GHC panic using TypeInType with minimal source code
The following source code causes GHC 8.4.3 on 64bit Linux to panic:
{-# LANGUAGE TypeInType #-}
module Lib where
import Data.Kind
class Contravariant f where
contramap :: (a -> b) -> f b -> f a
dimap :: (Contravariant (p :: * -> b -> p * b), Functor (p a)) => (z -> a) -> (b -> c) -> p a b -> p z c
dimap f g = contramap f . fmap g
I have no idea if it should compile or not, but it shouldn't do this:
ghc: panic! (the 'impossible' happened)
(GHC version 8.4.3 for x86_64-unknown-linux):
piResultTy
k_a34u[tau:1]
*
Call stack:
CallStack (from HasCallStack):
callStackDoc, called at compiler/utils/Outputable.hs:1150:37 in ghc:Outputable
pprPanic, called at compiler/types/Type.hs:947:35 in ghc:Type
Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug
Trac metadata
Trac field | Value |
---|---|
Version | 8.4.3 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
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Blocking | |
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