X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2Ftypecheck%2FTcMType.lhs;fp=compiler%2Ftypecheck%2FTcMType.lhs;h=6423a830a91e792f94e653f88d00be880c319641;hp=2c01d2300a4505c34164414c5f746b6d8f862d7c;hb=5c4a4c4bfe2a007f41f42ebab689bcd7219bed0d;hpb=792449f555bb4dfa8e718079f6d42dc9babe938a

diff --git a/compiler/typecheck/TcMType.lhs b/compiler/typecheck/TcMType.lhs
index 2c01d23..6423a83 100644
--- a/compiler/typecheck/TcMType.lhs
+++ b/compiler/typecheck/TcMType.lhs
@@ -1162,7 +1162,8 @@ check_pred_ty dflags ctxt pred@(ClassP cls tys)
 check_pred_ty dflags ctxt pred@(EqPred ty1 ty2)
   = do {	-- Equational constraints are valid in all contexts if type
 		-- families are permitted
-       ; checkTc (xopt Opt_TypeFamilies dflags) (eqPredTyErr pred)
+       ; checkTc (xopt Opt_TypeFamilies dflags || xopt Opt_GADTs dflags) 
+                 (eqPredTyErr pred)
        ; checkTc (case ctxt of ClassSCCtxt {} -> False; _ -> True)
                  (eqSuperClassErr pred)
 
@@ -1330,7 +1331,7 @@ badPredTyErr, eqPredTyErr, predTyVarErr :: PredType -> SDoc
 badPredTyErr pred = ptext (sLit "Illegal constraint") <+> pprPredTy pred
 eqPredTyErr  pred = ptext (sLit "Illegal equational constraint") <+> pprPredTy pred
 		    $$
-		    parens (ptext (sLit "Use -XTypeFamilies to permit this"))
+		    parens (ptext (sLit "Use -XGADTs or -XTypeFamilies to permit this"))
 predTyVarErr pred  = sep [ptext (sLit "Non type-variable argument"),
 			  nest 2 (ptext (sLit "in the constraint:") <+> pprPredTy pred)]
 dupPredWarn :: [[PredType]] -> SDoc