generics containing ClassNode
> com.example.Resource<com.example.FooAttributes> for the super class
> com.example.FooResource directly. You are not supposed to do this. Please
> create a new ClassNode referring to the old ClassNode and use the new
> ClassNode instead of the old one. Otherwise the compiler will create wrong
> descriptors and a potential NullPointerException in TypeResolver in the
> OpenJDK. If this is not your own doing, please report this bug to the writer
> of the transform.
> {code}
> However, there is no explanation of *how* to create the "new ClassNode", and
> [I couldn't find anything in the API that made the error go
> away|https://stackoverflow.com/questions/73749765/how-do-i-subclass-a-generic-base-class-in-a-groovy-ast-transformation].
> It would be helpful to ASTT neophytes if the error message specified the
> method call(s) suitable for this operation.
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