#4056: GHC panic with small TH code
---------------------------------+------------------------------------------
Reporter: verdelyi | Owner:
Type: bug | Status: new
Priority: normal | Milestone:
Component: Template Haskell | Version: 6.12.2
Keywords: | Difficulty:
Os: Unknown/Multiple | Testcase:
Architecture: Unknown/Multiple | Failure: Compile-time crash
---------------------------------+------------------------------------------
Description changed by igloo:
Old description:
> [verde...@localhost CompilerGenerator-Haskell]$ cat BUG.hs
> {-# LANGUAGE TemplateHaskell, TypeFamilies, RankNTypes, FlexibleContexts
> #-}
>
> import Language.Haskell.TH
>
> astTest :: Q [Dec]
> astTest = [d|
> generateWalker :: forall t . [t] -> [t]
> generateWalker = id
>
> class (Num (From t), Num (To t)) => TransformationPhase t where
> type From t
> type To t
> type Downwards t
> type Upwards t
>
> executeTransformationPhase :: [t] -> [t]
> executeTransformationPhase = undefined
> |]
> [verde...@localhost CompilerGenerator-Haskell]$ ghci BUG.hs
> GHCi, version 6.12.2: http://www.haskell.org/ghc/ :? for help
> Loading package ghc-prim ... linking ... done.
> Loading package integer-gmp ... linking ... done.
> Loading package base ... linking ... done.
> Loading package ffi-1.0 ... linking ... done.
> [1 of 1] Compiling Main ( BUG.hs, interpreted )
> ghc: panic! (the 'impossible' happened)
> (GHC version 6.12.2 for i386-unknown-linux):
> nameModule executeTransformationPhase{v agj}
>
> Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug
>
> >
New description:
{{{
[verde...@localhost CompilerGenerator-Haskell]$ cat BUG.hs
{-# LANGUAGE TemplateHaskell, TypeFamilies, RankNTypes, FlexibleContexts
#-}
import Language.Haskell.TH
astTest :: Q [Dec]
astTest = [d|
generateWalker :: forall t . [t] -> [t]
generateWalker = id
class (Num (From t), Num (To t)) => TransformationPhase t where
type From t
type To t
type Downwards t
type Upwards t
executeTransformationPhase :: [t] -> [t]
executeTransformationPhase = undefined
|]
[verde...@localhost CompilerGenerator-Haskell]$ ghci BUG.hs
GHCi, version 6.12.2: http://www.haskell.org/ghc/ :? for help
Loading package ghc-prim ... linking ... done.
Loading package integer-gmp ... linking ... done.
Loading package base ... linking ... done.
Loading package ffi-1.0 ... linking ... done.
[1 of 1] Compiling Main ( BUG.hs, interpreted )
ghc: panic! (the 'impossible' happened)
(GHC version 6.12.2 for i386-unknown-linux):
nameModule executeTransformationPhase{v agj}
Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug
>
}}}
--
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4056#comment:1>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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