Hmm, that produces the following:

```
Error: c.__overloadset is not an lvalue
```

Before it was:

```
Error: not a property c.__overloadset
```

So it was broken to begin with. I was thinking of maybe constructing some sort of `DotExp` which just points to one of the symbols in the overload set (such as `C [dot] y`), and then using that as the error message. But I'm not too sure how to do that.