Improve formatting of errors, and fix a typo

compiler/typecheck/TcType.lhs

@@ -451,9 +451,9 @@ pprSkolTvBinding tv
 
     ppr_skol UnkSkol	    = empty	-- Unhelpful; omit
     ppr_skol RuntimeUnkSkol = ptext SLIT("is an unknown runtime type")
-    ppr_skol info           = ptext SLIT("is a rigid type variable bound by") 
-				<+> sep [pprSkolInfo info, 
-					 nest 2 (ptext SLIT("at") <+> ppr (getSrcLoc tv))]
+    ppr_skol info           = sep [ptext SLIT("is a rigid type variable bound by"),
+				   sep [pprSkolInfo info, 
+					 nest 2 (ptext SLIT("at") <+> ppr (getSrcLoc tv))]]
  
 pprSkolInfo :: SkolemInfo -> SDoc
 pprSkolInfo (SigSkol ctxt)   = pprUserTypeCtxt ctxt

compiler/typecheck/TcUnify.lhs

@@ -1601,7 +1601,7 @@ ppr_ty :: TidyEnv -> TcType -> TcType -> TcM (TidyEnv, SDoc, SDoc)
 ppr_ty env ty other_ty 
   = do	{ ty' <- zonkTcType ty
 	; let (env1, tidy_ty) = tidyOpenType env ty'
-	; (env2, extra) <- ppr_extra env1 ty' other_ty
+	; (env2, extra) <- ppr_extra env1 tidy_ty other_ty
 	; return (env2, quotes (ppr tidy_ty), extra) }
 
 -- (ppr_extra env ty other_ty) shows extra info about 'ty'