[GROOVY-6856] Generics and static type checking: "Cannot return value of type W on method returning type W"

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.3.2
• Fix Version/s: 2.3.3
• Component/s: Compiler
• Environment: OS: Debian GNU/Linux 7 (32 bit)
• Assignee: Jochen Theodorou
• Reporter: Davide Cavestro
• Created: 10/Jun/14 04:09
• Updated: 11/Jun/14 14:25
• Resolved: 11/Jun/14 04:09

Description

As discussed into the mailing list the following snippet makes the groovy compiler complain for

[Static type checking] - Cannot return value of type W on method returning type W

even if it is valid groovy code

snippet.groovy

import groovy.transform.TypeChecked

class Wrapper {}

@TypeChecked
class Foo<W extends Wrapper> {
    W doIt (List<W> l) {
        l.iterator().next()//Static type check failure
    }
}

//new Foo().doIt([])//uncomment this line to run as a script on groovyConsole