\begin{code}
module RnNames (
rnImports, importsFromLocalDecls,
+ rnExports,
+ getLocalDeclBinders, extendRdrEnvRn,
reportUnusedNames, reportDeprecations,
- mkModDeps, exportsToAvails, exportsFromAvail
+ mkModDeps
) where
#include "HsVersions.h"
-import CmdLineOpts ( DynFlag(..) )
+import DynFlags ( DynFlag(..), GhcMode(..) )
import HsSyn ( IE(..), ieName, ImportDecl(..), LImportDecl,
- ForeignDecl(..), HsGroup(..), HsBindGroup(..),
- Sig(..), collectGroupBinders, tyClDeclNames
+ ForeignDecl(..), HsGroup(..), HsValBinds(..),
+ Sig(..), collectHsBindLocatedBinders, tyClDeclNames
)
import RnEnv
-import IfaceEnv ( lookupOrig, newGlobalBinder )
+import IfaceEnv ( ifaceExportNames )
import LoadIface ( loadSrcInterface )
import TcRnMonad
import FiniteMap
import PrelNames ( pRELUDE, isUnboundName, main_RDR_Unqual )
-import Module ( Module, moduleUserString,
- unitModuleEnv, unitModuleEnv,
+import Module ( Module, moduleString, unitModuleEnv,
lookupModuleEnv, moduleEnvElts, foldModuleEnv )
import Name ( Name, nameSrcLoc, nameOccName, nameModule, isWiredInName,
nameParent, nameParent_maybe, isExternalName,
isBuiltInSyntax )
import NameSet
import NameEnv
-import OccName ( srcDataName, isTcOcc, occNameFlavour, OccEnv,
- mkOccEnv, lookupOccEnv, emptyOccEnv, extendOccEnv )
-import HscTypes ( GenAvailInfo(..), AvailInfo, GhciMode(..),
- IfaceExport, HomePackageTable, PackageIfaceTable,
- availNames, unQualInScope,
+import OccName ( srcDataName, isTcOcc, pprNonVarNameSpace,
+ occNameSpace,
+ OccEnv, mkOccEnv, lookupOccEnv, emptyOccEnv,
+ extendOccEnv )
+import HscTypes ( GenAvailInfo(..), AvailInfo,
+ HomePackageTable, PackageIfaceTable,
+ unQualInScope,
Deprecs(..), ModIface(..), Dependencies(..),
lookupIface, ExternalPackageState(..)
)
import RdrName ( RdrName, rdrNameOcc, setRdrNameSpace,
GlobalRdrEnv, mkGlobalRdrEnv, GlobalRdrElt(..),
emptyGlobalRdrEnv, plusGlobalRdrEnv, globalRdrEnvElts,
- unQualOK, lookupGRE_Name,
- Provenance(..), ImportSpec(..),
- isLocalGRE, pprNameProvenance )
+ extendGlobalRdrEnv, lookupGlobalRdrEnv, unQualOK, lookupGRE_Name,
+ Provenance(..), ImportSpec(..), ImpDeclSpec(..), ImpItemSpec(..),
+ importSpecLoc, importSpecModule, isLocalGRE, pprNameProvenance )
import Outputable
import Maybes ( isNothing, catMaybes, mapCatMaybes, seqMaybe, orElse )
-import SrcLoc ( noSrcLoc, Located(..), mkGeneralSrcSpan,
- unLoc, noLoc, srcLocSpan, combineSrcSpans, SrcSpan )
+import SrcLoc ( Located(..), mkGeneralSrcSpan,
+ unLoc, noLoc, srcLocSpan, SrcSpan )
import BasicTypes ( DeprecTxt )
-import ListSetOps ( removeDups )
-import Util ( sortLe, notNull, isSingleton )
+import DriverPhases ( isHsBoot )
+import Util ( notNull )
import List ( partition )
import IO ( openFile, IOMode(..) )
\end{code}
qual_mod_name = case as_mod of
Nothing -> imp_mod_name
Just another_name -> another_name
- imp_spec = ImportSpec { is_mod = imp_mod_name, is_qual = qual_only,
- is_loc = loc, is_as = qual_mod_name }
+ imp_spec = ImpDeclSpec { is_mod = imp_mod_name, is_qual = qual_only,
+ is_dloc = loc, is_as = qual_mod_name }
in
-- Get the total imports, and filter them according to the import list
- exportsToAvails filtered_exports `thenM` \ total_avails ->
