matching type function application with type synonym application

When compiling this module:

{-# LANGUAGE TypeFamilies #-}

type family F a
type family G a

type H a = G a

newtype T0 a = Cons0 (F (G a))
newtype T1 a = Cons1 (F (H a))

f :: T0 Char -> T1 Char
f (Cons0 a) = Cons1 a

I get the type error

MatchTypeFunction.hs:12:21:
    Couldn't match expected type ‘F (H Char)’
                with actual type ‘F (G Char)’
    NB: ‘F’ is a type function, and may not be injective
    In the first argument of ‘Cons1’, namely ‘a’
    In the expression: Cons1 a

The code works with GHC-7.8 RC2 and GHC-7.4.2, but no longer with GHC-7.8.1. I guess there was some change in how deep GHC resolves type function application and type synonyms.

Trac metadata

Trac field	Value
Version	7.8.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler (Type checker)
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture