[project @ 2004-02-26 12:42:07 by simonpj]

Fix a long-standing bug, whereby 'hiding' hid the qualified name as
well as the unqualified one.

This bug is not as easy to fix in the 6.2 branch, unfortunately; don't merge.

diff --git a/ghc/compiler/rename/RnNames.lhs b/ghc/compiler/rename/RnNames.lhs
index 7be2214..7bc2cce 100644 (file)
--- a/ghc/compiler/rename/RnNames.lhs
+++ b/ghc/compiler/rename/RnNames.lhs
@@ -405,33 +405,36 @@ filterImports :: ModIface
              -> ImportSpec                     -- The span for the entire import decl
              -> Maybe (Bool, [Located (IE RdrName)])   -- Import spec; True => hiding
              -> [AvailInfo]                    -- What's available
-             -> RnM (AvailEnv,                 -- What's imported
-                     GlobalRdrEnv)             -- ...in two forms
+             -> RnM (AvailEnv,                 -- What's imported (qualified or unqualified)
+                     GlobalRdrEnv)             -- Same again, but in GRE form
 
        -- Complains if import spec mentions things that the module doesn't export
         -- Warns/informs if import spec contains duplicates.
-mkGenericRdrEnv imp_spec avails
-  = mkGlobalRdrEnv [ GRE { gre_name = name, gre_prov = Imported [imp_spec] False }
-                  | avail <- avails, name <- availNames avail ]
                        
 filterImports iface imp_spec Nothing total_avails
-  = returnM (mkAvailEnv total_avails, mkGenericRdrEnv imp_spec total_avails)
+  = returnM (mkAvailEnv total_avails, 
+            mkGlobalRdrEnv [ GRE { gre_name = name, gre_prov = Imported [imp_spec] False }
+                           | avail <- total_avails, name <- availNames avail ])
 
 filterImports iface imp_spec (Just (want_hiding, import_items)) total_avails
-  = mapAndUnzipM (addLocM get_item) import_items       `thenM` \ (avails, gres) ->
+  = mapAndUnzipM (addLocM get_item) import_items       `thenM` \ (avails_s, gres) ->
     let
-       all_avails = foldr plusAvailEnv     emptyAvailEnv     avails
-       rdr_env    = foldr plusGlobalRdrEnv emptyGlobalRdrEnv gres
+       avails = concat avails_s
+       rdr_env | not want_hiding 
+               = foldr plusGlobalRdrEnv emptyGlobalRdrEnv gres
+               | otherwise     -- Hiding; qualified-only import of hidden things
+               = mkGlobalRdrEnv [ GRE { gre_name = name, 
+                                        gre_prov = Imported [mk_imp_spec name] False }
+                                | avail <- total_avails, name <- availNames avail ]
+       hidden = availsToNameSet avails
+       mk_imp_spec n 
+         | n `elemNameSet` hidden = imp_spec { is_qual = True }
+         | otherwise              = imp_spec
     in
-    if not want_hiding then
-       returnM (all_avails, rdr_env)
-    else
-    let        -- Hide stuff in all_avails
-          hidden = availsToNameSet (availEnvElts all_avails)
-          keep n = not (n `elemNameSet` hidden)
-          pruned_avails = pruneAvails keep total_avails
-    in
-    returnM (mkAvailEnv pruned_avails, mkGenericRdrEnv imp_spec pruned_avails)
+    returnM (mkAvailEnv avails, rdr_env)
+       -- Hiding still imports everything qualified, so 'avails' is not 
+       -- conditional on hiding.  But the rdrenv is modified to 
+
   where
     import_fm :: OccEnv AvailInfo
     import_fm = mkOccEnv [ (nameOccName name, avail) 
@@ -442,12 +445,12 @@ filterImports iface imp_spec (Just (want_hiding, import_items)) total_avails
        -- in an import list map to TcOccs, not VarOccs.
 
     bale_out item = addErr (badImportItemErr iface imp_spec item)      `thenM_`
-                   returnM (emptyAvailEnv, emptyGlobalRdrEnv)
+                   returnM ([], emptyGlobalRdrEnv)
 
-    succeed_with :: Bool -> AvailInfo -> RnM (AvailEnv, GlobalRdrEnv)
+    succeed_with :: Bool -> AvailInfo -> RnM ([AvailInfo], GlobalRdrEnv)
     succeed_with all_explicit avail
       = do { loc <- getSrcSpanM
-          ; returnM (unitAvailEnv avail, 
+          ; returnM ([avail], 
                      mkGlobalRdrEnv (map (mk_gre loc) (availNames avail))) }
       where
        mk_gre loc name = GRE { gre_name = name, 
@@ -456,7 +459,7 @@ filterImports iface imp_spec (Just (want_hiding, import_items)) total_avails
        explicit name = all_explicit || name == main_name
        main_name = availName avail
 
-    get_item :: IE RdrName -> RnM (AvailEnv, GlobalRdrEnv)
+    get_item :: IE RdrName -> RnM ([AvailInfo], GlobalRdrEnv)
        -- Empty result for a bad item.
        -- Singleton result is typical case.
        -- Can have two when we are hiding, and mention C which might be
@@ -476,10 +479,11 @@ filterImports iface imp_spec (Just (want_hiding, import_items)) total_avails
 
     get_item item@(IEThingAbs n)
       | want_hiding    -- hiding( C ) 
-                       -- Here the 'C' can be a data constructor *or* a type/class
+                       -- Here the 'C' can be a data constructor 
+                       -- *or* a type/class, or even both
       = case catMaybes [check_item item, check_item (IEVar data_n)] of
          []     -> bale_out item
-         avails -> returnM (mkAvailEnv avails, emptyGlobalRdrEnv)
+         avails -> returnM (avails, emptyGlobalRdrEnv)
                        -- The GlobalRdrEnv result is irrelevant when hiding
       where
        data_n = setRdrNameSpace n srcDataName