Bye class

main.dart

class Bye {
  int a = 1;
}

class Say extends Bye {
  int a = 2;
}

void printBye<T extends Say>(T b) {
  print(b);    // prints Instance of Bye
  print("a: ${b.a}");  // not an error anymore
}

void main() {
  printBye(Say());
}