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Diffstat (limited to 'compiler/rename/RnNames.lhs')
| -rw-r--r-- | compiler/rename/RnNames.lhs | 1138 |
1 files changed, 1138 insertions, 0 deletions
diff --git a/compiler/rename/RnNames.lhs b/compiler/rename/RnNames.lhs new file mode 100644 index 0000000000..654c101cd5 --- /dev/null +++ b/compiler/rename/RnNames.lhs @@ -0,0 +1,1138 @@ +% +% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 +% +\section[RnNames]{Extracting imported and top-level names in scope} + +\begin{code} +module RnNames ( + rnImports, mkRdrEnvAndImports, importsFromLocalDecls, + rnExports, mkExportNameSet, + getLocalDeclBinders, extendRdrEnvRn, + reportUnusedNames, reportDeprecations + ) where + +#include "HsVersions.h" + +import DynFlags ( DynFlag(..), GhcMode(..) ) +import HsSyn ( IE(..), ieName, ImportDecl(..), LImportDecl, + ForeignDecl(..), HsGroup(..), HsValBinds(..), + Sig(..), collectHsBindLocatedBinders, tyClDeclNames, + LIE ) +import RnEnv +import IfaceEnv ( ifaceExportNames ) +import LoadIface ( loadSrcInterface ) +import TcRnMonad hiding (LIE) + +import FiniteMap +import PrelNames ( pRELUDE, isUnboundName, main_RDR_Unqual ) +import Module ( Module, moduleString, unitModuleEnv, + lookupModuleEnv, moduleEnvElts, foldModuleEnv ) +import Name ( Name, nameSrcLoc, nameOccName, nameModule, isWiredInName, + nameParent, nameParent_maybe, isExternalName, + isBuiltInSyntax ) +import NameSet +import NameEnv +import OccName ( srcDataName, isTcOcc, pprNonVarNameSpace, + occNameSpace, + OccEnv, mkOccEnv, lookupOccEnv, emptyOccEnv, + extendOccEnv ) +import HscTypes ( GenAvailInfo(..), AvailInfo, + HomePackageTable, PackageIfaceTable, + unQualInScope, + Deprecs(..), ModIface(..), Dependencies(..), + lookupIface, ExternalPackageState(..) + ) +import Packages ( PackageIdH(..) ) +import RdrName ( RdrName, rdrNameOcc, setRdrNameSpace, + GlobalRdrEnv, mkGlobalRdrEnv, GlobalRdrElt(..), + emptyGlobalRdrEnv, plusGlobalRdrEnv, globalRdrEnvElts, + extendGlobalRdrEnv, lookupGlobalRdrEnv, unQualOK, lookupGRE_Name, + Provenance(..), ImportSpec(..), ImpDeclSpec(..), ImpItemSpec(..), + importSpecLoc, importSpecModule, isLocalGRE, pprNameProvenance ) +import Outputable +import Maybes ( isNothing, catMaybes, mapCatMaybes, seqMaybe, orElse ) +import SrcLoc ( Located(..), mkGeneralSrcSpan, + unLoc, noLoc, srcLocSpan, SrcSpan ) +import BasicTypes ( DeprecTxt ) +import DriverPhases ( isHsBoot ) +import Util ( notNull ) +import List ( partition ) +import IO ( openFile, IOMode(..) ) +\end{code} + + + +%************************************************************************ +%* * + rnImports +%* * +%************************************************************************ + +\begin{code} +rnImports :: [LImportDecl RdrName] -> RnM [LImportDecl Name] +rnImports imports + -- PROCESS IMPORT DECLS + -- Do the non {- SOURCE -} ones first, so that we get a helpful + -- warning for {- SOURCE -} ones that are unnecessary + = do this_mod <- getModule + implicit_prelude <- doptM Opt_ImplicitPrelude + let all_imports = mk_prel_imports this_mod implicit_prelude ++ imports + (source, ordinary) = partition is_source_import all_imports + is_source_import (L _ (ImportDecl _ is_boot _ _ _)) = is_boot + get_imports = rnImportDecl this_mod + + stuff1 <- mapM get_imports ordinary + stuff2 <- mapM get_imports source + return (stuff1 ++ stuff2) + where +-- NB: opt_NoImplicitPrelude is slightly different to import Prelude (); +-- because the former doesn't even look at Prelude.hi for instance +-- declarations, whereas the latter does. + mk_prel_imports this_mod implicit_prelude + | this_mod == pRELUDE + || explicit_prelude_import + || not implicit_prelude + = [] + | otherwise = [preludeImportDecl] + explicit_prelude_import + = notNull [ () | L _ (ImportDecl mod _ _ _ _) <- imports, + unLoc mod == pRELUDE ] + +preludeImportDecl :: LImportDecl RdrName +preludeImportDecl + = L loc $ + ImportDecl (L loc pRELUDE) + False {- Not a boot interface -} + False {- Not qualified -} + Nothing {- No "as" -} + Nothing {- No import list -} + where + loc = mkGeneralSrcSpan FSLIT("Implicit import declaration") + +mkRdrEnvAndImports :: [LImportDecl Name] -> RnM (GlobalRdrEnv, ImportAvails) +mkRdrEnvAndImports imports + = do this_mod <- getModule + let get_imports = importsFromImportDecl this_mod + stuff <- mapM get_imports imports + let (imp_gbl_envs, imp_avails) = unzip stuff + gbl_env :: GlobalRdrEnv + gbl_env = foldr plusGlobalRdrEnv emptyGlobalRdrEnv imp_gbl_envs + + all_avails :: ImportAvails + all_avails = foldr plusImportAvails emptyImportAvails imp_avails + -- ALL DONE + return (gbl_env, all_avails) + +\end{code} + +\begin{code} +rnImportDecl :: Module + -> LImportDecl RdrName + -> RnM (LImportDecl Name) +rnImportDecl this_mod (L loc importDecl@(ImportDecl loc_imp_mod_name want_boot qual_only as_mod