-XAutoDeriveTypeable fails to generate instances
The following doesn't compile with GHC 7.8.3, but works with GHC HEAD. I couldn't find a matching ticket, so I don't know if this was fixed knowingly or not...
{-# LANGUAGE AutoDeriveTypeable #-}
import Data.Typeable (Typeable)
data T1 = C1 Int
deriving (Eq,Ord)
tvoid :: Typeable a => a -> IO ()
tvoid _ = return ()
main :: IO ()
main = tvoid (C1 0)- ..fails for GHC 7.8.3 with
No instance for (Typeable T1) arising from a use of ‘tvoid’
In the expression: tvoid (C1 0)
In an equation for ‘main’: main = tvoid (C1 0)I'm marking this with high priority, as it makes -XAutoDeriveTypeable unusable on GHC 7.8.3 as it stands.
Trac metadata
| Trac field | Value |
|---|---|
| Version | 7.8.3 |
| Type | Bug |
| TypeOfFailure | OtherFailure |
| Priority | high |
| Resolution | Unresolved |
| Component | Compiler |
| Test case | |
| Differential revisions | |
| BlockedBy | |
| Related | |
| Blocking | |
| CC | |
| Operating system | |
| Architecture |