+ ifaceExportNames filtered_exports `thenM` \ total_avails ->
filterImports iface imp_spec
imp_details total_avails `thenM` \ (avail_env, gbl_env) ->
ASSERT2( not (pkg `elem` dep_pkgs deps), ppr pkg <+> ppr (dep_pkgs deps) )
([], pkg : dep_pkgs deps)
+ -- True <=> import M ()
import_all = case imp_details of
- Just (is_hiding, ls) -- Imports are spec'd explicitly
- | not is_hiding -> Just (not (null ls))
- _ -> Nothing -- Everything is imported,
- -- (or almost everything [hiding])
+ Just (is_hiding, ls) -> not is_hiding && null ls
+ other -> False
-- unqual_avails is the Avails that are visible in *unqualified* form
-- We need to know this so we know what to export when we see
returnM (gbl_env, imports)
-exportsToAvails :: [IfaceExport] -> TcRnIf gbl lcl NameSet
-exportsToAvails exports
- = foldlM do_one emptyNameSet exports
- where
- do_one acc (mod, exports) = foldlM (do_avail mod) acc exports
- do_avail mod acc (Avail n) = do { n' <- lookupOrig mod n;
- ; return (addOneToNameSet acc n') }
- do_avail mod acc (AvailTC p_occ occs)
- = do { p_name <- lookupOrig mod p_occ
- ; ns <- mappM (lookup_sub p_name) occs
- ; return (addListToNameSet acc ns) }
- -- Remember that 'occs' is all the exported things, including
- -- the parent. It's possible to export just class ops without
- -- the class, via C( op ). If the class was exported too we'd
- -- have C( C, op )
- where
- lookup_sub parent occ
- = newGlobalBinder mod occ mb_parent noSrcLoc
- where
- mb_parent | occ == p_occ = Nothing
- | otherwise = Just parent
-
- -- The use of newGlobalBinder here (rather than lookupOrig)
- -- ensures that the subordinate names record their parent;
- -- and that in turn ensures that the GlobalRdrEnv
- -- has the correct parent for all the names in its range.
- -- For imported things, we only suck in the binding site later, if ever.
- -- Reason for all this:
- -- Suppose module M exports type A.T, and constructor A.MkT
- -- Then, we know that A.MkT is a subordinate name of A.T,
- -- even though we aren't at the binding site of A.T
- -- And it's important, because we may simply re-export A.T
- -- without ever sucking in the declaration itself.
-
warnRedundantSourceImport mod_name
= ptext SLIT("Unnecessary {- SOURCE -} in the import of module")
<+> quotes (ppr mod_name)
Complain about duplicate bindings
\begin{code}
-importsFromLocalDecls :: HsGroup RdrName
- -> RnM (GlobalRdrEnv, ImportAvails)
+importsFromLocalDecls :: HsGroup RdrName -> RnM TcGblEnv
importsFromLocalDecls group
- = getModule `thenM` \ this_mod ->
- getLocalDeclBinders this_mod group `thenM` \ avails ->
- -- The avails that are returned don't include the "system" names
- let
- all_names :: [Name] -- All the defns; no dups eliminated
- all_names = [name | avail <- avails, name <- availNames avail]
+ = do { gbl_env <- getGblEnv
- dups :: [[Name]]
- (_, dups) = removeDups compare all_names
- in
- -- Check for duplicate definitions
- -- The complaint will come out as "Multiple declarations of Foo.f" because
- -- since 'f' is in the env twice, the unQualInScope used by the error-msg
- -- printer returns False. It seems awkward to fix, unfortunately.
- mappM_ addDupDeclErr dups `thenM_`
-
- doptM Opt_ImplicitPrelude `thenM` \ implicit_prelude ->
- let
- prov = LocalDef this_mod
- gbl_env = mkGlobalRdrEnv gres
- gres = [ GRE { gre_name = name, gre_prov = prov}
- | name <- all_names]
+ ; names <- getLocalDeclBinders gbl_env group
+ ; implicit_prelude <- doptM Opt_ImplicitPrelude
+ ; let {
-- Optimisation: filter out names for built-in syntax
-- They just clutter up the environment (esp tuples), and the parser
-- will generate Exact RdrNames for them, so the cluttered
-- Ditto in fixity decls; e.g. infix 5 :
-- Sigh. It doesn't matter because it only affects the Data.Tuple really.
-- The important thing is to trim down the exports.
- filtered_names
- | implicit_prelude = all_names
- | otherwise = filter (not . isBuiltInSyntax) all_names
-
- imports = emptyImportAvails {
- imp_env = unitModuleEnv this_mod $
- mkNameSet filtered_names
- }
- in
- returnM (gbl_env, imports)
+ filtered_names
+ | implicit_prelude = names
+ | otherwise = filter (not . isBuiltInSyntax) names ;
+
+ ; this_mod = tcg_mod gbl_env
+ ; imports = emptyImportAvails {
+ imp_env = unitModuleEnv this_mod $
+ mkNameSet filtered_names
+ }
+ }
+
+ ; rdr_env' <- extendRdrEnvRn (tcg_rdr_env gbl_env) names
+
+ ; returnM (gbl_env { tcg_rdr_env = rdr_env',
+ tcg_imports = imports `plusImportAvails` tcg_imports gbl_env })
+ }
+
+extendRdrEnvRn :: GlobalRdrEnv -> [Name] -> RnM GlobalRdrEnv
+-- Add the new locally-bound names one by one, checking for duplicates as
+-- we do so. Remember that in Template Haskell the duplicates
+-- might *already be* in the GlobalRdrEnv from higher up the module
+extendRdrEnvRn rdr_env names
+ = foldlM add_local rdr_env names
+ where
+ add_local rdr_env name
+ | gres <- lookupGlobalRdrEnv rdr_env (nameOccName name)
+ , (dup_gre:_) <- filter isLocalGRE gres -- Check for existing *local* defns
+ = do { addDupDeclErr (gre_name dup_gre) name
+ ; return rdr_env }
+ | otherwise
+ = return (extendGlobalRdrEnv rdr_env new_gre)
+ where
+ new_gre = GRE {gre_name = name, gre_prov = LocalDef}
\end{code}
-
-%*********************************************************
-%* *
-\subsection{Getting binders out of a declaration}
-%* *
-%*********************************************************
-
@getLocalDeclBinders@ returns the names for an @HsDecl@. It's
used for source code.
*** See "THE NAMING STORY" in HsDecls ****
\begin{code}
-getLocalDeclBinders :: Module -> HsGroup RdrName -> RnM [AvailInfo]
-getLocalDeclBinders mod (HsGroup {hs_valds = val_decls,
- hs_tyclds = tycl_decls,
- hs_fords = foreign_decls })
- = -- For type and class decls, we generate Global names, with
- -- no export indicator. They need to be global because they get
- -- permanently bound into the TyCons and Classes. They don't need
- -- an export indicator because they are all implicitly exported.
