When compiling this minimal example:

{-# LANGUAGE StaticPointers #-}

import Data.Typeable (Typeable)
import GHC.StaticPtr (StaticPtr)

f :: Typeable a => StaticPtr (a -> a)
f = static (\a -> _)

main :: IO ()
main = return ()

I get this output:

Bug.hs:8:19: error:ghc: panic! (the 'impossible' happened)
  (GHC version 8.0.1 for x86_64-unknown-linux):
	No skolem info: a_aJo[sk]

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

Unlike similar reported bugs, this happens on both 8.0.1 and 8.0.2.

Edit: no need to activate GADTs.