From 7bb3d1fc79521d591cd9f824893963141a7997b6 Mon Sep 17 00:00:00 2001 From: "simonpj@microsoft.com" Date: Mon, 6 Jul 2009 11:25:03 +0000 Subject: [PATCH] Major patch to fix reporting of unused imports This patch, joint work between and Ian and Simon, fixes Trac #1074 by reporting unused import declarations much more accuratly than before. The specification is described at http://hackage.haskell.org/trac/ghc/wiki/Commentary/Compiler/UnusedImports The implementation is both easier to understand than before, and shorter too. Also fixed are #1148, #2267 Also fixed is -ddump-minimal imports, which now works properly, fixing Trac #1792. --- compiler/hsSyn/HsImpExp.lhs | 13 +- compiler/main/HscMain.lhs | 13 +- compiler/rename/RnEnv.lhs | 26 ++- compiler/rename/RnNames.lhs | 412 ++++++++++++++++--------------------- compiler/typecheck/TcRnDriver.lhs | 2 +- compiler/typecheck/TcRnMonad.lhs | 4 +- compiler/typecheck/TcRnTypes.lhs | 6 +- 7 files changed, 230 insertions(+), 246 deletions(-) diff --git a/compiler/hsSyn/HsImpExp.lhs b/compiler/hsSyn/HsImpExp.lhs index bc76b94..9465cd2 100644 --- a/compiler/hsSyn/HsImpExp.lhs +++ b/compiler/hsSyn/HsImpExp.lhs @@ -59,16 +59,17 @@ instance (Outputable name) => Outputable (ImportDecl name) where pp_qual True = ptext (sLit "qualified") pp_as Nothing = empty - pp_as (Just a) = ptext (sLit "as ") <+> ppr a + pp_as (Just a) = ptext (sLit "as") <+> ppr a ppr_imp True = ptext (sLit "{-# SOURCE #-}") ppr_imp False = empty - pp_spec Nothing = empty - pp_spec (Just (False, spec)) - = parens (interpp'SP spec) - pp_spec (Just (True, spec)) - = ptext (sLit "hiding") <+> parens (interpp'SP spec) + pp_spec Nothing = empty + pp_spec (Just (False, ies)) = ppr_ies ies + pp_spec (Just (True, ies)) = ptext (sLit "hiding") <+> ppr_ies ies + + ppr_ies [] = ptext (sLit "()") + ppr_ies ies = char '(' <+> interpp'SP ies <+> char ')' \end{code} %************************************************************************ diff --git a/compiler/main/HscMain.lhs b/compiler/main/HscMain.lhs index ba9e151..26247b1 100644 --- a/compiler/main/HscMain.lhs +++ b/compiler/main/HscMain.lhs @@ -229,12 +229,13 @@ hscTypecheckRename mod_summary rdr_module = do <- {-# SCC "Typecheck-Rename" #-} ioMsgMaybe $ tcRnModule hsc_env (ms_hsc_src mod_summary) True rdr_module - let rn_info = do decl <- tcg_rn_decls tc_result - imports <- tcg_rn_imports tc_result - let exports = tcg_rn_exports tc_result - let doc = tcg_doc tc_result - let hmi = tcg_hmi tc_result - return (decl,imports,exports,doc,hmi) + let -- This 'do' is in the Maybe monad! + rn_info = do { decl <- tcg_rn_decls tc_result + ; let imports = tcg_rn_imports tc_result + exports = tcg_rn_exports tc_result + doc = tcg_doc tc_result + hmi = tcg_hmi tc_result + ; return (decl,imports,exports,doc,hmi) } return (tc_result, rn_info) diff --git a/compiler/rename/RnEnv.lhs b/compiler/rename/RnEnv.lhs index 51432bd..2ecaf61 100644 --- a/compiler/rename/RnEnv.lhs +++ b/compiler/rename/RnEnv.lhs @@ -15,7 +15,7 @@ module RnEnv ( lookupInstDeclBndr, lookupRecordBndr, lookupConstructorFields, lookupSyntaxName, lookupSyntaxTable, lookupGreRn, lookupGreLocalRn, lookupGreRn_maybe, - getLookupOccRn, + getLookupOccRn, addUsedRdrNames, newLocalsRn, newIPNameRn, bindLocalNames, bindLocalNamesFV, @@ -68,6 +68,7 @@ import List ( nubBy ) import DynFlags import FastString import Control.Monad +import qualified Data.Set as Set \end{code} \begin{code} @@ -307,6 +308,7 @@ lookup_sub_bndr :: (GlobalRdrElt -> Bool) -> SDoc -> RdrName -> RnM Name lookup_sub_bndr is_good doc rdr_name | isUnqual rdr_name -- Find all the things the rdr-name maps to = do { -- and pick the one with the right parent name + ; addUsedRdrName rdr_name ; env <- getGlobalRdrEnv ; case filter is_good (lookupGlobalRdrEnv env (rdrNameOcc rdr_name)) of -- NB: lookupGlobalRdrEnv, not lookupGRE_RdrName! @@ -420,7 +422,27 @@ unboundName rdr_name lookupGreRn_maybe :: RdrName -> RnM (Maybe GlobalRdrElt) -- Just look up the RdrName in the GlobalRdrEnv lookupGreRn_maybe rdr_name - = lookupGreRn_help rdr_name (lookupGRE_RdrName rdr_name) + = do { mGre <- lookupGreRn_help rdr_name (lookupGRE_RdrName rdr_name) + ; case mGre of + Just gre -> + case gre_prov gre of + LocalDef -> return () + Imported _ -> addUsedRdrName rdr_name + Nothing -> + return () + ; return mGre } + +addUsedRdrName :: RdrName -> RnM () +addUsedRdrName rdr + = do { env <- getGblEnv + ; updMutVar (tcg_used_rdrnames env) + (\s -> Set.insert rdr s) } + +addUsedRdrNames :: [RdrName] -> RnM () +addUsedRdrNames rdrs + = do { env <- getGblEnv + ; updMutVar (tcg_used_rdrnames env) + (\s -> foldr Set.insert s rdrs) } lookupGreRn :: RdrName -> RnM GlobalRdrElt -- If not found, add error message, and return a fake GRE diff --git a/compiler/rename/RnNames.lhs b/compiler/rename/RnNames.lhs index 8aa33a2..781de31 100644 --- a/compiler/rename/RnNames.lhs +++ b/compiler/rename/RnNames.lhs @@ -26,7 +26,6 @@ import Module import Name import NameEnv import NameSet -import OccName import HscTypes import RdrName import Outputable @@ -34,12 +33,11 @@ import Maybes import SrcLoc import FiniteMap import ErrUtils -import BasicTypes ( WarningTxt(..) ) -import DriverPhases ( isHsBoot ) import Util import FastString import ListSetOps -import Data.List ( partition, concatMap, (\\), delete ) +import Data.List ( partition, (\\), delete ) +import qualified Data.Set as Set import IO ( openFile, IOMode(..) ) import Monad ( when, mplus ) \end{code} @@ -122,8 +120,7 @@ rnImportDecl :: Module rnImportDecl this_mod (L loc (ImportDecl loc_imp_mod_name mb_pkg want_boot qual_only as_mod imp_details)) - = - setSrcSpan loc $ do + = setSrcSpan loc $ do when (isJust mb_pkg) $ do pkg_imports <- doptM Opt_PackageImports @@ -745,6 +742,7 @@ type AvailEnv = NameEnv AvailInfo -- Maps a Name to the AvailInfo that contains emptyAvailEnv :: AvailEnv emptyAvailEnv = emptyNameEnv +{- Dead code unitAvailEnv :: AvailInfo -> AvailEnv unitAvailEnv a = unitNameEnv (availName a) a @@ -753,6 +751,7 @@ plusAvailEnv = plusNameEnv_C plusAvail availEnvElts :: AvailEnv -> [AvailInfo] availEnvElts = nameEnvElts +-} addAvail :: AvailEnv -> AvailInfo -> AvailEnv addAvail avails avail = extendNameEnv_C plusAvail avails (availName avail) avail @@ -852,7 +851,6 @@ rnExports explicit_mod exports tcg_dus = tcg_dus tcg_env `plusDU` usesOnly (availsToNameSet final_avails) }) } - exports_from_avail :: Maybe [LIE RdrName] -- Nothing => no explicit export list -> GlobalRdrEnv @@ -895,16 +893,22 @@ exports_from_avail (Just rdr_items) rdr_env imports this_mod | otherwise = do { implicit_prelude <- doptM Opt_ImplicitPrelude - ; let { exportValid = (mod `elem` imported_modules) + ; let { exportValid = (mod `elem` imported_modules) || (moduleName this_mod == mod) - ; gres = filter (isModuleExported implicit_prelude mod) - (globalRdrEnvElts rdr_env) - } + ; gres = filter (isModuleExported implicit_prelude mod) + (globalRdrEnvElts rdr_env) + ; names = map gre_name gres + } - ; checkErr exportValid (moduleNotImported mod) + ; checkErr exportValid (moduleNotImported mod) ; warnIf (exportValid && null gres) (nullModuleExport mod) - ; occs' <- check_occs ie occs (map gre_name gres) + ; addUsedRdrNames (concat [ [mkRdrQual mod occ, mkRdrUnqual occ] + | occ <- map nameOccName names ]) + -- The qualified and unqualified version of all of + -- these names are, in effect, used by