-
- mappM new_tc tycl_decls `thenM` \ tc_avails ->
-
+getLocalDeclBinders :: TcGblEnv -> HsGroup RdrName -> RnM [Name]
+getLocalDeclBinders gbl_env (HsGroup {hs_valds = ValBindsIn val_decls val_sigs,
+ hs_tyclds = tycl_decls,
+ hs_fords = foreign_decls })
+ = do { tc_names_s <- mappM new_tc tycl_decls
+ ; val_names <- mappM new_simple val_bndrs
+ ; return (foldr (++) val_names tc_names_s) }
+ where
+ mod = tcg_mod gbl_env
+ is_hs_boot = isHsBoot (tcg_src gbl_env) ;
+ val_bndrs | is_hs_boot = sig_hs_bndrs
+ | otherwise = for_hs_bndrs ++ val_hs_bndrs
-- In a hs-boot file, the value binders come from the
- -- *signatures*, and there should be no foreign binders
- tcIsHsBoot `thenM` \ is_hs_boot ->
- let val_bndrs | is_hs_boot = sig_hs_bndrs
- | otherwise = for_hs_bndrs ++ val_hs_bndrs
- in
- mappM new_simple val_bndrs `thenM` \ names ->
+ -- *signatures*, and there should be no foreign binders
- returnM (tc_avails ++ map Avail names)
- where
new_simple rdr_name = newTopSrcBinder mod Nothing rdr_name
- sig_hs_bndrs = [nm | HsBindGroup _ lsigs _ <- val_decls,
- L _ (Sig nm _) <- lsigs]
- val_hs_bndrs = collectGroupBinders val_decls
+ sig_hs_bndrs = [nm | L _ (TypeSig nm _) <- val_sigs]
+ val_hs_bndrs = collectHsBindLocatedBinders val_decls
for_hs_bndrs = [nm | L _ (ForeignImport nm _ _ _) <- foreign_decls]
new_tc tc_decl
- = newTopSrcBinder mod Nothing main_rdr `thenM` \ main_name ->
- mappM (newTopSrcBinder mod (Just main_name)) sub_rdrs `thenM` \ sub_names ->
- returnM (AvailTC main_name (main_name : sub_names))
+ = do { main_name <- newTopSrcBinder mod Nothing main_rdr
+ ; sub_names <- mappM (newTopSrcBinder mod (Just main_name)) sub_rdrs
+ ; return (main_name : sub_names) }
where
(main_rdr : sub_rdrs) = tyClDeclNames (unLoc tc_decl)
\end{code}
\begin{code}
filterImports :: ModIface
- -> ImportSpec -- The span for the entire import decl
+ -> ImpDeclSpec -- The span for the entire import decl
-> Maybe (Bool, [Located (IE RdrName)]) -- Import spec; True => hiding
-> NameSet -- What's available
-> RnM (NameSet, -- What's imported (qualified or unqualified)
-- Complains if import spec mentions things that the module doesn't export
-- Warns/informs if import spec contains duplicates.
-mkGenericRdrEnv imp_spec names
- = mkGlobalRdrEnv [ GRE { gre_name = name, gre_prov = Imported [imp_spec] False }
+mkGenericRdrEnv decl_spec names
+ = mkGlobalRdrEnv [ GRE { gre_name = name, gre_prov = Imported [imp_spec] }
| name <- nameSetToList names ]
+ where
+ imp_spec = ImpSpec { is_decl = decl_spec, is_item = ImpAll }
-filterImports iface imp_spec Nothing all_names
- = returnM (all_names, mkGenericRdrEnv imp_spec all_names)
+filterImports iface decl_spec Nothing all_names
+ = returnM (all_names, mkGenericRdrEnv decl_spec all_names)
-filterImports iface imp_spec (Just (want_hiding, import_items)) all_names
+filterImports iface decl_spec (Just (want_hiding, import_items)) all_names
= mappM (addLocM get_item) import_items `thenM` \ gres_s ->
let
gres = concat gres_s
keep n = not (n `elemNameSet` specified_names)
pruned_avails = filterNameSet keep all_names
in
- return (pruned_avails, mkGenericRdrEnv imp_spec pruned_avails)
+ return (pruned_avails, mkGenericRdrEnv decl_spec pruned_avails)
where
occ_env :: OccEnv Name -- Maps OccName to corresponding Name
sub_env :: NameEnv [Name]
sub_env = mkSubNameEnv all_names
- bale_out item = addErr (badImportItemErr iface imp_spec item) `thenM_`
+ bale_out item = addErr (badImportItemErr iface decl_spec item) `thenM_`
returnM []
succeed_with :: Bool -> [Name] -> RnM [GlobalRdrElt]
; returnM (map (mk_gre loc) names) }
where
mk_gre loc name = GRE { gre_name = name,
- gre_prov = Imported [this_imp_spec loc] (explicit name) }
- this_imp_spec loc = imp_spec { is_loc = loc }
- explicit name = all_explicit || isNothing (nameParent_maybe name)
+ gre_prov = Imported [imp_spec] }
+ where
+ imp_spec = ImpSpec { is_decl = decl_spec, is_item = item_spec }
+ item_spec = ImpSome { is_explicit = explicit, is_iloc = loc }
+ explicit = all_explicit || isNothing (nameParent_maybe name)
get_item :: IE RdrName -> RnM [GlobalRdrElt]
-- Empty result for a bad item.
