Breaking errors in D11.2 or D11.x

This looks good to me. I think given 3x is beta, release notes should just make it clear in case anyone is extending any constraints, that they should add the return types + types to their messages in order to remain compatible.

E.g.

class Class1 {
	public string $message = 'Great message.';
}

class Class2 extends Class1 {
	public $message = 'Great message.';
}
$class = new Class2();

Will result in

Fatal error: Type of Class2::$message must be string (as in class Class1)

And

class Class1 {
	public function myFunction(): string {
		return 'hello1';
	}
}

class Class2 extends Class1 {
	public function myFunction() {
		return 'hello2';
	}
}
$class = new Class2();
print $class->myFunction();

Will result in

Fatal error: Declaration of Class2::myFunction() must be compatible with Class1::myFunction(): string