[project @ 2000-11-01 17:15:28 by simonpj]

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

diff --git a/ghc/compiler/rename/RnNames.lhs b/ghc/compiler/rename/RnNames.lhs
index eaffb11..f62fc86 100644 (file)
--- a/ghc/compiler/rename/RnNames.lhs
+++ b/ghc/compiler/rename/RnNames.lhs
@@ -10,7 +10,7 @@ module RnNames (
 
 #include "HsVersions.h"
 
-import CmdLineOpts     ( DynFlag(..), opt_NoImplicitPrelude )
+import CmdLineOpts     ( DynFlag(..) )
 
 import HsSyn           ( HsModule(..), HsDecl(..), IE(..), ieName, ImportDecl(..),
                          ForeignDecl(..), ForKind(..), isDynamicExtName,
@@ -82,13 +82,17 @@ getGlobalNames this_mod (HsModule _ _ exports imports decls _ mod_loc)
                -- PROCESS IMPORT DECLS
                -- Do the non {- SOURCE -} ones first, so that we get a helpful
                -- warning for {- SOURCE -} ones that are unnecessary
+       doptRn Opt_NoImplicitPrelude                            `thenRn` \ opt_no_prelude -> 
        let
+         all_imports        = mk_prel_imports opt_no_prelude ++ imports
          (source, ordinary) = partition is_source_import all_imports
          is_source_import (ImportDecl _ ImportByUserSource _ _ _ _) = True
          is_source_import other                                     = False
+
+         get_imports = importsFromImportDecl this_mod_name rec_unqual_fn 
        in
-       mapAndUnzipRn (importsFromImportDecl rec_unqual_fn) ordinary    `thenRn` \ (imp_gbl_envs1, imp_avails_s1) ->
-       mapAndUnzipRn (importsFromImportDecl rec_unqual_fn) source      `thenRn` \ (imp_gbl_envs2, imp_avails_s2) ->
+       mapAndUnzipRn get_imports ordinary      `thenRn` \ (imp_gbl_envs1, imp_avails_s1) ->
+       mapAndUnzipRn get_imports source        `thenRn` \ (imp_gbl_envs2, imp_avails_s2) ->
 
                -- COMBINE RESULTS
                -- We put the local env second, so that a local provenance
@@ -117,34 +121,35 @@ getGlobalNames this_mod (HsModule _ _ exports imports decls _ mod_loc)
    )
   where
     this_mod_name = moduleName this_mod
-    all_imports = prel_imports ++ imports
 
        -- NB: opt_NoImplicitPrelude is slightly different to import Prelude ();
        -- because the former doesn't even look at Prelude.hi for instance declarations,
        -- whereas the latter does.
-    prel_imports | this_mod_name == pRELUDE_Name ||
-                  explicit_prelude_import ||
-                  opt_NoImplicitPrelude
-                = []
-
-                | otherwise = [ImportDecl pRELUDE_Name
-                                          ImportByUser
-                                          False        {- Not qualified -}
-                                          Nothing      {- No "as" -}
-                                          Nothing      {- No import list -}
-                                          mod_loc]
+    mk_prel_imports no_prelude
+       | this_mod_name == pRELUDE_Name ||
+         explicit_prelude_import ||
+         no_prelude
+       = []
+
+       | otherwise = [ImportDecl pRELUDE_Name
+                                 ImportByUser
+                                 False {- Not qualified -}
+                                 Nothing       {- No "as" -}
+                                 Nothing       {- No import list -}
+                                 mod_loc]
     
     explicit_prelude_import
       = not (null [ () | (ImportDecl mod _ _ _ _ _) <- imports, mod == pRELUDE_Name ])
 \end{code}
        
 \begin{code}
-importsFromImportDecl :: (Name -> Bool)                -- OK to omit qualifier
+importsFromImportDecl :: ModuleName
+                     -> (Name -> Bool)         -- OK to omit qualifier
                      -> RdrNameImportDecl
                      -> RnMG (GlobalRdrEnv, 
                               ExportAvails) 
 
-importsFromImportDecl is_unqual (ImportDecl imp_mod_name from qual_only as_mod import_spec iloc)
+importsFromImportDecl this_mod_name is_unqual (ImportDecl imp_mod_name from qual_only as_mod import_spec iloc)
   = pushSrcLocRn iloc $
     getInterfaceExports imp_mod_name from      `thenRn` \ (imp_mod, avails_by_module) ->
 
@@ -156,7 +161,26 @@ importsFromImportDecl is_unqual (ImportDecl imp_mod_name from qual_only as_mod i
 
     let
        avails :: Avails
-       avails = concat (map snd avails_by_module)
+       avails = [ avail | (mod_name, avails) <- avails_by_module,
+                          mod_name /= this_mod_name,
+                          avail <- avails ]
+       -- If the module exports anything defined in this module, just ignore it.
+       -- Reason: otherwise it looks as if there are two local definition sites
+       -- for the thing, and an error gets reported.  Easiest thing is just to
+       -- filter them out up front. This situation only arises if a module
+       -- imports itself, or another module that imported it.  (Necessarily,
+       -- this invoves a loop.)  
+       --
+       -- Tiresome consequence: if you say
+       --      module A where
+       --         import B( AType )
+       --         type AType = ...
+       --
+       --      module B( AType ) where
+       --         import {-# SOURCE #-} A( AType )
+       --
+       -- then you'll get a 'B does not export AType' message.  Oh well.
+
     in
     filterImports imp_mod_name import_spec avails      `thenRn` \ (filtered_avails, hides, explicits) ->
 
@@ -222,8 +246,7 @@ getLocalDeclBinders mod rec_exp_fn (ForD (ForeignDecl nm kind _ ext_nm _ loc))
     returnRn [avail]
 
   | otherwise          -- a foreign export
-  = lookupOrigName nm `thenRn_` 
-    returnRn []
+  = returnRn []
   where
     binds_haskell_name (FoImport _) = True
     binds_haskell_name FoLabel      = True