{-# LANGUAGE CPP #-}{-# LANGUAGE LambdaCase #-}{-# LANGUAGE NondecreasingIndentation #-}{-# LANGUAGE GeneralizedNewtypeDeriving #-}{-# LANGUAGE ScopedTypeVariables #-}{-# LANGUAGE TypeFamilies #-}moduleTcBackpack(findExtraSigImports' ,findExtraSigImports ,implicitRequirements' ,implicitRequirements ,checkUnitId ,tcRnCheckUnitId ,tcRnMergeSignatures ,mergeSignatures ,tcRnInstantiateSignature ,instantiateSignature ,)whereimportGhcPrelude importBasicTypes (defaultFixity )importPackages importTcRnExports importDynFlags importHsSyn importRdrName importTcRnMonad importTcTyDecls importInstEnv importFamInstEnv importInst importTcIface importTcMType importTcType importTcSimplify importLoadIface importRnNames importErrUtils importId importModule importName importNameEnv importNameSet importAvail importSrcLoc importHscTypes importOutputable importType importFastString importRnFixity (lookupFixityRn )importMaybes importTcEnv importVar importIfaceSyn importPrelNames importqualifiedData.MapasMapimportFinder importUniqDSet importNameShape importTcErrors importTcUnify importRnModIface importUtil importControl.MonadimportData.List(find)import{-# SOURCE#-}TcRnDriver #include "HsVersions.h"
fixityMisMatch::TyThing ->Fixity ->Fixity ->SDoc fixityMisMatch real_thing real_fixity sig_fixity =vcat [ppr real_thing <+> text "has conflicting fixities in the module",text "and its hsig file",text "Main module:"<+> ppr_fix real_fixity ,text "Hsig file:"<+> ppr_fix sig_fixity ]whereppr_fix f =ppr f <+> (iff ==defaultFixity thenparens (text "default")elseempty )checkHsigDeclM::ModIface ->TyThing ->TyThing ->TcRn ()checkHsigDeclM sig_iface sig_thing real_thing =doletname =getName real_thing -- TODO: Distinguish between signature merging and signature-- implementation cases.checkBootDeclM Falsesig_thing real_thing real_fixity <-lookupFixityRn name letsig_fixity =casemi_fix_fnsig_iface (occName name )ofNothing->defaultFixity Justf ->f when(real_fixity /=sig_fixity )$addErrAt (nameSrcSpan name )(fixityMisMatch real_thing real_fixity sig_fixity )-- | Given a 'ModDetails' of an instantiated signature (note that the-- 'ModDetails' must be knot-tied consistently with the actual implementation)-- and a 'GlobalRdrEnv' constructed from the implementor of this interface,-- verify that the actual implementation actually matches the original-- interface.---- Note that it is already assumed that the implementation *exports*-- a sufficient set of entities, since otherwise the renaming and then-- typechecking of the signature 'ModIface' would have failed.checkHsigIface::TcGblEnv ->GlobalRdrEnv ->ModIface ->ModDetails ->TcRn ()checkHsigIface tcg_env gr sig_iface ModDetails {md_insts=sig_insts ,md_fam_insts=sig_fam_insts ,md_types=sig_type_env ,md_exports=sig_exports }=dotraceTc "checkHsigIface"$vcat [ppr sig_type_env ,ppr sig_insts ,ppr sig_exports ]mapM_check_export (mapavailName sig_exports )unless(nullsig_fam_insts )$panic ("TcRnDriver.checkHsigIface: Cannot handle family "++"instances in hsig files yet...")-- Delete instances so we don't look them up when-- checking instance satisfiability-- TODO: this should not be necessarytcg_env <-getGblEnv setGblEnv tcg_env {tcg_inst_env=emptyInstEnv ,tcg_fam_inst_env=emptyFamInstEnv ,tcg_insts=[],tcg_fam_insts=[]}$domapM_check_inst sig_insts failIfErrsM where-- NB: the Names in sig_type_env are bogus. Let's say we have H.hsig-- in package p that defines T; and we implement with himpl:H. Then the-- Name is p[himpl:H]:H.T, NOT himplH:H.T. That's OK but we just-- have to look up the right name.sig_type_occ_env =mkOccEnv .map(\t ->(nameOccName (getName t ),t ))$nameEnvElts sig_type_env dfun_names =mapgetName sig_insts check_export name -- Skip instances, we'll check them later-- TODO: Actually this should never happen, because DFuns are-- never exported...