Commit 9992bfb6 authored by Simon Peyton Jones's avatar Simon Peyton Jones

Kill bogus duplicate-export warnings (fix Trac #2436)

The general rule is now that we don't complain about
a duplicate export from a "...".  See RnNames.dupExport_ok
parent ba33ff9b
......@@ -828,14 +828,14 @@ it re-exports @GHC@, which includes @takeMVar#@, whose type includes
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 @@ exports_from_avail (Just rdr_items) rdr_env imports this_mod
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 @@ exports_from_avail (Just rdr_items) rdr_env imports this_mod
-- 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 @@ exports_from_avail (Just rdr_items) rdr_env imports this_mod
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 @@ isModuleExported implicit_prelude mod (GRE { gre_name = name, gre_prov = prov })
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 @@ check_occs ie occs names
| 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
......@@ -1077,9 +1077,38 @@ check_occs ie occs names
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}
%*********************************************************
......@@ -1528,7 +1557,7 @@ typeItemErr name wherestr
= 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
......@@ -1572,7 +1601,7 @@ 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),
......
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