Merge branch 'master' of http://darcs.haskell.org/ghc

diff --combined compiler/rename/RnNames.lhs
index d8d8f3b,3867e17..ee6001b
--- 1/compiler/rename/RnNames.lhs
--- 2/compiler/rename/RnNames.lhs
+++ b/compiler/rename/RnNames.lhs
@@@ -828,14 -828,14 +828,14 @@@ it re-exports @GHC@, which includes @ta
  type ExportAccum        -- The type of the accumulating parameter of
                          -- the main worker function in rnExports
       = ([LIE Name],             -- Export items with Names
 -        ExportOccMap,                -- Tracks exported occurrence names
 +        ExportOccMap,           -- Tracks exported occurrence names
          [AvailInfo])            -- The accumulated exported stuff
                                  --   Not nub'd!
  
  emptyExportAccum :: ExportAccum
  emptyExportAccum = ([], emptyOccEnv, [])
  
 -type ExportOccMap = OccEnv (Name, IE RdrName)
 +type ExportOccMap = OccEnv (Name, IE Name)
          -- Tracks what a particular exported OccName
          --   in an export list refers to, and which item
          --   it came from.  It's illegal to export two distinct things
@@@ -912,7 -912,7 +912,7 @@@ exports_from_avail (Just rdr_items) rdr
  
      exports_from_item :: ExportAccum -> LIE RdrName -> RnM ExportAccum
      exports_from_item acc@(ie_names, occs, exports)
 -                      (L loc ie@(IEModuleContents mod))
 +                      (L loc (IEModuleContents mod))
          | let earlier_mods = [ mod | (L _ (IEModuleContents mod)) <- ie_names ]
          , mod `elem` earlier_mods    -- Duplicate export of M
          = do { warn_dup_exports <- doptM Opt_WarnDuplicateExports ;
@@@ -937,7 -937,7 +937,7 @@@
                          -- The qualified and unqualified version of all of
                          -- these names are, in effect, used by this export
  
 -             ; occs' <- check_occs ie occs names
 +             ; occs' <- check_occs (IEModuleContents mod) occs names
                        -- This check_occs not only finds conflicts
                        -- between this item and others, but also
                        -- internally within this item.  That is, if
@@@ -958,7 -958,7 +958,7 @@@
                    then return acc    -- Avoid error cascade
                    else do
  
 -             occs' <- check_occs ie occs (availNames avail)
 +             occs' <- check_occs new_ie occs (availNames avail)
  
               return (L loc new_ie : lie_names, occs', avail : exports)
  
@@@ -1054,8 -1054,8 +1054,8 @@@ isModuleExported implicit_prelude mod (
          Imported is -> any unQualSpecOK is && any (qualSpecOK mod) is
  
  -------------------------------
 -check_occs :: IE RdrName -> ExportOccMap -> [Name] -> RnM ExportOccMap
 -check_occs ie occs names
 +check_occs :: IE Name -> ExportOccMap -> [Name] -> RnM ExportOccMap
 +check_occs ie occs names  -- 'names' are the entities specifed by 'ie'
    = foldlM check occs names
    where
      check occs name
@@@ -1066,7 -1066,7 +1066,7 @@@
              | name == name'   -- Duplicate export
              -- But we don't want to warn if the same thing is exported
              -- by two different module exports. See ticket #4478.
 -            -> do unless (diffModules ie ie') $ do
 +            -> do unless (dupExport_ok name ie ie') $ do
                        warn_dup_exports <- doptM Opt_WarnDuplicateExports
                        warnIf warn_dup_exports (dupExportWarn name_occ ie ie')
                    return occs
@@@ -1077,38 -1077,9 +1077,38 @@@
                       return occs }
        where
          name_occ = nameOccName name
 -        -- True if the two IE RdrName are different module exports.
 -        diffModules (IEModuleContents n1) (IEModuleContents n2) = n1 /= n2
 -        diffModules _                     _                     = False
 +
 +
 +dupExport_ok :: Name -> IE Name -> IE Name -> Bool
 +-- The Name is exported by both IEs. Is that ok?
 +-- "No"  iff the name is mentioned explicitly in both IEs
 +-- "Yes" otherwise
 +-- 
 +-- Example of "no":  module M( f, f )
 +--
 +-- Example of "yes"
 +--    module M( module A, module B ) where
 +--        import A( f )
 +--        import B( f )
 +--
 +-- Example of "yes" (Trac #2436)
 +--    module M( C(..), T(..) ) where
 +--         class C a where { data T a }
 +--         instace C Int where { data T Int = TInt }
 +-- 
 +-- Example of "yes" (Trac #2436)
 +--    module Foo ( T ) where
 +--      data family T a
 +--    module Bar ( T(..), module Foo ) where
 +--        import Foo
 +--        data instance T Int = TInt
 +
 +dupExport_ok n ie1 ie2 
 +  = not (explicit_in ie1 && explicit_in ie2)
 +  where
 +    explicit_in (IEModuleContents _) = False
 +    explicit_in (IEThingAll n')      = n == n'
 +    explicit_in _                    = True
  \end{code}
  
  %*********************************************************
@@@ -1285,7 -1256,9 +1285,9 @@@ warnUnusedImportDecls gbl_en
         ; ifDOptM Opt_D_dump_minimal_imports $
           printMinimalImports usage }
    where
-     explicit_import (L loc _) = isGoodSrcSpan loc
+     explicit_import (L loc _) = case loc of
+                                 UnhelpfulSpan _ -> False
+                                 RealSrcSpan _ -> True
          -- Filter out the implicit Prelude import
          -- which we do not want to bleat about
  \end{code}
@@@ -1557,7 -1530,7 +1559,7 @@@ typeItemErr name wherest
    = sep [ ptext (sLit "Using 'type' tag on") <+> quotes (ppr name) <+> wherestr,
            ptext (sLit "Use -XTypeFamilies to enable this extension") ]
  
 -exportClashErr :: GlobalRdrEnv -> Name -> Name -> IE RdrName -> IE RdrName
 +exportClashErr :: GlobalRdrEnv -> Name -> Name -> IE Name -> IE Name
                 -> Message
  exportClashErr global_env name1 name2 ie1 ie2
    = vcat [ ptext (sLit "Conflicting exports for") <+> quotes (ppr occ) <> colon
@@@ -1601,7 -1574,7 +1603,7 @@@ addDupDeclErr names@(name : _
    where
      sorted_names = sortWith nameSrcLoc names
  
 -dupExportWarn :: OccName -> IE RdrName -> IE RdrName -> SDoc
 +dupExportWarn :: OccName -> IE Name -> IE Name -> SDoc
  dupExportWarn occ_name ie1 ie2
    = hsep [quotes (ppr occ_name),
            ptext (sLit "is exported by"), quotes (ppr ie1),