|name `elem`dfun_names =return()-- See if we can find the type directly in the hsig ModDetails-- TODO: need to special case wired in names|Justsig_thing <-lookupOccEnv sig_type_occ_env (nameOccName name )=do-- NB: We use tcLookupImported_maybe because we want to EXCLUDE-- tcg_env (TODO: but maybe this isn't relevant anymore).r <-tcLookupImported_maybe name caser ofFailed err ->addErr err Succeeded real_thing ->checkHsigDeclM sig_iface sig_thing real_thing -- The hsig did NOT define this function; that means it must-- be a reexport. In this case, make sure the 'Name' of the-- reexport matches the 'Name exported here.|[GRE {gre_name=name' }]<-lookupGlobalRdrEnv gr (nameOccName name )=when(name /=name' )$do-- See Note [Error reporting bad reexport]-- TODO: Actually this error swizzle doesn't workletp (L _ie )=name `elem`ieNames ie loc =casetcg_rn_exportstcg_env ofJustes |Juste <-findp (mapfstes )-- TODO: maybe we can be a little more-- precise here and use the Located-- info for the *specific* name we matched.->getLoc e _->nameSrcSpan name dflags <-getDynFlags addErrAt loc (badReexportedBootThing dflags Falsename name' )-- This should actually never happen, but whatever...|otherwise=addErrAt (nameSrcSpan name )(missingBootThing Falsename "exported by")-- Note [Error reporting bad reexport]-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~-- NB: You want to be a bit careful about what location you report on reexports.-- If the name was declared in the hsig file, 'nameSrcSpan name' is indeed the-- correct source location. However, if it was *reexported*, obviously the name-- is not going to have the right location. In this case, we need to grovel in-- tcg_rn_exports to figure out where the reexport came from.-- | Checks if a 'ClsInst' is "defined". In general, for hsig files we can't-- assume that the implementing file actually implemented the instances (they-- may be reexported from elsewhere). Where should we look for the instances?-- We do the same as we would otherwise: consult the EPS. This isn't perfect-- (we might conclude the module exports an instance when it doesn't, see-- #9422), but we will never refuse to compile something.check_inst::ClsInst ->TcM ()check_inst sig_inst =do-- TODO: This could be very well generalized to support instance-- declarations in boot files.tcg_env <-getGblEnv -- NB: Have to tug on the interface, not necessarily-- tugged... but it didn't work?mapM_tcLookupImported_maybe (nameSetElemsStable (orphNamesOfClsInst sig_inst ))-- Based off of 'simplifyDeriv'letty =idType (instanceDFunId sig_inst )skol_info =InstSkol -- Based off of tcSplitDFunTy(tvs ,theta ,pred )=casetcSplitForAllTys ty of{(tvs ,rho )->casesplitFunTys rho of{(theta ,pred )->(tvs ,theta ,pred )}}origin =InstProvidedOrigin (tcg_semantic_modtcg_env )sig_inst (skol_subst ,tvs_skols )<-tcInstSkolTyVars tvs -- Skolemize(tclvl ,cts )<-pushTcLevelM $dowanted <-newWanted origin (JustTypeLevel )(substTy skol_subst pred )givens <-forMtheta $\given ->doloc <-getCtLocM origin (JustTypeLevel )letgiven_pred =substTy skol_subst given new_ev <-newEvVar given_pred returnCtGiven {ctev_pred=given_pred -- Doesn't matter, make something up,ctev_evar=new_ev ,ctev_loc=loc }return$wanted :givens unsolved <-simplifyWantedsTcM cts (implic ,_)<-buildImplicationFor tclvl skol_info tvs_skols []unsolved reportAllUnsolved (mkImplicWC implic )-- | Return this list of requirement interfaces that need to be merged-- to form @mod_name@, or @[]@ if this is not a requirement.requirementMerges::DynFlags ->ModuleName ->[IndefModule ]requirementMerges dflags mod_name =fromMaybe[](Map.lookupmod_name (requirementContext(pkgStatedflags )))-- | For a module @modname@ of type 'HscSource', determine the list-- of extra "imports" of other