[GROOVY-10271] Wrong inference when using ternary operator with closure and variable

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 4.0.0-alpha-3, 4.0.0-beta-1, 3.0.9
• Fix Version/s: 4.0.5, 3.0.20
• Component/s: Static compilation, Static Type Checker
• Assignee: Eric Milles
• Reporter: Stefanos Chaliasos
• Created: 29/Sep/21 08:23
• Updated: 30/Nov/23 16:48
• Resolved: 19/May/22 17:49

Description

I have the following Groovy program.

import java.util.function.Supplier;

@groovy.transform.TypeChecked
class Main {
  static final void foo(Supplier<Integer> x) {}

  public static final void main() {
      Supplier<Integer> y = { -> 5 }
      Supplier<Integer> z = (true) ? y : {-> 5}
  }
}

Actual Behavior

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

org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed:
Main.groovy: 11: [Static type checking] - Cannot assign value of type java.lang.Object to variable of type java.util.function.Supplier<java.lang.Integer>
 @ line 11, column 29.
         Supplier<Integer> z = (true) ? y : {-> 5}
                               ^

1 error

Expected Behavior

Compile successfully.

Comment

Tested against 4-beta-1, 4-alpha-3, 3.0.9, and master (commit: b26dbbeabe1e3d27d30c936701b1a571e24d5ab2). Maybe similar to GROOVY-10114, but with function types.

Issue Links

• relates to: GROOVY-10701 NullPointerException in instruction selection phase when having conditionals with lambdas and function references