Standalone deriving of Functor does not work for HsDoc
I tried to use the new DerivingFunctor
extension to derive Functor
for the HsDoc
type from the ghc package:
{-# StandaloneDeriving, DerivingFunctor #-}
import HsDoc
deriving instance Functor HsDoc
But I got this error message:
david@david-laptop:~/dev/test$ /home/david/ghc-head/bin/ghc --make Test.hs -package ghc
[1 of 1] Compiling Test ( Test.hs, Test.o )
Test.hs:9:0:
Couldn't match expected type `b' against inferred type `a'
`b' is a rigid type variable bound by
the type signature for `fmap' at <no location info>
`a' is a rigid type variable bound by
the type signature for `fmap' at <no location info>
Expected type: HsDoc b
Inferred type: HsDoc a
In the first argument of `DocAppend', namely `a1'
In the expression: DocAppend a1 a2
Trac metadata
Trac field | Value |
---|---|
Version | 6.11 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | |
Architecture |