this export + + ; occs' <- check_occs ie occs names -- This check_occs not only finds conflicts -- between this item and others, but also -- internally within this item. That is, if @@ -1137,13 +1141,10 @@ this is, after all, wired-in stuff. \begin{code} reportUnusedNames :: Maybe [LIE RdrName] -- Export list -> TcGblEnv -> RnM () -reportUnusedNames export_decls gbl_env +reportUnusedNames _export_decls gbl_env = do { traceRn ((text "RUN") <+> (ppr (tcg_dus gbl_env))) - ; warnUnusedTopBinds unused_locals - ; warnUnusedModules unused_imp_mods - ; warnUnusedImports unused_imports - ; warnDuplicateImports defined_and_used - ; printMinimalImports minimal_imports } + ; warnUnusedImportDecls gbl_env + ; warnUnusedTopBinds unused_locals } where used_names :: NameSet used_names = findUses (tcg_dus gbl_env) emptyNameSet @@ -1157,8 +1158,8 @@ reportUnusedNames export_decls gbl_env -- Note that defined_and_used, defined_but_not_used -- are both [GRE]; that's why we need defined_and_used -- rather than just used_names - defined_and_used, defined_but_not_used :: [GlobalRdrElt] - (defined_and_used, defined_but_not_used) + _defined_and_used, defined_but_not_used :: [GlobalRdrElt] + (_defined_and_used, defined_but_not_used) = partition (gre_is_used used_names) defined_names kids_env = mkChildEnv defined_names @@ -1179,220 +1180,174 @@ reportUnusedNames export_decls gbl_env unused_locals = filter is_unused_local defined_but_not_used is_unused_local :: GlobalRdrElt -> Bool is_unused_local gre = isLocalGRE gre && isExternalName (gre_name gre) - - unused_imports :: [GlobalRdrElt] - unused_imports = mapCatMaybes unused_imp defined_but_not_used - unused_imp :: GlobalRdrElt -> Maybe GlobalRdrElt -- Result has trimmed Imported provenances - unused_imp (GRE {gre_prov = LocalDef}) = Nothing - unused_imp gre@(GRE {gre_prov = Imported imp_specs}) - | null trimmed_specs = Nothing - | otherwise = Just (gre {gre_prov = Imported trimmed_specs}) - where - trimmed_specs = filter report_if_unused imp_specs - - -- To figure out the minimal set of imports, start with the things - -- that are in scope (i.e. in gbl_env). Then just combine them - -- into a bunch of avails, so they are properly grouped - -- - -- BUG WARNING: this does not deal properly with qualified imports! - minimal_imports :: FiniteMap ModuleName AvailEnv - minimal_imports0 = foldr add_expall emptyFM expall_mods - minimal_imports1 = foldr add_name minimal_imports0 defined_and_used - minimal_imports = foldr add_inst_mod minimal_imports1 direct_import_mods - -- The last line makes sure that we retain all direct imports - -- even if we import nothing explicitly. - -- It's not necessarily redundant to import such modules. Consider - -- module This - -- import M () - -- - -- The import M() is not *necessarily* redundant, even if - -- we suck in no instance decls from M (e.g. it contains - -- no instance decls, or This contains no code). It may be - -- that we import M solely to ensure that M's orphan instance - -- decls (or those in its imports) are visible to people who - -- import This. Sigh. - -- There's really no good way to detect this, so the error message - -- in RnEnv.warnUnusedModules is weakened instead - - -- We've carefully preserved the provenance so that we can - -- construct minimal imports that import the name by (one of) - -- the same route(s) as the programmer originally did. - add_name gre@(GRE {gre_prov = Imported (imp_spec:_)}) acc - = addToFM_C plusAvailEnv acc - (importSpecModule imp_spec) (unitAvailEnv (greAvail gre)) - add_name _ acc = acc -- Local - - -- Modules mentioned as 'module M' in the export list - expall_mods = case export_decls of - Nothing -> [] - Just