[GROOVY-10992] Unexpected type mismatch when calling a parameterized function with a bounded type parameter

• Type: Bug
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Component/s: Static Type Checker
• Assignee: Unassigned
• Reporter: Thodoris Sotiropoulos
• Created: 28/Mar/23 09:07
• Updated: 15/Apr/23 15:51

Description

Possible regression? Groovyc 4.0.10 compiles the program

I have the following program

import java.util.function.Supplier;
import java.util.function.BinaryOperator;
import java.util.stream.Stream;

class Main {
  static final <X extends Number> void test() {
    Supplier<Stream<X>> x = null;
    X y = null;
    BinaryOperator<X> z = null;

    X result = x.get().reduce(y, z);
  }
}

Actual behavior

org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed:
test.groovy: 11: [Static type checking] - Cannot call java.util.stream.Stream#reduce(X, java.util.function.BinaryOperator<X extends java.lang.Number>) with arguments [X, java.util.function.BinaryOperator<X>]
 @ line 11, column 16.
       X result = x.get().reduce(y, z);
                  ^

1 error

Expected behavior

Compile successfully

Notes: The type parameter X should have an upper bound in order to trigger the error.

Tested against master (commit: a29ce1ce64d565526b70e145ace665dd0617ec9b)