Now that we have a heuristic algorithm for infinitely expanding generics, we can go back to comparing signatures using contextual signature instantiation. For example:

var f: (s: string) => number;
var g: <T>(s: T) => T;
f = g;
g = f;

Both of these should ideally fail. The reason we could not do this earlier was because we could not detect infinitely expanding generics properly. But the current algorithm would prevent us from blowing up in the cases where the previous algorithm failed.