[GROOVY-11110] STC mixes names of bounded type parameters

• Type: Bug
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Component/s: Static Type Checker
• Labels: bounded-polymorphism
• Assignee: Unassigned
• Reporter: Thodoris Sotiropoulos
• Created: 22/Jun/23 12:51
• Updated: 22/Jun/23 12:51

Description

I have the following program

import java.util.stream.*;

class Main {
  static final <T extends Number>void test() {
    java.util.function.BiConsumer<T, T> func = null;
    Stream<String> stream = null;
    T res = stream.<T>collect(() -> (T) null, (T finisher, String hijacking) -> { }, func);
  }
}

Actual behavior

org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed:
Main.groovy: 8: [Static type checking] - Cannot assign value of type java.lang.String to variable of type T
 @ line 8, column 13.
       T res = stream.<T>collect(() -> (T) null, (T finisher, String hijacking) -> { }, func);
               ^

1 error

Expected behavior

Compile successfully

Notes

To trigger the bug, the type parameter of method test() should be bounded with name T.