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https://issues.apache.org/jira/browse/GROOVY-12247?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Paul King updated GROOVY-12247:
-------------------------------
Fix Version/s: 4.0.34
5.1.0
> NPE "Cannot invoke MetaMethod.isAbstract() because method is null" on super
> call to inherited generic method with default parameter
> -----------------------------------------------------------------------------------------------------------------------------------
>
> Key: GROOVY-12247
> URL: https://issues.apache.org/jira/browse/GROOVY-12247
> Project: Groovy
> Issue Type: Bug
> Components: groovy-runtime
> Affects Versions: 5.0.8, 6.0.0-beta-1
> Reporter: Sean Fitts
> Assignee: Paul King
> Priority: Major
> Fix For: 4.0.34, 5.1.0, 6.0.0-beta-2
>
>
> A dynamic super. call throws:
> {quote}java.lang.NullPointerException: Cannot invoke
> "groovy.lang.MetaMethod.isAbstract()" because "method" is null
> at
> groovy.lang.MetaClassImpl.getSuperMethodWithCaching(MetaClassImpl.java:1423)
> at groovy.lang.MetaClassImpl.getMethodWithCaching(MetaClassImpl.java:1368)
> at groovy.lang.MetaClassImpl.getMetaMethod(MetaClassImpl.java:1263)
> at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1117)
> at
> org.codehaus.groovy.runtime.ScriptBytecodeAdapter.invokeMethodOnSuperN(ScriptBytecodeAdapter.java:143)
> {quote}
> when all of the following hold:
> # The super method is declared in a generic class, uses the type variable as
> a parameter type, and has a default parameter value (which generates a
> short-form overload). Declaring two explicit overloads instead of using a
> default parameter fails the same way.
> # An intermediate class binds the type parameter, so the overriding class
> sits two levels below the generic declaration. (If the overriding class
> extends the generic class directly, it works.)
> # A subclass overrides the short-form overload with the concrete type
> argument (producing a bridge method) and invokes it via super. with the
> optional argument omitted.
> Reproducer (tried attaching file, but that failed):
>
> abstract class Base<T extends Number> {
> protected String process(T value, String extra = null) {
> return "base(${value}, ${extra})"
> }
> }
> abstract class Mid extends Base<Integer> {}
> class Sub extends Mid {
> @Override
> protected String process(Integer value) {
> return 'sub->' + super.process(value)
> }
> }
> // Expected (Groovy 3/4): sub->base(42, null)
> // Groovy 5.0.8 / 6.0.0-beta-1: NPE "Cannot invoke
> groovy.lang.MetaMethod.isAbstract() because method is null"
> println new Sub().process(42)
>
> Expected output sub->base(42, null), as produced by Groovy 3 and 4).
> Removing any one ingredient avoids the failure: dropping the default
> parameter (so the method is not overloaded), removing the intermediate class
> Mid, or calling the full-arity form explicitly (super.process(value, null)),
> which is a usable workaround.
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