#5441: unsafeCoerce'ing function to GHC.Prim.Any causes segfault
---------------------------------+------------------------------------------
Reporter: ulfn | Owner:
Type: bug | Status: new
Priority: normal | Component: Compiler
Version: 7.2.1 | Keywords:
Testcase: | Blockedby:
Os: Unknown/Multiple | Blocking:
Architecture: x86 | Failure: Runtime crash
---------------------------------+------------------------------------------
Changes (by ulfn):
* failure: None/Unknown => Runtime crash
Comment:
Wiki-fu fail. New attempt with proper code block (can I edit the
original?)
{{{
module Any where
import Unsafe.Coerce (unsafeCoerce)
import GHC.Prim (Any)
listmap :: (a -> b) -> [a] -> [b]
listmap f [] = []
listmap f (x : xs) = f x : listmap f xs
data Nat = Z | S Nat
{-# NOINLINE inject #-}
inject :: Nat -> Nat -> Nat
inject m i = i
{-# NOINLINE look #-}
look :: Nat -> String -> Char
look Z _ = '0'
showDigit :: Nat -> () -> Nat -> Char
showDigit base prf d = look (inject base d) ""
toDigits :: Nat -> Nat -> [Nat]
toDigits Z Z = [Z]
coe1 :: (Nat -> String) -> Any
coe1 = unsafeCoerce
coe2 :: Any -> (Nat -> String)
coe2 = unsafeCoerce
showInBase :: Nat -> Any
showInBase base
= coe1 (\n -> listmap
(showDigit base ())
(toDigits base n))
showNat :: Nat -> String
showNat = coe2 (showInBase Z)
}}}
{{{
-- Main.hs
import Any
main = putStrLn (showNat Z)
}}}
{{{
$ ghc -O --make Main.hs
$ ./Main
Bus error: 10
}}}
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5441#comment:1>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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