From 36f5406a714f0f1225377a7d601358ee7146fae8 Mon Sep 17 00:00:00 2001
From: "simonpj@microsoft.com" <unknown>
Date: Thu, 25 May 2006 09:45:45 +0000
Subject: [PATCH] Improve error reporting in interface typechecking

---
 compiler/iface/IfaceEnv.lhs |   14 ++++++++------
 compiler/iface/IfaceSyn.lhs |    1 -
 2 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/compiler/iface/IfaceEnv.lhs b/compiler/iface/IfaceEnv.lhs
index 40b7d31..3c1db55 100644
--- a/compiler/iface/IfaceEnv.lhs
+++ b/compiler/iface/IfaceEnv.lhs
@@ -288,9 +288,10 @@ initOrigNames names = foldl extendOrigNameCache emptyModuleEnv names
 tcIfaceLclId :: OccName -> IfL Id
 tcIfaceLclId occ
   = do	{ lcl <- getLclEnv
-	; return (lookupOccEnv (if_id_env lcl) occ
-		  `orElse` 
-		  pprPanic "tcIfaceLclId" (ppr occ)) }
+	; case (lookupOccEnv (if_id_env lcl) occ) of
+            Just ty_var -> return ty_var
+            Nothing     -> failIfM (text "Iface id out of scope: " <+> ppr occ)
+        }
 
 refineIfaceIdEnv :: TypeRefinement -> IfL a -> IfL a
 refineIfaceIdEnv (tv_subst, _) thing_inside
@@ -311,9 +312,10 @@ extendIfaceIdEnv ids thing_inside
 tcIfaceTyVar :: OccName -> IfL TyVar
 tcIfaceTyVar occ
   = do	{ lcl <- getLclEnv
-	; return (lookupOccEnv (if_tv_env lcl) occ
-		  `orElse`
-		  pprPanic "tcIfaceTyVar" (ppr occ)) }
+	; case (lookupOccEnv (if_tv_env lcl) occ) of
+            Just ty_var -> return ty_var
+            Nothing     -> failIfM (text "Iface type variable out of scope: " <+> ppr occ)
+        }
 
 extendIfaceTyVarEnv :: [TyVar] -> IfL a -> IfL a
 extendIfaceTyVarEnv tyvars thing_inside
diff --git a/compiler/iface/IfaceSyn.lhs b/compiler/iface/IfaceSyn.lhs
index d4a6eec..5309367 100644
--- a/compiler/iface/IfaceSyn.lhs
+++ b/compiler/iface/IfaceSyn.lhs
@@ -654,7 +654,6 @@ toIfaceExpr ext (Lit l)       = IfaceLit l
 toIfaceExpr ext (Type ty)     = IfaceType (toIfaceType ext ty)
 toIfaceExpr ext (Lam x b)     = IfaceLam (toIfaceBndr ext x) (toIfaceExpr ext b)
 toIfaceExpr ext (App f a)     = toIfaceApp ext f [a]
--- gaw 2004
 toIfaceExpr ext (Case s x ty as) = IfaceCase (toIfaceExpr ext s) (getOccName x) (toIfaceType ext ty) (map (toIfaceAlt ext) as)
 toIfaceExpr ext (Let b e)     = IfaceLet (toIfaceBind ext b) (toIfaceExpr ext e)
 toIfaceExpr ext (Note n e)    = IfaceNote (toIfaceNote ext n) (toIfaceExpr ext e)
-- 
1.7.10.4