Displaying pattern synonym for a GADT

Define

{-# LANGUAGE PatternSynonyms, GADTs #-}
data A x y where
  B :: A x x

pattern P = B

and in GHCi we see

λ> :i P
pattern (t ~ t) => P :: A t t1 	-- Defined at X.hs:5:9

It should be (t ~ t1). Just a problem with displaying, the pattern works correctly.

Trac metadata

Trac field	Value
Version	7.7
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC	cactus
Operating system
Architecture