imp_details)) + = setSrcSpan loc $ + do iface <- loadSrcInterface doc imp_mod_name want_boot + let qual_mod_name = case as_mod of + Nothing -> imp_mod_name + Just another_name -> another_name + imp_spec = ImpDeclSpec { is_mod = imp_mod_name, is_qual = qual_only, + is_dloc = loc, is_as = qual_mod_name } + total_avails <- ifaceExportNames (mi_exports iface) + importDecl' <- rnImportDecl' iface imp_spec importDecl total_avails + return (L loc importDecl') + where imp_mod_name = unLoc loc_imp_mod_name + doc = ppr imp_mod_name <+> ptext SLIT("is directly imported") + +rnImportDecl' :: ModIface -> ImpDeclSpec -> ImportDecl RdrName -> NameSet -> RnM (ImportDecl Name) +rnImportDecl' iface decl_spec (ImportDecl mod_name want_boot qual_only as_mod Nothing) all_names + = return $ ImportDecl mod_name want_boot qual_only as_mod Nothing +rnImportDecl' iface decl_spec (ImportDecl mod_name want_boot qual_only as_mod (Just (want_hiding,import_items))) all_names + = do import_items_mbs <- mapM (srcSpanWrapper) import_items + let rn_import_items = concat . catMaybes $ import_items_mbs + return $ ImportDecl mod_name want_boot qual_only as_mod (Just (want_hiding,rn_import_items)) + where + srcSpanWrapper (L span ieRdr) + = setSrcSpan span $ + case get_item ieRdr of + Nothing + -> do addErr (badImportItemErr iface decl_spec ieRdr) + return Nothing + Just ieNames + -> return (Just [L span ie | ie <- ieNames]) + occ_env :: OccEnv Name -- Maps OccName to corresponding Name + occ_env = mkOccEnv [(nameOccName n, n) | n <- nameSetToList all_names] + -- This env will have entries for data constructors too, + -- they won't make any difference because naked entities like T + -- in an import list map to TcOccs, not VarOccs. + + sub_env :: NameEnv [Name] + sub_env = mkSubNameEnv all_names + + get_item :: IE RdrName -> Maybe [IE Name] + -- Empty result for a bad item. + -- Singleton result is typical case. + -- Can have two when we are hiding, and mention C which might be + -- both a class and a data constructor. + get_item item@(IEModuleContents _) + = Nothing + get_item (IEThingAll tc) + = do name <- check_name tc + return [IEThingAll name] + get_item (IEThingAbs tc) + | want_hiding -- hiding ( C ) + -- Here the 'C' can be a data constructor + -- *or* a type/class, or even both + = case catMaybes [check_name tc, check_name (setRdrNameSpace tc srcDataName)] of + [] -> Nothing + names -> return [ IEThingAbs n | n <- names ] + | otherwise + = do name <- check_name tc + return [IEThingAbs name] + get_item (IEThingWith n ns) -- import (C (A,B)) + = do name <- check_name n + let env = mkOccEnv [(nameOccName s, s) | s <- subNames sub_env name] + mb_names = map (lookupOccEnv env . rdrNameOcc) ns + names <- sequence mb_names + return [IEThingWith name names] + get_item (IEVar n) + = do name <- check_name n + return [IEVar name] + + check_name :: RdrName -> Maybe Name + check_name rdrName + = lookupOccEnv occ_env (rdrNameOcc rdrName) + + +importsFromImportDecl :: Module + -> LImportDecl Name + -> RnM (GlobalRdrEnv, ImportAvails) + +importsFromImportDecl this_mod + (L loc (ImportDecl loc_imp_mod_name want_boot qual_only as_mod imp_details)) + = + setSrcSpan loc $ + + -- 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 <+> ptext SLIT("is directly imported") + in + loadSrcInterface doc imp_mod_name want_boot `thenM` \ iface -> + + -- Compiler sanity check: if the import didn't say + -- {-# SOURCE #-} we should not get a hi-boot file + WARN( not want_boot && mi_boot iface, ppr imp_mod_name ) + + -- 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)) + (warnRedundantSourceImport imp_mod_name) `thenM_` + + let + imp_mod = mi_module iface + deprecs = mi_deprecs iface + is_orph = mi_orphan iface + deps = mi_deps iface + + filtered_exports = filter not_this_mod (mi_exports iface) + not_this_mod (mod,_) = mod /= this_mod + -- 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 invoves a loop.) + -- + -- Tiresome consequence: if you say + -- module A where + -- import B( AType ) + -- type AType = ... + -- + -- module B( AType ) where + -- import {-# SOURCE #-} A( AType ) + -- + -- then you'll get a 'B does not export AType' message. Oh well. + + qual_mod_name = case as_mod of + Nothing -> imp_mod_name + Just another_name -> another_name + imp_spec = ImpDeclSpec { is_mod = imp_mod_name, is_qual = qual_only, + is_dloc = loc, is_as = qual_mod_name } + in + -- Get the total imports, and filter them according to the import list + ifaceExportNames filtered_exports `thenM` \ total_avails -> + filterImports iface imp_spec + imp_details total_avails `thenM` \ (avail_env, gbl_env) -> + + getDOpts `thenM` \ dflags -> + + let + -- Compute new transitive dependencies + + orphans | is_orph = ASSERT( not (imp_mod_name `elem` dep_orphs deps) ) + imp_mod_name : dep_orphs deps + | otherwise = dep_orphs deps + + (dependent_mods, dependent_pkgs) + = case