[switch][pattern] Scope of pattern binding extends illegally resulting in wrong diagnostic

[srikanth-sankaran]

Consider the program:

public class X {
    public static void main(String[] args) {
		Object o = new Object();
		switch (o) {
		case String s :
			if (!(o instanceof String str))
				throw new RuntimeException();
		case null : 
			if (!(o instanceof String str))
				throw new RuntimeException();
		default:
                        System.out.println("Default");
		}
	}
}

ECJ rejects this with: Duplicate local variable str but that is wrong. Javac compiles the code and when run it prints "Default" as it should

[srikanth-sankaran]

See also https://bugs.eclipse.org/bugs/show_bug.cgi?id=577415 - related but different bug