Check that exported modules were actually imported; fixes #1384

[ghc-hetmet.git] / compiler / rename / RnNames.lhs

diff --git a/compiler/rename/RnNames.lhs b/compiler/rename/RnNames.lhs
index 39b43ac..76da335 100644 (file)
--- a/compiler/rename/RnNames.lhs
+++ b/compiler/rename/RnNames.lhs
@@ -65,9 +65,7 @@ rnImports imports
          -- warning for {- SOURCE -} ones that are unnecessary
     = do this_mod <- getModule
          implicit_prelude <- doptM Opt_ImplicitPrelude
-         implicit_ndp     <- doptM Opt_Vectorise
          let prel_imports      = mkPrelImports this_mod implicit_prelude imports
-             ndp_imports        = mkNDPImports implicit_ndp
              (source, ordinary) = partition is_source_import imports
              is_source_import (L _ (ImportDecl _ is_boot _ _ _)) = is_boot
 
@@ -75,9 +73,7 @@ rnImports imports
             when (notNull prel_imports) $ addWarn (implicitPreludeWarn)
           )
 
-         stuff1 <- mapM (rnImportDecl this_mod) (prel_imports
-                                                 ++ ndp_imports
-                                                 ++ ordinary)
+         stuff1 <- mapM (rnImportDecl this_mod) (prel_imports ++ ordinary)
          stuff2 <- mapM (rnImportDecl this_mod) source
          let (decls, rdr_env, imp_avails,hpc_usage) = combine (stuff1 ++ stuff2)
          return (decls, rdr_env, imp_avails,hpc_usage) 
@@ -121,20 +117,6 @@ mkPrelImports this_mod implicit_prelude import_decls
 
       loc = mkGeneralSrcSpan FSLIT("Implicit import declaration")         
 
-mkNDPImports :: Bool -> [LImportDecl RdrName]
-mkNDPImports False = []
-mkNDPImports True  = [ndpImportDecl]
-  where
-    ndpImportDecl
-      = L loc $
-        ImportDecl (L loc nDP_INTERFACE_NAME)
-             False                -- not a boot interface
-             True                 -- qualified
-             (Just nDP_BUILTIN)   -- "as"
-             Nothing              -- no import list
-
-    loc = mkGeneralSrcSpan FSLIT("Implicit import declaration")
-
 
 rnImportDecl  :: Module
              -> LImportDecl RdrName
@@ -247,7 +229,7 @@ rnImportDecl this_mod (L loc (ImportDecl loc_imp_mod_name want_boot
                        other                -> False
 
        imports   = ImportAvails { 
-                       imp_mods     = unitModuleEnv imp_mod (imp_mod, import_all, loc),
+                       imp_mods     = unitModuleEnv imp_mod (imp_mod, [(qual_mod_name, import_all, loc)]),
                        imp_orphs    = orphans,
                        imp_finsts   = finsts,
                        imp_dep_mods = mkModDeps dependent_mods,
@@ -777,6 +759,10 @@ exports_from_avail (Just rdr_items) rdr_env imports this_mod
     kids_env :: NameEnv [Name] -- Maps a parent to its in-scope children
     kids_env = mkChildEnv (globalRdrEnvElts rdr_env)
 
+    imported_modules = [ qual_name
+                       | (_, xs) <- moduleEnvElts $ imp_mods imports,
+                         (qual_name, _, _) <- xs ]
+
     exports_from_item :: ExportAccum -> LIE RdrName -> RnM ExportAccum
     exports_from_item acc@(ie_names, occs, exports) 
                       (L loc ie@(IEModuleContents mod))
@@ -788,10 +774,14 @@ exports_from_avail (Just rdr_items) rdr_env imports this_mod
 
        | otherwise
        = do { implicit_prelude <- doptM Opt_ImplicitPrelude
-            ; let gres = filter (isModuleExported implicit_prelude mod) 
-                                (globalRdrEnvElts rdr_env)
+         ; let { exportValid = (mod `elem` imported_modules)
+                            || (moduleName this_mod == mod)
+               ; gres = filter (isModuleExported implicit_prelude mod)
+                               (globalRdrEnvElts rdr_env)
+               }
 
-            ; warnIf (null gres) (nullModuleExport mod)
+         ; checkErr exportValid (moduleNotImported mod)
+            ; warnIf (exportValid && null gres) (nullModuleExport mod)
 
             ; occs' <- check_occs ie occs (map gre_name gres)
                       -- This check_occs not only finds conflicts
@@ -1128,7 +1118,7 @@ reportUnusedNames export_decls gbl_env
        -- qualified imports into account.  But it's an improvement.
     add_expall mod acc = addToFM_C plusAvailEnv acc mod emptyAvailEnv
 
-    add_inst_mod (mod,_,_) acc 
+    add_inst_mod (mod, _) acc 
       | mod_name `elemFM` acc = acc    -- We import something already
       | otherwise            = addToFM acc mod_name emptyAvailEnv
       where
@@ -1138,7 +1128,7 @@ reportUnusedNames export_decls gbl_env
    
     imports = tcg_imports gbl_env
 
-    direct_import_mods :: [(Module, Bool, SrcSpan)]
+    direct_import_mods :: [(Module, [(ModuleName, Bool, SrcSpan)])]
        -- See the type of the imp_mods for this triple
     direct_import_mods = moduleEnvElts (imp_mods imports)
 
@@ -1147,10 +1137,11 @@ reportUnusedNames export_decls gbl_env
     -- [Note: not 'minimal_imports', because that includes directly-imported
     --       modules even if we use nothing from them; see notes above]
     --
-    -- BUG WARNING: does not deal correctly with multiple imports of the same module
-    --             becuase direct_import_mods has only one entry per module
+    -- BUG WARNING: this code is generally buggy
     unused_imp_mods :: [(ModuleName, SrcSpan)]
-    unused_imp_mods = [(mod_name,loc) | (mod,no_imp,loc) <- direct_import_mods,
+    unused_imp_mods = [(mod_name,loc)
+                    | (mod, xs) <- direct_import_mods,
+                      (_, no_imp, loc) <- xs,
                       let mod_name = moduleName mod,
                       not (mod_name `elemFM` minimal_imports1),
                       mod /= pRELUDE,
@@ -1372,6 +1363,11 @@ dupModuleExport mod
          quotes (ptext SLIT("Module") <+> ppr mod), 
           ptext SLIT("in export list")]
 
+moduleNotImported :: ModuleName -> SDoc
+moduleNotImported mod
+  = ptext SLIT("The export item `module") <+> ppr mod <>
+    ptext SLIT("' is not imported")
+
 nullModuleExport mod
   = ptext SLIT("The export item `module") <+> ppr mod <> ptext SLIT("' exports nothing")