{- (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 Extracting imported and top-level names in scope -} {-# LANGUAGE CPP, NondecreasingIndentation #-} {-# LANGUAGE FlexibleContexts #-} {-# LANGUAGE RankNTypes #-} {-# LANGUAGE ScopedTypeVariables #-} {-# LANGUAGE TypeFamilies #-} {-# OPTIONS_GHC -Wno-incomplete-uni-patterns #-} {-# OPTIONS_GHC -Wno-incomplete-record-updates #-} module GHC.Rename.Names ( rnImports, getLocalNonValBinders, newRecordSelector, extendGlobalRdrEnvRn, gresFromAvails, calculateAvails, reportUnusedNames, checkConName, mkChildEnv, findChildren, dodgyMsg, dodgyMsgInsert, findImportUsage, getMinimalImports, printMinimalImports, ImportDeclUsage ) where #include "HsVersions.h" import GHC.Prelude import GHC.Driver.Env import GHC.Driver.Session import GHC.Driver.Ppr import GHC.Rename.Env import GHC.Rename.Fixity import GHC.Rename.Utils ( warnUnusedTopBinds, mkFieldEnv ) import GHC.Tc.Utils.Env import GHC.Tc.Utils.Monad import GHC.Hs import GHC.Iface.Load ( loadSrcInterface ) import GHC.Builtin.Names import GHC.Parser.PostProcess ( setRdrNameSpace ) import GHC.Core.Type import GHC.Core.PatSyn import GHC.Core.TyCo.Ppr import qualified GHC.LanguageExtensions as LangExt import GHC.Utils.Outputable as Outputable import GHC.Utils.Misc as Utils import GHC.Utils.Panic import GHC.Types.Fixity.Env import GHC.Types.SafeHaskell import GHC.Types.Name import GHC.Types.Name.Env import GHC.Types.Name.Set import GHC.Types.Name.Reader import GHC.Types.Avail import GHC.Types.FieldLabel import GHC.Types.SourceFile import GHC.Types.SrcLoc as SrcLoc import GHC.Types.Basic ( TopLevelFlag(..) ) import GHC.Types.SourceText import GHC.Types.Id import GHC.Types.HpcInfo import GHC.Unit import GHC.Unit.Module.Warnings import GHC.Unit.Module.ModIface import GHC.Unit.Module.Imported import GHC.Unit.Module.Deps import GHC.Data.Maybe import GHC.Data.FastString import GHC.Data.FastString.Env import Control.Monad import Data.Either ( partitionEithers, isRight, rights ) import Data.Map ( Map ) import qualified Data.Map as Map import Data.Ord ( comparing ) import Data.List ( partition, (\\), find, sortBy, groupBy, sortOn ) import Data.Function ( on ) import qualified Data.Set as S import System.FilePath (()) import System.IO {- ************************************************************************ * * \subsection{rnImports} * * ************************************************************************ Note [Tracking Trust Transitively] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ When we import a package as well as checking that the direct imports are safe according to the rules outlined in the Note [Safe Haskell Trust Check] in GHC.Driver.Main we must also check that these rules hold transitively for all dependent modules and packages. Doing this without caching any trust information would be very slow as we would need to touch all packages and interface files a module depends on. To avoid this we make use of the property that if a modules Safe Haskell mode changes, this triggers a recompilation from that module in the dependcy graph. So we can just worry mostly about direct imports. There is one trust property that can change for a package though without recompilation being triggered: package trust. So we must check that all packages a module transitively depends on to be trusted are still trusted when we are compiling this module (as due to recompilation avoidance some modules below may not be considered trusted any more without recompilation being triggered). We handle this by augmenting the existing transitive list of packages a module M depends on with a bool for each package that says if it must be trusted when the module M is being checked for trust. This list of trust required packages for a single import is gathered in the rnImportDecl function and stored in an ImportAvails data structure. The union of these trust required packages for all imports is done by the rnImports function using the combine function which calls the plusImportAvails function that is a union operation for the ImportAvails type. This gives us in an ImportAvails structure all packages required to be trusted for the module we are currently compiling. Checking that these packages are still trusted (and that direct imports are trusted) is done in GHC.Driver.Main.checkSafeImports. See the note below, [Trust Own Package] for a corner case in this method and how its handled. Note [Trust Own Package] ~~~~~~~~~~~~~~~~~~~~~~~~ There is a corner case of package trust checking that the usual transitive check doesn't cover. (For how the usual check operates see the Note [Tracking Trust Transitively] below). The case is when you import a -XSafe module M and M imports a -XTrustworthy module N. If N resides in a different package than M, then the usual check works as M will record a package dependency on N's package and mark it as required to be trusted. If N resides in the same package as M though, then importing M should require its own package be trusted due to N (since M is -XSafe so doesn't create this requirement by itself). The usual check fails as a module doesn't record a package dependency of its own package. So instead we now have a bool field in a modules interface file that simply states if the module requires its own package to be trusted. This field avoids us having to load all interface files that the module depends on to see if one is trustworthy. Note [Trust Transitive Property] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ So there is an interesting design question in regards to transitive trust checking. Say I have a module B compiled with -XSafe. B is dependent on a bunch of modules and packages, some packages it requires to be trusted as its using -XTrustworthy modules from them. Now if I have a module A that doesn't use safe haskell at all and simply imports B, should A inherit all the trust requirements from B? Should A now also require that a package p is trusted since B required it? We currently say no but saying yes also makes sense. The difference is, if a module M that doesn't use Safe Haskell imports a module N that does, should all the trusted package requirements be dropped since M didn't declare that it cares about Safe Haskell (so -XSafe is more strongly associated with the module doing the importing) or should it be done still since the author of the module N that uses Safe Haskell said they cared (so -XSafe is more strongly associated with the module that was compiled that used it). Going with yes is a simpler semantics we think and harder for the user to stuff up but it does mean that Safe Haskell will affect users who don't care about Safe Haskell as they might grab a package from Cabal which uses safe haskell (say network) and that packages imports -XTrustworthy modules from another package (say bytestring), so requires that package is trusted. The user may now get compilation errors in code that doesn't do anything with Safe Haskell simply because they are using the network package. They will have to call 'ghc-pkg trust network' to get everything working. Due to this invasive nature of going with yes we have gone with no for now. -} -- | Process Import Decls. See 'rnImportDecl' for a description of what -- the return types represent. -- Note: Do the non SOURCE ones first, so that we get a helpful warning -- for SOURCE ones that are unnecessary rnImports :: [LImportDecl GhcPs] -> RnM ([LImportDecl GhcRn], GlobalRdrEnv, ImportAvails, AnyHpcUsage) rnImports imports = do tcg_env <- getGblEnv -- NB: want an identity module here, because it's OK for a signature -- module to import from its implementor let this_mod = tcg_mod tcg_env let (source, ordinary) = partition is_source_import imports is_source_import d = ideclSource (unLoc d) == IsBoot stuff1 <- mapAndReportM (rnImportDecl this_mod) ordinary stuff2 <- mapAndReportM (rnImportDecl this_mod) source -- Safe Haskell: See Note [Tracking Trust Transitively] let (decls, rdr_env, imp_avails, hpc_usage) = combine (stuff1 ++ stuff2) return (decls, rdr_env, imp_avails, hpc_usage) where -- See Note [Combining ImportAvails] combine :: [(LImportDecl GhcRn, GlobalRdrEnv, ImportAvails, AnyHpcUsage)] -> ([LImportDecl GhcRn], GlobalRdrEnv, ImportAvails, AnyHpcUsage) combine ss = let (decls, rdr_env, imp_avails, hpc_usage, finsts) = foldr plus ([], emptyGlobalRdrEnv, emptyImportAvails, False, emptyModuleSet) ss in (decls, rdr_env, imp_avails { imp_finsts = moduleSetElts finsts }, hpc_usage) plus (decl, gbl_env1, imp_avails1, hpc_usage1) (decls, gbl_env2, imp_avails2, hpc_usage2, finsts_set) = ( decl:decls, gbl_env1 `plusGlobalRdrEnv` gbl_env2, imp_avails1' `plusImportAvails` imp_avails2, hpc_usage1 || hpc_usage2, extendModuleSetList finsts_set new_finsts ) where imp_avails1' = imp_avails1 { imp_finsts = [] } new_finsts = imp_finsts imp_avails1 {- Note [Combining ImportAvails] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ imp_finsts in ImportAvails is a list of family instance modules transitively depended on by an import. imp_finsts for a currently compiled module is a union of all the imp_finsts of imports. Computing the union of two lists of size N is O(N^2) and if we do it to M imports we end up with O(M*N^2). That can get very expensive for bigger module hierarchies. Union can be optimized to O(N log N) if we use a Set. imp_finsts is converted back and forth between dep_finsts, so changing a type of imp_finsts means either paying for the conversions or changing the type of dep_finsts as well. I've measured that the conversions would cost 20% of allocations on my test case, so that can be ruled out. Changing the type of dep_finsts forces checkFamInsts to get the module lists in non-deterministic order. If we wanted to restore the deterministic order, we'd have to sort there, which is an additional cost. As far as I can tell, using a non-deterministic order is fine there, but that's a brittle nonlocal property which I'd like to avoid. Additionally, dep_finsts is read from an interface file, so its "natural" type is a list. Which makes it a natural type for imp_finsts. Since rnImports.combine is really the only place that would benefit from it being a Set, it makes sense to optimize the hot loop in rnImports.combine without changing the representation. So here's what we do: instead of naively merging ImportAvails with plusImportAvails in a loop, we make plusImportAvails merge empty imp_finsts and compute the union on the side using Sets. When we're done, we can convert it back to a list. One nice side effect of this approach is that if there's a lot of overlap in the imp_finsts of imports, the Set doesn't really need to grow and we don't need to allocate. Running generateModules from #14693 with DEPTH=16, WIDTH=30 finishes in 23s before, and 11s after. -} -- | Given a located import declaration @decl@ from @this_mod@, -- calculate the following pieces of information: -- -- 1. An updated 'LImportDecl', where all unresolved 'RdrName' in -- the entity lists have been resolved into 'Name's, -- -- 2. A 'GlobalRdrEnv' representing the new identifiers that were -- brought into scope (taking into account module qualification -- and hiding), -- -- 3. 'ImportAvails' summarizing the identifiers that were imported -- by this declaration, and -- -- 4. A boolean 'AnyHpcUsage' which is true if the imported module -- used HPC. rnImportDecl :: Module -> LImportDecl GhcPs -> RnM (LImportDecl GhcRn, GlobalRdrEnv, ImportAvails, AnyHpcUsage) rnImportDecl this_mod (L loc decl@(ImportDecl { ideclExt = noExtField , ideclName = loc_imp_mod_name , ideclPkgQual = mb_pkg , ideclSource = want_boot, ideclSafe = mod_safe , ideclQualified = qual_style, ideclImplicit = implicit , ideclAs = as_mod, ideclHiding = imp_details })) = setSrcSpan loc $ do when (isJust mb_pkg) $ do pkg_imports <- xoptM LangExt.PackageImports when (not pkg_imports) $ addErr packageImportErr let qual_only = isImportDeclQualified qual_style -- If there's an error in loadInterface, (e.g. interface -- file not found) we get lots of spurious errors from 'filterImports' let imp_mod_name = unLoc loc_imp_mod_name doc = ppr imp_mod_name <+> text "is directly imported" -- Check for self-import, which confuses the typechecker (#9032) -- ghc --make rejects self-import cycles already, but batch-mode may not -- at least not until GHC.IfaceToCore.tcHiBootIface, which is too late to avoid -- typechecker crashes. (Indirect self imports are not caught until -- GHC.IfaceToCore, see #10337 tracking how to make this error better.) -- -- Originally, we also allowed 'import {-# SOURCE #-} M', but this -- caused bug #10182: in one-shot mode, we should never load an hs-boot -- file for the module we are compiling into the EPS. In principle, -- it should be possible to support this mode of use, but we would have to -- extend Provenance to support a local definition in a qualified location. -- For now, we don't support it, but see #10336 when (imp_mod_name == moduleName this_mod && (case mb_pkg of -- If we have import "" M, then we should -- check that "" is "this" (which is magic) -- or the name of this_mod's package. Yurgh! -- c.f. GHC.findModule, and #9997 Nothing -> True Just (StringLiteral _ pkg_fs) -> pkg_fs == fsLit "this" || fsToUnit pkg_fs == moduleUnit this_mod)) (addErr (text "A module cannot import itself:" <+> ppr imp_mod_name)) -- Check for a missing import list (Opt_WarnMissingImportList also -- checks for T(..) items but that is done in checkDodgyImport below) case imp_details of Just (False, _) -> return () -- Explicit import list _ | implicit -> return () -- Do not bleat for implicit imports | qual_only -> return () | otherwise -> whenWOptM Opt_WarnMissingImportList $ addWarn (Reason Opt_WarnMissingImportList) (missingImportListWarn imp_mod_name) iface <- loadSrcInterface doc imp_mod_name want_boot (fmap sl_fs mb_pkg) -- Compiler sanity check: if the import didn't say -- {-# SOURCE #-} we should not get a hi-boot file WARN( (want_boot == NotBoot) && (mi_boot iface == IsBoot), ppr imp_mod_name ) do -- 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. -- -- 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 <- getDynFlags warnIf ((want_boot == IsBoot) && (mi_boot iface == NotBoot) && isOneShot (ghcMode dflags)) (warnRedundantSourceImport imp_mod_name) when (mod_safe && not (safeImportsOn dflags)) $ addErr (text "safe import can't be used as Safe Haskell isn't on!" $+$ ptext (sLit $ "please enable Safe Haskell through either " ++ "Safe, Trustworthy or Unsafe")) let qual_mod_name = fmap unLoc as_mod `orElse` imp_mod_name imp_spec = ImpDeclSpec { is_mod = imp_mod_name, is_qual = qual_only, is_dloc = loc, is_as = qual_mod_name } -- filter the imports according to the import declaration (new_imp_details, gres) <- filterImports iface imp_spec imp_details -- for certain error messages, we’d like to know what could be imported -- here, if everything were imported potential_gres <- mkGlobalRdrEnv . snd <$> filterImports iface imp_spec Nothing let gbl_env = mkGlobalRdrEnv gres is_hiding | Just (True,_) <- imp_details = True | otherwise = False -- should the import be safe? mod_safe' = mod_safe || (not implicit && safeDirectImpsReq dflags) || (implicit && safeImplicitImpsReq dflags) hsc_env <- getTopEnv let home_unit = hsc_home_unit hsc_env imv = ImportedModsVal { imv_name = qual_mod_name , imv_span = loc , imv_is_safe = mod_safe' , imv_is_hiding = is_hiding , imv_all_exports = potential_gres , imv_qualified = qual_only } imports = calculateAvails home_unit iface mod_safe' want_boot (ImportedByUser imv) -- Complain if we import a deprecated module whenWOptM Opt_WarnWarningsDeprecations ( case (mi_warns iface) of WarnAll txt -> addWarn (Reason Opt_WarnWarningsDeprecations) (moduleWarn imp_mod_name txt) _ -> return () ) -- Complain about -Wcompat-unqualified-imports violations. warnUnqualifiedImport decl iface let new_imp_decl = L loc (decl { ideclExt = noExtField, ideclSafe = mod_safe' , ideclHiding = new_imp_details , ideclName = ideclName decl , ideclAs = ideclAs decl }) return (new_imp_decl, gbl_env, imports, mi_hpc iface) -- | Calculate the 'ImportAvails' induced by an import of a particular -- interface, but without 'imp_mods'. calculateAvails :: HomeUnit -> ModIface -> IsSafeImport -> IsBootInterface -> ImportedBy -> ImportAvails calculateAvails home_unit iface mod_safe' want_boot imported_by = let imp_mod = mi_module iface imp_sem_mod= mi_semantic_module iface orph_iface = mi_orphan (mi_final_exts iface) has_finsts = mi_finsts (mi_final_exts iface) deps = mi_deps iface trust = getSafeMode $ mi_trust iface trust_pkg = mi_trust_pkg iface -- If the module exports anything defined in this module, just -- ignore it. Reason: otherwise it looks as if there are two -- local definition sites for the thing, and an error gets -- reported. Easiest thing is just to filter them out up -- front. This situation only arises if a module imports -- itself, or another module that imported it. (Necessarily, -- this involves a loop.) -- -- We do this *after* filterImports, so that if you say -- module A where -- import B( AType ) -- type AType = ... -- -- module B( AType ) where -- import {-# SOURCE #-} A( AType ) -- -- then you won't get a 'B does not export AType' message. -- Compute new transitive dependencies -- -- 'dep_orphs' and 'dep_finsts' do NOT include the imported module -- itself, but we DO need to include this module in 'imp_orphs' and -- 'imp_finsts' if it defines an orphan or instance family; thus the -- orph_iface/has_iface tests. orphans | orph_iface = ASSERT2( not (imp_sem_mod `elem` dep_orphs deps), ppr imp_sem_mod <+> ppr (dep_orphs deps) ) imp_sem_mod : dep_orphs deps | otherwise = dep_orphs deps finsts | has_finsts = ASSERT2( not (imp_sem_mod `elem` dep_finsts deps), ppr imp_sem_mod <+> ppr (dep_orphs deps) ) imp_sem_mod : dep_finsts deps | otherwise = dep_finsts deps pkg = moduleUnit (mi_module iface) ipkg = toUnitId pkg -- Does this import mean we now require our own pkg -- to be trusted? See Note [Trust Own Package] ptrust = trust == Sf_Trustworthy || trust_pkg (dependent_mods, dependent_pkgs, pkg_trust_req) | isHomeUnit home_unit pkg = -- Imported module is from the home package -- Take its dependent modules and add imp_mod itself -- Take its dependent packages unchanged -- -- NB: (dep_mods deps) might include a hi-boot file -- for the module being compiled, CM. Do *not* filter -- this out (as we used to), because when we've -- finished dealing with the direct imports we want to -- know if any of them depended on CM.hi-boot, in -- which case we should do the hi-boot consistency -- check. See GHC.Iface.Load.loadHiBootInterface ( GWIB { gwib_mod = moduleName imp_mod, gwib_isBoot = want_boot } : dep_mods deps , dep_pkgs deps , ptrust ) | otherwise = -- Imported module is from another package -- Dump the dependent modules -- Add the package imp_mod comes from to the dependent packages ASSERT2( not (ipkg `elem` (map fst $ dep_pkgs deps)) , ppr ipkg <+> ppr (dep_pkgs deps) ) ([], (ipkg, False) : dep_pkgs deps, False) in ImportAvails { imp_mods = unitModuleEnv (mi_module iface) [imported_by], imp_orphs = orphans, imp_finsts = finsts, imp_dep_mods = mkModDeps dependent_mods, imp_dep_pkgs = S.fromList . map fst $ dependent_pkgs, -- Add in the imported modules trusted package -- requirements. ONLY do this though if we import the -- module as a safe import. -- See Note [Tracking Trust Transitively] -- and Note [Trust Transitive Property] imp_trust_pkgs = if mod_safe' then S.fromList . map fst $ filter snd dependent_pkgs else S.empty, -- Do we require our own pkg to be trusted? -- See Note [Trust Own Package] imp_trust_own_pkg = pkg_trust_req } -- | Issue a warning if the user imports Data.List without either an import -- list or `qualified`. This is part of the migration plan for the -- `Data.List.singleton` proposal. See #17244. warnUnqualifiedImport :: ImportDecl GhcPs -> ModIface -> RnM () warnUnqualifiedImport decl iface = whenWOptM Opt_WarnCompatUnqualifiedImports $ when bad_import $ addWarnAt (Reason Opt_WarnCompatUnqualifiedImports) loc warning where mod = mi_module iface loc = getLoc $ ideclName decl is_qual = isImportDeclQualified (ideclQualified decl) has_import_list = -- We treat a `hiding` clause as not having an import list although -- it's not entirely clear this is the right choice. case ideclHiding decl of Just (False, _) -> True _ -> False bad_import = mod `elemModuleSet` qualifiedMods && not is_qual && not has_import_list warning = vcat [ text "To ensure compatibility with future core libraries changes" , text "imports to" <+> ppr (ideclName decl) <+> text "should be" , text "either qualified or have an explicit import list." ] -- Modules for which we warn if we see unqualified imports qualifiedMods = mkModuleSet [ dATA_LIST ] warnRedundantSourceImport :: ModuleName -> SDoc warnRedundantSourceImport mod_name = text "Unnecessary {-# SOURCE #-} in the import of module" <+> quotes (ppr mod_name) {- ************************************************************************ * * \subsection{importsFromLocalDecls} * * ************************************************************************ From the top-level declarations of this module produce * the lexical environment * the ImportAvails created by its bindings. Note [Top-level Names in Template Haskell decl quotes] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ See also: Note [Interactively-bound Ids in GHCi] in GHC.Driver.Env Note [Looking up Exact RdrNames] in GHC.Rename.Env Consider a Template Haskell declaration quotation like this: module M where f x = h [d| f = 3 |] 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. This is done by GHC.Rename.Env.newTopSrcBinder. 2. We make them *shadow* the outer bindings. See Note [GlobalRdrEnv shadowing] 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. -} extendGlobalRdrEnvRn :: [AvailInfo] -> MiniFixityEnv -> RnM (TcGblEnv, TcLclEnv) -- Updates both the GlobalRdrEnv and the FixityEnv -- 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 avails new_fixities = do { (gbl_env, lcl_env) <- getEnvs ; stage <- getStage ; isGHCi <- getIsGHCi ; let rdr_env = tcg_rdr_env gbl_env fix_env = tcg_fix_env gbl_env th_bndrs = tcl_th_bndrs lcl_env th_lvl = thLevel stage -- Delete new_occs from global and local envs -- If we are in a TemplateHaskell decl bracket, -- we are going to shadow them -- See Note [GlobalRdrEnv shadowing] inBracket = isBrackStage stage lcl_env_TH = lcl_env { tcl_rdr = delLocalRdrEnvList (tcl_rdr lcl_env) new_occs } -- See Note [GlobalRdrEnv shadowing] lcl_env2 | inBracket = lcl_env_TH | otherwise = lcl_env -- Deal with shadowing: see Note [GlobalRdrEnv shadowing] want_shadowing = isGHCi || inBracket rdr_env1 | want_shadowing = shadowNames rdr_env new_names | otherwise = rdr_env lcl_env3 = lcl_env2 { tcl_th_bndrs = extendNameEnvList th_bndrs [ (n, (TopLevel, th_lvl)) | n <- new_names ] } ; rdr_env2 <- foldlM add_gre rdr_env1 new_gres ; let fix_env' = foldl' extend_fix_env fix_env new_gres gbl_env' = gbl_env { tcg_rdr_env = rdr_env2, tcg_fix_env = fix_env' } ; traceRn "extendGlobalRdrEnvRn 2" (pprGlobalRdrEnv True rdr_env2) ; return (gbl_env', lcl_env3) } where new_names = concatMap availNames avails new_occs = map nameOccName new_names -- If there is a fixity decl for the gre, add it to the fixity env extend_fix_env fix_env gre | Just (L _ fi) <- lookupFsEnv new_fixities (occNameFS occ) = extendNameEnv fix_env name (FixItem occ fi) | otherwise = fix_env where name = gre_name gre occ = greOccName gre new_gres :: [GlobalRdrElt] -- New LocalDef GREs, derived from avails new_gres = concatMap localGREsFromAvail avails add_gre :: GlobalRdrEnv -> GlobalRdrElt -> RnM GlobalRdrEnv -- Extend the GlobalRdrEnv with a LocalDef GRE -- If there is already a LocalDef GRE with the same OccName, -- report an error and discard the new GRE -- This establishes INVARIANT 1 of GlobalRdrEnvs add_gre env gre | not (null dups) -- Same OccName defined