Fix Trac #3221: renamer warnings for deriving clauses

[ghc-hetmet.git] / compiler / rename / RnSource.lhs

diff --git a/compiler/rename/RnSource.lhs b/compiler/rename/RnSource.lhs
index 442d465..5a071ee 100644 (file)
--- a/compiler/rename/RnSource.lhs
+++ b/compiler/rename/RnSource.lhs
@@ -216,6 +216,8 @@ rnTyClDecls tycl_decls = do  (decls', _fvs) <- rnList rnTyClDecl tycl_decls
                             return decls'
 
 addTcgDUs :: TcGblEnv -> DefUses -> TcGblEnv 
+-- This function could be defined lower down in the module hierarchy, 
+-- but there doesn't seem anywhere very logical to put it.
 addTcgDUs tcg_env dus = tcg_env { tcg_dus = tcg_dus tcg_env `plusDU` dus }
 
 rnList :: (a -> RnM (b, FreeVars)) -> [Located a] -> RnM ([Located b], FreeVars)
@@ -659,10 +661,10 @@ rnTyClDecl (tydecl@TyData {tcdND = new_or_data, tcdCtxt = context,
                    else lookupLocatedTopBndrRn tycon
        ; context' <- rnContext data_doc context
        ; typats' <- rnTyPats data_doc typatsMaybe
-       ; (derivs', deriv_fvs) <- rn_derivs derivs
        ; condecls' <- rnConDecls (unLoc tycon') condecls
                -- No need to check for duplicate constructor decls
                -- since that is done by RnNames.extendGlobalRdrEnvRn
+       ; (derivs', deriv_fvs) <- rn_derivs derivs
        ; return (TyData {tcdND = new_or_data, tcdCtxt = context', 
                           tcdLName = tycon', tcdTyVars = tyvars', 
                           tcdTyPats = typats', tcdKindSig = Nothing, 
@@ -689,11 +691,11 @@ rnTyClDecl (tydecl@TyData {tcdND = new_or_data, tcdCtxt = context,
                -- do not scope over the constructor signatures
                --      data T a where { T1 :: forall b. b-> b }
 
-       ; (derivs', deriv_fvs) <- rn_derivs derivs
        ; condecls' <- rnConDecls (unLoc tycon') condecls
                -- No need to check for duplicate constructor decls
                -- since that is done by RnNames.extendGlobalRdrEnvRn
 
+       ; (derivs', deriv_fvs) <- rn_derivs derivs
        ; return (TyData {tcdND = new_or_data, tcdCtxt = noLoc [], 
                           tcdLName = tycon', tcdTyVars = tyvars', 
                           tcdTyPats = typats', tcdKindSig = sig,