\begin{code}
module RnNames (
rnImports, getLocalNonValBinders,
- rnExports, extendGlobalRdrEnvRn,
+ rnExports, extendGlobalRdrEnvRn,
+ gresFromAvails,
reportUnusedNames, finishWarnings,
) where
import DynFlags
import HsSyn
+import TcEnv ( isBrackStage )
import RnEnv
import RnHsDoc ( rnHsDoc )
import IfaceEnv ( ifaceExportNames )
-import LoadIface ( loadSrcInterface, loadSysInterface )
-import TcRnMonad hiding (LIE)
+import LoadIface ( loadSrcInterface )
+import TcRnMonad
+import HeaderInfo ( mkPrelImports )
import PrelNames
import Module
import Name
import NameEnv
import NameSet
-import OccName
import HscTypes
import RdrName
import Outputable
import Maybes
import SrcLoc
-import FiniteMap
import ErrUtils
-import BasicTypes ( WarningTxt(..) )
-import DriverPhases ( isHsBoot )
import Util
import FastString
import ListSetOps
-import Data.List ( partition, concatMap, (\\), delete )
-import IO ( openFile, IOMode(..) )
-import Monad ( when, mplus )
+import Data.List ( partition, (\\), delete )
+import qualified Data.Set as Set
+import System.IO
+import Control.Monad
+import Data.Map (Map)
+import qualified Data.Map as Map
\end{code}
-- Do the non {- SOURCE -} ones first, so that we get a helpful
-- warning for {- SOURCE -} ones that are unnecessary
= do this_mod <- getModule
- implicit_prelude <- doptM Opt_ImplicitPrelude
- let prel_imports = mkPrelImports this_mod implicit_prelude imports
+ implicit_prelude <- xoptM Opt_ImplicitPrelude
+ let prel_imports = mkPrelImports (moduleName this_mod) implicit_prelude imports
(source, ordinary) = partition is_source_import imports
is_source_import (L _ (ImportDecl _ _ is_boot _ _ _)) = is_boot
- ifOptM Opt_WarnImplicitPrelude (
+ ifDOptM Opt_WarnImplicitPrelude (
when (notNull prel_imports) $ addWarn (implicitPreludeWarn)
)
- 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)
+ stuff1 <- mapM (rnImportDecl this_mod True) prel_imports
+ stuff2 <- mapM (rnImportDecl this_mod False) ordinary
+ stuff3 <- mapM (rnImportDecl this_mod False) source
+ let (decls, rdr_env, imp_avails, hpc_usage) = combine (stuff1 ++ stuff2 ++ stuff3)
+ return (decls, rdr_env, imp_avails, hpc_usage)
where
combine :: [(LImportDecl Name, GlobalRdrEnv, ImportAvails,AnyHpcUsage)]
imp_avails1 `plusImportAvails` imp_avails2,
hpc_usage1 || hpc_usage2)
-mkPrelImports :: Module -> Bool -> [LImportDecl RdrName] -> [LImportDecl RdrName]
--- Consruct the implicit declaration "import Prelude" (or not)
---
--- 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.
-mkPrelImports this_mod implicit_prelude import_decls
- | this_mod == pRELUDE
- || explicit_prelude_import
- || not implicit_prelude
- = []
- | otherwise = [preludeImportDecl]
- where
- explicit_prelude_import
- = notNull [ () | L _ (ImportDecl mod Nothing _ _ _ _) <- import_decls,
- unLoc mod == pRELUDE_NAME ]
-
- preludeImportDecl :: LImportDecl RdrName
- preludeImportDecl
- = L loc $
- ImportDecl (L loc pRELUDE_NAME)
- Nothing {- no specific package -}
- False {- Not a boot interface -}
- False {- Not qualified -}
- Nothing {- No "as" -}
- Nothing {- No import list -}
-
- loc = mkGeneralSrcSpan (fsLit "Implicit import declaration")
-
-
-rnImportDecl :: Module
+rnImportDecl :: Module -> Bool
-> LImportDecl RdrName
-> RnM (LImportDecl Name, GlobalRdrEnv, ImportAvails,AnyHpcUsage)
-rnImportDecl this_mod (L loc (ImportDecl loc_imp_mod_name mb_pkg want_boot
- qual_only as_mod imp_details))
- =
- setSrcSpan loc $ do
+rnImportDecl this_mod implicit_prelude
+ (L loc (ImportDecl { ideclName = loc_imp_mod_name, ideclPkgQual = mb_pkg
+ , ideclSource = want_boot, ideclQualified = qual_only
+ , ideclAs = as_mod, ideclHiding = imp_details }))
+ = setSrcSpan loc $ do
when (isJust mb_pkg) $ do
- pkg_imports <- doptM Opt_PackageImports
+ pkg_imports <- xoptM Opt_PackageImports
when (not pkg_imports) $ addErr packageImportErr
-- If there's an error in loadInterface, (e.g. interface
imp_mod_name = unLoc loc_imp_mod_name
doc = ppr imp_mod_name <+> ptext (sLit "is directly imported")
+ let isExplicit lie = case unLoc lie of
+ IEThingAll _ -> False
+ _ -> True
+ case imp_details of
+ Just (False, lies)
+ | all isExplicit lies ->
+ return ()
+ _ ->
+ unless implicit_prelude $
+ ifDOptM Opt_WarnMissingImportList (addWarn (missingImportListWarn imp_mod_name))
+
iface <- loadSrcInterface doc imp_mod_name want_boot mb_pkg
-- Compiler sanity check: if the import didn't say
-- Issue a user warning for a redundant {- SOURCE -} import
-- NB that we arrange to read all the ordinary imports before
- -- any of the {- SOURCE -} imports
- warnIf (want_boot && not (mi_boot iface))
+ -- any of the {- SOURCE -} imports.
