Type checker loops with innocent looking associated type synonym

[Manuel M T Chakravarty]

Stefan Holdermans:
> Should I report this a bug? Or is it perhaps already been taken care  
> of in the head?

Probably the latter.

But really as, Bulat wrote, type families in 6.8 are unsupported.   
Please test your code with a HEAD snapshot.  If that goes wrong, a bug  
report on Trac would be most appreciated.

Manuel