twice = do { addDupDeclErr (gre : dups); return env } | otherwise = return (extendGlobalRdrEnv env gre) where occ = greOccName gre dups = filter isDupGRE (lookupGlobalRdrEnv env occ) -- Duplicate GREs are those defined locally with the same OccName, -- except cases where *both* GREs are DuplicateRecordFields (#17965). isDupGRE gre' = isLocalGRE gre' && not (isOverloadedRecFldGRE gre && isOverloadedRecFldGRE gre') {- ********************************************************************* * * getLocalDeclBindersd@ returns the names for an HsDecl It's used for source code. *** See Note [The Naming story] in GHC.Hs.Decls **** * * ********************************************************************* -} getLocalNonValBinders :: MiniFixityEnv -> HsGroup GhcPs -> RnM ((TcGblEnv, TcLclEnv), NameSet) -- Get all the top-level binders bound the group *except* -- for value bindings, which are treated separately -- Specifically we return AvailInfo for -- * type decls (incl constructors and record selectors) -- * class decls (including class ops) -- * associated types -- * foreign imports -- * value signatures (in hs-boot files only) getLocalNonValBinders fixity_env (HsGroup { hs_valds = binds, hs_tyclds = tycl_decls, hs_fords = foreign_decls }) = do { -- Process all type/class decls *except* family instances ; let inst_decls = tycl_decls >>= group_instds ; overload_ok <- xoptM LangExt.DuplicateRecordFields ; (tc_avails, tc_fldss) <- fmap unzip $ mapM (new_tc overload_ok) (tyClGroupTyClDecls tycl_decls) ; traceRn "getLocalNonValBinders 1" (ppr tc_avails) ; envs <- extendGlobalRdrEnvRn tc_avails fixity_env ; setEnvs envs $ do { -- Bring these things into scope first -- See Note [Looking up family names in family instances] -- Process all family instances -- to bring new data constructors into scope ; (nti_availss, nti_fldss) <- mapAndUnzipM (new_assoc overload_ok) inst_decls -- Finish off with value binders: -- foreign decls and pattern synonyms for an ordinary module -- type sigs in case of a hs-boot file only ; is_boot <- tcIsHsBootOrSig ; let val_bndrs | is_boot = hs_boot_sig_bndrs | otherwise = for_hs_bndrs ; val_avails <- mapM new_simple val_bndrs ; let avails = concat nti_availss ++ val_avails new_bndrs = availsToNameSetWithSelectors avails `unionNameSet` availsToNameSetWithSelectors tc_avails flds = concat nti_fldss ++ concat tc_fldss ; traceRn "getLocalNonValBinders 2" (ppr avails) ; (tcg_env, tcl_env) <- extendGlobalRdrEnvRn avails fixity_env -- Extend tcg_field_env with new fields (this used to be the -- work of extendRecordFieldEnv) ; let field_env = extendNameEnvList (tcg_field_env tcg_env) flds envs = (tcg_env { tcg_field_env = field_env }, tcl_env) ; traceRn "getLocalNonValBinders 3" (vcat [ppr flds, ppr field_env]) ; return (envs, new_bndrs) } } where ValBinds _ _val_binds val_sigs = binds for_hs_bndrs :: [Located RdrName] for_hs_bndrs = hsForeignDeclsBinders foreign_decls -- In a hs-boot file, the value binders come from the -- *signatures*, and there should be no foreign binders hs_boot_sig_bndrs = [ L decl_loc (unLoc n) | L decl_loc (TypeSig _ ns _) <- val_sigs, n <- ns] -- the SrcSpan attached to the input should be the span of the -- declaration, not just the name new_simple :: Located RdrName -> RnM AvailInfo new_simple rdr_name = do{ nm <- newTopSrcBinder rdr_name ; return (avail nm) } new_tc :: Bool -> LTyClDecl GhcPs -> RnM (AvailInfo, [(Name, [FieldLabel])]) new_tc overload_ok tc_decl -- NOT for type/data instances = do { let (bndrs, flds) = hsLTyClDeclBinders tc_decl ; names@(main_name : sub_names) <- mapM newTopSrcBinder bndrs ; flds' <- mapM (newRecordSelector overload_ok sub_names) flds ; let fld_env = case unLoc tc_decl of DataDecl { tcdDataDefn = d } -> mk_fld_env d names flds' _ -> [] ; return (AvailTC main_name names flds', fld_env) } -- Calculate the mapping from constructor names to fields, which -- will go in tcg_field_env. It's convenient to do this here where -- we are working with a single datatype definition. mk_fld_env :: HsDataDefn GhcPs -> [Name] -> [FieldLabel] -> [(Name, [FieldLabel])] mk_fld_env d names flds = concatMap find_con_flds (dd_cons d) where find_con_flds (L _ (ConDeclH98 { con_name = L _ rdr , con_args = RecCon cdflds })) = [( find_con_name rdr , concatMap find_con_decl_flds (unLoc cdflds) )] find_con_flds (L _ (ConDeclGADT { con_names = rdrs , con_args = RecCon flds })) = [ ( find_con_name rdr , concatMap find_con_decl_flds (unLoc flds)) | L _ rdr <- rdrs ] find_con_flds _ = [] find_con_name rdr = expectJust "getLocalNonValBinders/find_con_name" $ find (\ n -> nameOccName n == rdrNameOcc rdr) names find_con_decl_flds (L _ x) = map find_con_decl_fld (cd_fld_names x) find_con_decl_fld (L _ (FieldOcc _ (L _ rdr))) = expectJust "getLocalNonValBinders/find_con_decl_fld" $ find (\ fl -> flLabel fl == lbl) flds where lbl = occNameFS (rdrNameOcc rdr) new_assoc :: Bool -> LInstDecl GhcPs -> RnM ([AvailInfo], [(Name, [FieldLabel])]) new_assoc _ (L _ (TyFamInstD {})) = return ([], []) -- type instances don't bind new names new_assoc overload_ok (L _ (DataFamInstD _ d)) = do { (avail, flds) <- new_di overload_ok Nothing d ; return ([avail], flds) } new_assoc overload_ok (L _ (ClsInstD _ (ClsInstDecl { cid_poly_ty = inst_ty , cid_datafam_insts = adts }))) = do -- First, attempt to grab the name of the class from the instance. -- This step could fail if the instance is not headed by a class, -- such as in the following examples: -- -- (1) The class is headed by a bang pattern, such as in -- `instance !Show Int` (#3811c) -- (2) The class is headed by a type variable, such as in -- `instance c` (#16385) -- -- If looking up the class name fails, then mb_cls_nm will -- be Nothing. mb_cls_nm <- runMaybeT $ do -- See (1) above L loc cls_rdr <- MaybeT $ pure $ getLHsInstDeclClass_maybe inst_ty -- See (2) above MaybeT $ setSrcSpan loc $ lookupGlobalOccRn_maybe cls_rdr -- Assuming the previous step succeeded, process any associated data -- family instances. If the previous step failed, bail out. case mb_cls_nm of Nothing -> pure ([], []) Just cls_nm -> do (avails, fldss) <- mapAndUnzipM (new_loc_di overload_ok (Just cls_nm)) adts pure (avails, concat fldss) new_di :: Bool -> Maybe Name -> DataFamInstDecl GhcPs -> RnM (AvailInfo, [(Name, [FieldLabel])]) new_di overload_ok mb_cls dfid@(DataFamInstDecl { dfid_eqn = HsIB { hsib_body = ti_decl }}) = do { main_name <- lookupFamInstName mb_cls (feqn_tycon ti_decl) ; let (bndrs, flds) = hsDataFamInstBinders dfid ; sub_names <- mapM newTopSrcBinder bndrs ; flds' <- mapM (newRecordSelector overload_ok sub_names) flds ; let avail = AvailTC (unLoc main_name) sub_names flds' -- main_name is not bound here! fld_env = mk_fld_env (feqn_rhs ti_decl) sub_names flds' ; return (avail, fld_env) } new_loc_di :: Bool -> Maybe Name -> LDataFamInstDecl GhcPs -> RnM (AvailInfo, [(Name, [FieldLabel])]) new_loc_di overload_ok mb_cls (L _ d) = new_di overload_ok mb_cls d newRecordSelector :: Bool -> [Name] -> LFieldOcc GhcPs -> RnM FieldLabel newRecordSelector _ [] _ = error "newRecordSelector: datatype has no constructors!" newRecordSelector overload_ok (dc:_) (L loc (FieldOcc _ (L _ fld))) = do { selName <- newTopSrcBinder $ L loc $ field ; return $ qualFieldLbl { flSelector = selName } } where fieldOccName = occNameFS $ rdrNameOcc fld qualFieldLbl = mkFieldLabelOccs fieldOccName (nameOccName dc) overload_ok field | isExact fld = fld -- use an Exact RdrName as is to preserve the bindings -- of an already renamer-resolved field and its use -- sites. This is needed to correctly support record -- selectors in Template Haskell. See Note [Binders in -- Template Haskell] in "GHC.ThToHs" and Note [Looking up -- Exact RdrNames] in "GHC.Rename.Env". | otherwise = mkRdrUnqual (flSelector qualFieldLbl) {- 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. Solution is simple: process the type family declarations first, extend the environment, and then process the type