Panic whilst compiling syb due to OptCoercion
Here is the minimised test case with most definitions inlined.
module Data.Generics.Aliases where
import Control.Monad
import Data.Data
mkMp :: ( MonadPlus m
, Typeable a
, Typeable b
)
=> (b -> m b)
-> a
-> m a
mkMp ext = unM (maybe (M (const mzero)) id (gcast (M ext)))
newtype M m x = M { unM :: x -> m x }
Panics with -O2
as follows,
~/Documents/haskell/syb-0.6:ghc-7.11.20151214 Aliases.hs -O2
[1 of 1] Compiling Data.Generics.Aliases ( Aliases.hs, Aliases.o )
ghc: panic! (the 'impossible' happened)
(GHC version 7.11.20151214 for x86_64-apple-darwin):
ASSERT failed! file compiler/types/OptCoercion.hs, line 234
Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug
Trac metadata
Trac field | Value |
---|---|
Version | 7.10.3 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | high |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | goldfire |
Operating system | |
Architecture |