mi_package iface of + HomePackage -> + -- 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 LoadIface.loadHiBootInterface + ((imp_mod_name, want_boot) : dep_mods deps, dep_pkgs deps) + + ExtPackage pkg -> + -- Imported module is from another package + -- Dump the dependent modules + -- Add the package imp_mod comes from to the dependent packages + ASSERT2( not (pkg `elem` dep_pkgs deps), ppr pkg <+> ppr (dep_pkgs deps) ) + ([], pkg : dep_pkgs deps) + + -- True <=> import M () + import_all = case imp_details of + Just (is_hiding, ls) -> not is_hiding && null ls + other -> False + + -- unqual_avails is the Avails that are visible in *unqualified* form + -- We need to know this so we know what to export when we see + -- module M ( module P ) where ... + -- Then we must export whatever came from P unqualified. + imports = ImportAvails { + imp_env = unitModuleEnv qual_mod_name avail_env, + imp_mods = unitModuleEnv imp_mod (imp_mod, import_all, loc), + imp_orphs = orphans, + imp_dep_mods = mkModDeps dependent_mods, + imp_dep_pkgs = dependent_pkgs } + + in + -- Complain if we import a deprecated module + ifOptM Opt_WarnDeprecations ( + case deprecs of + DeprecAll txt -> addWarn (moduleDeprec imp_mod_name txt) + other -> returnM () + ) `thenM_` + + returnM (gbl_env, imports) + +warnRedundantSourceImport mod_name + = ptext SLIT("Unnecessary {- SOURCE -} in the import of module") + <+> quotes (ppr mod_name) +\end{code} + + +%************************************************************************ +%* * + importsFromLocalDecls +%* * +%************************************************************************ + +From the top-level declarations of this module produce + * the lexical environment + * the ImportAvails +created by its bindings. + +Complain about duplicate bindings + +\begin{code} +importsFromLocalDecls :: HsGroup RdrName -> RnM TcGblEnv +importsFromLocalDecls group + = do { gbl_env <- getGblEnv + + ; names <- getLocalDeclBinders gbl_env group + + ; implicit_prelude <- doptM Opt_ImplicitPrelude + ; let { + -- Optimisation: filter out names for built-in syntax + -- They just clutter up the environment (esp tuples), and the parser + -- will generate Exact RdrNames for them, so the cluttered + -- envt is no use. To avoid doing this filter all the time, + -- we use -fno-implicit-prelude 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 + -- + -- Note: don't filter the gbl_env (hence all_names, not filered_all_names + -- in defn of gres above). Stupid reason: when parsing + -- data type decls, the constructors start as Exact tycon-names, + -- and then get turned into data con names by zapping the name space; + -- but that stops them being Exact, so they get looked up. + -- Ditto in fixity decls; e.g. infix 5 : + -- Sigh. It doesn't matter because it only affects the Data.Tuple really. + -- The important thing is to trim down the exports. + filtered_names + | implicit_prelude = names + | otherwise = filter (not . isBuiltInSyntax) names ; + + ; this_mod = tcg_mod gbl_env + ; imports = emptyImportAvails { + imp_env = unitModuleEnv this_mod $ + mkNameSet filtered_names + } + } + + ; rdr_env' <- extendRdrEnvRn (tcg_rdr_env gbl_env) names + + ; returnM (gbl_env { tcg_rdr_env = rdr_env', + tcg_imports = imports `plusImportAvails` tcg_imports gbl_env }) + } + +extendRdrEnvRn :: GlobalRdrEnv -> [Name] -> RnM GlobalRdrEnv +-- Add the new locally-bound names one by one, checking for duplicates as +-- we do so. Remember that in Template Haskell the duplicates +-- might *already be* in the GlobalRdrEnv from higher up the module +extendRdrEnvRn rdr_env names + = foldlM add_local rdr_env names + where + add_local rdr_env name + | gres <- lookupGlobalRdrEnv rdr_env (nameOccName name) + , (dup_gre:_) <- filter isLocalGRE gres -- Check for existing *local* defns + = do { addDupDeclErr (gre_name dup_gre) name + ; return rdr_env } + | otherwise + = return (extendGlobalRdrEnv rdr_env new_gre) + where + new_gre = GRE {gre_name = name, gre_prov = LocalDef} +\end{code} + +@getLocalDeclBinders@ returns the names for an @HsDecl@. It's +used for source code. + + *** See "THE NAMING STORY" in HsDecls **** + +\begin{code} +getLocalDeclBinders :: TcGblEnv -> HsGroup RdrName -> RnM [Name] +getLocalDeclBinders gbl_env (HsGroup {hs_valds = ValBindsIn val_decls val_sigs, + hs_tyclds = tycl_decls, + hs_fords = foreign_decls }) + = do { tc_names_s <- mappM new_tc tycl_decls + ; val_names <- mappM new_simple val_bndrs + ; return (foldr (++) val_names tc_names_s) } + where + mod = tcg_mod gbl_env + is_hs_boot = isHsBoot (tcg_src gbl_env) ; + val_bndrs | is_hs_boot = sig_hs_bndrs + | otherwise = for_hs_bndrs ++ val_hs_bndrs + -- In a hs-boot file, the value binders come from the + -- *signatures*, and there should be no foreign binders + + new_simple rdr_name = newTopSrcBinder mod Nothing rdr_name + + sig_hs_bndrs = [nm | L _ (TypeSig nm _) <- val_sigs] + val_hs_bndrs = collectHsBindLocatedBinders val_decls + for_hs_bndrs = [nm | L _ (ForeignImport nm _ _ _) <- foreign_decls] + + new_tc tc_decl + = do { main_name <- newTopSrcBinder mod Nothing main_rdr + ; sub_names <- mappM (newTopSrcBinder mod (Just main_name)) sub_rdrs + ; return (main_name : sub_names) } + where + (main_rdr : sub_rdrs) = tyClDeclNames (unLoc tc_decl) +\end{code} + + +%************************************************************************ +%* * +\subsection{Filtering imports} +%* * +%************************************************************************ + +@filterImports@ takes the @ExportEnv@ telling what the imported module makes +available, and filters it through the import spec (if any). + +\begin{code} +filterImports :: ModIface + -> ImpDeclSpec -- The span for the entire import decl + -> Maybe (Bool, [LIE Name]) -- Import spec; True => hiding + -> NameSet -- What's available + -> RnM (NameSet, -- What's imported (qualified or unqualified) + GlobalRdrEnv) -- Same again, but in GRE form + + -- Complains if import spec mentions things that the module doesn't export + -- Warns/informs if import spec contains duplicates. + +mkGenericRdrEnv decl_spec names + = mkGlobalRdrEnv [ GRE { gre_name = name, gre_prov = Imported [imp_spec] } + | name <- nameSetToList names ] + where + imp_spec = ImpSpec { is_decl = decl_spec, is_item = ImpAll } + +filterImports iface decl_spec Nothing all_names + = return (all_names, mkGenericRdrEnv decl_spec all_names) + +filterImports iface decl_spec (Just (want_hiding, import_items)) all_names + = mapM (addLocM get_item) import_items >>= \gres_s -> + let gres = concat gres_s + specified_names = mkNameSet (map gre_name gres) + in if not want_hiding then + return (specified_names, mkGlobalRdrEnv gres) + else let keep n = not (n `elemNameSet` specified_names) + pruned_avails = filterNameSet keep all_names + in return (pruned_avails, mkGenericRdrEnv decl_spec pruned_avails) + where + sub_env :: NameEnv [Name] -- Classify each name by its parent + sub_env = mkSubNameEnv all_names + + succeed_with :: Bool -> [Name] -> RnM [GlobalRdrElt] + succeed_with all_explicit names + = do { loc <- getSrcSpanM + ; returnM (map (mk_gre loc) names) } + where + mk_gre loc name = GRE { gre_name = name, + gre_prov = Imported [imp_spec] } + where + imp_spec = ImpSpec { is_decl = decl_spec, is_item = item_spec } + item_spec = ImpSome { is_explicit = explicit, is_iloc = loc } + explicit = all_explicit || isNothing (nameParent_maybe name) + + get_item :: IE Name -> RnM [GlobalRdrElt] + -- Empty result for a bad item. + -- Singleton result is typical case. + -- Can have two when we are hiding, and mention C which might be + -- both a class and a data constructor. + get_item item@(IEModuleContents _) + -- This case should be filtered out by 'rnImports'. + = panic "filterImports: IEModuleContents?" + + get_item (IEThingAll name) + = case subNames sub_env name of + [] -> -- This occurs when you import T(..), but + -- only export T abstractly. + do ifOptM Opt_WarnDodgyImports (addWarn (dodgyImportWarn name)) + succeed_with False [name] + names -> succeed_with False (name:names) + + get_item (IEThingAbs name) + = succeed_with True [name] + + get_item (IEThingWith name names) + = succeed_with True (name:names) + get_item (IEVar name) + = succeed_with True [name] + +\end{code} + + +%************************************************************************ +%* * +\subsection{Export list processing} +%* * +%************************************************************************ + +Processing the export list. + +You might think that we should record things that appear in the export +list as ``occurrences'' (using @addOccurrenceName@), but you'd be +wrong. We do check (here) that they are in scope, but there is no +need to slurp in their actual declaration (which is what +@addOccurrenceName@ forces). + +Indeed, doing so would big trouble when compiling @PrelBase@, because +it re-exports @GHC@, which includes @takeMVar#@, whose type includes +@ConcBase.StateAndSynchVar#@, and so on... + +\begin{code} +type ExportAccum -- The type of the accumulating parameter of + -- the main worker function in rnExports + = ([Module], -- 'module M's seen so far + ExportOccMap, -- Tracks exported occurrence names + NameSet) -- The accumulated exported stuff +emptyExportAccum = ([], emptyOccEnv, emptyNameSet) + +type ExportOccMap = OccEnv (Name, IE RdrName) + -- Tracks what a particular exported OccName + -- in an export list refers to, and which item + -- it came from. It's illegal to export two distinct things + -- that have the same occurrence name + +rnExports :: Maybe [LIE RdrName] + -> RnM (Maybe [LIE Name]) +rnExports Nothing = return Nothing +rnExports (Just exports) + = do TcGblEnv { tcg_imports = ImportAvails { imp_env = imp_env } } <- getGblEnv + let sub_env :: NameEnv [Name] -- Classify each name by its parent + sub_env = mkSubNameEnv (foldModuleEnv unionNameSets emptyNameSet imp_env) + rnExport (IEVar rdrName) + = do name <- lookupGlobalOccRn rdrName + return (IEVar name) + rnExport (IEThingAbs rdrName) + = do name <- lookupGlobalOccRn rdrName + return (IEThingAbs name) + rnExport (IEThingAll rdrName) + = do name <- lookupGlobalOccRn rdrName + return (IEThingAll name) + rnExport ie@(IEThingWith rdrName rdrNames) + = do name <- lookupGlobalOccRn rdrName + if isUnboundName name + then return (IEThingWith name []) + else do + let env = mkOccEnv [(nameOccName s, s) | s <- subNames sub_env name] + mb_names = map (lookupOccEnv env . rdrNameOcc) rdrNames + if any isNothing mb_names + then do addErr (exportItemErr ie) + return (IEThingWith name []) + else return (IEThingWith name (catMaybes mb_names)) + rnExport (IEModuleContents mod) + = return (IEModuleContents mod) + rn_exports <- mapM (wrapLocM rnExport) exports + return (Just rn_exports) + +mkExportNameSet :: Bool -- False => no 'module M(..) where' header at all + -> Maybe ([LIE Name], [LIE RdrName]) -- Nothing => no explicit export list + -> RnM NameSet + -- Complains if two distinct exports have same OccName + -- Warns about identical exports. + -- Complains about exports items not in scope + +mkExportNameSet explicit_mod exports + = do TcGblEnv { tcg_rdr_env = rdr_env, + tcg_imports = imports } <- getGblEnv + + -- If the module header is omitted altogether, then behave + -- as if the user had written "module Main(main) where..." + -- EXCEPT in interactive mode, when we behave as if he had + -- written "module Main where ..." + -- Reason: don't want to complain about 'main' not in scope + -- in interactive mode + ghc_mode <- getGhcMode + real_exports <- case () of + () | explicit_mod + -> return exports + | ghc_mode == Interactive + -> return Nothing + | otherwise + -> do mainName <- lookupGlobalOccRn main_RDR_Unqual + return (Just ([noLoc (IEVar mainName)] + ,[noLoc (IEVar main_RDR_Unqual)])) + -- ToDo: the 'noLoc' here is unhelpful if 'main' turns out to be out of scope + exports_from_avail real_exports rdr_env imports + + +exports_from_avail Nothing rdr_env imports + = -- Export all locally-defined things + -- We do this by filtering the global RdrEnv, + -- keeping only things that are locally-defined + return (mkNameSet [ gre_name gre + | gre <- globalRdrEnvElts rdr_env, + isLocalGRE gre ]) + +exports_from_avail (Just (items,origItems)) rdr_env (ImportAvails { imp_env = imp_env }) + = do (_, _, exports) <- foldlM do_litem emptyExportAccum (zip items origItems) + return exports + where + sub_env :: NameEnv [Name] -- Classify each name by its parent + sub_env = mkSubNameEnv (foldModuleEnv unionNameSets emptyNameSet imp_env) + + do_litem :: ExportAccum -> (LIE Name, LIE RdrName) -> RnM ExportAccum + do_litem acc (ieName, ieRdr) + = addLocM (exports_from_item acc (unLoc ieRdr)) ieName + + exports_from_item :: ExportAccum -> IE RdrName -> IE Name -> RnM ExportAccum + exports_from_item acc@(mods, occs, exports) ieRdr@(IEModuleContents mod) ie + | mod `elem` mods -- Duplicate export of M + = do { warn_dup_exports <- doptM Opt_WarnDuplicateExports ; + warnIf warn_dup_exports (dupModuleExport mod) ; + returnM acc } + + | otherwise + = case lookupModuleEnv imp_env mod of + Nothing -> do addErr (modExportErr mod) + return acc + Just names + -> do let new_exports = filterNameSet (inScopeUnqual rdr_env) names + -- This check_occs not only finds conflicts between this item + -- and others, but also internally within this item. That is, + -- if 'M.x' is in scope in several ways, we'll have several + -- members of mod_avails with the same OccName. + occs' <- check_occs ieRdr occs (nameSetToList new_exports) + return (mod:mods, occs', exports `unionNameSets` new_exports) + + exports_from_item acc@(mods, occs, exports) ieRdr ie + = if isUnboundName (ieName ie) + then return acc -- Avoid error cascade + else let new_exports = filterAvail ie sub_env in + do -- checkErr (not (null (drop 1 new_exports))) (exportItemErr ie) + checkForDodgyExport ie new_exports + occs' <- check_occs ieRdr occs new_exports + return (mods, occs', addListToNameSet exports new_exports) + +------------------------------- +filterAvail :: IE Name -- Wanted + -> NameEnv [Name] -- Maps type/class names to their sub-names + -> [Name] + +filterAvail (IEVar n) subs = [n] +filterAvail (IEThingAbs n) subs = [n] +filterAvail (IEThingAll n) subs = n : subNames subs n +filterAvail (IEThingWith n ns) subs = n : ns +filterAvail (IEModuleContents _) _ = panic "filterAvail" + +subNames :: NameEnv [Name] -> Name -> [Name] +subNames env n = lookupNameEnv env n `orElse` [] + +mkSubNameEnv :: NameSet -> NameEnv [Name] +-- Maps types and classes to their constructors/classops respectively +-- This