X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2Frename%2FRnNames.lhs;h=781de3190e18046b3753a64c41f367099cb534fa;hp=67b1dd1ec731ad8af3be74e852e02c998a22aa78;hb=7bb3d1fc79521d591cd9f824893963141a7997b6;hpb=526c3af1dc98987b6949f4df73c0debccf9875bd diff --git a/compiler/rename/RnNames.lhs b/compiler/rename/RnNames.lhs index 67b1dd1..781de31 100644 --- a/compiler/rename/RnNames.lhs +++ b/compiler/rename/RnNames.lhs @@ -7,13 +7,14 @@ module RnNames ( rnImports, getLocalNonValBinders, rnExports, extendGlobalRdrEnvRn, - reportUnusedNames, finishDeprecations, + reportUnusedNames, finishWarnings, ) where #include "HsVersions.h" import DynFlags import HsSyn +import TcEnv ( isBrackStage ) import RnEnv import RnHsDoc ( rnHsDoc ) import IfaceEnv ( ifaceExportNames ) @@ -25,7 +26,6 @@ import Module import Name import NameEnv import NameSet -import OccName import HscTypes import RdrName import Outputable @@ -33,12 +33,11 @@ import Maybes import SrcLoc import FiniteMap import ErrUtils -import BasicTypes ( DeprecTxt ) -import DriverPhases ( isHsBoot ) import Util import FastString import ListSetOps -import Data.List ( partition, concatMap, (\\), delete ) +import Data.List ( partition, (\\), delete ) +import qualified Data.Set as Set import IO ( openFile, IOMode(..) ) import Monad ( when, mplus ) \end{code} @@ -63,7 +62,7 @@ rnImports imports implicit_prelude <- doptM Opt_ImplicitPrelude let prel_imports = mkPrelImports this_mod implicit_prelude imports (source, ordinary) = partition is_source_import imports - is_source_import (L _ (ImportDecl _ is_boot _ _ _)) = is_boot + is_source_import (L _ (ImportDecl _ _ is_boot _ _ _)) = is_boot ifOptM Opt_WarnImplicitPrelude ( when (notNull prel_imports) $ addWarn (implicitPreludeWarn) @@ -99,13 +98,14 @@ mkPrelImports this_mod implicit_prelude import_decls | otherwise = [preludeImportDecl] where explicit_prelude_import - = notNull [ () | L _ (ImportDecl mod _ _ _ _) <- import_decls, + = 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" -} @@ -118,10 +118,13 @@ rnImportDecl :: Module -> LImportDecl RdrName -> RnM (LImportDecl Name, GlobalRdrEnv, ImportAvails,AnyHpcUsage) -rnImportDecl this_mod (L loc (ImportDecl loc_imp_mod_name want_boot +rnImportDecl this_mod (L loc (ImportDecl loc_imp_mod_name mb_pkg want_boot qual_only as_mod imp_details)) - = - setSrcSpan loc $ do + = setSrcSpan loc $ do + + when (isJust mb_pkg) $ do + pkg_imports <- doptM Opt_PackageImports + when (not pkg_imports) $ addErr packageImportErr -- If there's an error in loadInterface, (e.g. interface -- file not found) we get lots of spurious errors from 'filterImports' @@ -129,7 +132,7 @@ rnImportDecl this_mod (L loc (ImportDecl loc_imp_mod_name want_boot imp_mod_name = unLoc loc_imp_mod_name doc = ppr imp_mod_name <+> ptext (sLit "is directly imported") - iface <- loadSrcInterface doc imp_mod_name want_boot + iface <- loadSrcInterface doc imp_mod_name want_boot mb_pkg -- Compiler sanity check: if the import didn't say -- {-# SOURCE #-} we should not get a hi-boot file @@ -137,13 +140,19 @@ rnImportDecl this_mod (L loc (ImportDecl loc_imp_mod_name want_boot -- 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 imp_mod = mi_module iface - deprecs = mi_deprecs iface + warns = mi_warns iface orph_iface = mi_orphan iface has_finsts = mi_finsts iface deps = mi_deps iface @@ -233,13 +242,13 @@ rnImportDecl this_mod (L loc (ImportDecl loc_imp_mod_name want_boot } -- Complain if we import a deprecated module - ifOptM Opt_WarnDeprecations ( - case deprecs of - DeprecAll txt -> addWarn (moduleDeprec imp_mod_name txt) - _ -> return () + ifOptM Opt_WarnWarningsDeprecations ( + case warns of + WarnAll txt -> addWarn (moduleWarn imp_mod_name txt) + _ -> return () ) - let new_imp_decl = L loc (ImportDecl loc_imp_mod_name want_boot + let new_imp_decl = L loc (ImportDecl loc_imp_mod_name mb_pkg want_boot qual_only as_mod new_imp_details) return (new_imp_decl, gbl_env, imports, mi_hpc iface) @@ -263,44 +272,57 @@ From the top-level declarations of this module produce * 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. +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'. + + 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. -Hence the shadowP boolean passed in. +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] + -- 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 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) @@ -335,14 +357,48 @@ used for source code. 