+ --
+ -- in --make and GHCi, the compilation manager checks for this,
+ -- and indeed we shouldn't do it here because the existence of
+ -- the non-boot module depends on the compilation order, which
+ -- is not deterministic. The hs-boot test can show this up.
+ dflags <- getDOpts
+ warnIf (want_boot && not (mi_boot iface) && isOneShot (ghcMode dflags))
(warnRedundantSourceImport imp_mod_name)
let
}
-- Complain if we import a deprecated module
- ifOptM Opt_WarnWarningsDeprecations (
+ ifDOptM Opt_WarnWarningsDeprecations (
case warns of
WarnAll txt -> addWarn (moduleWarn imp_mod_name txt)
_ -> return ()
* the ImportAvails
created by its bindings.
-Note [Shadowing in extendGlobalRdrEnvRn]
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-Usually when etending the GlobalRdrEnv we complain if a new binding
-duplicates an existing one. By adding the bindings one at a time,
-this check also complains if we add two new bindings for the same name.
-(Remember that in Template Haskell the duplicates might *already be*
-in the GlobalRdrEnv from higher up the module.)
-
-But with a Template Haskell quotation we want to *shadow*:
+Note [Top-level Names in Template Haskell decl quotes]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Consider a Template Haskell declaration quotation like this:
+ module M where
f x = h [d| f = 3 |]
-Here the inner binding for 'f' simply shadows the outer one.
-And that applies even if the binding for 'f' is in a where-clause,
-and hence is in the *local* RdrEnv not the *global* RdrEnv.
-
-Hence the shadowP boolean passed in.
+When renaming the declarations inside [d| ...|], we treat the
+top level binders specially in two ways
+
+1. We give them an Internal name, not (as usual) an External one.
+ Otherwise the NameCache gets confused by a second allocation of
+ M.f. (We used to invent a fake module ThFake to avoid this, but
+ that had other problems, notably in getting the correct answer for
+ nameIsLocalOrFrom in lookupFixity. So we now leave tcg_module
+ unaffected.)
+
+2. We make them *shadow* the outer bindings. If we don't do that,
+ we'll get a complaint when extending the GlobalRdrEnv, saying that
+ there are two bindings for 'f'. There are several tricky points:
+
+ * This shadowing applies even if the binding for 'f' is in a
+ where-clause, and hence is in the *local* RdrEnv not the *global*
+ RdrEnv.
+
+ * The *qualified* name M.f from the enclosing module must certainly
+ still be available. So we don't nuke it entirely; we just make
+ it seem like qualified import.
+
+ * We only shadow *External* names (which come from the main module)
+ Do not shadow *Inernal* names because in the bracket
+ [d| class C a where f :: a
+ f = 4 |]
+ rnSrcDecls will first call extendGlobalRdrEnvRn with C[f] from the
+ class decl, and *separately* extend the envt with the value binding.
+
+3. We find out whether we are inside a [d| ... |] by testing the TH
+ stage. This is a slight hack, because the stage field was really
+ meant for the type checker, and here we are not interested in the
+ fields of Brack, hence the error thunks in thRnBrack.
\begin{code}
-extendGlobalRdrEnvRn :: Bool -- Note [Shadowing in extendGlobalRdrEnvRn]
- -> [AvailInfo]
+extendGlobalRdrEnvRn :: [AvailInfo]
-> MiniFixityEnv
-> RnM (TcGblEnv, TcLclEnv)
-- Updates both the GlobalRdrEnv and the FixityEnv
- -- We return a new TcLclEnv only becuase we might have to
- -- delete some bindings from it; see Note [Shadowing in extendGlobalRdrEnvRn]
+ -- We return a new TcLclEnv only because we might have to
+ -- delete some bindings from it;
+ -- see Note [Top-level Names in Template Haskell decl quotes]
-extendGlobalRdrEnvRn shadowP avails new_fixities
+extendGlobalRdrEnvRn avails new_fixities
= do { (gbl_env, lcl_env) <- getEnvs
+ ; stage <- getStage
; let rdr_env = tcg_rdr_env gbl_env
fix_env = tcg_fix_env gbl_env
-- Delete new_occs from global and local envs
- -- We are going to shadow them
- -- See Note [Shadowing in extendGlobalRdrEnvRn]
+ -- If we are in a TemplateHaskell decl bracket,
+ -- we are going to shadow them
+ -- See Note [Top-level Names in Template Haskell decl quotes]
+ shadowP = isBrackStage stage
new_occs = map (nameOccName . gre_name) gres
- rdr_env1 = hideSomeUnquals rdr_env new_occs
+ rdr_env1 = transformGREs qual_gre new_occs rdr_env
lcl_env1 = lcl_env { tcl_rdr = delListFromOccEnv (tcl_rdr lcl_env) new_occs }
-
- -- Note [Shadowing in extendGlobalRdrEnvRn]
(rdr_env2, lcl_env2) | shadowP = (rdr_env1, lcl_env1)
| otherwise = (rdr_env, lcl_env)
where
name = gre_name gre
occ = nameOccName name
+
+ qual_gre :: GlobalRdrElt -> GlobalRdrElt
+ -- Transform top-level GREs from the module being compiled
+ -- so that they are out of the way of new definitions in a Template
+ -- Haskell bracket
+ -- See Note [Top-level Names in Template Haskell decl quotes]
+ -- Seems like 5 times as much work as it deserves!
