#5303: GHC crash (panic) with -O2 and nonexistent .hi
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Reporter: mornfall | Owner:
Type: bug | Status: new
Priority: high | Milestone: 7.2.1
Component: Compiler | Version: 7.0.3
Keywords: | Testcase:
Blockedby: | Difficulty:
Os: Linux | Blocking:
Architecture: x86 | Failure: Compile-time crash
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Comment(by mornfall):
Ok, I distilled the test case further (still crashing for me):
{{{
{-# LANGUAGE KindSignatures, GADTs, TypeFamilies, MultiParamTypeClasses,
FlexibleContexts, ScopedTypeVariables, TypeSynonymInstances,
FlexibleInstances #-}
module Test( showContextSeries ) where
import Control.Monad.State.Strict( StateT )
import Control.Monad.Trans ( lift )
data Tree m = Tree {}
data FL (a :: * -> * -> *) x z where
(:>:) :: a x y -> FL a y z -> FL a x z
NilFL :: FL a x x
class (Functor m, Monad m) => ApplyMonad m (state :: (* -> *) -> *)
class Apply (p :: * -> * -> *) where
type ApplyState p :: (* -> *) -> *
apply :: ApplyMonad m (ApplyState p) => p x y -> m ()
class (Functor m, Monad m, ApplyMonad (ApplyMonadOver m state) state)
=> ApplyMonadTrans m (state :: (* -> *) -> *) where
type ApplyMonadOver m state :: * -> *
runApplyMonad :: (ApplyMonadOver m state) x -> state m -> m (x, state m)
instance (Functor m, Monad m) => ApplyMonadTrans m Tree where
type ApplyMonadOver m Tree = TreeMonad m
runApplyMonad = virtualTreeMonad
instance (Functor m, Monad m) => ApplyMonad (TreeMonad m) Tree
-- | Internal state of the 'TreeIO' monad. Keeps track of the current Tree
-- content, unsync'd changes and a current working directory (of the
monad).
data TreeState m = TreeState { tree :: !(Tree m) }
type TreeMonad m = StateT (TreeState m) m
type TreeIO = TreeMonad IO
virtualTreeMonad :: (Functor m, Monad m) => TreeMonad m a -> Tree m -> m
(a, Tree m)
virtualTreeMonad action t = undefined
applyToState :: forall p m x y. (Apply p, ApplyMonadTrans m (ApplyState
p))
=> p x y -> (ApplyState p) m -> m ((ApplyState p) m)
applyToState _ _ = snd `fmap` runApplyMonad undefined undefined
showContextSeries :: (Apply p, ApplyState p ~ Tree) => FL p x y -> TreeIO
()
showContextSeries (p:>:_) = (undefined >>= lift . applyToState p) >>
return ()
}}}
Still needs MTL, but you could at least in theory get rid of that as well.
Whether it is practical, I can't say without trying.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5303#comment:4>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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