#4169: TH vs. default function implementation: internal error
---------------------------------+------------------------------------------
Reporter: verdelyi | Owner:
Type: bug | Status: new
Priority: normal | Component: Compiler
Version: 6.12.3 | Keywords:
Os: Unknown/Multiple | Testcase:
Architecture: Unknown/Multiple | Failure: None/Unknown
---------------------------------+------------------------------------------
Testcase:
{{{
{-# LANGUAGE TemplateHaskell #-}
import Language.Haskell.TH
class Numeric a where
fromIntegerNum :: a
fromIntegerNum = undefined
ast :: Q [Dec]
ast = [d|
instance Numeric Int
|]
}}}
It gives an internal error:
{{{
InstanceGenerator.hs:9:13:
GHC internal error: `Main.$dmfromIntegerNum' is not in scope during
type checking, but it passed the renamer
tcg_type_env of environment: [(rgd, Class `Numeric'),
(rgf, Identifier `fromIntegerNum'),
(rgm, Data constructor
`Main.D:Numeric'),
(rgn, Type constructor
`Main.T:Numeric'),
(rgr, Type constructor
`Main.NTCo:T:Numeric'),
(rgs, Identifier `Main.D:Numeric')]
In the instance declaration for `Numeric Int'
In the Template Haskell quotation
[d|
instance Numeric Int where |]
In the expression:
[d|
instance Numeric Int where |]
Failed, modules loaded: none.
}}}
May be related to Ticket #4056 (?)
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4169>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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