+ --
+ -- For a LocalDef we make a (fake) qualified imported GRE for a
+ -- local GRE so that the original *qualified* name is still in scope
+ -- but the *unqualified* one no longer is. What a hack!
+
+ qual_gre gre@(GRE { gre_prov = LocalDef, gre_name = name })
+ | isExternalName name = gre { gre_prov = Imported [imp_spec] }
+ | otherwise = gre
+ -- Do not shadow Internal (ie Template Haskell) Names
+ -- See Note [Top-level Names in Template Haskell decl quotes]
+ where
+ mod = ASSERT2( isExternalName name, ppr name) moduleName (nameModule name)
+ imp_spec = ImpSpec { is_item = ImpAll, is_decl = decl_spec }
+ decl_spec = ImpDeclSpec { is_mod = mod, is_as = mod,
+ is_qual = True, -- Qualified only!
+ is_dloc = srcLocSpan (nameSrcLoc name) }
+
+ qual_gre gre@(GRE { gre_prov = Imported specs })
+ = gre { gre_prov = Imported (map qual_spec specs) }
+
+ qual_spec spec@(ImpSpec { is_decl = decl_spec })
+ = spec { is_decl = decl_spec { is_qual = True } }
\end{code}
@getLocalDeclBinders@ returns the names for an @HsDecl@. It's
Instances of type families
~~~~~~~~~~~~~~~~~~~~~~~~~~
-Indexed data/newtype instances contain data constructors that we need to
-collect, too. Moreover, we need to descend into the data/newtypes instances
-of associated families.
+Family instances contain data constructors that we need to collect and we also
+need to descend into the type instances of associated families in class
+instances. The type constructor of a family instance is a usage occurence.
+Hence, we don't return it as a subname in 'AvailInfo'; otherwise, we would get
+a duplicate declaration error.
-We need to be careful with the handling of the type constructor of each type
-instance as the family constructor is already defined, and we want to avoid
-raising a duplicate declaration error. So, we make a new name for it, but
-don't return it in the 'AvailInfo'.
+Note [Looking up family names in family instances]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Consider
+
+ module M where
+ type family T a :: *
+ type instance M.T Int = Bool
+
+We might think that we can simply use 'lookupOccRn' when processing the type
+instance to look up 'M.T'. Alas, we can't! The type family declaration is in
+the *same* HsGroup as the type instance declaration. Hence, as we are
+currently collecting the binders declared in that HsGroup, these binders will
+not have been added to the global environment yet.
+
+In the case of type classes, this problem does not arise, as a class instance
+does not define any binders of it's own. So, we simply don't attempt to look
+up the class names of class instances in 'get_local_binders' below.
+
+If we don't look up class instances, can't we get away without looking up type
+instances, too? No, we can't. Data type instances define data constructors
+and we need to
+
+ (1) collect those in 'get_local_binders' and
+ (2) we need to get their parent name in 'get_local_binders', too, to
+ produce an appropriate 'AvailTC'.
+
+This parent name is exactly the family name of the type instance that is so
+difficult to look up.
+
+We solve this problem as follows:
+
+ (a) We process all type declarations other than type instances first.
+ (b) Then, we compute a 'GlobalRdrEnv' from the result of the first step.
+ (c) Finally, we process all type instances (both those on the toplevel and
+ those nested in class instances) and check for the family names in the
+ 'GlobalRdrEnv' produced in the previous step before using 'lookupOccRn'.
\begin{code}
getLocalNonValBinders :: HsGroup RdrName -> RnM [AvailInfo]
-- Get all the top-level binders bound the group *except*
-- for value bindings, which are treated separately
-- Specificaly we return AvailInfo for
--- type decls
--- class decls
+-- type decls (incl constructors and record selectors)
+-- class decls (including class ops)
-- associated types
-- foreign imports
-- (in hs-boot files) value signatures
hs_tyclds = tycl_decls,
hs_instds = inst_decls,
hs_fords = foreign_decls })
- = do { tc_names_s <- mapM new_tc tycl_decls
- ; at_names_s <- mapM inst_ats inst_decls
- ; val_names <- mapM new_simple val_bndrs
- ; return (val_names ++ tc_names_s ++ concat at_names_s) }
+ = do { -- separate out the family instance declarations
+ let (tyinst_decls1, tycl_decls_noinsts)
+ = partition (isFamInstDecl . unLoc) tycl_decls
+ tyinst_decls = tyinst_decls1 ++ instDeclATs inst_decls
+
+ -- process all type/class decls except family instances
+ ; tc_names <- mapM new_tc tycl_decls_noinsts
+
+ -- create a temporary rdr env of the type binders
+ ; let tc_gres = gresFromAvails LocalDef tc_names
+ tc_name_env = foldl extendGlobalRdrEnv emptyGlobalRdrEnv tc_gres
+
+ -- process all family instances
+ ; ti_names <- mapM (new_ti tc_name_env) tyinst_decls
+
+ -- finish off with value binder in case of a hs-boot file
+ ; val_names <- mapM new_simple val_bndrs
+ ; return (val_names ++ tc_names ++ ti_names) }
where
- mod = tcg_mod gbl_env
is_hs_boot = isHsBoot (tcg_src gbl_env) ;
for_hs_bndrs :: [Located RdrName]
new_simple :: Located RdrName -> RnM (GenAvailInfo Name)
new_simple rdr_name = do
- nm <- newTopSrcBinder mod rdr_name
+ nm <- newTopSrcBinder rdr_name
return (Avail nm)
- new_tc tc_decl
- | isFamInstDecl (unLoc tc_decl)
- = do { main_name <- lookupFamInstDeclBndr mod main_rdr
- ; sub_names <- mapM (newTopSrcBinder mod) sub_rdrs
- ; return (AvailTC main_name sub_names) }
- -- main_name is not bound here!
