private field override does not work (unrelated classes in the same library, override induced with mixins)

[jmesserly]

found while investigating dart-lang/language#104 (comment)

class M {
  int _foo = 42;
  int get foo => _foo;
}
class N {
  int _foo = 123;
}
class C extends M with N {}
main() {
  print(C().foo);
}

dartdevc prints the wrong answer. It should virtualize both M._foo and N._foo.

[jmesserly]

there's probably an issue with library cycles too: dart-lang/language#104 (comment)