class methods with associated equality constraints panic

The following file causes a panic ("getEqPredTys"):

{-# LANGUAGE ConstraintKinds, TypeFamilies #-}
import GHC.Exts

class Pair p where
	type Ctxt p a :: Constraint
	l :: Ctxt p a => p a -> a

data Unit a = Unit

instance Pair Unit where
	type Ctxt Unit a = a ~ ()
	l _ = ()

Trac metadata

Trac field	Value
Version	7.6.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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