TemplateHaskell and Data.Typeable - tcIfaceGlobal (local): not found
The following code produces an ghc panic error:
{-# LANGUAGE TemplateHaskell #-}
{-# LANGUAGE ScopedTypeVariables #-}
module TH where
import Language.Haskell.TH
import Language.Haskell.TH.Syntax
import Data.Typeable
usingType :: forall a. Typeable a => a -> Q [Dec]
usingType _ = do
-- Try to get anything using typeRep.
let name = (tyConName $ typeRepTyCon $ typeRep (Proxy :: Proxy a)) `seq` "The name!"
-- theF = "The name!"
return [FunD (mkName "theF") [Clause [] (NormalB $ LitE $ StringL name ) []]]
{-# LANGUAGE TemplateHaskell #-}
module Main where
import TH
data A = A Int
-- Changing the argument to (A 3) does not help.
$(usingType (undefined :: A))
main = putStrLn $ theF
The error:
ghc: panic! (the 'impossible' happened)
(GHC version 8.0.1 for x86_64-unknown-linux):
tcIfaceGlobal (local): not found:
$tcA
[r5m0 :-> Type constructor ‘A’, r5m3 :-> Data constructor ‘A’,
r5m9 :-> Identifier ‘A’]
Trac metadata
Trac field | Value |
---|---|
Version | 8.0.1 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | |
Architecture |