Surprising accepted constructor for GADT instance of data family

-- Accepted:
data family Foo (x :: *) :: * -> *
data instance Foo Int Char where
  Foo :: Foo Int Char

-- Not accepted
data Bar Char where
  Bar :: Bar Char

It seems the second example, using a simple GADT, is syntactically barred from having a specific type constructor in its "head". That syntactic restriction is relaxed, however, for all arguments of the data instance, even though I'd expect it only for the first argument.

Trac metadata

Trac field	Value
Version	7.10.3
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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