recursive_inheritance_test fails in strong mode

[jmesserly]

we do correctly reject the code (new MI() not being legal in strong mode), but it seems like we're going off the rails a bit here. I would expect the error at the new expressions. Instead we seem to infer non-sensical type arguments for new MI and new PMI.

import "package:expect/expect.dart";

// Regression test for recursive inheritance patterns
abstract class Comparable<T> {
  int compare(T a);
}
class MI<T extends MI<T>> {}

class PMI<T extends Comparable<T>> extends MI<PMI<T>> {}

void main() {
  var a = new MI();
  var b = new PMI();
  // [error] A value of type 'PMI<Comparable<Comparable<T>>>' cannot be assigned to a variable of type 'MI<MI<MI<T>>>'
  a = b;
  Expect.isTrue(a is MI);
  Expect.isTrue(b is PMI);
  Expect.isTrue(b is MI);
  Expect.isTrue(b is MI<PMI>);
}

[jmesserly]

This may have been improved by a recent commit: 0fe54a6, or we may have another similar issue. There were a couple of things wrong with inference and recursive bounds.

[jmesserly]

According to @vsmenon this is now fixed when he brings the latest Analyzer into DDC \o/

[zoechi]

@jmesserly does this fix #25530 as well?

[jmesserly]

yeah @zoechi, I wondered the same thing! Will have to try it. In general these patterns are kind of unsound, so it may still be valid to reject the code. But I hope it rejects the code with a valid error, not because it was going off the rails and computing crazy types. :)