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https://issues.apache.org/jira/browse/GROOVY-11549?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17910602#comment-17910602
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Paul King commented on GROOVY-11549:
------------------------------------
This does look like a bug. Since "I1" already extends "IO<String>" you can
re-write your Groovy class as:
{code:groovy}
class B implements I1 {
}
{code}
Which seems to work, though I agree your original should still work.
> False positive "Can't have an abstract method in a non-abstract class." when
> implement Java interfaces
> ------------------------------------------------------------------------------------------------------
>
> Key: GROOVY-11549
> URL: https://issues.apache.org/jira/browse/GROOVY-11549
> Project: Groovy
> Issue Type: Bug
> Components: Compiler
> Affects Versions: 5.0.0-alpha-11, 4.0.24
> Reporter: Xiaotian Ma
> Priority: Major
>
> h1. Source code
> The following code should be compiled, but actually not.
> {code:java}
> // Java Files
> // FILE: I0.java
> public interface I0<T> {
> public T func();
> }
> // FILE: I1.java
> public interface I1 extends I0<String> {
> @Override
> default String func() {
> return "I1";
> }
> }
> {code}
> {code:groovy}
> // Groovy File
> // FILE: B.groovy
> public class B implements I1, I0<String> {
> }
> {code}
> h1. Error
> {code:none}
> B.groovy
> Groovyc: Can't have an abstract method in a non-abstract class. The class 'B'
> must be declared abstract or the method 'java.lang.Object func()' must be
> implemented.
> {code}
> h1. Expected output
> Compiler should pass this code.
> h1. Other
> Method "java.lang.Object func()" has already overridden in Java interface
> "I1" with a type argument "String". If I remove the type parameter "T" in
> "I0", like this:
> {code:java}
> // Java Files
> // FILE: I0.java
> public interface I0 {
> public String func();
> }
> // FILE: I1.java
> public interface I1 extends I0 {
> @Override
> default String func() {
> return "I1";
> }
> }
> {code}
> the error disappear. As far as I know, Java compiler will generate a bridge
> method "java.lang.Object func()" in "I1" in bytecode. So maybe the groovy
> compiler misread the bridge method in "I1"?
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