Spurious warning with new associated types and MultiParamTypeClasses

Consider this program:

{-# LANGUAGE TypeFamilies, MultiParamTypeClasses #-}
module Overlap where

class Foo a b where
  type Typ a

instance Foo Int Int where
  type Typ Int = Bool

instance Foo Int Bool where

We get a warning:

Overlap.hs:10:1:
    Warning: No explicit AT declaration for `Typ'
    In the instance declaration for `Foo Int Bool'

But inserting such an AT declaration would be an error!

Overlap.hs:8:8:
    Conflicting family instance declarations:
      type Typ Int -- Defined at Overlap.hs:8:8
      type Typ Int -- Defined at Overlap.hs:11:8

Trac metadata

Trac field	Value
Version	7.3
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture