isInstance does not work on Typeable with base-4.8 anymore

> :set -XTemplateHaskell
> :m +Data.Typeable
> :m +Language.Haskell.TH

--- With GHC 7.8 or earlier versions of GHC (I only tried with GHC 7.6, but my friends tried on 7.8 and earlier versions)
> $(isInstance ''Typeable [ConT ''Char] >>= stringE.show)
"True"

--- With GHC 7.10.1
> $(isInstance ''Typeable [ConT ''Char] >>= stringE.show)
"False"

I have noticed that standalone derivings of Typeable instances in Data.Typeable are disappared magically in base-4.8 of GHC 7.10,also one cannot query the instances of it by using :i Typeable in GHCi, however, obviously, I can use typeOf function in base-4.8 to get the TypeRep of Char.

The problem is that isInstance in template-haskell library doesn't know Char and many other types are instances of Typeable anymore.

Trac metadata

Trac field	Value
Version	7.10.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	libraries/base
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture