X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2Ftypecheck%2FTcEnv.lhs;h=4c87a12671f75fd9b35e31a4de4aa6aec1171776;hp=63b73fcbf6e83fe8c002e67a6faaf3c0dcabde29;hb=6a05ec5ef5373f61b7f9f5bdc344483417fa801b;hpb=25f84fa7e4b84c3db5ba745a7881c009b778e0b1

diff --git a/compiler/typecheck/TcEnv.lhs b/compiler/typecheck/TcEnv.lhs
index 63b73fc..4c87a12 100644
--- a/compiler/typecheck/TcEnv.lhs
+++ b/compiler/typecheck/TcEnv.lhs
@@ -110,7 +110,7 @@ tcLookupGlobal name
   = do	{ env <- getGblEnv
 	
 		-- Try local envt
-	; case lookupNameEnv (tcg_type_env env) name of {
+	; case lookupNameEnv (tcg_type_env env) name of { 
 		Just thing -> return thing ;
 		Nothing	   -> do 
 	 
@@ -123,12 +123,12 @@ tcLookupGlobal name
 
 		-- Should it have been in the local envt?
 	{ case nameModule_maybe name of
-		Nothing -> notFound name	-- Internal names can happen in GHCi
+		Nothing -> notFound name env -- Internal names can happen in GHCi
 
 		Just mod | mod == tcg_mod env 	-- Names from this module 
-			 -> notFound name	-- should be in tcg_type_env
+			 -> notFound name env -- should be in tcg_type_env
 			 | mod == thFAKE	-- Names bound in TH declaration brackets
-			 -> notFound name	-- should be in tcg_env
+			 -> notFound name env -- should be in tcg_env
 			 | otherwise
 		         -> tcImportDecl name	-- Go find it in an interface
 	}}}}}
@@ -553,12 +553,12 @@ thLevel (Brack l _ _) = l
 
 
 checkWellStaged :: SDoc		-- What the stage check is for
-		-> ThLevel 	-- Binding level
+		-> ThLevel 	-- Binding level (increases inside brackets)
 	        -> ThStage	-- Use stage
 		-> TcM ()	-- Fail if badly staged, adding an error
 checkWellStaged pp_thing bind_lvl use_stage
-  | bind_lvl <= use_lvl 	-- OK!
-  = returnM ()	
+  | use_lvl >= bind_lvl 	-- OK! Used later than bound
+  = returnM ()			-- E.g.  \x -> [| $(f x) |]
 
   | bind_lvl == topLevel	-- GHC restriction on top level splices
   = failWithTc $ 
@@ -566,7 +566,7 @@ checkWellStaged pp_thing bind_lvl use_stage
 	 nest 2 (ptext SLIT("is used in a top-level splice, and must be imported, not defined locally"))]
 
   | otherwise			-- Badly staged
-  = failWithTc $ 
+  = failWithTc $ 		-- E.g.  \x -> $(f x)
     ptext SLIT("Stage error:") <+> pp_thing <+> 
 	hsep   [ptext SLIT("is bound at stage") <+> ppr bind_lvl,
 		ptext SLIT("but used at stage") <+> ppr use_lvl]
@@ -708,9 +708,11 @@ pprBinders :: [Name] -> SDoc
 pprBinders [bndr] = quotes (ppr bndr)
 pprBinders bndrs  = pprWithCommas ppr bndrs
 
-notFound name 
-  = failWithTc (ptext SLIT("GHC internal error:") <+> quotes (ppr name) <+> 
-		ptext SLIT("is not in scope"))
+notFound name env
+  = failWithTc (vcat[ptext SLIT("GHC internal error:") <+> quotes (ppr name) <+> 
+                     ptext SLIT("is not in scope during type checking, but it passed the renamer"),
+                     ptext SLIT("tcg_type_env of environment:") <+> ppr (tcg_type_env env)]
+                    )
 
 wrongThingErr expected thing name
   = failWithTc (pprTcTyThingCategory thing <+> quotes (ppr name) <+>