X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Ftypecheck%2FTcPat.lhs;h=376385aaa69025f35af9ebc9efa0ccf5c8227bdc;hb=8897e76874e10daa4dc695342e68b15e114a6de0;hp=e21fb6883e7aa5ae8ca39231eb877e6a95cad996;hpb=a17d329568660592dad5c7668fb09f31ab77cd69;p=ghc-hetmet.git

diff --git a/compiler/typecheck/TcPat.lhs b/compiler/typecheck/TcPat.lhs
index e21fb68..376385a 100644
--- a/compiler/typecheck/TcPat.lhs
+++ b/compiler/typecheck/TcPat.lhs
@@ -37,6 +37,7 @@ import TyCon
 import DataCon
 import PrelNames
 import BasicTypes hiding (SuccessFlag(..))
+import DynFlags	( DynFlag( Opt_GADTs ) )
 import SrcLoc
 import ErrUtils
 import Util
@@ -180,7 +181,7 @@ tcPatBndr :: PatState -> Name -> BoxySigmaType -> TcM TcId
 tcPatBndr (PS { pat_ctxt = LetPat lookup_sig }) bndr_name pat_ty
   | Just mono_ty <- lookup_sig bndr_name
   = do	{ mono_name <- newLocalName bndr_name
-	; boxyUnify mono_ty pat_ty
+	; _ <- boxyUnify mono_ty pat_ty
 	; return (Id.mkLocalId mono_name mono_ty) }
 
   | otherwise
@@ -237,7 +238,7 @@ unBoxArgType ty pp_this
 		return ty'
 	  else do 	-- OpenTypeKind, so constrain it
 	{ ty2 <- newFlexiTyVarTy argTypeKind
-	; unifyType ty' ty2
+	; _ <- unifyType ty' ty2
 	; return ty' }}
   where
     msg = pp_this <+> ptext (sLit "cannot be bound to an unboxed tuple")
@@ -364,12 +365,15 @@ tc_pat pstate lpat@(LazyPat pat) pat_ty thing_inside
 	-- getLIE/extendLIEs: see Note [Hopping the LIE in lazy patterns]
 
 	-- Check no existentials
-	; if (null pat_tvs) then return ()
-	  else lazyPatErr lpat pat_tvs
+	; unless (null pat_tvs) $ lazyPatErr lpat pat_tvs
+
+	-- Check there are no unlifted types under the lazy pattern
+	; when (any (isUnLiftedType . idType) $ collectPatBinders pat') $
+               lazyUnliftedPatErr lpat
 
 	-- Check that the pattern has a lifted type
 	; pat_tv <- newBoxyTyVar liftedTypeKind
-	; boxyUnify pat_ty (mkTyVarTy pat_tv)
+	; _ <- boxyUnify pat_ty (mkTyVarTy pat_tv)
 
 	; return (LazyPat pat', [], res) }
 
@@ -670,6 +674,12 @@ tcConPat pstate con_span data_con tycon pat_ty arg_pats thing_inside
 	      pstate' | no_equalities = pstate
 		      | otherwise     = pstate { pat_eqs = True }
 
+        ; gadts_on <- doptM Opt_GADTs
+	; checkTc (no_equalities || gadts_on)
+	  	  (ptext (sLit "A pattern match on a GADT requires -XGADTs"))
+		  -- Trac #2905 decided that a *pattern-match* of a GADT
+		  -- should require the GADT language flag
+
 	; unless no_equalities $ checkTc (isRigidTy pat_ty) $
                                  nonRigidMatch (pat_ctxt pstate) data_con
 
@@ -1033,6 +1043,12 @@ lazyPatErr _ tvs
     hang (ptext (sLit "A lazy (~) pattern cannot match existential or GADT data constructors"))
        2 (vcat (map pprSkolTvBinding tvs))
 
+lazyUnliftedPatErr :: OutputableBndr name => Pat name -> TcM ()
+lazyUnliftedPatErr pat
+  = failWithTc $
+    hang (ptext (sLit "A lazy (~) pattern cannot contain unlifted types"))
+       2 (ppr pat)
+
 nonRigidMatch :: PatCtxt -> DataCon -> SDoc
 nonRigidMatch ctxt con
   =  hang (ptext (sLit "GADT pattern match in non-rigid context for") <+> quotes (ppr con))