Fix Trac #2310: result type signatures are not supported any more

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

diff --git a/compiler/rename/RnBinds.lhs b/compiler/rename/RnBinds.lhs
index 6ca3bdb..2ae46bf 100644 (file)
--- a/compiler/rename/RnBinds.lhs
+++ b/compiler/rename/RnBinds.lhs
@@ -22,10 +22,10 @@ import HsSyn
 import RdrHsSyn
 import RnHsSyn
 import TcRnMonad
-import RnTypes        ( rnHsSigType, rnLHsType, rnHsTypeFVs,checkPrecMatch)
+import RnTypes        ( rnHsSigType, rnLHsType, checkPrecMatch)
 import RnPat          (rnPatsAndThen_LocalRightwards, rnBindPat,
-                       NameMaker, localRecNameMaker, topRecNameMaker, applyNameMaker, 
-                       patSigErr)
+                       NameMaker, localRecNameMaker, topRecNameMaker, applyNameMaker
+                      )
                       
 import RnEnv
 import PrelNames       ( mkUnboundName )
@@ -792,31 +792,27 @@ rnMatch :: HsMatchContext Name -> LMatch RdrName -> RnM (LMatch Name, FreeVars)
 rnMatch ctxt  = wrapLocFstM (rnMatch' ctxt)
 
 rnMatch' :: HsMatchContext Name -> Match RdrName -> RnM (Match Name, FreeVars)
-rnMatch' ctxt (Match pats maybe_rhs_sig grhss)
-  = 
-       -- Deal with the rhs type signature
-    bindPatSigTyVarsFV rhs_sig_tys     $ do
-    opt_PatternSignatures <- doptM Opt_PatternSignatures
-    (maybe_rhs_sig', ty_fvs) <-
-      case maybe_rhs_sig of
-        Nothing -> return (Nothing, emptyFVs)
-        Just ty | opt_PatternSignatures -> do (ty', ty_fvs) <- rnHsTypeFVs doc_sig ty
-                                              return (Just ty', ty_fvs)
-                | otherwise             -> do addLocErr ty patSigErr
-                                              return (Nothing, emptyFVs)
-
-       -- Now the main event
-       -- note that there are no local ficity decls for matches
-    rnPatsAndThen_LocalRightwards ctxt pats    $ \ pats' -> do
-      (grhss', grhss_fvs) <- rnGRHSs ctxt grhss
-
-      return (Match pats' maybe_rhs_sig' grhss', grhss_fvs `plusFV` ty_fvs)
+rnMatch' ctxt match@(Match pats maybe_rhs_sig grhss)
+  = do         {       -- Result type signatures are no longer supported
+         case maybe_rhs_sig of 
+               Nothing -> return ()
+               Just ty -> addLocErr ty (resSigErr ctxt match)
+
+
+              -- Now the main event
+              -- note that there are no local ficity decls for matches
+       ; rnPatsAndThen_LocalRightwards ctxt pats       $ \ pats' -> do
+       { (grhss', grhss_fvs) <- rnGRHSs ctxt grhss
+
+       ; return (Match pats' Nothing grhss', grhss_fvs) }}
        -- The bindPatSigTyVarsFV and rnPatsAndThen will remove the bound FVs
   where
-     rhs_sig_tys =  case maybe_rhs_sig of
-                       Nothing -> []
-                       Just ty -> [ty]
-     doc_sig = text "In a result type-signature"
+
+resSigErr :: HsMatchContext Name -> Match RdrName -> HsType RdrName -> SDoc 
+resSigErr ctxt match ty
+   = vcat [ ptext (sLit "Illegal result type signature") <+> quotes (ppr ty)
+         , nest 2 $ ptext (sLit "Result signatures are no longer supported in pattern matches")
+         , pprMatchInCtxt ctxt match ]
 \end{code}