X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2Ftypecheck%2FTcDeriv.lhs;h=65c425d255d1c9522b34585dd3e0d658fdca6a31;hp=95d9697c0c67f716b970a85add2b890e733fd918;hb=afef39736dcde6f4947a6f362f9e6b3586933db4;hpb=7f0ce617a0380339da927433dc816e45704db0be

diff --git a/compiler/typecheck/TcDeriv.lhs b/compiler/typecheck/TcDeriv.lhs
index 95d9697..65c425d 100644
--- a/compiler/typecheck/TcDeriv.lhs
+++ b/compiler/typecheck/TcDeriv.lhs
@@ -31,10 +31,10 @@ import RnEnv		( bindLocalNames )
 import HscTypes		( FixityEnv )
 
 import Class		( className, classArity, classKey, classTyVars, classSCTheta, Class )
-import Type		( zipOpenTvSubst, substTheta, pprThetaArrow, pprClassPred )
+import Type		( zipOpenTvSubst, substTheta, pprThetaArrow, pprClassPred, mkTyVarTy )
 import ErrUtils		( dumpIfSet_dyn )
 import MkId		( mkDictFunId )
-import DataCon		( isNullarySrcDataCon, isVanillaDataCon, dataConOrigArgTys )
+import DataCon		( isNullarySrcDataCon, isVanillaDataCon, dataConOrigArgTys, dataConInstOrigArgTys )
 import Maybes		( catMaybes )
 import RdrName		( RdrName )
 import Name		( Name, getSrcLoc )
@@ -568,7 +568,7 @@ mkDataTypeEqn tycon clas
     ordinary_constraints
       = [ mkClassPred clas [arg_ty] 
         | data_con <- tyConDataCons tycon,
-          arg_ty   <- dataConOrigArgTys data_con,
+          arg_ty <- dataConInstOrigArgTys data_con (map mkTyVarTy (tyConTyVars tycon)),
           not (isUnLiftedType arg_ty)	-- No constraints for unlifted types?
         ]
 
@@ -729,9 +729,9 @@ solveDerivEqns overlap_flag orig_eqns
     gen_soln (_, clas, tc,tyvars,deriv_rhs)
       = setSrcSpan (srcLocSpan (getSrcLoc tc))	$
 	do { let inst_tys = [mkTyConApp tc (mkTyVarTys tyvars)]
-	   ; theta <- addErrCtxt (derivInstCtxt [] clas inst_tys) $
+	   ; theta <- addErrCtxt (derivInstCtxt1 clas inst_tys) $
 		      tcSimplifyDeriv tc tyvars deriv_rhs
-	   ; addErrCtxt (derivInstCtxt theta clas inst_tys) $
+	   ; addErrCtxt (derivInstCtxt2 theta clas inst_tys) $
 	     checkValidInstance tyvars theta clas inst_tys
 	   ; return (sortLe (<=) theta) }	-- Canonicalise before returning the soluction
       where
@@ -952,7 +952,7 @@ genTaggeryBinds infos
 \begin{code}
 derivingThingErr clas tys tycon tyvars why
   = sep [hsep [ptext SLIT("Can't make a derived instance of"), quotes (ppr pred)],
-	 parens why]
+	 nest 2 (parens why)]
   where
     pred = mkClassPred clas (tys ++ [mkTyConApp tycon (mkTyVarTys tyvars)])
 
@@ -960,8 +960,12 @@ derivCtxt :: TyCon -> SDoc
 derivCtxt tycon
   = ptext SLIT("When deriving instances for") <+> quotes (ppr tycon)
 
-derivInstCtxt theta clas inst_tys
-  = hang (ptext SLIT("In the derived instance"))
-       2 (ptext SLIT("instance") <+> sep [pprThetaArrow theta, pprClassPred clas inst_tys])
+derivInstCtxt1 clas inst_tys
+  = ptext SLIT("When deriving the instance for") <+> quotes (pprClassPred clas inst_tys)
+
+derivInstCtxt2 theta clas inst_tys
+  = vcat [ptext SLIT("In the derived instance declaration"),
+          nest 2 (ptext SLIT("instance") <+> sep [pprThetaArrow theta, 
+						  pprClassPred clas inst_tys])]
 \end{code}