[dart2wasm] Generics unexpected runtimeType when extends to nullable

[huanghui1998hhh]

void main() {
  print(AlwaysNullableData('').runtimeType);
}

abstract class BaseData<T> {
  BaseData(this.data);

  T data;
}

class AlwaysNullableData<T> extends BaseData<T?> {
  AlwaysNullableData(super.data);
}

This code will print AlwaysNullableData<String> on other platform, but on dart2wasm it print AlwaysNullableData<String?>

[lrhn]

That is a bug. The inferred type argument of AlwaysNullableData('') is <String>, so that's what T should be bound to, and then the type argument to BaseData is T?.

[mkustermann]

That is a bug. The inferred type argument of AlwaysNullableData('') is , so that's what T should be bound to, and then the type argument to BaseData is T?.

@lrhn to clarify: It should print AlwaysNullableData<String?>? Then it would be a bug in other platforms, not in wasm, right?

[eernstg]

It should print AlwaysNullableData<String>, but is BaseData<String?> should be true.

[mkustermann]

Don't know what I was thinking, yes of course the RTT is from the bottom class and it has to print the non-nullable one.

I think the type parameter sharing we do doesn't consider nullability, we'll fix it.

[lrhn]

doesn't consider nullability

That sound ... plausible.

[mkustermann]

cl/366940 should fix it.