instances. ************************************************************************ * * \subsection{Filtering imports} * * ************************************************************************ @filterImports@ takes the @ExportEnv@ telling what the imported module makes available, and filters it through the import spec (if any). Note [Dealing with imports] ~~~~~~~~~~~~~~~~~~~~~~~~~~~ For import M( ies ), we take the mi_exports of M, and make imp_occ_env :: OccEnv (Name, AvailInfo, Maybe Name) One entry for each Name that M exports; the AvailInfo is the AvailInfo exported from M that exports that Name. The situation is made more complicated by associated types. E.g. module M where class C a where { data T a } instance C Int where { data T Int = T1 | T2 } instance C Bool where { data T Int = T3 } Then M's export_avails are (recall the AvailTC invariant from Avails.hs) C(C,T), T(T,T1,T2,T3) Notice that T appears *twice*, once as a child and once as a parent. From this list we construct a raw list including T -> (T, T( T1, T2, T3 ), Nothing) T -> (C, C( C, T ), Nothing) and we combine these (in function 'combine' in 'imp_occ_env' in 'filterImports') to get T -> (T, T(T,T1,T2,T3), Just C) So the overall imp_occ_env is C -> (C, C(C,T), Nothing) T -> (T, T(T,T1,T2,T3), Just C) T1 -> (T1, T(T,T1,T2,T3), Nothing) -- similarly T2,T3 If we say import M( T(T1,T2) ) then we get *two* Avails: C(T), T(T1,T2) Note that the imp_occ_env will have entries for data constructors too, although we never look up data constructors. -} filterImports :: ModIface -> ImpDeclSpec -- The span for the entire import decl -> Maybe (Bool, Located [LIE GhcPs]) -- Import spec; True => hiding -> RnM (Maybe (Bool, Located [LIE GhcRn]), -- Import spec w/ Names [GlobalRdrElt]) -- Same again, but in GRE form filterImports iface decl_spec Nothing = return (Nothing, gresFromAvails (Just imp_spec) (mi_exports iface)) where imp_spec = ImpSpec { is_decl = decl_spec, is_item = ImpAll } filterImports iface decl_spec (Just (want_hiding, L l import_items)) = do -- check for errors, convert RdrNames to Names items1 <- mapM lookup_lie import_items let items2 :: [(LIE GhcRn, AvailInfo)] items2 = concat items1 -- NB the AvailInfo may have duplicates, and several items -- for the same parent; e.g N(x) and N(y) names = availsToNameSetWithSelectors (map snd items2) keep n = not (n `elemNameSet` names) pruned_avails = filterAvails keep all_avails hiding_spec = ImpSpec { is_decl = decl_spec, is_item = ImpAll } gres | want_hiding = gresFromAvails (Just hiding_spec) pruned_avails | otherwise = concatMap (gresFromIE decl_spec) items2 return (Just (want_hiding, L l (map fst items2)), gres) where all_avails = mi_exports iface -- See Note [Dealing with imports] imp_occ_env :: OccEnv (Name, -- the name AvailInfo, -- the export item providing the name Maybe Name) -- the parent of associated types imp_occ_env = mkOccEnv_C combine [ (occ, (n, a, Nothing)) | a <- all_avails , (n, occ) <- availNamesWithOccs a] where -- See Note [Dealing with imports] -- 'combine' is only called for associated data types which appear -- twice in the all_avails. In the example, we combine -- T(T,T1,T2,T3) and C(C,T) to give (T, T(T,T1,T2,T3), Just C) -- NB: the AvailTC can have fields as well as data constructors (#12127) combine (name1, a1@(AvailTC p1 _ _), mp1) (name2, a2@(AvailTC p2 _ _), mp2) = ASSERT2( name1 == name2 && isNothing mp1 && isNothing mp2 , ppr name1 <+> ppr name2 <+> ppr mp1 <+> ppr mp2 ) if p1 == name1 then (name1, a1, Just p2) else (name1, a2, Just p1) combine x y = pprPanic "filterImports/combine" (ppr x $$ ppr y) lookup_name :: IE GhcPs -> RdrName -> IELookupM (Name, AvailInfo, Maybe Name) lookup_name ie rdr | isQual rdr = failLookupWith (QualImportError rdr) | Just succ <- mb_success = return succ | otherwise = failLookupWith (BadImport ie) where mb_success = lookupOccEnv imp_occ_env (rdrNameOcc rdr) lookup_lie :: LIE GhcPs -> TcRn [(LIE GhcRn, AvailInfo)] lookup_lie (L loc ieRdr) = do (stuff, warns) <- setSrcSpan loc $ liftM (fromMaybe ([],[])) $ run_lookup (lookup_ie ieRdr) mapM_ emit_warning warns return [ (L loc ie, avail) | (ie,avail) <- stuff ] where -- Warn when importing T(..) if T was exported abstractly emit_warning (DodgyImport n) = whenWOptM Opt_WarnDodgyImports $ addWarn (Reason Opt_WarnDodgyImports) (dodgyImportWarn n) emit_warning MissingImportList = whenWOptM Opt_WarnMissingImportList $ addWarn (Reason Opt_WarnMissingImportList) (missingImportListItem ieRdr) emit_warning (BadImportW ie) = whenWOptM Opt_WarnDodgyImports $ addWarn (Reason Opt_WarnDodgyImports) (lookup_err_msg (BadImport ie)) run_lookup :: IELookupM a -> TcRn (Maybe a) run_lookup m = case m of Failed err -> addErr (lookup_err_msg err) >> return Nothing Succeeded a -> return (Just a) lookup_err_msg err = case err of BadImport ie -> badImportItemErr iface decl_spec ie all_avails IllegalImport -> illegalImportItemErr QualImportError rdr -> qualImportItemErr rdr -- For each import item, we convert its RdrNames to Names, -- and at the same time construct an AvailInfo corresponding -- to what is actually imported by this item. -- Returns Nothing on error. -- We return a list here, because in the case of an import -- item like C, if we are hiding, then C refers to *both* a -- type/class and a data constructor. Moreover, when we import -- data constructors of an associated family, we need separate -- AvailInfos for the data constructors and the family (as they have -- different parents). See Note [Dealing with imports] lookup_ie :: IE GhcPs -> IELookupM ([(IE GhcRn, AvailInfo)], [IELookupWarning]) lookup_ie ie = handle_bad_import $ do case ie of IEVar _ (L l n) -> do (name, avail, _) <- lookup_name ie $ ieWrappedName n return ([(IEVar noExtField (L l (replaceWrappedName n name)), trimAvail avail name)], []) IEThingAll _ (L l tc) -> do (name, avail, mb_parent) <- lookup_name ie $ ieWrappedName tc let warns = case avail of Avail {} -- e.g. f(..) -> [DodgyImport $ ieWrappedName tc] AvailTC _ subs fs | null (drop 1 subs) && null fs -- e.g. T(..) where T is a synonym -> [DodgyImport $ ieWrappedName tc] | not (is_qual decl_spec) -- e.g. import M( T(..) ) -> [MissingImportList] | otherwise -> [] renamed_ie = IEThingAll noExtField (L l (replaceWrappedName tc name)) sub_avails = case avail of Avail {} -> [] AvailTC name2 subs fs -> [(renamed_ie, AvailTC name2 (subs \\ [name]) fs)] case mb_parent of Nothing -> return ([(renamed_ie, avail)], warns) -- non-associated ty/cls Just parent -> return ((renamed_ie, AvailTC parent [name] []) : sub_avails, warns) -- associated type IEThingAbs _ (L l tc') | want_hiding -- hiding ( C ) -- Here the 'C' can be a data constructor -- *or* a type/class, or even both -> let tc = ieWrappedName tc' tc_name = lookup_name ie tc dc_name = lookup_name ie (setRdrNameSpace tc srcDataName) in case catIELookupM [ tc_name, dc_name ] of [] -> failLookupWith (BadImport ie) names -> return ([mkIEThingAbs tc' l name | name <- names], []) | otherwise -> do nameAvail <- lookup_name ie (ieWrappedName tc') return ([mkIEThingAbs tc' l nameAvail] , []) IEThingWith xt ltc@(L l rdr_tc) wc rdr_ns rdr_fs -> ASSERT2(null rdr_fs, ppr rdr_fs) do (name, avail, mb_parent) <- lookup_name (IEThingAbs noExtField ltc) (ieWrappedName rdr_tc) let (ns,subflds) = case avail of AvailTC _ ns' subflds' -> (ns',subflds') Avail _ -> panic "filterImports" -- Look up the children in the sub-names of the parent let subnames = case ns of -- The tc is first in ns, [] -> [] -- if it is there at all -- See the AvailTC Invariant in -- GHC.Types.Avail (n1:ns1) | n1 == name -> ns1 | otherwise -> ns case lookupChildren (map Left subnames ++ map Right subflds) rdr_ns of Failed rdrs -> failLookupWith (BadImport (IEThingWith xt ltc wc rdrs [])) -- We are trying to import T( a,b,c,d ), and failed -- to find 'b' and 'd'. So we make up an import item -- to report as failing, namely T( b, d ). -- c.f. #15412 Succeeded (childnames, childflds) -> case mb_parent of -- non-associated ty/cls Nothing -> return ([(IEThingWith