No error reported when a const makes explicit use of a type parameter

[stereotype441]

Consider the following code:

class C<T> {
  const C();
}

class D<T> {
  final x = const C<T>(); // (1)
}

main() {
  print(new D<int>().x.runtimeType);
}

The VM, dart2js, and the common front end agree that this code has an error at the line marked (1), because a constant expression cannot refer to type variables in enclosing scopes.

The analyzer reports no error.

[sigmundch]

DBC

I should note that we have run into this a few times with internal customers when defining default values. The most subtle case has been when using a generic function, which gets instantiated with a class type variable implicitly. You can find examples in #33438

[MichaelRFairhurst]

Saw this while investigating #32913 and thought it'd be a good place to start.....however, this is already fixed, it seems.