- | otherwise
- = do { main_name <- newTopSrcBinder mod main_rdr
- ; sub_names <- mapM (newTopSrcBinder mod) sub_rdrs
+ new_tc tc_decl -- NOT for type/data instances
+ = do { main_name <- newTopSrcBinder main_rdr
+ ; sub_names <- mapM newTopSrcBinder sub_rdrs
; return (AvailTC main_name (main_name : sub_names)) }
where
- (main_rdr : sub_rdrs) = tyClDeclNames (unLoc tc_decl)
+ (main_rdr : sub_rdrs) = hsTyClDeclBinders tc_decl
- inst_ats inst_decl
- = mapM new_tc (instDeclATs (unLoc inst_decl))
+ new_ti tc_name_env ti_decl -- ONLY for type/data instances
+ = do { main_name <- lookupFamInstDeclBndr tc_name_env main_rdr
+ ; sub_names <- mapM newTopSrcBinder sub_rdrs
+ ; return (AvailTC main_name sub_names) }
+ -- main_name is not bound here!
+ where
+ (main_rdr : sub_rdrs) = hsTyClDeclBinders ti_decl
get_local_binders _ g = pprPanic "get_local_binders" (ppr g)
\end{code}
filterImports iface decl_spec (Just (want_hiding, import_items)) all_avails
= do -- check for errors, convert RdrNames to Names
- opt_typeFamilies <- doptM Opt_TypeFamilies
+ opt_typeFamilies <- xoptM Opt_TypeFamilies
items1 <- mapM (lookup_lie opt_typeFamilies) import_items
let items2 :: [(LIE Name, AvailInfo)]
-- Warn when importing T(..) if T was exported abstractly
checkDodgyImport stuff
| IEThingAll n <- ieRdr, (_, AvailTC _ [_]):_ <- stuff
- = ifOptM Opt_WarnDodgyImports (addWarn (dodgyImportWarn n))
+ = ifDOptM Opt_WarnDodgyImports (addWarn (dodgyImportWarn n))
-- NB. use the RdrName for reporting the warning
checkDodgyImport _
= return ()
-- different parents). See the discussion at occ_env.
lookup_ie :: Bool -> IE RdrName -> MaybeErr Message [(IE Name,AvailInfo)]
lookup_ie opt_typeFamilies ie
- = let bad_ie = Failed (badImportItemErr iface decl_spec ie)
+ = let bad_ie :: MaybeErr Message a
+ bad_ie = Failed (badImportItemErr iface decl_spec ie)
- lookup_name rdrName =
- case lookupOccEnv occ_env (rdrNameOcc rdrName) of
- Nothing -> bad_ie
- Just n -> return n
+ lookup_name rdr
+ | isQual rdr = Failed (qualImportItemErr rdr)
+ | Just nm <- lookupOccEnv occ_env (rdrNameOcc rdr) = return nm
+ | otherwise = bad_ie
in
case ie of
IEVar n -> do
mkChildEnv :: [GlobalRdrElt] -> NameEnv [Name]
mkChildEnv gres = foldr add emptyNameEnv gres
where
- add (GRE { gre_name = n, gre_par = ParentIs p }) env = extendNameEnv_C (++) env p [n]
+ add (GRE { gre_name = n, gre_par = ParentIs p }) env = extendNameEnv_Acc (:) singleton env p n
add _ env = env
findChildren :: NameEnv [Name] -> Name -> [Name]
emptyAvailEnv :: AvailEnv
emptyAvailEnv = emptyNameEnv
+{- Dead code
unitAvailEnv :: AvailInfo -> AvailEnv
unitAvailEnv a = unitNameEnv (availName a) a
availEnvElts :: AvailEnv -> [AvailInfo]
availEnvElts = nameEnvElts
+-}
addAvail :: AvailEnv -> AvailInfo -> AvailEnv
addAvail avails avail = extendNameEnv_C plusAvail avails (availName avail) avail
tcg_dus = tcg_dus tcg_env `plusDU`
usesOnly (availsToNameSet final_avails) }) }
-
exports_from_avail :: Maybe [LIE RdrName]
-- Nothing => no explicit export list
-> GlobalRdrEnv
return acc }
| otherwise
- = do { implicit_prelude <- doptM Opt_ImplicitPrelude
- ; let { exportValid = (mod `elem` imported_modules)
+ = do { implicit_prelude <- xoptM Opt_ImplicitPrelude
+ ; warnDodgyExports <- doptM Opt_WarnDodgyExports
+ ; let { exportValid = (mod `elem` imported_modules)
|| (moduleName this_mod == mod)
- ; gres = filter (isModuleExported implicit_prelude mod)
- (globalRdrEnvElts rdr_env)
- }
+ ; gres = filter (isModuleExported implicit_prelude mod)
+ (globalRdrEnvElts rdr_env)
+ ; names = map gre_name gres
+ }
+
+ ; checkErr exportValid (moduleNotImported mod)
+ ; warnIf (warnDodgyExports && exportValid && null gres) (nullModuleExport mod)
- ; checkErr exportValid (moduleNotImported mod)
- ; warnIf (exportValid && null gres) (nullModuleExport mod)
+ ; addUsedRdrNames (concat [ [mkRdrQual mod occ, mkRdrUnqual occ]
+ | occ <- map nameOccName names ])
+ -- The qualified and unqualified version of all of
+ -- these names are, in effect, used by this export
- ; occs' <- check_occs ie occs (map gre_name gres)
+ ; occs' <- check_occs ie occs names
-- This check_occs not only finds conflicts
-- between this item and others, but also
-- internally within this item. That is, if
lookup_ie ie@(IEThingAll rdr)
= do name <- lookupGlobalOccRn rdr
let kids = findChildren kids_env name
- when (null kids)
- (if (isTyConName name) then addWarn (dodgyExportWarn name)
- -- This occurs when you export T(..), but
- -- only import T abstractly, or T is a synonym.
