Generalized newtype deriving with associated types

When I have a

    class Foo a where
	type Bar a
	foobar :: a -> Bar a

an

instance Foo Fooey ...

and

newtype Fooey2 = F2 (Fooey) deriving (Foo) 

I expect the automatically generated deriving to include

type Bar Fooey2 = Bar Fooey

but this is not the case: I cannot get an associated type from a newtype to resolve to anything. My guess is that the combination of -XTypeFamilies and -XGeneralizedNewtypeDeriving is rare enough that this may simply not have been thought of yet, but it's something I'd like to see fixed.

Trac metadata

Trac field	Value
Version	6.10.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture

mentioned in issue #2850 (closed)

changed weight to 5

added Tbug Trac import labels

Attached file Funky.hs ($329).

A test example.

closed

Trac metadata

Trac field	Value
Resolution	Unresolved → ResolvedDuplicate

(duplicate of #2850 (closed) in case you find this one first)

I don't think this is a duplicate of #2850 (closed), but I do think it is a duplicate of #8165 (closed).

Trac metadata

Trac field	Value
TypeOfFailure	- → OtherFailure

Correct; #8165 (closed) is the relevant ticket, and has a good discussion string.

Simon

added Pnormal label