[GROOVY-9983] Type argument inference does not work in ternary operator

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 4.0.0-beta-1, 3.0.11, 2.5.19
• Component/s: Static compilation, Static Type Checker
• Assignee: Eric Milles
• Reporter: Stefanos Chaliasos
• Created: 15/Mar/21 09:36
• Updated: 03/Sep/22 00:37
• Resolved: 16/May/21 19:00

Description

I have the following Groovy program.

@groovy.transform.CompileStatic
public class Test {
  public static void main(String[] args) {
      final A<B> x = (true ? new A<>(new B()): new A<>(new C()))
      bar(x) // compiles
      bar((true ? new A<>(new B()): new A<>(new C()))) // does not compile
  }

  public static void bar(A<B> x) {}
}

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


class B {}
class C extends B{}

Actual Behavior

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

org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed:
Test.groovy: 6: [Static type checking] - Cannot call Test#bar(A <B>) with arguments [A <? extends B>]
 @ line 6, column 7.
         bar((true ? new A<>(new B()): new A<>(new C())))
         ^

1 error

Expected Behavior

Compile successfully.

Comment

This should be a regression bug because it compiles with the 4.0.0-alpha-2 compiler.

Affected Version

This programs fails when compiled with the compiler from the master (commit: f0eea862549529ef4e93fafe337f86dd4ac98751).