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. + +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. -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'. +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] @@ -364,40 +420,57 @@ get_local_binders gbl_env (HsGroup {hs_valds = ValBindsIn _ val_sigs, 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 ++ + concatMap (instDeclATs . unLoc) 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] for_hs_bndrs = [nm | L _ (ForeignImport nm _ _) <- foreign_decls] -- In a hs-boot file, the value binders come from the -- *signatures*, and there should be no foreign binders + val_bndrs :: [Located RdrName] val_bndrs | is_hs_boot = [nm | L _ (TypeSig nm _) <- val_sigs] | otherwise = for_hs_bndrs + new_simple :: Located RdrName -> RnM (GenAvailInfo Name) new_simple rdr_name = do nm <- newTopSrcBinder mod 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 + new_tc tc_decl -- NOT for type/data instances = do { main_name <- newTopSrcBinder mod main_rdr ; sub_names <- mapM (newTopSrcBinder mod) sub_rdrs ; return (AvailTC main_name (main_name : sub_names)) } where (main_rdr : sub_rdrs) = tyClDeclNames (unLoc 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 mod) sub_rdrs + ; return (AvailTC main_name sub_names) } + -- main_name is not bound here! + where + (main_rdr : sub_rdrs) = tyClDeclNames (unLoc ti_decl) get_local_binders _ g = pprPanic "get_local_binders" (ppr g) \end{code} @@ -633,7 +706,7 @@ filterAvail keep ie rest = let left = filter keep ns in if null left then rest else AvailTC tc left : rest --- | Given an import/export spec, construct the appropriate 'GlobalRdrElt's. +-- | Given an import\/export spec, construct the appropriate 'GlobalRdrElt's. gresFromIE :: ImpDeclSpec -> (LIE Name, AvailInfo) -> [GlobalRdrElt] gresFromIE decl_spec (L loc ie, avail) = gresFromAvail prov_fn avail @@ -669,6 +742,7 @@ type AvailEnv = NameEnv AvailInfo -- Maps a Name to the AvailInfo that contains emptyAvailEnv :: AvailEnv emptyAvailEnv = emptyNameEnv +{- Dead code unitAvailEnv :: AvailInfo -> AvailEnv unitAvailEnv a = unitNameEnv (availName a) a @@ -677,6 +751,7 @@ plusAvailEnv = plusNameEnv_C plusAvail availEnvElts :: AvailEnv -> [AvailInfo] availEnvElts = nameEnvElts +-} addAvail :: AvailEnv -> AvailInfo -> AvailEnv addAvail avails avail = extendNameEnv_C plusAvail avails (availName avail) avail @@ -776,7 +851,6 @@ rnExports explicit_mod exports tcg_dus = tcg_dus tcg_env `plusDU` usesOnly (availsToNameSet final_avails) }) } - exports_from_avail :: Maybe [LIE RdrName] -- Nothing => no explicit export list -> GlobalRdrEnv @@ -819,16 +893,22 @@ exports_from_avail (Just rdr_items) rdr_env imports this_mod | otherwise = do { implicit_prelude <- doptM Opt_ImplicitPrelude - ; let { exportValid = (mod `elem` imported_modules) + ; 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) + ; checkErr exportValid (moduleNotImported mod) ; warnIf (exportValid && null gres) (nullModuleExport mod) - ; occs' <- check_occs ie occs (map gre_name gres) + ; 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 names -- This check_occs not only finds conflicts -- between this item and others, but also -- internally within this item. That is, if @@ -926,14 +1006,16 @@ isModuleExported implicit_prelude mod (GRE { gre_name = name, gre_prov = prov }) -- They just clutter up the environment (esp tuples), and the parser -- will generate Exact RdrNames for