import DynFlags ( DynFlag(..) )
import Maybes ( seqMaybe )
import Maybe ( isNothing, isJust )
-import Monad ( liftM )
+import Monad ( liftM, when )
import BasicTypes ( Boxity(..) )
\end{code}
<- mapFvRn (wrapLocFstM rnDefaultDecl) default_decls ;
let {
- rn_at_decls = concat
- [ats | L _ (InstDecl _ _ _ ats) <- rn_inst_decls] ;
rn_group = HsGroup { hs_valds = rn_val_decls,
- hs_tyclds = rn_tycl_decls ++ rn_at_decls,
+ hs_tyclds = rn_tycl_decls,
hs_instds = rn_inst_decls,
hs_fixds = rn_fix_decls,
hs_depds = [],
let
at_doc = text "In the associated types in an instance declaration"
at_names = map (head . tyClDeclNames . unLoc) ats
- (_, rdrCtxt, _, _) = splitHsInstDeclTy (unLoc inst_ty)
in
checkDupNames at_doc at_names `thenM_`
- rnATDefs rdrCtxt ats `thenM` \ (ats', at_fvs) ->
+ rnATInsts ats `thenM` \ (ats', at_fvs) ->
-- Rename the bindings
-- The typechecker (not the renamer) checks that all
-- to remove the context).
\end{code}
-Renaming of the associated data definitions requires adding the instance
-context, as the rhs of an AT declaration may use ATs from classes in the
-context.
+Renaming of the associated types in instances.
+
+* We raise an error if we encounter a kind signature in an instance.
\begin{code}
-rnATDefs :: HsContext RdrName -> [LTyClDecl RdrName]
- -> RnM ([LTyClDecl Name], FreeVars)
-rnATDefs ctxt atDecls =
- mapFvRn (wrapLocFstM addCtxtAndRename) atDecls
+rnATInsts :: [LTyClDecl RdrName] -> RnM ([LTyClDecl Name], FreeVars)
+rnATInsts atDecls =
+ mapFvRn (wrapLocFstM rnATInst) atDecls
where
- -- The parser won't accept anything, but a data declaration
- addCtxtAndRename ty@TyData {tcdCtxt = L l tyCtxt} =
- rnTyClDecl (ty {tcdCtxt = L l (ctxt ++ tyCtxt)})
- -- The source loc is somewhat half hearted... -=chak
+ rnATInst tydecl@TyFunction {} =
+ do
+ addErr noKindSig
+ rnTyClDecl tydecl
+ rnATInst tydecl@TySynonym {} = rnTyClDecl tydecl
+ rnATInst tydecl@TyData {} =
+ do
+ checkM (not . isKindSigDecl $ tydecl) $ addErr noKindSig
+ rnTyClDecl tydecl
+ rnATInst _ =
+ panic "RnSource.rnATInsts: not a type declaration"
+
+noKindSig = text "Instances cannot have kind signatures"
\end{code}
For the method bindings in class and instance decls, we extend the
-- Rename associated type declarations (in classes)
--
--- * This can be data declarations, type function signatures, and (default)
--- type function equations.
+-- * This can be kind signatures and (default) type function equations.
--
rnATs :: [LTyClDecl RdrName] -> RnM ([LTyClDecl Name], FreeVars)
rnATs ats = mapFvRn (wrapLocFstM rn_at) ats
where
rn_at (tydecl@TyData {}) = rnTySig tydecl lookupIdxVars
rn_at (tydecl@TyFunction {}) = rnTySig tydecl lookupIdxVars
- rn_at (tydecl@TySynonym {}) = rnTyClDecl tydecl
+ rn_at (tydecl@TySynonym {}) =
+ do
+ checkM (isNothing (tcdTyPats tydecl)) $ addErr noPatterns
+ rnTyClDecl tydecl
rn_at _ = panic "RnSource.rnATs: invalid TyClDecl"
- lookupIdxVars _ tyvars cont = mappM lookupIdxVar tyvars >>= cont
- --
+ lookupIdxVars _ tyvars cont =
+ do { checkForDups tyvars;
+ ; tyvars' <- mappM lookupIdxVar tyvars
+ ; cont tyvars'
+ }
-- Type index variables must be class parameters, which are the only
-- type variables in scope at this point.
lookupIdxVar (L l tyvar) =
name' <- lookupOccRn (hsTyVarName tyvar)
return $ L l (replaceTyVarName tyvar name')
+ -- Type variable may only occur once.
+ --
+ checkForDups [] = return ()
+ checkForDups (L loc tv:ltvs) =
+ do { setSrcSpan loc $
+ when (hsTyVarName tv `ltvElem` ltvs) $
+ addErr (repeatedTyVar tv)
+ ; checkForDups ltvs
+ }
+
+ rdrName `ltvElem` [] = False
+ rdrName `ltvElem` (L _ tv:ltvs)
+ | rdrName == hsTyVarName tv = True
+ | otherwise = rdrName `ltvElem` ltvs
+
+noPatterns = text "Default definition for an associated synonym cannot have"
+ <+> text "type pattern"
+
+repeatedTyVar tv = ptext SLIT("Illegal repeated type variable") <+>
+ quotes (ppr tv)
+
-- This data decl will parse OK
-- data T = a Int
-- treating "a" as the constructor.