get_item item@(IEThingAbs n)
| want_hiding -- hiding( C )
-- Here the 'C' can be a data constructor
- -- *or* a type/class, or even both
+ -- *or* a type/class, or even both
= case concat [check_item item, check_item (IEVar data_n)] of
[] -> bale_out item
names -> succeed_with True names
\begin{code}
type ExportAccum -- The type of the accumulating parameter of
- -- the main worker function in exportsFromAvail
+ -- the main worker function in rnExports
= ([Module], -- 'module M's seen so far
ExportOccMap, -- Tracks exported occurrence names
NameSet) -- The accumulated exported stuff
-- that have the same occurrence name
-exportsFromAvail :: Bool -- False => no 'module M(..) where' header at all
- -> Maybe [Located (IE RdrName)] -- Nothing => no explicit export list
- -> RnM NameSet
+rnExports :: Bool -- False => no 'module M(..) where' header at all
+ -> Maybe [Located (IE RdrName)] -- Nothing => no explicit export list
+ -> RnM NameSet
-- Complains if two distinct exports have same OccName
-- Warns about identical exports.
-- Complains about exports items not in scope
-exportsFromAvail explicit_mod exports
+rnExports explicit_mod exports
= do { TcGblEnv { tcg_rdr_env = rdr_env,
tcg_imports = imports } <- getGblEnv ;
| explicit_mod = exports
| ghci_mode == Interactive = Nothing
| otherwise = Just [noLoc (IEVar main_RDR_Unqual)] } ;
+ -- ToDo: the 'noLoc' here is unhelpful if 'main' turns out to be out of scope
exports_from_avail real_exports rdr_env imports }
where
env = mkOccEnv [(nameOccName s, s) | s <- subNames subs n]
mb_names = map (lookupOccEnv env . rdrNameOcc) rdrs
+filterAvail (IEModuleContents _) _ _ = panic "filterAvail"
subNames :: NameEnv [Name] -> Name -> [Name]
subNames env n = lookupNameEnv env n `orElse` []
reportDeprecations tcg_env
= ifOptM Opt_WarnDeprecations $
do { (eps,hpt) <- getEpsAndHpt
+ -- By this time, typechecking is complete,
+ -- so the PIT is fully populated
; mapM_ (check hpt (eps_PIT eps)) all_gres }
where
- used_names = findUses (tcg_dus tcg_env) emptyNameSet
+ used_names = allUses (tcg_dus tcg_env)
+ -- Report on all deprecated uses; hence allUses
all_gres = globalRdrEnvElts (tcg_rdr_env tcg_env)
- check hpt pit (GRE {gre_name = name, gre_prov = Imported (imp_spec:_) _})
+ check hpt pit (GRE {gre_name = name, gre_prov = Imported (imp_spec:_)})
| name `elemNameSet` used_names
, Just deprec_txt <- lookupDeprec hpt pit name
- = setSrcSpan (is_loc imp_spec) $
+ = setSrcSpan (importSpecLoc imp_spec) $
addWarn (sep [ptext SLIT("Deprecated use of") <+>
- occNameFlavour (nameOccName name) <+>
+ pprNonVarNameSpace (occNameSpace (nameOccName name)) <+>
quotes (ppr name),
- (parens imp_msg),
+ (parens imp_msg) <> colon,
(ppr deprec_txt) ])
where
name_mod = nameModule name
- imp_mod = is_mod imp_spec
+ imp_mod = importSpecModule imp_spec
imp_msg = ptext SLIT("imported from") <+> ppr imp_mod <> extra
extra | imp_mod == name_mod = empty
| otherwise = ptext SLIT(", but defined in") <+> ppr name_mod
%*********************************************************
\begin{code}
-reportUnusedNames :: TcGblEnv -> RnM ()
-reportUnusedNames gbl_env
- = do { warnUnusedTopBinds unused_locals
+reportUnusedNames :: Maybe [Located (IE RdrName)] -- Export list