noExtField (L l name') wc childnames' childflds, AvailTC name (name:map unLoc childnames) (map unLoc childflds))], []) where name' = replaceWrappedName rdr_tc name childnames' = map to_ie_post_rn childnames -- childnames' = postrn_ies childnames -- associated ty Just parent -> return ([(IEThingWith noExtField (L l name') wc childnames' childflds, AvailTC name (map unLoc childnames) (map unLoc childflds)), (IEThingWith noExtField (L l name') wc childnames' childflds, AvailTC parent [name] [])], []) where name' = replaceWrappedName rdr_tc name childnames' = map to_ie_post_rn childnames _other -> failLookupWith IllegalImport -- could be IEModuleContents, IEGroup, IEDoc, IEDocNamed -- all errors. where mkIEThingAbs tc l (n, av, Nothing ) = (IEThingAbs noExtField (L l (replaceWrappedName tc n)), trimAvail av n) mkIEThingAbs tc l (n, _, Just parent) = (IEThingAbs noExtField (L l (replaceWrappedName tc n)) , AvailTC parent [n] []) handle_bad_import m = catchIELookup m $ \err -> case err of BadImport ie | want_hiding -> return ([], [BadImportW ie]) _ -> failLookupWith err type IELookupM = MaybeErr IELookupError data IELookupWarning = BadImportW (IE GhcPs) | MissingImportList | DodgyImport RdrName -- NB. use the RdrName for reporting a "dodgy" import data IELookupError = QualImportError RdrName | BadImport (IE GhcPs) | IllegalImport failLookupWith :: IELookupError -> IELookupM a failLookupWith err = Failed err catchIELookup :: IELookupM a -> (IELookupError -> IELookupM a) -> IELookupM a catchIELookup m h = case m of Succeeded r -> return r Failed err -> h err catIELookupM :: [IELookupM a] -> [a] catIELookupM ms = [ a | Succeeded a <- ms ] {- ************************************************************************ * * \subsection{Import/Export Utils} * * ************************************************************************ -} -- | Given an import\/export spec, construct the appropriate 'GlobalRdrElt's. gresFromIE :: ImpDeclSpec -> (LIE GhcRn, AvailInfo) -> [GlobalRdrElt] gresFromIE decl_spec (L loc ie, avail) = gresFromAvail prov_fn avail where is_explicit = case ie of IEThingAll _ name -> \n -> n == lieWrappedName name _ -> \_ -> True prov_fn name = Just (ImpSpec { is_decl = decl_spec, is_item = item_spec }) where item_spec = ImpSome { is_explicit = is_explicit name, is_iloc = loc } {- Note [Children for duplicate record fields] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Consider the module {-# LANGUAGE DuplicateRecordFields #-} module M (F(foo, MkFInt, MkFBool)) where data family F a data instance F Int = MkFInt { foo :: Int } data instance F Bool = MkFBool { foo :: Bool } The `foo` in the export list refers to *both* selectors! For this reason, lookupChildren builds an environment that maps the FastString to a list of items, rather than a single item. -} mkChildEnv :: [GlobalRdrElt] -> NameEnv [GlobalRdrElt] mkChildEnv gres = foldr add emptyNameEnv gres where add gre env = case gre_par gre of FldParent p _ -> extendNameEnv_Acc (:) Utils.singleton env p gre ParentIs p -> extendNameEnv_Acc (:) Utils.singleton env p gre NoParent -> env findChildren :: NameEnv [a] -> Name -> [a] findChildren env n = lookupNameEnv env n `orElse` [] lookupChildren :: [Either Name FieldLabel] -> [LIEWrappedName RdrName] -> MaybeErr [LIEWrappedName RdrName] -- The ones for which the lookup failed ([Located Name], [Located FieldLabel]) -- (lookupChildren all_kids rdr_items) maps each rdr_item to its -- corresponding Name all_kids, if the former exists -- The matching is done by FastString, not OccName, so that -- Cls( meth, AssocTy ) -- will correctly find AssocTy among the all_kids of Cls, even though -- the RdrName for AssocTy may have a (bogus) DataName namespace -- (Really the rdr_items should be FastStrings in the first place.) lookupChildren all_kids rdr_items | null fails = Succeeded (fmap concat (partitionEithers oks)) -- This 'fmap concat' trickily applies concat to the /second/ component -- of the pair, whose type is ([Located Name], [[Located FieldLabel]]) | otherwise = Failed fails where mb_xs = map doOne rdr_items fails = [ bad_rdr | Failed bad_rdr <- mb_xs ] oks = [ ok | Succeeded ok <- mb_xs ] oks :: [Either (Located Name) [Located FieldLabel]] doOne item@(L l r) = case (lookupFsEnv kid_env . occNameFS . rdrNameOcc . ieWrappedName) r of Just [Left n] -> Succeeded (Left (L l n)) Just rs | all isRight rs -> Succeeded (Right (map (L l) (rights rs))) _ -> Failed item -- See Note [Children for duplicate record fields] kid_env = extendFsEnvList_C (++) emptyFsEnv [(either (occNameFS . nameOccName) flLabel x, [x]) | x <- all_kids] ------------------------------- {- ********************************************************* * * \subsection{Unused names} * * ********************************************************* -} reportUnusedNames :: TcGblEnv -> HscSource -> RnM () reportUnusedNames gbl_env hsc_src = do { keep <- readTcRef (tcg_keep gbl_env) ; traceRn "RUN" (ppr (tcg_dus gbl_env)) ; warnUnusedImportDecls gbl_env hsc_src ; warnUnusedTopBinds $ unused_locals keep ; warnMissingSignatures gbl_env } where used_names :: NameSet -> NameSet used_names keep = findUses (tcg_dus gbl_env) emptyNameSet `unionNameSet` keep -- NB: currently, if f x = g, we only treat 'g' as used if 'f' is used -- Hence findUses -- Collect the defined names from the in-scope environment defined_names :: [GlobalRdrElt] defined_names = globalRdrEnvElts (tcg_rdr_env gbl_env) kids_env = mkChildEnv defined_names -- This is done in mkExports too; duplicated work gre_is_used :: NameSet -> GlobalRdrElt -> Bool gre_is_used used_names (GRE {gre_name = name}) = name `elemNameSet` used_names || any (\ gre -> gre_name gre `elemNameSet` used_names) (findChildren kids_env name) -- A use of C implies a use of T, -- if C was brought into scope by T(..) or T(C) -- Filter out the ones that are -- (a) defined in this module, and -- (b) not defined by a 'deriving' clause -- The latter have an Internal Name, so we can filter them out easily unused_locals :: NameSet -> [GlobalRdrElt] unused_locals keep = let -- 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) = partition (gre_is_used (used_names keep)) defined_names in filter is_unused_local defined_but_not_used is_unused_local :: GlobalRdrElt -> Bool is_unused_local gre = isLocalGRE gre && isExternalName (gre_name gre) {- ********************************************************************* * * Missing signatures * * ********************************************************************* -} -- | Warn the user about top level binders that lack type signatures. -- Called /after/ type inference, so that we can report the -- inferred type of the function warnMissingSignatures :: TcGblEnv -> RnM () warnMissingSignatures gbl_env = do { let exports = availsToNameSet (tcg_exports gbl_env) sig_ns = tcg_sigs gbl_env -- We use sig_ns to exclude top-level bindings that are generated by GHC binds = collectHsBindsBinders $ tcg_binds gbl_env pat_syns = tcg_patsyns gbl_env -- Warn about missing signatures -- Do this only when we have a type to offer ; warn_missing_sigs <- woptM Opt_WarnMissingSignatures ; warn_only_exported <- woptM Opt_WarnMissingExportedSignatures ; warn_pat_syns <- woptM Opt_WarnMissingPatternSynonymSignatures ; let add_sig_warns | warn_only_exported = add_warns Opt_WarnMissingExportedSignatures | warn_missing_sigs = add_warns Opt_WarnMissingSignatures | warn_pat_syns = add_warns Opt_WarnMissingPatternSynonymSignatures | otherwise = return () add_warns flag = when warn_pat_syns (mapM_ add_pat_syn_warn pat_syns) >> when (warn_missing_sigs || warn_only_exported) (mapM_ add_bind_warn binds) where add_pat_syn_warn p = add_warn name $ hang (text "Pattern synonym with no type signature:") 2 (text "pattern" <+> pprPrefixName name <+> dcolon <+> pp_ty) where name = patSynName p pp_ty = pprPatSynType p add_bind_warn :: Id -> IOEnv (Env TcGblEnv TcLclEnv) () add_bind_warn id = do { env <- tcInitTidyEnv -- Why not use emptyTidyEnv? ; let name = idName id (_, ty) = tidyOpenType env (idType id) ty_msg = pprSigmaType ty ; add_warn name $ hang (text "Top-level binding with no type signature:") 2 (pprPrefixName name <+> dcolon <+> ty_msg) } add_warn name msg = when (name `elemNameSet` sig_ns && export_check name) (addWarnAt (Reason flag) (getSrcSpan name) msg) export_check name = not warn_only_exported || name `elemNameSet` exports ; add_sig_warns } {- ********************************************************* * * \subsection{Unused imports} * * ********************************************************* This code finds which import declarations are unused. The specification and implementation notes are here: https://gitlab.haskell.org/ghc/ghc/wikis/commentary/compiler/unused-imports See also Note [Choosing the best import declaration] in GHC.Types.Name.Reader -} type ImportDeclUsage = ( LImportDecl GhcRn -- The import declaration , [GlobalRdrElt] -- What *is* used (normalised) , [Name] ) -- What is imported but *not* used warnUnusedImportDecls :: TcGblEnv -> HscSource -> RnM () warnUnusedImportDecls gbl_env hsc_src = do { uses <- readMutVar (tcg_used_gres gbl_env) ; let user_imports = filterOut (ideclImplicit . unLoc) (tcg_rn_imports gbl_env) -- This whole function deals only with *user* imports -- both for warning about unnecessary ones, and for -- deciding the minimal ones rdr_env = tcg_rdr_env gbl_env fld_env = mkFieldEnv rdr_env ; let usage :: [ImportDeclUsage] usage = findImportUsage user_imports uses ; traceRn "warnUnusedImportDecls" $ (vcat [ text "Uses:" <+> ppr uses , text "Import usage" <+> ppr usage]) ; whenWOptM Opt_WarnUnusedImports $ mapM_ (warnUnusedImport Opt_WarnUnusedImports fld_env) usage ; whenGOptM Opt_D_dump_minimal_imports $ printMinimalImports hsc_src usage } findImportUsage :: [LImportDecl GhcRn] -> [GlobalRdrElt] -> [ImportDeclUsage] findImportUsage imports used_gres = map unused_decl imports where import_usage :: ImportMap import_usage = mkImportMap used_gres unused_decl :: LImportDecl GhcRn -> (LImportDecl GhcRn, [GlobalRdrElt], [Name]) unused_decl decl@(L loc (ImportDecl { ideclHiding = imps })) = (decl, used_gres, nameSetElemsStable unused_imps) where used_gres = lookupSrcLoc (srcSpanEnd loc) import_usage -- srcSpanEnd: see Note [The ImportMap] `orElse` [] used_names = mkNameSet (map gre_name used_gres) used_parents = mkNameSet (mapMaybe greParent_maybe used_gres) unused_imps -- Not trivial; see eg #7454 = case imps of Just (False, L _ imp_ies) -> foldr (add_unused . unLoc) emptyNameSet imp_ies _other -> emptyNameSet -- No explicit import list => no unused-name list add_unused :: IE GhcRn -> NameSet -> NameSet add_unused (IEVar _ n) acc = add_unused_name (lieWrappedName n) acc add_unused (IEThingAbs _ n) acc = add_unused_name (lieWrappedName n) acc add_unused (IEThingAll _ n) acc = add_unused_all (lieWrappedName n) acc add_unused (IEThingWith _ p wc ns fs) acc = add_wc_all (add_unused_with pn xs acc) where pn = lieWrappedName p xs = map lieWrappedName ns ++ map (flSelector . unLoc) fs add_wc_all = case wc of NoIEWildcard -> id IEWildcard _ -> add_unused_all pn add_unused _ acc = acc add_unused_name n acc | n `elemNameSet` used_names = acc | otherwise = acc `extendNameSet` n add_unused_all n acc | n `elemNameSet` used_names = acc | n `elemNameSet` used_parents = acc | otherwise = acc `extendNameSet` n add_unused_with p ns acc | all (`elemNameSet` acc1) ns = add_unused_name p acc1 | otherwise = acc1 where acc1 = foldr add_unused_name acc 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 the two cases in add_unused_with. {- Note [The ImportMap] ~~~~~~~~~~~~~~~~~~~~~~~ The ImportMap is a short-lived intermediate data structure 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 END of a particular 'import' declaration. Why *END*? Because we don't want to get confused by the implicit Prelude import. Consider (#7476) the module import Foo( foo ) main = print foo There is an implicit 'import Prelude(print)', and it gets a SrcSpan of line 1:1 (just the point, not a span). If we use the *START* of the SrcSpan to identify the import decl, we'll confuse the implicit import Prelude with the explicit 'import Foo'. So we use the END. It's just a cheap hack; we could equally well use the Span too. The [GlobalRdrElt] are the things imported from that decl. -} type ImportMap = Map RealSrcLoc [GlobalRdrElt] -- See [The ImportMap] -- If loc :-> gres, then -- 'loc' = the end loc of the bestImport of each GRE in 'gres' mkImportMap :: [GlobalRdrElt] -> ImportMap -- For each of a list of used GREs, 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 mkImportMap gres = foldr add_one Map.empty gres where add_one gre@(GRE { gre_imp = imp_specs }) imp_map = case srcSpanEnd (is_dloc (is_decl best_imp_spec)) of -- For srcSpanEnd see Note [The ImportMap] RealSrcLoc decl_loc _ -> Map.insertWith add decl_loc [gre] imp_map UnhelpfulLoc _ -> imp_map where best_imp_spec = bestImport imp_specs add _ gres = gre : gres warnUnusedImport :: WarningFlag -> NameEnv (FieldLabelString, Name) -> ImportDeclUsage -> RnM () warnUnusedImport flag fld_env (L loc decl, used, unused) -- Do not warn for 'import M()' | Just (False,L _ []) <- ideclHiding decl = return () -- Note [Do not warn about Prelude hiding] | Just (True, L _ hides) <- ideclHiding decl , not (null hides) , pRELUDE_NAME == unLoc (ideclName decl) = return () -- Nothing used; drop entire declaration | null used = addWarnAt (Reason flag) loc msg1 -- Everything imported is used; nop | null unused = return () -- Only one import is unused, with `SrcSpan` covering only the unused item instead of -- the whole import statement | Just (_, L _ imports) <- ideclHiding decl , length unused == 1 , Just (L loc _) <- find (\(L _ ie) -> ((ieName ie) :: Name) `elem` unused) imports = addWarnAt (Reason flag) loc msg2 -- Some imports are unused | otherwise = addWarnAt (Reason flag) loc msg2 where msg1 = vcat [ pp_herald <+> quotes pp_mod <+> is_redundant , nest 2 (text "except perhaps to import instances from" <+> quotes pp_mod) , text "To import instances alone, use:" <+> text "import" <+> pp_mod <> parens Outputable.empty ] msg2 = sep [ pp_herald <+> quotes sort_unused , text "from module" <+> quotes pp_mod <+> is_redundant] pp_herald = text "The" <+> pp_qual <+> text "import of" pp_qual | isImportDeclQualified (ideclQualified decl)= text "qualified" | otherwise = Outputable.empty pp_mod = ppr (unLoc (ideclName decl)) is_redundant = text "is redundant" -- In warning message, pretty-print identifiers unqualified unconditionally -- to improve the consistent for ambiguous/unambiguous identifiers. -- See trac#14881. ppr_possible_field n = case lookupNameEnv fld_env n of Just (fld, p) -> pprNameUnqualified p <> parens (ppr fld) Nothing -> pprNameUnqualified n -- Print unused names in a deterministic (lexicographic) order sort_unused :: SDoc sort_unused = pprWithCommas ppr_possible_field $ sortBy (comparing nameOccName) unused {- Note [Do not warn about Prelude hiding] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ We do not warn about import Prelude hiding( x, y ) because even if nothing else from Prelude is used, it may be essential to hide x,y to avoid name-shadowing warnings. Example (#9061) import Prelude hiding( log ) f x = log where log = () Note [Printing minimal imports] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 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 discard a decl altogether; we might need instances from it. Instead we just trim to an empty import list -} getMinimalImports :: [ImportDeclUsage] -> RnM [LImportDecl GhcRn] getMinimalImports = fmap combine . mapM mk_minimal where mk_minimal (L l decl, used_gres, 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 (fmap sl_fs mb_pkg) ; let used_avails = gresToAvailInfo used_gres lies = map (L l) (concatMap (to_ie iface) used_avails) ; return (L l (decl { ideclHiding = Just (False, L l lies) })) } where doc = text "Compute minimal imports for" <+> ppr decl to_ie :: ModIface -> AvailInfo -> [IE GhcRn] -- 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) = [IEVar noExtField (to_ie_post_rn $ noLoc n)] to_ie _ (AvailTC n [m] []) | n==m = [IEThingAbs noExtField (to_ie_post_rn $ noLoc n)] to_ie iface (AvailTC n ns fs) = case [(xs,gs) | AvailTC x xs gs <- mi_exports iface , x == n , x `elem` xs -- Note [Partial export] ] of [xs] | all_used xs -> [IEThingAll noExtField (to_ie_post_rn $ noLoc n)] | otherwise -> [IEThingWith noExtField (to_ie_post_rn $ noLoc n) NoIEWildcard (map (to_ie_post_rn . noLoc) (filter (/= n) ns)) (map noLoc fs)] -- Note [Overloaded field import] _other | all_non_overloaded fs -> map (IEVar noExtField . to_ie_post_rn_var . noLoc) $ ns ++ map flSelector fs | otherwise -> [IEThingWith noExtField (to_ie_post_rn $ noLoc n) NoIEWildcard (map (to_ie_post_rn . noLoc) (filter (/= n) ns)) (map noLoc fs)] where fld_lbls = map flLabel fs all_used (avail_occs, avail_flds) = all (`elem` ns) avail_occs && all (`elem` fld_lbls) (map flLabel avail_flds) all_non_overloaded = all (not . flIsOverloaded) combine :: [LImportDecl GhcRn] -> [LImportDecl GhcRn] combine = map merge . groupBy ((==) `on` getKey) . sortOn getKey getKey :: LImportDecl GhcRn -> (Bool, Maybe ModuleName, ModuleName) getKey decl = ( isImportDeclQualified . ideclQualified $ idecl -- is this qualified? (important that this be first) , unLoc <$> ideclAs idecl -- what is the qualifier (inside Maybe monad) , unLoc . ideclName $ idecl -- Module Name ) where idecl :: ImportDecl GhcRn idecl = unLoc decl merge :: [LImportDecl GhcRn] -> LImportDecl GhcRn merge [] = error "getMinimalImports: unexpected empty list" merge decls@((L l decl) : _) = L l (decl { ideclHiding = Just (False, L l lies) }) where lies = concatMap (unLoc . snd) $ mapMaybe (ideclHiding . unLoc) decls printMinimalImports :: HscSource -> [ImportDeclUsage] -> RnM () -- See Note [Printing minimal imports] printMinimalImports hsc_src imports_w_usage = do { imports' <- getMinimalImports imports_w_usage ; this_mod <- getModule ; dflags <- getDynFlags ; liftIO $ withFile (mkFilename dflags this_mod) WriteMode $ \h -> printForUser dflags h neverQualify AllTheWay (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 dflags this_mod | Just d <- dumpDir dflags = d basefn | otherwise = basefn where suffix = case hsc_src of HsBootFile -> ".imports-boot" HsSrcFile -> ".imports" HsigFile -> ".imports" basefn = moduleNameString (moduleName this_mod) ++ suffix to_ie_post_rn_var :: (HasOccName name) => Located name -> LIEWrappedName name to_ie_post_rn_var (L l n) | isDataOcc $ occName n = L l (IEPattern (L l n)) | otherwise = L l (IEName (L l n)) to_ie_post_rn :: (HasOccName name) => Located name -> LIEWrappedName name to_ie_post_rn (L l n) | isTcOcc occ && isSymOcc occ = L l (IEType (L l n)) | otherwise = L l (IEName (L l n)) where occ = occName n {- 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. Note [Overloaded field import] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ On the other hand, if we have {-# LANGUAGE DuplicateRecordFields #-} module A where data T = MkT { foo :: Int } module B where import A f = ...foo... then the minimal import for module B must be import A ( T(foo) ) because when DuplicateRecordFields is enabled, field selectors are not in scope without their enclosing datatype. ************************************************************************ * * \subsection{Errors} * * ************************************************************************ -} qualImportItemErr :: RdrName -> SDoc qualImportItemErr rdr = hang (text "Illegal qualified name in import item:") 2 (ppr rdr) pprImpDeclSpec :: ModIface -> ImpDeclSpec -> SDoc pprImpDeclSpec iface decl_spec = quotes (ppr (is_mod decl_spec)) <+> case mi_boot iface of IsBoot -> text "(hi-boot interface)" NotBoot -> Outputable.empty badImportItemErrStd :: ModIface -> ImpDeclSpec -> IE GhcPs -> SDoc badImportItemErrStd iface decl_spec ie = sep [text "Module", pprImpDeclSpec iface decl_spec, text "does not export", quotes (ppr ie)] badImportItemErrDataCon :: OccName -> ModIface -> ImpDeclSpec -> IE GhcPs -> SDoc badImportItemErrDataCon dataType_occ iface decl_spec ie = vcat [ text "In module" <+> pprImpDeclSpec iface decl_spec <> colon , nest 2 $ quotes datacon <+> text "is a data constructor of" <+> quotes dataType , text "To import it use" , nest 2 $ text "import" <+> ppr (is_mod decl_spec) <> parens_sp (dataType <> parens_sp datacon) , text "or" , nest 2 $ text "import" <+> ppr (is_mod decl_spec) <> parens_sp (dataType <> text "(..)") ] where datacon_occ = rdrNameOcc $ ieName ie datacon = parenSymOcc datacon_occ (ppr datacon_occ) dataType = parenSymOcc dataType_occ (ppr dataType_occ) parens_sp d = parens (space <> d <> space) -- T( f,g ) badImportItemErr :: ModIface -> ImpDeclSpec -> IE GhcPs -> [AvailInfo] -> SDoc badImportItemErr iface decl_spec ie avails = case find checkIfDataCon avails of Just con -> badImportItemErrDataCon (availOccName con) iface decl_spec ie Nothing -> badImportItemErrStd iface decl_spec ie where checkIfDataCon (AvailTC _ ns _) = case find (\n -> importedFS == nameOccNameFS n) ns of Just n -> isDataConName n Nothing -> False checkIfDataCon _ = False availOccName = nameOccName . availName nameOccNameFS = occNameFS . nameOccName importedFS = occNameFS . rdrNameOcc $ ieName ie illegalImportItemErr :: SDoc illegalImportItemErr = text "Illegal import item" dodgyImportWarn :: RdrName -> SDoc dodgyImportWarn item = dodgyMsg (text "import") item (dodgyMsgInsert item :: IE GhcPs) dodgyMsg :: (Outputable a, Outputable b) => SDoc -> a -> b -> SDoc dodgyMsg kind tc ie = sep [ text "The" <+> kind <+> ptext (sLit "item") -- <+> quotes (ppr (IEThingAll (noLoc (IEName $ noLoc tc)))) <+> quotes (ppr ie) <+> text "suggests that", quotes (ppr tc) <+> text "has (in-scope) constructors or class methods,", text "but it has none" ] dodgyMsgInsert :: forall p . IdP (GhcPass p) -> IE (GhcPass p) dodgyMsgInsert tc = IEThingAll noExtField ii where ii :: LIEWrappedName (IdP (GhcPass p)) ii = noLoc (IEName $ noLoc tc) addDupDeclErr :: [GlobalRdrElt] -> TcRn () addDupDeclErr [] = panic "addDupDeclErr: empty list" addDupDeclErr gres@(gre : _) = addErrAt (getSrcSpan (last sorted_names)) $ -- Report the error at the later location vcat [text "Multiple declarations of" <+> quotes (ppr (greOccName gre)), -- NB. print the OccName, not the Name, because the -- latter might not be in scope in the RdrEnv and so will -- be printed qualified. text "Declared at:" <+> vcat (map (ppr . nameSrcLoc) sorted_names)] where sorted_names = sortBy (SrcLoc.leftmost_smallest `on` nameSrcSpan) (map gre_name gres) missingImportListWarn :: ModuleName -> SDoc missingImportListWarn mod = text "The module" <+> quotes (ppr mod) <+> ptext (sLit "does not have an explicit import list") missingImportListItem :: IE GhcPs -> SDoc missingImportListItem ie = text "The import item" <+> quotes (ppr ie) <+> ptext (sLit "does not have an explicit import list") moduleWarn :: ModuleName -> WarningTxt -> SDoc moduleWarn mod (WarningTxt _ txt) = sep [ text "Module" <+> quotes (ppr mod) <> ptext (sLit ":"), nest 2 (vcat (map (ppr . sl_fs . unLoc) txt)) ] moduleWarn mod (DeprecatedTxt _ txt) = sep [ text "Module" <+> quotes (ppr mod) <+> text "is deprecated:", nest 2 (vcat (map (ppr . sl_fs . unLoc) txt)) ] packageImportErr :: SDoc packageImportErr = text "Package-qualified imports are not enabled; use PackageImports" -- This data decl will parse OK -- data T = a Int -- treating "a" as the constructor. -- It is really hard to make the parser spot this malformation. -- So the renamer has to check that the constructor is legal -- -- We can get an operator as the constructor, even in the prefix form: -- data T = :% Int Int -- from interface files, which always print in prefix form checkConName :: RdrName -> TcRn () checkConName name = checkErr (isRdrDataCon name) (badDataCon name) badDataCon :: RdrName -> SDoc badDataCon name = hsep [text "Illegal data constructor name", quotes (ppr name)]