them, so the cluttered -- envt is no use. To avoid doing this filter all the time, - -- we use -fno-implicit-prelude as a clue that the filter is + -- we use -XNoImplicitPrelude as a clue that the filter is -- worth while. Really, it's only useful for GHC.Base and GHC.Tuple. -- -- It's worth doing because it makes the environment smaller for -- 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 ------------------------------- @@ -966,23 +1048,23 @@ check_occs ie occs names %********************************************************* \begin{code} -finishDeprecations :: DynFlags -> Maybe DeprecTxt - -> TcGblEnv -> RnM TcGblEnv --- (a) Report usasge of deprecated imports --- (b) If the whole module is deprecated, update tcg_deprecs --- All this happens only once per module -finishDeprecations dflags mod_deprec tcg_env +finishWarnings :: DynFlags -> Maybe WarningTxt + -> TcGblEnv -> RnM TcGblEnv +-- (a) Report usage of imports that are deprecated or have other warnings +-- (b) If the whole module is warned about or deprecated, update tcg_warns +-- All this happens only once per module +finishWarnings dflags mod_warn tcg_env = do { (eps,hpt) <- getEpsAndHpt - ; ifOptM Opt_WarnDeprecations $ + ; ifOptM Opt_WarnWarningsDeprecations $ mapM_ (check hpt (eps_PIT eps)) all_gres -- By this time, typechecking is complete, -- so the PIT is fully populated - -- Deal with a module deprecation; it overrides all existing deprecs - ; let new_deprecs = case mod_deprec of - Just txt -> DeprecAll txt - Nothing -> tcg_deprecs tcg_env - ; return (tcg_env { tcg_deprecs = new_deprecs }) } + -- Deal with a module deprecation; it overrides all existing warns + ; let new_warns = case mod_warn of + Just txt -> WarnAll txt + Nothing -> tcg_warns tcg_env + ; return (tcg_env { tcg_warns = new_warns }) } where used_names = allUses (tcg_dus tcg_env) -- Report on all deprecated uses; hence allUses @@ -992,13 +1074,13 @@ finishDeprecations dflags mod_deprec tcg_env | name `elemNameSet` used_names , Just deprec_txt <- lookupImpDeprec dflags hpt pit gre = addWarnAt (importSpecLoc imp_spec) - (sep [ptext (sLit "Deprecated use of") <+> + (sep [ptext (sLit "In the use of") <+> pprNonVarNameSpace (occNameSpace (nameOccName name)) <+> quotes (ppr name), (parens imp_msg) <> colon, (ppr deprec_txt) ]) where - name_mod = nameModule name + name_mod = ASSERT2( isExternalName name, ppr name ) nameModule name imp_mod = importSpecModule imp_spec imp_msg = ptext (sLit "imported from") <+> ppr imp_mod <> extra extra | imp_mod == moduleName name_mod = empty @@ -1013,18 +1095,19 @@ finishDeprecations dflags mod_deprec tcg_env -- interface lookupImpDeprec :: DynFlags -> HomePackageTable -> PackageIfaceTable - -> GlobalRdrElt -> Maybe DeprecTxt + -> GlobalRdrElt -> Maybe WarningTxt -- The name is definitely imported, so look in HPT, PIT lookupImpDeprec dflags hpt pit gre - = case lookupIfaceByModule dflags hpt pit (nameModule name) of - Just iface -> mi_dep_fn iface name `mplus` -- Bleat if the thing, *or + = case lookupIfaceByModule dflags hpt pit mod of + Just iface -> mi_warn_fn iface name `mplus` -- Bleat if the thing, *or case gre_par gre of - ParentIs p -> mi_dep_fn iface p -- its parent*, is deprec'd + ParentIs p -> mi_warn_fn iface p -- its parent*, is warn'd NoParent -> Nothing Nothing -> Nothing -- See Note [Used names with interface not loaded] where - name = gre_name gre + name = gre_name gre + mod = ASSERT2( isExternalName name, ppr name ) nameModule name \end{code} Note [Used names with interface not loaded] @@ -1038,7 +1121,7 @@ a) It might be a WiredInName; in that case we may not load its interface (although we could). b) It might be GHC.Real.fromRational, or GHC.Num.fromInteger - These are seen as "used" by the renamer (if -fno-implicit-prelude) + These are seen as "used" by the renamer (if -XNoImplicitPrelude) is on), but the typechecker may discard their uses if in fact the in-scope fromRational is GHC.Read.fromRational, (see