+ -> TcGblEnv -> RnM ()
+reportUnusedNames export_decls gbl_env
+ = do { traceRn ((text "RUN") <+> (ppr (tcg_dus gbl_env)))
+ ; warnUnusedTopBinds unused_locals
; warnUnusedModules unused_imp_mods
; warnUnusedImports unused_imports
- ; warnDuplicateImports dup_imps
+ ; warnDuplicateImports defined_and_used
; printMinimalImports minimal_imports }
where
used_names, all_used_names :: NameSet
used_names = findUses (tcg_dus gbl_env) emptyNameSet
+ -- NB: currently, if f x = g, we only treat 'g' as used if 'f' is used
+ -- Hence findUses
+
all_used_names = used_names `unionNameSets`
mkNameSet (mapCatMaybes nameParent_maybe (nameSetToList used_names))
-- A use of C implies a use of T,
(defined_and_used, defined_but_not_used)
= partition (gre_is_used all_used_names) defined_names
- -- Find the duplicate imports
- dup_imps = filter is_dup defined_and_used
- is_dup (GRE {gre_prov = Imported imp_spec True}) = not (isSingleton imp_spec)
- is_dup other = False
-
-- Filter out the ones that are
-- (a) defined in this module, and
-- (b) not defined by a 'deriving' clause
unused_imports :: [GlobalRdrElt]
unused_imports = filter unused_imp defined_but_not_used
- unused_imp (GRE {gre_prov = Imported imp_specs True})
- = not (all (module_unused . is_mod) imp_specs)
+ unused_imp (GRE {gre_prov = Imported imp_specs})
+ = not (all (module_unused . importSpecModule) imp_specs)
+ && or [exp | ImpSpec { is_item = ImpSome { is_explicit = exp } } <- imp_specs]
-- Don't complain about unused imports if we've already said the
-- entire import is unused
unused_imp other = False
-- To figure out the minimal set of imports, start with the things
-- that are in scope (i.e. in gbl_env). Then just combine them
-- into a bunch of avails, so they are properly grouped
+ --
+ -- BUG WARNING: this does not deal properly with qualified imports!
minimal_imports :: FiniteMap Module AvailEnv
- minimal_imports0 = emptyFM
+ minimal_imports0 = foldr add_expall emptyFM expall_mods
minimal_imports1 = foldr add_name minimal_imports0 defined_and_used
minimal_imports = foldr add_inst_mod minimal_imports1 direct_import_mods
-- The last line makes sure that we retain all direct imports
-- We've carefully preserved the provenance so that we can
-- construct minimal imports that import the name by (one of)
-- the same route(s) as the programmer originally did.
- add_name (GRE {gre_name = n, gre_prov = Imported imp_specs _}) acc
- = addToFM_C plusAvailEnv acc (is_mod (head imp_specs))
+ add_name (GRE {gre_name = n, gre_prov = Imported imp_specs}) acc
+ = addToFM_C plusAvailEnv acc (importSpecModule (head imp_specs))
(unitAvailEnv (mk_avail n (nameParent_maybe n)))
add_name other acc
= acc
+ -- Modules mentioned as 'module M' in the export list
+ expall_mods = case export_decls of
+ Nothing -> []
+ Just es -> [m | L _ (IEModuleContents m) <- es]
+
+ -- This is really bogus. The idea is that if we see 'module M' in
+ -- the export list we must retain the import decls that drive it
+ -- If we aren't careful we might see
+ -- module A( module M ) where
+ -- import M
+ -- import N
+ -- and suppose that N exports everything that M does. Then we
+ -- must not drop the import of M even though N brings it all into
+ -- scope.
