QuantifiedConstraints not fully described in manual
As pointed out in ticket:15351#comment:156470, the section in the manual on
-XQuantifiedConstraints says that an
=> is essential in a quantified constraint. However, the following is accepted:
class C a foo :: (forall x. C x) => () foo = ()
Note that there is no
=> in the quantified constraint. We need to update the manual accordingly.