Deriving higher-arity instances for newtype family instances fails

{-# LANGUAGE TypeFamilies, GeneralizedNewtypeDeriving #-}
module Baz where

class Bar f where
	bar :: f a -> Int

data family Foo k :: * -> *

instance Bar Maybe where
	bar Nothing = 0
	bar Just{} = 1

newtype instance Foo Int a = FooInt (Maybe a) deriving (Bar)

fails with

Baz.hs:13:56:
    Derived instance `Bar (Foo Int)'
      requires illegal partial application of data type family Foo
    In the newtype instance declaration for `Foo'

Attempting to use StandaloneDeriving:

{-# LANGUAGE StandaloneDeriving, TypeFamilies, GeneralizedNewtypeDeriving #-}
module Baz where

class Bar f where
	bar :: f a -> Int

data family Foo k :: * -> *

instance Bar Maybe where
	bar Nothing = 0
	bar Just{} = 1

newtype instance Foo Int a = FooInt (Maybe a)

deriving instance Bar (Foo Int)

gives the super-weird error

Baz.hs:15:0:
    No family instance for `Foo Int'
    In the stand-alone deriving instance for `Bar (Foo Int)'

Trac metadata

Trac field	Value
Version	6.12.3
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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