es -> [m | L _ (IEModuleContents m) <- es] - - -- This is really bogus. The idea is that if we see 'module M' in - -- the export list we must retain the import decls that drive it - -- If we aren't careful we might see - -- module A( module M ) where - -- import M - -- import N - -- and suppose that N exports everything that M does. Then we - -- must not drop the import of M even though N brings it all into - -- scope. - -- - -- BUG WARNING: 'module M' exports aside, what if M.x is mentioned?! - -- - -- The reason that add_expall is bogus is that it doesn't take - -- qualified imports into account. But it's an improvement. - add_expall mod acc = addToFM_C plusAvailEnv acc mod emptyAvailEnv +\end{code} + +%********************************************************* +%* * + Unused imports +%* * +%********************************************************* + +This code finds which import declarations are unused. The +specification and implementation notes are here: + http://hackage.haskell.org/trac/ghc/wiki/Commentary/Compiler/UnusedImports + +\begin{code} +type ImportDeclUsage + = ( LImportDecl Name -- The import declaration + , [AvailInfo] -- What *is* used (normalised) + , [Name] ) -- What is imported but *not* used +\end{code} + +\begin{code} +warnUnusedImportDecls :: TcGblEnv -> RnM () +warnUnusedImportDecls gbl_env + = do { uses <- readMutVar (tcg_used_rdrnames gbl_env) + ; let imports = filter explicit_import (tcg_rn_imports gbl_env) + rdr_env = tcg_rdr_env gbl_env + + ; let usage :: [ImportDeclUsage] + usage = findImportUsage imports rdr_env (Set.elems uses) + + ; ifOptM Opt_WarnUnusedImports $ + mapM_ warnUnusedImport usage + + ; ifOptM Opt_D_dump_minimal_imports $ + printMinimalImports usage } + where + explicit_import (L loc _) = isGoodSrcSpan loc + -- Filter out the implicit Prelude import + -- which we do not want to bleat about +\end{code} + +\begin{code} +findImportUsage :: [LImportDecl Name] + -> GlobalRdrEnv + -> [RdrName] + -> [ImportDeclUsage] + +type ImportMap = FiniteMap SrcLoc [AvailInfo] + -- The intermediate data struture records, for each import + -- declaration, what stuff brought into scope by that + -- declaration is actually used in the module. + -- + -- The SrcLoc is the location of the start + -- of a particular 'import' declaration + -- + -- The AvailInfos are the things imported from that decl + -- (just a list, not normalised) + +findImportUsage imports rdr_env rdrs + = map unused_decl imports + where + import_usage :: ImportMap + import_usage = foldr add_rdr emptyFM rdrs - add_inst_mod (mod, _) acc - | mod_name `elemFM` acc = acc -- We import something already - | otherwise = addToFM acc mod_name emptyAvailEnv + unused_decl decl@(L loc (ImportDecl { ideclHiding = imps })) + = (decl, nubAvails used_avails, unused_imps) where - mod_name = moduleName mod - -- Add an empty collection of imports for a module - -- from which we have sucked only instance decls - - imports = tcg_imports gbl_env - - direct_import_mods :: [(Module, [(ModuleName, Bool, SrcSpan)])] - -- See the type of the imp_mods for this triple - direct_import_mods = fmToList (imp_mods imports) - - -- unused_imp_mods are the directly-imported modules - -- that are not mentioned in minimal_imports1 - -- [Note: not 'minimal_imports', because that includes directly-imported - -- modules even if we use nothing from them; see notes above] - -- - -- BUG WARNING: this code is generally buggy - unused_imp_mods :: [(ModuleName, SrcSpan)] - unused_imp_mods = [(mod_name,loc) - | (mod, xs) <- direct_import_mods, - (_, no_imp, loc) <- xs, - let mod_name = moduleName mod, - not (mod_name `elemFM` minimal_imports1), - moduleName mod /= pRELUDE_NAME, - -- XXX not really correct, but we don't want - -- to generate warnings when compiling against - -- a compat version of base. - not no_imp] - -- The not no_imp part is not to complain about - -- import M (), which is an idiom for importing - -- instance declarations - - module_unused :: ModuleName -> Bool - module_unused mod = any (((==) mod) . fst) unused_imp_mods - - report_if_unused :: ImportSpec -> Bool - -- Do we want to report this as an unused import? - report_if_unused (ImpSpec {is_decl = d, is_item = i}) - = not (module_unused (is_mod d)) -- Not if we've already said entire import is unused - && isExplicitItem i -- Only if the import was explicit + used_avails = lookupFM import_usage (srcSpanStart loc) `orElse` [] + used_names = availsToNameSet used_avails + + unused_imps = case imps of + Just (False, imp_ies) -> nameSetToList unused_imps + where + imp_names = mkNameSet (concatMap (ieNames . unLoc) imp_ies) + unused_imps = imp_names `minusNameSet` used_names + + _other -> [] -- No explicit import list => no unused-name list ---------------------- -warnDuplicateImports :: [GlobalRdrElt] -> RnM () --- Given the GREs for names that are used, figure out which imports --- could be omitted without changing the top-level environment. --- --- NB: Given import Foo( T ) --- import qualified Foo --- we do not report a duplicate import, even though Foo.T is brought --- into scope by both, because there's nothing you can *omit* without --- changing the top-level environment. So we complain only if it's --- explicitly named in both imports or neither. --- --- Furthermore, we complain about Foo.T only if --- there is no complaint about (unqualified) T - -warnDuplicateImports gres - = ifOptM Opt_WarnUnusedImports $ - sequence_ [ warn name pr - | GRE { gre_name = name, gre_prov = Imported imps } <- gres - , pr <- redundants imps ] + add_rdr :: RdrName -> ImportMap -> ImportMap + add_rdr rdr iu + = case lookupGRE_RdrName rdr rdr_env of + [gre] | Imported imps <- gre_prov gre + -> add_imp gre (bestImport imps) iu + _other -> iu + + add_imp :: GlobalRdrElt -> ImportSpec -> ImportMap -> ImportMap + add_imp gre (ImpSpec { is_decl = imp_decl_spec }) iu + = addToFM_C add iu decl_loc [avail] + where + add avails _ = avail : avails + decl_loc = srcSpanStart (is_dloc imp_decl_spec) + name = gre_name gre + avail = case gre_par gre of + ParentIs p -> AvailTC p [p,name] + NoParent | isTyConName name -> AvailTC name [name] + | otherwise -> Avail name + -- If you use (+) from Num, then for this purpose we want + -- to say that Num is used as well. That is why in the + -- ParentIs case we have [p,name] in the ParentIs case + +bestImport :: [ImportSpec] -> ImportSpec +bestImport iss + = case partition isImpAll iss of + ([], imp_somes) -> textuallyFirst imp_somes + (imp_alls, _) -> textuallyFirst imp_alls + +textuallyFirst :: [ImportSpec] -> ImportSpec +textuallyFirst iss = case sortWith (is_dloc . is_decl) iss of + [] -> pprPanic "textuallyFirst" (ppr iss) + (is:_) -> is + +isImpAll :: ImportSpec -> Bool +isImpAll (ImpSpec { is_item = ImpAll }) = True +isImpAll _other = False +\end{code} + +\begin{code} +warnUnusedImport :: ImportDeclUsage -> RnM () +warnUnusedImport (L loc decl, used, unused) + | Just (False,[]) <- ideclHiding decl + = return () -- Do not warn for 'import M()' + | null used = addWarnAt loc msg1 -- Nothing used; drop entire decl + | null unused = return () -- Everything imported is used; nop + | otherwise = addWarnAt loc msg2 -- Some imports are unused where - warn name (red_imp, cov_imp) - = addWarnAt (importSpecLoc red_imp) - (vcat [ptext (sLit "Redundant import of:") <+> quotes pp_name, - ptext (sLit "It is also") <+> ppr