mapping just makes it easier to deal with A(..) export items +mkSubNameEnv names + = foldNameSet add_name emptyNameEnv names + where + add_name name env + | Just parent <- nameParent_maybe name + = extendNameEnv_C (\ns _ -> name:ns) env parent [name] + | otherwise = env + +------------------------------- +inScopeUnqual :: GlobalRdrEnv -> Name -> Bool +-- Checks whether the Name is in scope unqualified, +-- regardless of whether it's ambiguous or not +inScopeUnqual env n = any unQualOK (lookupGRE_Name env n) + +------------------------------- +checkForDodgyExport :: IE Name -> [Name] -> RnM () +checkForDodgyExport ie@(IEThingAll tc) [n] + | isTcOcc (nameOccName n) = addWarn (dodgyExportWarn tc) + -- This occurs when you export T(..), but + -- only import T abstractly, or T is a synonym. + -- The single [n] is the type or class itself + | otherwise = addErr (exportItemErr ie) + -- This happes if you export x(..), which is bogus +checkForDodgyExport _ _ = return () + +------------------------------- +check_occs :: IE RdrName -> ExportOccMap -> [Name] -> RnM ExportOccMap +check_occs ie occs names + = foldlM check occs names + where + check occs name + = case lookupOccEnv occs name_occ of + Nothing -> returnM (extendOccEnv occs name_occ (name, ie)) + + Just (name', ie') + | name == name' -- Duplicate export + -> do { warn_dup_exports <- doptM Opt_WarnDuplicateExports ; + warnIf warn_dup_exports (dupExportWarn name_occ ie ie') ; + returnM occs } + + | otherwise -- Same occ name but different names: an error + -> do { global_env <- getGlobalRdrEnv ; + addErr (exportClashErr global_env name name' ie ie') ; + returnM occs } + where + name_occ = nameOccName name +\end{code} + +%********************************************************* +%* * + Deprecations +%* * +%********************************************************* + +\begin{code} +reportDeprecations :: TcGblEnv -> RnM () +reportDeprecations tcg_env + = ifOptM Opt_WarnDeprecations $ + do { (eps,hpt) <- getEpsAndHpt + -- By this time, typechecking is complete, + -- so the PIT is fully populated + ; mapM_ (check hpt (eps_PIT eps)) all_gres } + where + used_names = allUses (tcg_dus tcg_env) + -- Report on all deprecated uses; hence allUses + all_gres = globalRdrEnvElts (tcg_rdr_env tcg_env) + + check hpt pit (GRE {gre_name = name, gre_prov = Imported (imp_spec:_)}) + | name `elemNameSet` used_names + , Just deprec_txt <- lookupDeprec hpt pit name + = setSrcSpan (importSpecLoc imp_spec) $ + addWarn (sep [ptext SLIT("Deprecated use of") <+> + pprNonVarNameSpace (occNameSpace (nameOccName name)) <+> + quotes (ppr name), + (parens imp_msg) <> colon, + (ppr deprec_txt) ]) + where + name_mod = nameModule name + imp_mod = importSpecModule imp_spec + imp_msg = ptext SLIT("imported from") <+> ppr imp_mod <> extra + extra | imp_mod == name_mod = empty + | otherwise = ptext SLIT(", but defined in") <+> ppr name_mod + + check hpt pit ok_gre = returnM () -- Local, or not used, or not deprectated + -- The Imported pattern-match: don't deprecate locally defined names + -- For a start, we may be exporting a deprecated thing + -- Also we may use a deprecated thing in the defn of another + -- deprecated things. We may even use a deprecated thing in + -- the defn of a non-deprecated thing, when changing a module's + -- interface + +lookupDeprec :: HomePackageTable -> PackageIfaceTable + -> Name -> Maybe DeprecTxt +lookupDeprec hpt pit n + = case lookupIface hpt pit (nameModule n) of + Just iface -> mi_dep_fn iface n `seqMaybe` -- Bleat if the thing, *or + mi_dep_fn iface (nameParent n) -- its parent*, is deprec'd + Nothing + | isWiredInName n -> Nothing + -- We have not necessarily loaded the .hi file for a + -- wired-in name (yet), although we *could*. + -- And we never deprecate them + + | otherwise -> pprPanic "lookupDeprec" (ppr n) + -- By now all the interfaces should have been loaded + +gre_is_used :: NameSet -> GlobalRdrElt -> Bool +gre_is_used used_names gre = gre_name gre `elemNameSet` used_names +\end{code} + +%********************************************************* +%* * + Unused names +%* * +%********************************************************* + +\begin{code} +reportUnusedNames :: Maybe [LIE RdrName] -- Export list + -> TcGblEnv -> RnM () +reportUnusedNames export_decls gbl_env + = do { traceRn ((text "RUN") <+> (ppr (tcg_dus gbl_env))) + ; warnUnusedTopBinds unused_locals + ; warnUnusedModules unused_imp_mods + ; warnUnusedImports unused_imports + ; warnDuplicateImports defined_and_used + ; printMinimalImports minimal_imports } + where + used_names, all_used_names :: NameSet + used_names = findUses (tcg_dus gbl_env) emptyNameSet + -- NB: currently, if f x = g, we only treat 'g' as used if 'f' is used + -- Hence findUses + + all_used_names = used_names `unionNameSets` + mkNameSet (mapCatMaybes nameParent_maybe (nameSetToList