matchGroupArity panic with PatternSynonyms

{-# LANGUAGE PatternSynonyms, ViewPatterns, EmptyCase #-}

pattern Id <- (id -> _) where

which gives:

% ghc -ignore-dot-ghci tmp.FbbzjZ48OO.hs 
[1 of 1] Compiling Main             ( tmp.FbbzjZ48OO.hs, tmp.FbbzjZ48OO.o )
ghc: panic! (the 'impossible' happened)
  (GHC version 7.10.0.20150316 for i386-unknown-linux):
        matchGroupArity

Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug

Trac metadata

Trac field	Value
Version	7.10.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system	Linux
Architecture	x86