+ --
+ -- BUG WARNING: 'module M' exports aside, what if M.x is mentioned?!
+ --
+ -- The reason that add_expall is bogus is that it doesn't take
+ -- qualified imports into account. But it's an improvement.
+ add_expall mod acc = addToFM_C plusAvailEnv acc mod emptyAvailEnv
+
-- n is the name of the thing, p is the name of its parent
mk_avail n (Just p) = AvailTC p [p,n]
mk_avail n Nothing | isTcOcc (nameOccName n) = AvailTC n [n]
imports = tcg_imports gbl_env
- direct_import_mods :: [(Module, Maybe Bool, SrcSpan)]
+ direct_import_mods :: [(Module, Bool, SrcSpan)]
-- See the type of the imp_mods for this triple
direct_import_mods = moduleEnvElts (imp_mods imports)
-- that are not mentioned in minimal_imports1
-- [Note: not 'minimal_imports', because that includes directly-imported
-- modules even if we use nothing from them; see notes above]
- unused_imp_mods = [(mod,loc) | (mod,imp,loc) <- direct_import_mods,
+ --
+ -- BUG WARNING: does not deal correctly with multiple imports of the same module
+ -- becuase direct_import_mods has only one entry per module
+ unused_imp_mods = [(mod,loc) | (mod,no_imp,loc) <- direct_import_mods,
not (mod `elemFM` minimal_imports1),
mod /= pRELUDE,
- imp /= Just False]
- -- The Just False part is not to complain about
+ not no_imp]
+ -- The not no_imp part is not to complain about
-- import M (), which is an idiom for importing
-- instance declarations
---------------------
warnDuplicateImports :: [GlobalRdrElt] -> RnM ()
+-- Given the GREs for names that are used, figure out which imports
+-- could be omitted without changing the top-level environment.
+--
+-- NB: Given import Foo( T )
+-- import qualified Foo
+-- we do not report a duplicate import, even though Foo.T is brought
+-- into scope by both, because there's nothing you can *omit* without
+-- changing the top-level environment. So we complain only if it's
+-- explicitly named in both imports or neither.
+--
+-- Furthermore, we complain about Foo.T only if
+-- there is no complaint about (unqualified) T
+
warnDuplicateImports gres
- = ifOptM Opt_WarnUnusedImports (mapM_ warn gres)
+ = ifOptM Opt_WarnUnusedImports $
+ sequenceM_ [ warn name pr
+ -- The 'head' picks the first offending group
+ -- for this particular name
+ | GRE { gre_name = name, gre_prov = Imported imps } <- gres
+ , pr <- redundants imps ]
where
- warn (GRE { gre_name = name, gre_prov = Imported imps _ })
- = addWarn ((quotes (ppr name) <+> ptext SLIT("is imported more than once:"))
- $$ nest 2 (vcat (map ppr imps)))
-
+ warn name (red_imp, cov_imp)
+ = addWarnAt (importSpecLoc red_imp)
+ (vcat [ptext SLIT("Redundant import of:") <+> quotes pp_name,
+ ptext SLIT("It is also") <+> ppr cov_imp])
+ where
+ pp_name | is_qual red_decl = ppr (is_as red_decl) <> dot <> ppr occ
+ | otherwise = ppr occ
+ occ = nameOccName name
+ red_decl = is_decl red_imp
+
+ redundants :: [ImportSpec] -> [(ImportSpec,ImportSpec)]
+ -- The returned pair is (redundant-import, covering-import)
+ redundants imps
+ = [ (red_imp, cov_imp)
+ | red_imp <- imps
+ , cov_imp <- take 1 (filter (covers red_imp) imps) ]
+
+ -- "red_imp" is a putative redundant import
+ -- "cov_imp" potentially covers it
+ -- This test decides whether red_imp could be dropped
+ --
+ -- NOTE: currently the test does not warn about
+ -- import M( x )
+ -- imoprt N( x )
+ -- even if the same underlying 'x' is involved, because dropping
+ -- either import would change the qualified names in scope (M.x, N.x)
+ -- But if the qualified names aren't used, the import is indeed redundant
+ -- Sadly we don't know that. Oh well.