used_names)) + -- A use of C implies a use of T, + -- if C was brought into scope by T(..) or T(C) + + -- Collect the defined names from the in-scope environment + defined_names :: [GlobalRdrElt] + defined_names = globalRdrEnvElts (tcg_rdr_env 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 all_used_names + defined_and_used, defined_but_not_used :: [GlobalRdrElt] + (defined_and_used, defined_but_not_used) + = partition (gre_is_used all_used_names) defined_names + + -- 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 :: [GlobalRdrElt] + 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 = filter unused_imp defined_but_not_used + unused_imp (GRE {gre_prov = Imported imp_specs}) + = not (all (module_unused . importSpecModule) imp_specs) + && or [exp | ImpSpec { is_item = ImpSome { is_explicit = exp } } <- imp_specs] + -- Don't complain about unused imports if we've already said the + -- entire import is unused + unused_imp other = False + + -- To figure out the minimal set of imports, start with the things + -- that are in scope (i.e. in gbl_env). Then just combine them + -- into a bunch of avails, so they are properly grouped + -- + -- BUG WARNING: this does not deal properly with qualified imports! + minimal_imports :: FiniteMap Module AvailEnv + minimal_imports0 = 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_name = n, gre_prov = Imported imp_specs}) acc + = addToFM_C plusAvailEnv acc (importSpecModule (head imp_specs)) + (unitAvailEnv (mk_avail n (nameParent_maybe n))) + add_name other acc + = acc + + -- Modules mentioned as 'module M' in the export list + expall_mods = case export_decls of + Nothing -> [] + Just es -> [m | L _ (IEModuleContents m) <- es] + + -- This is really bogus. The idea is that if we see 'module M' in + -- the export list we must retain the import decls that drive it + -- If we aren't careful we might see + -- module A( module M ) where + -- import M + -- import N + -- and suppose that N exports everything that M does. Then we + -- must not drop the import of M even though N brings it all into + -- scope. + -- + -- BUG WARNING: 'module M' exports aside, what if M.x is mentioned?! + -- + -- The reason that add_expall is bogus is that it doesn't take + -- qualified imports into account. But it's an improvement. + add_expall mod acc = addToFM_C plusAvailEnv acc mod emptyAvailEnv + + -- n is the name of the thing, p is the name of its parent + mk_avail n (Just p) = AvailTC p [p,n] + mk_avail n Nothing | isTcOcc (nameOccName n) = AvailTC n [n] + | otherwise = Avail n + + add_inst_mod (mod,_,_) acc + | mod `elemFM` acc = acc -- We import something already + | otherwise = addToFM acc mod emptyAvailEnv + where + -- 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, Bool, SrcSpan)] + -- See the type of the imp_mods for this triple + direct_import_mods = moduleEnvElts (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: does not deal correctly with multiple imports of the same module + -- becuase direct_import_mods has only one entry per module + unused_imp_mods = [(mod,loc) | (mod,no_imp,loc) <- direct_import_mods, + not (mod `elemFM` minimal_imports1), + mod /= pRELUDE, + 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 :: Module -> Bool + module_unused mod = any (((==) mod) . fst) unused_imp_mods + +--------------------- +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 $ + sequenceM_ [ warn name pr + -- The 'head' picks the first offending group + -- for this particular name + | GRE { gre_name = name, gre_prov = Imported imps } <- gres + , pr <- redundants imps ] + where + warn name (red_imp, cov_imp) + = addWarnAt (importSpecLoc red_imp) + (vcat [ptext SLIT("Redundant import of:") <+> quotes pp_name, + ptext SLIT("It is also") <+> ppr cov_imp]) + where + pp_name | is_qual red_decl = ppr (is_as red_decl) <> dot <> ppr occ + | otherwise = ppr occ + occ = nameOccName name + red_decl = is_decl red_imp + + redundants :: [ImportSpec] -> [(ImportSpec,ImportSpec)] + -- The returned pair is (redundant-import, covering-import) + redundants imps + = [ (red_imp, cov_imp) + | red_imp <- imps + , cov_imp <- take 1 (filter (covers red_imp) imps) ] + + -- "red_imp" is a putative redundant import + -- "cov_imp" potentially covers it + -- This test decides whether red_imp could be dropped + -- + -- NOTE: currently the test does not warn about + -- import M( x ) + -- imoprt N( x ) + -- even if the same underlying 'x' is involved, because dropping + -- either import would change the qualified names in scope (M.x, N.x) + -- But if the qualified names aren't used, the import is indeed redundant + -- Sadly we don't know that. Oh well. + covers red_imp@(ImpSpec { is_decl = red_decl, is_item = red_item }) + cov_imp@(ImpSpec { is_decl = cov_decl, is_item = cov_item }) + | red_loc == cov_loc + = False -- Ignore diagonal elements + | not (is_as red_decl == is_as cov_decl) + = False -- They bring into scope different qualified names + | not (is_qual red_decl) && is_qual cov_decl + = False -- Covering one doesn't bring unqualified name into scope + | red_selective + = not cov_selective -- Redundant one is selective and covering one isn't + || red_later -- Both are explicit; tie-break using red_later + | otherwise + = not cov_selective -- Neither import is selective + && (is_mod red_decl == is_mod cov_decl) -- They import the same module + && red_later -- Tie-break + where + red_loc = importSpecLoc red_imp + cov_loc = importSpecLoc cov_imp + red_later = red_loc > cov_loc + cov_selective = selectiveImpItem cov_item + red_selective = selectiveImpItem red_item + +selectiveImpItem :: ImpItemSpec -> Bool +selectiveImpItem ImpAll = False +selectiveImpItem (ImpSome {}) = True + +-- ToDo: deal with original imports with 'qualified' and 'as M' clauses +printMinimalImports :: FiniteMap Module AvailEnv -- Minimal imports + -> RnM () +printMinimalImports imps + = ifOptM Opt_D_dump_minimal_imports $ do { + + mod_ies <- mappM to_ies (fmToList imps) ; + this_mod <- getModule ; + rdr_env <- getGlobalRdrEnv ; + ioToTcRn (do { h <- openFile (mkFilename this_mod) WriteMode ; + printForUser h (unQualInScope rdr_env) + (vcat (map ppr_mod_ie mod_ies)) }) + } + where + mkFilename this_mod = moduleString this_mod ++ ".imports" + ppr_mod_ie (mod_name, ies) + | mod_name == 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) + returnM (mod, ies) + + to_ie :: AvailInfo -> RnM (IE Name) + -- The main trick here is that if we're importing all the constructors + -- we want to say "T(..)", but if we're importing only a subset we want + -- to say "T(A,B,C)". So we have to find out what the module exports. + to_ie (Avail n) = returnM (IEVar n) + to_ie (AvailTC n [m]) = ASSERT( n==m ) + returnM (IEThingAbs n) + to_ie (AvailTC n ns) + = loadSrcInterface doc n_mod False `thenM` \ iface -> + case [xs | (m,as) <- mi_exports iface, + m == n_mod, + AvailTC x xs <- as, + x == nameOccName n] of + [xs] | all_used xs -> returnM (IEThingAll n) + | otherwise -> returnM (IEThingWith n (filter (/= n) ns)) + other -> pprTrace "to_ie" (ppr n <+> ppr n_mod <+> ppr other) $ + returnM (IEVar n) + where + all_used avail_occs = all (`elem` map nameOccName ns) avail_occs + doc = text "Compute minimal imports from" <+> ppr n + n_mod = nameModule n +\end{code} + + +%************************************************************************ +%* * +\subsection{Errors} +%* * +%************************************************************************ + +\begin{code} +badImportItemErr iface decl_spec ie + = sep [ptext SLIT("Module"), quotes (ppr (is_mod decl_spec)), source_import, + ptext SLIT("does not export"), quotes (ppr ie)] + where + source_import | mi_boot iface = ptext SLIT("(hi-boot interface)") + | otherwise = empty + +dodgyImportWarn item = dodgyMsg (ptext SLIT("import")) item +dodgyExportWarn item = dodgyMsg (ptext SLIT("export")) item + +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 constructor or class methods"), + ptext SLIT("but it has none; it is a type synonym or abstract type or class") ] + +modExportErr mod + = hsep [ ptext SLIT("Unknown module in export list: module"), quotes (ppr mod)] + +exportItemErr export_item + = sep [ ptext SLIT("The export item") <+> quotes (ppr export_item), + ptext SLIT("attempts to export constructors or class methods that are not visible here") ] + +exportClashErr global_env name1 name2 ie1 ie2 + = vcat [ ptext SLIT("Conflicting exports for") <+> quotes (ppr occ) <> colon + , ppr_export ie1 name1 + , ppr_export ie2 name2 ] + where + occ = nameOccName name1 + ppr_export ie name = nest 2 (quotes (ppr ie) <+> ptext SLIT("exports") <+> + quotes (ppr name) <+> pprNameProvenance (get_gre name)) + + -- get_gre finds a GRE for the Name, so that we can show its provenance + get_gre name + = case lookupGRE_Name global_env name of + (gre:_) -> gre + [] -> pprPanic "exportClashErr" (ppr name) + +addDupDeclErr :: Name -> Name -> TcRn () +addDupDeclErr name_a name_b + = addErrAt (srcLocSpan loc2) $ + vcat [ptext SLIT("Multiple declarations of") <+> quotes (ppr name1), + ptext SLIT("Declared at:") <+> vcat [ppr (nameSrcLoc name1), ppr loc2]] + where + loc2 = nameSrcLoc name2 + (name1,name2) | nameSrcLoc name_a > nameSrcLoc name_b = (name_b,name_a) + | otherwise = (name_a,name_b) + -- Report the error at the later location + +dupExportWarn occ_name ie1 ie2 + = hsep [quotes (ppr occ_name), + ptext SLIT("is exported by"), quotes (ppr ie1), + ptext SLIT("and"), quotes (ppr ie2)] + +dupModuleExport mod + = hsep [ptext SLIT("Duplicate"), + quotes (ptext SLIT("Module") <+> ppr mod), + ptext SLIT("in export list")] + +moduleDeprec mod txt + = sep [ ptext SLIT("Module") <+> quotes (ppr mod) <+> ptext SLIT("is deprecated:"), + nest 4 (ppr txt) ] +\end{code} |