[GROOVY-10294] Variable's inferred type is upcasted to an Object

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 4.0.0-beta-2, 2.5.19, 3.0.13
• Component/s: Static Type Checker
• Assignee: Eric Milles
• Reporter: Thodoris Sotiropoulos
• Created: 11/Oct/21 14:10
• Updated: 30/Aug/22 15:39
• Resolved: 31/Oct/21 00:26

Description

I am not sure if this is a bug or a feature (or a general limitation of flow typing employed by Groovy).

I have the following program

class A {
  A foo() {
    def x = new A()
    if (false) {
      x = null
    }
    x
  }
}

Actual behavior

org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed:
test.groovy: 7: [Static type checking] - Cannot return value of type java.lang.Object on method returning type A
 @ line 7, column 5.
       x
       ^

1 error

Expected behaviour

Compile successfully

Tested against master