[project @ 2000-05-09 13:15:37 by simonpj]

Get package names right.  Again.

diff --git a/ghc/compiler/rename/RnEnv.lhs b/ghc/compiler/rename/RnEnv.lhs
index f27dec8..118267f 100644 (file)
--- 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