[GROOVY-9995] Wrong inference inside closure when having a bounded type parameter

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.0.7, 4.0.0-alpha-2
• Fix Version/s: 4.0.0-alpha-3, 3.0.11, 2.5.19
• Component/s: Static compilation, Static Type Checker
• Assignee: Eric Milles
• Reporter: Stefanos Chaliasos
• Created: 22/Mar/21 08:24
• Updated: 06/Sep/22 13:33
• Resolved: 24/Mar/21 14:45

Description

I have the following Groovy program.

@groovy.transform.CompileStatic
public class Main {
  public static void main(String[] args) {
    Closure<A<Long>> closure =  { -> {
      final x = (Long) 1;
      new A<>(x);
    }}
    // If I remove 'extends Number' in class A, the following code
    // works as expected.
    final Long y = closure().f;
  }
}

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

Actual Behavior

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

org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed:
Main.groovy: 10: [Static type checking] - Cannot assign value of type java.lang.Number to variable of type java.lang.Long
 @ line 10, column 20.
       final Long y = closure().f;
                      ^

1 error

Expected Behavior

Compile successfully.

Affected Version

I have also tested it with the compiler from Master (commit: e69c874e1a6a3cdeb236bad6a6faa061a30c88ca).