ghc master (8.1.20161206) panics with assertion failure with devel2 flavor and -O

ghc version: 41ec722d with assertion that fails in #12926 (closed) commented out

{-# LANGUAGE TypeFamilies #-}

module Numeric.Polynomial.Log () where

class AdditiveGroup v where
  (^+^) :: v -> v -> v
  negateV :: v -> v
  (^-^) :: v -> v -> v
  v ^-^ v' = v ^+^ negateV v'
  
class AdditiveGroup v => VectorSpace v where
  type Scalar v :: *
  (*^) :: Scalar v -> v -> v
  
  
data Poly1 a = Poly1 a a

data IntOfLog poly a = IntOfLog !a !(poly a)

instance Num a => AdditiveGroup (Poly1 a) where
    {-# INLINE (^+^) #-}
    {-# INLINE negateV #-}
    Poly1 a b ^+^ Poly1 a' b' = Poly1 (a + a') (b + b')
    negateV (Poly1 a b) = Poly1 (negate a) (negate b)
    
    
instance (AdditiveGroup (poly a), Num a) => AdditiveGroup (IntOfLog poly a) where
    {-# INLINE (^+^) #-}
    {-# INLINE negateV #-}
    IntOfLog k p ^+^ IntOfLog k' p' = IntOfLog (k + k') (p ^+^ p')
    negateV (IntOfLog k p) = IntOfLog (negate k) (negateV p)
    {-# SPECIALISE instance Num a => AdditiveGroup (IntOfLog Poly1 a) #-}
    
instance (VectorSpace (poly a), Scalar (poly a) ~ a, Num a) => VectorSpace (IntOfLog poly a) where
    type Scalar (IntOfLog poly a) = a
    s *^ IntOfLog k p = IntOfLog (s * k) (s *^ p)

ghc: panic! (the 'impossible' happened)
  (GHC version 8.1.20161206 for x86_64-unknown-linux):
        ASSERT failed!
  $dAdditiveGroup_aIU
  Call stack:
      CallStack (from HasCallStack):
        prettyCurrentCallStack, called at compiler/utils/Outputable.hs:1114:58 in ghc:Outputable
        callStackDoc, called at compiler/utils/Outputable.hs:1163:22 in ghc:Outputable
        assertPprPanic, called at compiler/stgSyn/CoreToStg.hs:967:78 in ghc:CoreToStg
  Call stack:
      CallStack (from HasCallStack):
        prettyCurrentCallStack, called at compiler/utils/Outputable.hs:1114:58 in ghc:Outputable
        callStackDoc, called at compiler/utils/Outputable.hs:1118:37 in ghc:Outputable
        pprPanic, called at compiler/utils/Outputable.hs:1161:5 in ghc:Outputable
        assertPprPanic, called at compiler/stgSyn/CoreToStg.hs:967:78 in ghc:CoreToStg

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

Trac metadata

Trac field	Value
Version	8.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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