In generics a restricted parameterized type behaves like dynamic if not specified

[fromlabs]

I know that parameterized type is optional and that for example List is a shorthand for List<dynamic> but when I declare a class with a parameterized type?

I think that the following example is a bug:

abstract class NumList<T extends num> implements List<T> {
}
abstract class DefNumList implements NumList<num> {
}
main() {
  NumList<num> numList;
  numList.add("10"); // ERROR
  numList.add(10); // OK

  NumList numList2;
  numList2.add("10"); // OK??? why, the base parameterized type is num not dynamic...
  numList2.add(10); // OK

  DefNumList numList3;
  numList3.add("10"); // ERROR
  numList3.add(10); // OK
}

[zoechi]

For standard Dart this is as designed.

For strong mode see #26310

[fromlabs]

Thanks Günter, I haven't looked yet at the strong mode documentation.