[GROOVY-5439] error: incompatible types on Java stubs returning generics

• Type: Bug
• Status: Closed
• Priority: Blocker
• Resolution: Fixed
• Affects Version/s: 2.0-beta-3
• Fix Version/s: 2.0.4, 2.1.0-beta-1, 1.8.9
• Component/s: Stub generator / Joint compiler
• Environment: 2.0.0-beta-3-SNAPSHOT, JDK 1.7
• Assignee: Guillaume Sauthier
• Reporter: Renato Garcia
• Created: 03/May/12 17:32
• Updated: 21/Sep/12 16:58
• Resolved: 18/Sep/12 07:28

Description

The following class definition fails to compile the Java stubs:

class GenericReturn {
    public <T extends List> T foo() {
        null
    }
}

Error:

tmp/groovy-java-stubs/GenericReturn.java:16: error: incompatible types
public <T extends java.util.List> T foo() { return (java.util.List)null;}
                                                   ^
  required: T
  found:    List
  where T is a type-variable:
    T extends List declared in method <T>foo()

It compiles with no errors on 2.0-beta-2 and 1.8.6