[GROOVY-9931] !instanceof inference does not work

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Duplicate
• Affects Version/s: 3.0.7
• Component/s: Static Type Checker
• Assignee: Eric Milles
• Reporter: Stefanos Chaliasos
• Created: 08/Feb/21 09:17
• Updated: 27/Nov/22 20:11
• Resolved: 18/May/22 16:46

Description

I have the following Groovy program

 

@groovy.transform.CompileStatic
class Main {
    static Integer bar(Object o) {
        if (o !instanceof Integer) {
            return 0
        } else {
            return o
        }
    }
}

Actual Behavior

The program does not compile, and I get the following error.

org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed:
Main.groovy: 7: [Static type checking] - Cannot return value of type java.lang.Object on method returning type java.lang.Integer
 @ line 7, column 9.
           o
           ^

1 error

Expected Behavior

Compile successfully.

Issue Links

• duplicates: GROOVY-8412 Support !instanceof flow typing for else case
• relates to: GROOVY-6429 flow typing detects unexpected error at if-else flow