- else addErr (exportItemErr ie))
-
+ mkKidRdrName = case isQual_maybe rdr of
+ Nothing -> mkRdrUnqual
+ Just (modName, _) -> mkRdrQual modName
+ addUsedRdrNames $ map (mkKidRdrName . nameOccName) kids
+ warnDodgyExports <- doptM Opt_WarnDodgyExports
+ when (null kids) $
+ if isTyConName name
+ then when warnDodgyExports $ addWarn (dodgyExportWarn name)
+ else -- This occurs when you export T(..), but
+ -- only import T abstractly, or T is a synonym.
+ addErr (exportItemErr ie)
+
return (IEThingAll name, AvailTC name (name:kids))
lookup_ie ie@(IEThingWith rdr sub_rdrs)
then do addErr (exportItemErr ie)
return (IEThingWith name [], AvailTC name [name])
else do let names = catMaybes mb_names
- optTyFam <- doptM Opt_TypeFamilies
+ optTyFam <- xoptM Opt_TypeFamilies
when (not optTyFam && any isTyConName names) $
addErr (typeItemErr ( head
. filter isTyConName
-- every module that imports the Prelude
| otherwise
= case prov of
- LocalDef -> moduleName (nameModule name) == mod
+ LocalDef | Just name_mod <- nameModule_maybe name
+ -> moduleName name_mod == mod
+ | otherwise -> False
Imported is -> any unQualSpecOK is && any (qualSpecOK mod) is
-------------------------------
-- All this happens only once per module
finishWarnings dflags mod_warn tcg_env
= do { (eps,hpt) <- getEpsAndHpt
- ; ifOptM Opt_WarnWarningsDeprecations $
+ ; ifDOptM Opt_WarnWarningsDeprecations $
mapM_ (check hpt (eps_PIT eps)) all_gres
-- By this time, typechecking is complete,
-- so the PIT is fully populated
\begin{code}
reportUnusedNames :: Maybe [LIE RdrName] -- Export list
-> TcGblEnv -> RnM ()
-reportUnusedNames export_decls gbl_env
+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 defined_and_used
- ; printMinimalImports minimal_imports }
+ ; warnUnusedImportDecls gbl_env
+ ; warnUnusedTopBinds unused_locals }
where
used_names :: NameSet
used_names = findUses (tcg_dus gbl_env) emptyNameSet
-- Note that defined_and_used, defined_but_not_used
-- are both [GRE]; that's why we need defined_and_used
-- rather than just used_names
- defined_and_used, defined_but_not_used :: [GlobalRdrElt]
- (defined_and_used, defined_but_not_used)
+ _defined_and_used, defined_but_not_used :: [GlobalRdrElt]
+ (_defined_and_used, defined_but_not_used)
= partition (gre_is_used used_names) defined_names
kids_env = mkChildEnv defined_names
unused_locals = filter is_unused_local defined_but_not_used
is_unused_local :: GlobalRdrElt -> Bool
is_unused_local gre = isLocalGRE gre && isExternalName (gre_name gre)
-
- unused_imports :: [GlobalRdrElt]
- unused_imports = mapCatMaybes unused_imp defined_but_not_used
- unused_imp :: GlobalRdrElt -> Maybe GlobalRdrElt -- Result has trimmed Imported provenances
- unused_imp (GRE {gre_prov = LocalDef}) = Nothing
- unused_imp gre@(GRE {gre_prov = Imported imp_specs})
- | null trimmed_specs = Nothing
- | otherwise = Just (gre {gre_prov = Imported trimmed_specs})
- where
- trimmed_specs = filter report_if_unused imp_specs
-
- -- 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 ModuleName AvailEnv
- 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
- -- even if we import nothing explicitly.
- -- It's not necessarily redundant to import such modules. Consider
- -- module This
- -- import M ()
- --
- -- The import M() is not *necessarily* redundant, even if
- -- we suck in no instance decls from M (e.g. it contains
- -- no instance decls, or This contains no code). It may be
- -- that we import M solely to ensure that M's orphan instance
- -- decls (or those in its imports) are visible to people who
- -- import This. Sigh.
