[GROOVY-5106] Same interface can be implemented with two different generic types

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.4.0-beta-3
• Fix Version/s: 4.0.0
• Component/s: Compiler

Language

groovy

• Assignee: Eric Milles
• Reporter: Cédric Champeau
• Created: 28/Oct/11 15:52
• Updated: 25/Oct/24 16:55
• Resolved: 05/Jan/22 20:38

Description

Given the following code :

interface One<T> {
    void echo(T obj);
}

interface Two extends One<String> {}

class OneImpl implements Two,One<Integer> {

    public void echo(String obj) { println obj }
}

def o = new OneImpl()

The "One" interface is implemented twice with two different generic types, which should not be allowed. Here's another example, more complex :

interface Transcoder<T, U> {
    T transcode(U obj);
}

interface TranscoderToString<V> extends Transcoder<String, V>{
}

abstract class AbstractToStringTranscoder<V> implements TranscoderToString<V> {

    public String transcode(final V obj) {
        return obj.toString();
    }
}

class IntegerToStringTranscoder extends AbstractToStringTranscoder<Integer> implements TranscoderToString<Boolean> {

}

Issue Links

• causes: GROOVY-11508 Multiple traits with related generic types cannot be used
• relates to: GROOVY-10439 No error/warning for @Delegate introducing conflicting interface generics