+ covers red_imp@(ImpSpec { is_decl = red_decl, is_item = red_item })
+ cov_imp@(ImpSpec { is_decl = cov_decl, is_item = cov_item })
+ | red_loc == cov_loc
+ = False -- Ignore diagonal elements
+ | not (is_as red_decl == is_as cov_decl)
+ = False -- They bring into scope different qualified names
+ | not (is_qual red_decl) && is_qual cov_decl
+ = False -- Covering one doesn't bring unqualified name into scope
+ | red_selective
+ = not cov_selective -- Redundant one is selective and covering one isn't
+ || red_later -- Both are explicit; tie-break using red_later
+ | otherwise
+ = not cov_selective -- Neither import is selective
+ && (is_mod red_decl == is_mod cov_decl) -- They import the same module
+ && red_later -- Tie-break
+ where
+ red_loc = importSpecLoc red_imp
+ cov_loc = importSpecLoc cov_imp
+ red_later = red_loc > cov_loc
+ cov_selective = selectiveImpItem cov_item
+ red_selective = selectiveImpItem red_item
+
+selectiveImpItem :: ImpItemSpec -> Bool
+selectiveImpItem ImpAll = False
+selectiveImpItem (ImpSome {}) = True
-- ToDo: deal with original imports with 'qualified' and 'as M' clauses
printMinimalImports :: FiniteMap Module AvailEnv -- Minimal imports
(vcat (map ppr_mod_ie mod_ies)) })
}
where
- mkFilename this_mod = moduleUserString this_mod ++ ".imports"
+ mkFilename this_mod = moduleString this_mod ++ ".imports"
ppr_mod_ie (mod_name, ies)
| mod_name == pRELUDE
= empty
%************************************************************************
\begin{code}
-badImportItemErr iface imp_spec ie
- = sep [ptext SLIT("Module"), quotes (ppr (is_mod imp_spec)), source_import,
+badImportItemErr iface decl_spec ie
+ = sep [ptext SLIT("Module"), quotes (ppr (is_mod decl_spec)), source_import,
ptext SLIT("does not export"), quotes (ppr ie)]
where
source_import | mi_boot iface = ptext SLIT("(hi-boot interface)")
(gre:_) -> gre
[] -> pprPanic "exportClashErr" (ppr name)
-addDupDeclErr :: [Name] -> TcRn ()
-addDupDeclErr names
- = addErrAt big_loc $
+addDupDeclErr :: Name -> Name -> TcRn ()
+addDupDeclErr name_a name_b
+ = addErrAt (srcLocSpan loc2) $
vcat [ptext SLIT("Multiple declarations of") <+> quotes (ppr name1),
- ptext SLIT("Declared at:") <+> vcat (map ppr sorted_locs)]
+ ptext SLIT("Declared at:") <+> vcat [ppr (nameSrcLoc name1), ppr loc2]]
where
- locs = map nameSrcLoc names
- big_loc = foldr1 combineSrcSpans (map srcLocSpan locs)
- name1 = head names
- sorted_locs = sortLe (<=) (sortLe (<=) locs)
+ loc2 = nameSrcLoc name2
+ (name1,name2) | nameSrcLoc name_a > nameSrcLoc name_b = (name_b,name_a)
+ | otherwise = (name_a,name_b)
+ -- Report the error at the later location
dupExportWarn occ_name ie1 ie2
= hsep [quotes (ppr occ_name),
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