[GROOVY-10011] Combining flow typing and type argument inference does not work as expected

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 3.0.8, 4.0.0-alpha-3
• Component/s: Static Type Checker
• Assignee: Eric Milles
• Reporter: Thodoris Sotiropoulos
• Created: 05/Apr/21 19:48
• Updated: 02/May/21 09:16
• Resolved: 10/Apr/21 22:16

Description

I have the following program

class A<T> {
  T f;
  public A(T f) {
    this.f = f;
  }
}

class Foo {}
class Bar extends Foo {}

public class Main {
  public static void bar(Foo x) {
    if (x instanceof Bar) {
      A<Bar> a = new A<>(x)
    }
  }
}

Actual Behavior

org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed:
test.groovy: 15: [Static type checking] - Incompatible generic argument types. Cannot assign A <Foo> to: A <Bar>
 @ line 15, column 18.
         A<Bar> a = new A<>(x)
                    ^1 error

Expected Behavior

Compile successfully

 

Tested against https://github.com/apache/groovy/commit/359be2b662be646d2d59db8b999412691891231d