X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Frename%2FRnEnv.lhs;h=118267f893a78920c8bb93be57690cd740d1ba86;hb=8111e8c5719e0b37a16f3895a2dfb083fd3abc1c;hp=f27dec8312d12c8337aaca859b2a8192b9451e46;hpb=35cd30bf8587a216449fc7925d0ea90524c9eaf4;p=ghc-hetmet.git

diff --git a/ghc/compiler/rename/RnEnv.lhs b/ghc/compiler/rename/RnEnv.lhs
index f27dec8..118267f 100644
--- a/ghc/compiler/rename/RnEnv.lhs
+++ b/ghc/compiler/rename/RnEnv.lhs
@@ -149,15 +149,33 @@ mkImportedGlobalName mod_name occ
 		     new_cache  = addToFM cache key name
 
 updateProvenances :: [Name] -> RnM d ()
+-- Update the provenances of everything that is in scope.
+-- We must be careful not to disturb the Module package info
+-- already in the cache.  Why not?  Consider
+--   module A		module M( f )
+--	import M( f )	  import N( f)
+--	import N
+-- So f is defined in N, and M re-exports it.
+-- When processing module A:
+--	1. We read M.hi first, and make a vanilla name N.f 
+--	   (without reading N.hi). The package info says <THIS> 
+--	   for lack of anything better.  
+--	2. Now we read N, which update the cache to record 
+--	   the correct package for N.f.
+--	3. Finally we update provenances (once we've read all imports).
+-- Step 3 must not destroy package info recorded in Step 2.
+
 updateProvenances names
   = getNameSupplyRn		`thenRn` \ (us, inst_ns, cache, ipcache) ->
-    setNameSupplyRn (us, inst_ns, update cache names, ipcache)
+    setNameSupplyRn (us, inst_ns, foldr update cache names, ipcache)
   where
-    update cache [] 	      = cache
-    update cache (name:names) = WARN( not (key `elemFM` cache), ppr name )
-				update (addToFM cache key name) names
- 			      where
-				key = (moduleName (nameModule name), nameOccName name)
+    update name cache = addToFM_C update_prov cache key name
+		      where
+		   	key = (moduleName (nameModule name), nameOccName name)
+
+    update_prov name_in_cache name_with_prov
+	= setNameProvenance name_in_cache (getNameProvenance name_with_prov)
+			
 
 
 mkImportedGlobalFromRdrName :: RdrName -> RnM d Name