- -- There's really no good way to detect this, so the error message
- -- in RnEnv.warnUnusedModules is weakened instead
-
- -- 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 {gre_prov = Imported (imp_spec:_)}) acc
- = addToFM_C plusAvailEnv acc
- (importSpecModule imp_spec) (unitAvailEnv (greAvail gre))
- add_name _ acc = acc -- Local
-
- -- 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
+\end{code}
+
+%*********************************************************
+%* *
+ Unused imports
+%* *
+%*********************************************************
+
+This code finds which import declarations are unused. The
+specification and implementation notes are here:
+ http://hackage.haskell.org/trac/ghc/wiki/Commentary/Compiler/UnusedImports
+
+\begin{code}
+type ImportDeclUsage
+ = ( LImportDecl Name -- The import declaration
+ , [AvailInfo] -- What *is* used (normalised)
+ , [Name] ) -- What is imported but *not* used
+\end{code}
+
+\begin{code}
+warnUnusedImportDecls :: TcGblEnv -> RnM ()
+warnUnusedImportDecls gbl_env
+ = do { uses <- readMutVar (tcg_used_rdrnames gbl_env)
+ ; let imports = filter explicit_import (tcg_rn_imports gbl_env)
+ rdr_env = tcg_rdr_env gbl_env
- add_inst_mod (mod, _) acc
- | mod_name `elemFM` acc = acc -- We import something already
- | otherwise = addToFM acc mod_name emptyAvailEnv
+ ; let usage :: [ImportDeclUsage]
+ usage = findImportUsage imports rdr_env (Set.elems uses)
+
+ ; ifDOptM Opt_WarnUnusedImports $
+ mapM_ warnUnusedImport usage
+
+ ; ifDOptM Opt_D_dump_minimal_imports $
+ printMinimalImports usage }
+ where
+ explicit_import (L loc _) = isGoodSrcSpan loc
+ -- Filter out the implicit Prelude import
+ -- which we do not want to bleat about
+\end{code}
+
+\begin{code}
+findImportUsage :: [LImportDecl Name]
+ -> GlobalRdrEnv
+ -> [RdrName]
+ -> [ImportDeclUsage]
+
+type ImportMap = Map SrcLoc [AvailInfo]
+ -- The intermediate data struture records, for each import
+ -- declaration, what stuff brought into scope by that
+ -- declaration is actually used in the module.
+ --
+ -- The SrcLoc is the location of the start
+ -- of a particular 'import' declaration
+ --
+ -- The AvailInfos are the things imported from that decl
+ -- (just a list, not normalised)
+
+findImportUsage imports rdr_env rdrs
+ = map unused_decl imports
+ where
+ import_usage :: ImportMap
+ import_usage = foldr (addUsedRdrName rdr_env) Map.empty rdrs
+
+ unused_decl decl@(L loc (ImportDecl { ideclHiding = imps }))
+ = (decl, nubAvails used_avails, unused_imps)
where
- mod_name = moduleName mod
- -- Add an empty collection of imports for a module
- -- from which we have sucked only instance decls
-
- imports = tcg_imports gbl_env
-
- direct_import_mods :: [(Module, [(ModuleName, Bool, SrcSpan)])]
- -- See the type of the imp_mods for this triple
- direct_import_mods = fmToList (imp_mods imports)
-
- -- unused_imp_mods are the directly-imported modules
- -- 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]
- --
- -- BUG WARNING: this code is generally buggy
- unused_imp_mods :: [(ModuleName, SrcSpan)]
- 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),
- moduleName mod /= pRELUDE_NAME,
- -- XXX not really correct, but we don't want
- -- to generate warnings when compiling against
- -- a compat version of base.
- not no_imp]
- -- The not no_imp part is not to complain about
- -- import M (), which is an idiom for importing
- -- instance declarations
-
- module_unused :: ModuleName -> Bool
- module_unused mod = any (((==) mod) . fst) unused_imp_mods
-
- report_if_unused :: ImportSpec -> Bool
- -- Do we want to report this as an unused import?
