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https://issues.apache.org/jira/browse/GROOVY-11549?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17910608#comment-17910608
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Xiaotian Ma commented on GROOVY-11549:
--------------------------------------
Yes, but sometimes for the sake of reflection convenience or compatibility, we
also repeatedly write some interfaces, just like Java's ArrayList. Its parent
class AbstractList has already implemented the List interface, but the
ArrayList is still implemented once. However, such situations may not be common.
> 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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