tcPat.tcOverloadedLit), and the typechecker sees that the type @@ -1058,13 +1141,10 @@ this is, after all, wired-in stuff. \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 @@ -1078,8 +1158,8 @@ reportUnusedNames export_decls gbl_env -- 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 @@ -1100,217 +1180,174 @@ reportUnusedNames export_decls gbl_env 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} - add_inst_mod (mod, _) acc - | mod_name `elemFM` acc = acc -- We import something already - | otherwise = addToFM acc mod_name emptyAvailEnv +%********************************************************* +%* * + 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 + + ; let usage :: [ImportDeclUsage] + usage = findImportUsage imports rdr_env (Set.elems uses) + + ; ifOptM Opt_WarnUnusedImports $ + mapM_ warnUnusedImport usage + + ; ifOptM 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 = FiniteMap 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 add_rdr emptyFM 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), - mod /= pRELUDE, - 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 = lookupFM import_usage (srcSpanStart loc) `orElse` [] + used_names = availsToNameSet used_avails + + 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` used_names + + _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 ] + add_rdr :: RdrName -> ImportMap -> ImportMap + add_rdr rdr iu + = case lookupGRE_RdrName rdr rdr_env of + [gre] | Imported imps <- gre_prov gre + -> add_imp gre (bestImport imps) iu + _other -> iu + + add_imp :: GlobalRdrElt -> ImportSpec -> ImportMap -> ImportMap + add_imp gre (ImpSpec { is_decl = imp_decl_spec }) iu + = addToFM_C add iu decl_loc [avail] + where + add avails _ = avail : avails + decl_loc = srcSpanStart (is_dloc imp_decl_spec) + name = gre_name gre + avail = case gre_par gre of + ParentIs p -> AvailTC p [p,name] + NoParent | isTyConName name -> AvailTC name [name] + | otherwise -> Avail name + -- If you use (+) from Num, then for this purpose we want + -- to say that Num is used as well. That is why in the + -- ParentIs case we have [p,name] in the ParentIs case + +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 - 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)) - } + 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 { ies <- initIfaceTcRn $ mapM to_ie used + ; return (L l (decl { ideclHiding = Just (False, map (L l) ies) })) } to_ie :: AvailInfo -> IfG (IE Name) -- The main trick here is that if we're importing all the constructors @@ -1332,10 +1369,9 @@ printMinimalImports imps where all_used avail_occs = all (`elem` map nameOccName ns) avail_occs doc = text "Compute minimal imports from" <+> ppr n - n_mod = nameModule n + n_mod = ASSERT( isExternalName n ) nameModule n \end{code} - %************************************************************************ %* * \subsection{Errors} @@ -1361,8 +1397,9 @@ dodgyExportWarn item = dodgyMsg (ptext (sLit "export")) item 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 @@ -1428,12 +1465,20 @@ nullModuleExport :: ModuleName -> SDoc nullModuleExport mod = ptext (sLit "The export item `module") <+> ppr mod <> ptext (sLit "' exports nothing") -moduleDeprec :: ModuleName -> DeprecTxt -> SDoc -moduleDeprec mod txt - = sep [ ptext (sLit "Module") <+> quotes (ppr mod) <+> ptext (sLit "is deprecated:"), - nest 4 (ppr txt) ] +moduleWarn :: ModuleName -> WarningTxt -> SDoc +moduleWarn mod (WarningTxt txt) + = sep [ ptext (sLit "Module") <+> quotes (ppr mod) <> ptext (sLit ":"), + nest 4 (ppr txt) ] +moduleWarn mod (DeprecatedTxt txt) + = sep [ ptext (sLit "Module") <+> quotes (ppr mod) + <+> ptext (sLit "is deprecated:"), + nest 4 (ppr txt) ] implicitPreludeWarn :: SDoc implicitPreludeWarn = ptext (sLit "Module `Prelude' implicitly imported") + +packageImportErr :: SDoc +packageImportErr + = ptext (sLit "Package-qualified imports are not enabled; use -XPackageImports") \end{code}