- report_if_unused (ImpSpec {is_decl = d, is_item = i})
- = not (module_unused (is_mod d)) -- Not if we've already said entire import is unused
- && isExplicitItem i -- Only if the import was explicit
+ used_avails = Map.lookup (srcSpanStart loc) import_usage `orElse` []
+ dont_report_as_unused = foldr add emptyNameSet used_avails
+ add (Avail n) s = s `addOneToNameSet` n
+ add (AvailTC n ns) s = s `addListToNameSet` (n:ns)
+ -- If you use 'signum' from Num, then the user may well have
+ -- imported Num(signum). We don't want to complain that
+ -- Num is not itself mentioned. Hence adding 'n' as
+ -- well to the list of of "don't report if unused" names
+
+ unused_imps = case imps of
+ Just (False, imp_ies) -> nameSetToList unused_imps
+ where
+ imp_names = mkNameSet (concatMap (ieNames . unLoc) imp_ies)
+ unused_imps = imp_names `minusNameSet` dont_report_as_unused
+
+ _other -> [] -- No explicit import list => no unused-name list
----------------------
-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 $
- sequence_ [ warn name pr
- | GRE { gre_name = name, gre_prov = Imported imps } <- gres
- , pr <- redundants imps ]
+addUsedRdrName :: GlobalRdrEnv -> RdrName -> ImportMap -> ImportMap
+-- For a used RdrName, find all the import decls that brought
+-- it into scope; choose one of them (bestImport), and record
+-- the RdrName in that import decl's entry in the ImportMap
+addUsedRdrName rdr_env rdr imp_map
+ | [gre] <- lookupGRE_RdrName rdr rdr_env
+ , Imported imps <- gre_prov gre
+ = add_imp gre (bestImport imps) imp_map
+ | otherwise
+ = imp_map
where
- 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
- , isExplicitItem (is_item red_imp)
- -- Complain only about redundant imports
- -- mentioned explicitly by the user
- , cov_imp <- take 1 (filter (covers red_imp) imps) ]
- -- The 'take 1' picks the first offending group
- -- for this particular name
-
- -- "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 )
- -- import 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 })
- 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
- | otherwise
- = not (isExplicitItem cov_item) -- Redundant one is selective and covering one isn't
- || red_later -- or both are explicit; tie-break using red_later
-{-
- | 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
-
--- ToDo: deal with original imports with 'qualified' and 'as M' clauses
-printMinimalImports :: FiniteMap ModuleName AvailEnv -- Minimal imports
- -> RnM ()
-printMinimalImports imps
- = ifOptM Opt_D_dump_minimal_imports $ do {
-
- mod_ies <- initIfaceTcRn $ mapM to_ies (fmToList imps) ;
- this_mod <- getModule ;
- rdr_env <- getGlobalRdrEnv ;
- dflags <- getDOpts ;
- liftIO $ do h <- openFile (mkFilename this_mod) WriteMode
- printForUser h (mkPrintUnqualified dflags rdr_env)
- (vcat (map ppr_mod_ie mod_ies))
- }
+ add_imp :: GlobalRdrElt -> ImportSpec -> ImportMap -> ImportMap
+ add_imp gre (ImpSpec { is_decl = imp_decl_spec }) imp_map
+ = Map.insertWith add decl_loc [avail] imp_map
+ where
+ add _ avails = avail : avails -- add is really just a specialised (++)
+ decl_loc = srcSpanStart (is_dloc imp_decl_spec)
+ name = gre_name gre
+ avail = case gre_par gre of
+ ParentIs p -> AvailTC p [name]
+ NoParent | isTyConName name -> AvailTC name [name]
+ | otherwise -> Avail name
+
+ bestImport :: [ImportSpec] -> ImportSpec
+ bestImport iss
+ = case partition isImpAll iss of
+ ([], imp_somes) -> textuallyFirst imp_somes
+ (imp_alls, _) -> textuallyFirst imp_alls
+
+ textuallyFirst :: [ImportSpec] -> ImportSpec
+ textuallyFirst iss = case sortWith (is_dloc . is_decl) iss of
+ [] -> pprPanic "textuallyFirst" (ppr iss)
+ (is:_) -> is
+
+ isImpAll :: ImportSpec -> Bool
+ isImpAll (ImpSpec { is_item = ImpAll }) = True
+ isImpAll _other = False
+\end{code}
+
+\begin{code}
+warnUnusedImport :: ImportDeclUsage -> RnM ()
+warnUnusedImport (L loc decl, used, unused)
+ | Just (False,[]) <- ideclHiding decl
+ = return () -- Do not warn for 'import M()'
+ | null used = addWarnAt loc msg1 -- Nothing used; drop entire decl
+ | null unused = return () -- Everything imported is used; nop
+ | otherwise = addWarnAt loc msg2 -- Some imports are unused
+ where
+ msg1 = vcat [pp_herald <+> quotes pp_mod <+> pp_not_used,
+ nest 2 (ptext (sLit "except perhaps to import instances from")
+ <+> quotes pp_mod),
+ ptext (sLit "To import instances alone, use:")
+ <+> ptext (sLit "import") <+> pp_mod <> parens empty ]
+ msg2 = sep [pp_herald <+> quotes (pprWithCommas ppr unused),
+ text "from module" <+> quotes pp_mod <+> pp_not_used]
+ pp_herald = text "The import of"
+ pp_mod = ppr (unLoc (ideclName decl))
+ pp_not_used = text "is redundant"
+\end{code}
+
+To print the minimal imports we walk over the user-supplied import
+decls, and simply trim their import lists. NB that
+
+ * We do *not* change the 'qualified' or 'as' parts!
+
+ * We do not disard a decl altogether; we might need instances
+ from it. Instead we just trim to an empty import list
+
+\begin{code}
+printMinimalImports :: [ImportDeclUsage] -> RnM ()
+printMinimalImports imports_w_usage
+ = do { imports' <- mapM mk_minimal imports_w_usage
+ ; this_mod <- getModule
+ ; liftIO $
+ do { h <- openFile (mkFilename this_mod) WriteMode
+ ; printForUser h neverQualify (vcat (map ppr imports')) }
+ -- The neverQualify is important. We are printing Names
+ -- but they are in the context of an 'import' decl, and
+ -- we never qualify things inside there
+ -- E.g. import Blag( f, b )
+ -- not import Blag( Blag.f, Blag.g )!
