Type operators in existential context cannot be parsed

{-# LANGUAGE TypeOperators, MultiParamTypeClasses, ExistentialQuantification #-}

class a + b

data D1 = forall a b. (a + b) => D1 a b
data D2 = forall a b.  a + b  => D2 a b

The declaration D1 is accepted, while D2 is rejected. There is no reason to reject D2 except for shortcomings of the current grammar.

Trac metadata

Trac field	Value
Version	8.4.3
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler (Parser)
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture