[GROOVY-5883] @CompileStatic incorrectly inferred closure return type upper bound

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.0.6
• Fix Version/s: 2.1.7, 2.2.0-beta-2
• Component/s: Static Type Checker
• Assignee: Jochen Theodorou
• Reporter: Dimitar Dimitrov
• Created: 07/Jan/13 00:23
• Updated: 14/Oct/13 16:53
• Resolved: 22/Jul/13 05:02

Description

@CompileStatic
class Test<T> {
    def map(Closure<T> mapper) { }

    def failing(Closure<Boolean> predicate) {
        map { T it -> return predicate(it) ? it : null }
    }
    
    def passing(Closure<Boolean> predicate) {
        map { T it -> return predicate(it) ? it : (T) null }
    }

    def failingWithExplicitCast(Closure<Boolean> predicate) {
        Closure<T> c = { T it -> return predicate(it) ? it : null }
        map(c)
    }
}

In the last case, I would expect the compiler to obey the forced cast even at the risk of producing class-cast exception at runtime.