cov_imp]) - where - pp_name | is_qual red_decl = ppr (is_as red_decl) <> dot <> ppr occ - | otherwise = ppr occ - occ = nameOccName name - red_decl = is_decl red_imp - - redundants :: [ImportSpec] -> [(ImportSpec,ImportSpec)] - -- The returned pair is (redundant-import, covering-import) - redundants imps - = [ (red_imp, cov_imp) - | red_imp <- imps - , isExplicitItem (is_item red_imp) - -- Complain only about redundant imports - -- mentioned explicitly by the user - , cov_imp <- take 1 (filter (covers red_imp) imps) ] - -- The 'take 1' picks the first offending group - -- for this particular name - - -- "red_imp" is a putative redundant import - -- "cov_imp" potentially covers it - -- This test decides whether red_imp could be dropped - -- - -- NOTE: currently the test does not warn about - -- import M( x ) - -- import N( x ) - -- even if the same underlying 'x' is involved, because dropping - -- either import would change the qualified names in scope (M.x, N.x) - -- But if the qualified names aren't used, the import is indeed redundant - -- Sadly we don't know that. Oh well. - covers red_imp@(ImpSpec { is_decl = red_decl }) - cov_imp@(ImpSpec { is_decl = cov_decl, is_item = cov_item }) - | red_loc == cov_loc - = False -- Ignore diagonal elements - | not (is_as red_decl == is_as cov_decl) - = False -- They bring into scope different qualified names - | not (is_qual red_decl) && is_qual cov_decl - = False -- Covering one doesn't bring unqualified name into scope - | otherwise - = not (isExplicitItem cov_item) -- Redundant one is selective and covering one isn't - || red_later -- or both are explicit; tie-break using red_later -{- - | red_selective - = not cov_selective -- Redundant one is selective and covering one isn't - || red_later -- Both are explicit; tie-break using red_later - | otherwise - = not cov_selective -- Neither import is selective - && (is_mod red_decl == is_mod cov_decl) -- They import the same module - && red_later -- Tie-break --} - where - red_loc = importSpecLoc red_imp - cov_loc = importSpecLoc cov_imp - red_later = red_loc > cov_loc - --- ToDo: deal with original imports with 'qualified' and 'as M' clauses -printMinimalImports :: FiniteMap ModuleName AvailEnv -- Minimal imports - -> RnM () -printMinimalImports imps - = ifOptM Opt_D_dump_minimal_imports $ do { - - mod_ies <- initIfaceTcRn $ mapM to_ies (fmToList imps) ; - this_mod <- getModule ; - rdr_env <- getGlobalRdrEnv ; - dflags <- getDOpts ; - liftIO $ do h <- openFile (mkFilename this_mod) WriteMode - printForUser h (mkPrintUnqualified dflags rdr_env) - (vcat (map ppr_mod_ie mod_ies)) - } + msg1 = vcat [pp_herald <+> quotes pp_mod <+> pp_not_used, + nest 2 (ptext (sLit "except perhaps to import instances from") + <+> quotes pp_mod), + ptext (sLit "To import instances alone, use:") + <+> ptext (sLit "import") <+> pp_mod <> parens empty ] + msg2 = sep [pp_herald <+> quotes (pprWithCommas ppr unused), + text "from module" <+> quotes pp_mod <+> pp_not_used] + pp_herald = text "The import of" + pp_mod = ppr (unLoc (ideclName decl)) + pp_not_used = text "is redundant" +\end{code} + +To print the minimal imports we walk over the user-supplied import +decls, and simply trim their import lists. NB that + + * We do *not* change the 'qualified' or 'as' parts! + + * We do not disard a decl altogether; we might need instances + from it. Instead we just trim to an empty import list + +\begin{code} +printMinimalImports :: [ImportDeclUsage] -> RnM () +printMinimalImports imports_w_usage + = do { imports' <- mapM mk_minimal imports_w_usage + ; this_mod <- getModule + ; liftIO $ + do { h <- openFile (mkFilename this_mod) WriteMode + ; printForUser