panic! (the `impossible' happened): TcTyClsDecls:get_sig

[Sengan]

ghc -c  -fglasgow-exts -cpp -O2 -fvia-C -O2-for-C  -syslib data -syslib lang -syslib concurrent MonadErr.lhs 

panic! (the `impossible' happened):
        TcTyClsDecls:get_sig

Please report it as a compiler bug to glasgow-haskell-bugs at haskell.org.

As soon as I add inlining.... I get:
Without inlining I get zonkIdOcc's.

> module MonadErr where

> data ERR a b = EOK a | ERR b deriving (Show)

> class MonadErr m e | m -> e where
>    {-# INLINE rreturn #-}
>    {-# INLINE (>>>=)  #-}
>    errturn  ::           e   -> m a
>    rreturn  ::           a   -> m a
>    errcatch ::           m a -> (e -> m b) -> (a -> m b) -> m b
>    (>>>=)   ::           m a -> (a -> m b) -> m b
>    (>>>)    ::           m a -> m b        -> m b


> sequence_E []     = rreturn []
> sequence_E (c:cs) = c                 >>>= \x ->
>                     sequence_E cs     >>>= \xs ->
>                     rreturn  (x:xs)
> mapM_E f          = sequence_E . map f

Senagn