+ }
where
mkFilename this_mod = moduleNameString (moduleName this_mod) ++ ".imports"
- ppr_mod_ie (mod_name, ies)
- | mod_name == moduleName pRELUDE
- = empty
- | null ies -- Nothing except instances comes from here
- = ptext (sLit "import") <+> ppr mod_name <> ptext (sLit "() -- Instances only")
- | otherwise
- = ptext (sLit "import") <+> ppr mod_name <>
- parens (fsep (punctuate comma (map ppr ies)))
- to_ies (mod, avail_env) = do ies <- mapM to_ie (availEnvElts avail_env)
- return (mod, ies)
+ mk_minimal (L l decl, used, unused)
+ | null unused
+ , Just (False, _) <- ideclHiding decl
+ = return (L l decl)
+ | otherwise
+ = do { let ImportDecl { ideclName = L _ mod_name
+ , ideclSource = is_boot
+ , ideclPkgQual = mb_pkg } = decl
+ ; iface <- loadSrcInterface doc mod_name is_boot mb_pkg
+ ; let lies = map (L l) (concatMap (to_ie iface) used)
+ ; return (L l (decl { ideclHiding = Just (False, lies) })) }
+ where
+ doc = text "Compute minimal imports for" <+> ppr decl
- to_ie :: AvailInfo -> IfG (IE Name)
+ to_ie :: ModIface -> AvailInfo -> [IE Name]
-- The main trick here is that if we're importing all the constructors
-- we want to say "T(..)", but if we're importing only a subset we want
-- to say "T(A,B,C)". So we have to find out what the module exports.
- to_ie (Avail n) = return (IEVar n)
- to_ie (AvailTC n [m]) = ASSERT( n==m )
- return (IEThingAbs n)
- to_ie (AvailTC n ns) = do
- iface <- loadSysInterface doc n_mod
- case [xs | (m,as) <- mi_exports iface,
- m == n_mod,
- AvailTC x xs <- as,
- x == nameOccName n] of
- [xs] | all_used xs -> return (IEThingAll n)
- | otherwise -> return (IEThingWith n (filter (/= n) ns))
- other -> pprTrace "to_ie" (ppr n <+> ppr n_mod <+> ppr other) $
- return (IEVar n)
+ to_ie _ (Avail n)
+ = [IEVar n]
+ to_ie _ (AvailTC n [m])
+ | n==m = [IEThingAbs n]
+ to_ie iface (AvailTC n ns)
+ = case [xs | (m,as) <- mi_exports iface
+ , m == n_mod
+ , AvailTC x xs <- as
+ , x == nameOccName n
+ , x `elem` xs -- Note [Partial export]
+ ] of
+ [xs] | all_used xs -> [IEThingAll n]
+ | otherwise -> [IEThingWith n (filter (/= n) ns)]
+ _other -> (map IEVar ns)
where
all_used avail_occs = all (`elem` map nameOccName ns) avail_occs
- doc = text "Compute minimal imports from" <+> ppr n
n_mod = ASSERT( isExternalName n ) nameModule n
\end{code}
+Note [Partial export]
+~~~~~~~~~~~~~~~~~~~~~
+Suppose we have
+
+ module A( op ) where
+ class C a where
+ op :: a -> a
+
+ module B where
+ import A
+ f = ..op...
+
+Then the minimal import for module B is
+ import A( op )
+not
+ import A( C( op ) )
+which we would usually generate if C was exported from B. Hence
+the (x `elem` xs) test when deciding what to generate.
+
%************************************************************************
%* *
%************************************************************************
\begin{code}
+qualImportItemErr :: RdrName -> SDoc
+qualImportItemErr rdr
+ = hang (ptext (sLit "Illegal qualified name in import item:"))
+ 2 (ppr rdr)
+
badImportItemErr :: ModIface -> ImpDeclSpec -> IE RdrName -> SDoc
badImportItemErr iface decl_spec ie
= sep [ptext (sLit "Module"), quotes (ppr (is_mod decl_spec)), source_import,
dodgyMsg :: OutputableBndr n => SDoc -> n -> SDoc
dodgyMsg kind tc
- = sep [ ptext (sLit "The") <+> kind <+> ptext (sLit "item") <+> quotes (ppr (IEThingAll tc)),
- ptext (sLit "suggests that") <+> quotes (ppr tc) <+> ptext (sLit "has constructors or class methods,"),
+ = sep [ ptext (sLit "The") <+> kind <+> ptext (sLit "item") <+> quotes (ppr (IEThingAll tc))
+ <+> ptext (sLit "suggests that"),
+ quotes (ppr tc) <+> ptext (sLit "has (in-scope) constructors or class methods,"),
ptext (sLit "but it has none") ]
exportItemErr :: IE RdrName -> SDoc
nullModuleExport mod
= ptext (sLit "The export item `module") <+> ppr mod <> ptext (sLit "' exports nothing")
+missingImportListWarn :: ModuleName -> SDoc
+missingImportListWarn mod
+ = ptext (sLit "The module") <+> quotes (ppr mod) <+> ptext (sLit "does not have an explicit import list")
+
moduleWarn :: ModuleName -> WarningTxt -> SDoc
moduleWarn mod (WarningTxt txt)
= sep [ ptext (sLit "Module") <+> quotes (ppr mod) <> ptext (sLit ":"),
- nest 4 (ppr txt) ]
+ nest 2 (vcat (map ppr txt)) ]
moduleWarn mod (DeprecatedTxt txt)
= sep [ ptext (sLit "Module") <+> quotes (ppr mod)
<+> ptext (sLit "is deprecated:"),
- nest 4 (ppr txt) ]
+ nest 2 (vcat (map ppr txt)) ]
implicitPreludeWarn :: SDoc
implicitPreludeWarn