h neverQualify (vcat (map ppr imports')) } + -- The neverQualify is important. We are printing Names + -- but they are in the context of an 'import' decl, and + -- we never qualify things inside there + -- E.g. import Blag( f, b ) + -- not import Blag( Blag.f, Blag.g )! + } where mkFilename this_mod = moduleNameString (moduleName this_mod) ++ ".imports" - ppr_mod_ie (mod_name, ies) - | mod_name == moduleName pRELUDE - = empty - | null ies -- Nothing except instances comes from here - = ptext (sLit "import") <+> ppr mod_name <> ptext (sLit "() -- Instances only") - | otherwise - = ptext (sLit "import") <+> ppr mod_name <> - parens (fsep (punctuate comma (map ppr ies))) - to_ies (mod, avail_env) = do ies <- mapM to_ie (availEnvElts avail_env) - return (mod, ies) + mk_minimal (L l decl, used, unused) + | null unused + , Just (False, _) <- ideclHiding decl + = return (L l decl) + | otherwise + = do { ies <- initIfaceTcRn $ mapM to_ie used + ; return (L l (decl { ideclHiding = Just (False, map (L l) ies) })) } to_ie :: AvailInfo -> IfG (IE Name) -- The main trick here is that if we're importing all the constructors @@ -1417,7 +1372,6 @@ printMinimalImports imps n_mod = ASSERT( isExternalName n ) nameModule n \end{code} - %************************************************************************ %* * \subsection{Errors} diff --git a/compiler/typecheck/TcRnDriver.lhs b/compiler/typecheck/TcRnDriver.lhs index 7a3eb1d..30574ae 100644 --- a/compiler/typecheck/TcRnDriver.lhs +++ b/compiler/typecheck/TcRnDriver.lhs @@ -236,7 +236,7 @@ tcRnImports hsc_env this_mod import_decls gbl { tcg_rdr_env = plusOccEnv (tcg_rdr_env gbl) rdr_env, tcg_imports = tcg_imports gbl `plusImportAvails` imports, - tcg_rn_imports = fmap (const rn_imports) (tcg_rn_imports gbl), + tcg_rn_imports = rn_imports, tcg_inst_env = extendInstEnvList (tcg_inst_env gbl) home_insts, tcg_fam_inst_env = extendFamInstEnvList (tcg_fam_inst_env gbl) home_fam_insts, diff --git a/compiler/typecheck/TcRnMonad.lhs b/compiler/typecheck/TcRnMonad.lhs index 1de7404..dbe822a 100644 --- a/compiler/typecheck/TcRnMonad.lhs +++ b/compiler/typecheck/TcRnMonad.lhs @@ -73,6 +73,7 @@ initTc hsc_env hsc_src keep_rn_syntax mod do_this tvs_var <- newIORef emptyVarSet ; dfuns_var <- newIORef emptyNameSet ; keep_var <- newIORef emptyNameSet ; + used_rdrnames_var <- newIORef Set.empty ; th_var <- newIORef False ; dfun_n_var <- newIORef 1 ; type_env_var <- case hsc_type_env_var hsc_env of { @@ -98,9 +99,10 @@ initTc hsc_env hsc_src keep_rn_syntax mod do_this tcg_th_used = th_var, tcg_exports = [], tcg_imports = emptyImportAvails, + tcg_used_rdrnames = used_rdrnames_var, tcg_dus = emptyDUs, - tcg_rn_imports = maybe_rn_syntax [], + tcg_rn_imports = [], tcg_rn_exports = maybe_rn_syntax [], tcg_rn_decls = maybe_rn_syntax emptyRnGroup, diff --git a/compiler/typecheck/TcRnTypes.lhs b/compiler/typecheck/TcRnTypes.lhs index cbc0fe4..c8d7550 100644 --- a/compiler/typecheck/TcRnTypes.lhs +++ b/compiler/typecheck/TcRnTypes.lhs @@ -70,6 +70,7 @@ import FastString import Data.Maybe import Data.List +import Data.Set (Set) \end{code} @@ -236,8 +237,11 @@ data TcGblEnv -- The binds, rules and foreign-decl fiels are collected -- initially in un-zonked form and are finally zonked in tcRnSrcDecls - tcg_rn_imports :: Maybe [LImportDecl Name], tcg_rn_exports :: Maybe [Located (IE Name)], + tcg_rn_imports :: [LImportDecl Name], + -- Keep the renamed imports regardless. They are not + -- voluminous and are needed if you want to report unused imports + tcg_used_rdrnames :: TcRef (Set RdrName), tcg_rn_decls :: Maybe (HsGroup Name), -- ^ Renamed decls, maybe. @Nothing@ <=> Don't retain renamed -- decls. -- 1.7.10.4