requirements which should be considered part of-- the import of the requirement, because it transitively depends on those-- requirements by imports of modules from other packages. The situation-- is something like this:---- unit p where-- signature A-- signature B-- import A---- unit q where-- dependency p[A=<A>,B=<B>]-- signature A-- signature B---- Although q's B does not directly import A, we still have to make sure we-- process A first, because the merging process will cause B to indirectly-- import A. This function finds the TRANSITIVE closure of all such imports-- we need to make.findExtraSigImports'::HscEnv ->HscSource ->ModuleName ->IO(UniqDSet ModuleName )findExtraSigImports' hsc_env HsigFile modname =fmapunionManyUniqDSets (forMreqs $\(IndefModule iuid mod_name )->(initIfaceLoad hsc_env .withException $moduleFreeHolesPrecise (text "findExtraSigImports")(mkModule (IndefiniteUnitId iuid )mod_name )))wherereqs =requirementMerges (hsc_dflagshsc_env )modname findExtraSigImports'___=returnemptyUniqDSet -- | 'findExtraSigImports', but in a convenient form for "GhcMake" and-- "TcRnDriver".findExtraSigImports::HscEnv ->HscSource ->ModuleName ->IO[(MaybeFastString ,Located ModuleName )]findExtraSigImports hsc_env hsc_src modname =doextra_requirements <-findExtraSigImports' hsc_env hsc_src modname return[(Nothing,noLoc mod_name )|mod_name <-uniqDSetToList extra_requirements ]-- A version of 'implicitRequirements'' which is more friendly-- for "GhcMake" and "TcRnDriver".implicitRequirements::HscEnv ->[(MaybeFastString ,Located ModuleName )]->IO[(MaybeFastString ,Located ModuleName )]implicitRequirements hsc_env normal_imports =domns <-implicitRequirements' hsc_env normal_imports return[(Nothing,noLoc mn )|mn <-mns ]-- Given a list of 'import M' statements in a module, figure out-- any extra implicit requirement imports they may have. For-- example, if they 'import M' and M resolves to p[A=<B>], then-- they actually also import the local requirement B.implicitRequirements'::HscEnv ->[(MaybeFastString ,Located ModuleName )]->IO[ModuleName ]implicitRequirements' hsc_env normal_imports =fmapconcat$forMnormal_imports $\(mb_pkg ,L _imp )->dofound <-findImportedModule hsc_env imp mb_pkg casefound ofFound _mod |thisPackage dflags /=moduleUnitIdmod ->return(uniqDSetToList (moduleFreeHoles mod ))_->return[]wheredflags =hsc_dflagshsc_env -- | Given a 'UnitId', make sure it is well typed. This is because-- unit IDs come from Cabal, which does not know if things are well-typed or-- not; a component may have been filled with implementations for the holes-- that don't actually fulfill the requirements.---- INVARIANT: the UnitId is NOT a InstalledUnitIdcheckUnitId::UnitId ->TcM ()checkUnitId uid =docasesplitUnitIdInsts uid of(_,Justindef )->letinsts =indefUnitIdInstsindef inforM_insts $\(mod_name ,mod )->-- NB: direct hole instantiations are well-typed by construction-- (because we FORCE things to be merged in), so don't check themwhen(not(isHoleModule mod ))$docheckUnitId (moduleUnitIdmod )_<-mod `checkImplements `IndefModule indef mod_name return()_->return()-- if it's hashed, must be well-typed-- | Top-level driver for signature instantiation (run when compiling-- an @hsig@ file.)tcRnCheckUnitId::HscEnv ->UnitId ->IO(Messages ,Maybe())tcRnCheckUnitId hsc_env uid =withTiming (puredflags )(text "Check unit id"<+> ppr uid )(const())$initTc hsc_env HsigFile -- bogusFalsemAIN -- bogus(realSrcLocSpan (mkRealSrcLoc (fsLit loc_str )00))-- bogus$checkUnitId uid wheredflags =hsc_dflagshsc_env loc_str ="Command line argument: -unit-id "++showSDoc dflags (ppr uid )-- TODO: Maybe lcl_iface0 should be pre-renamed to the right thing? Unclear...-- | Top-level driver for signature merging (run after typechecking-- an @hsig@ file).tcRnMergeSignatures::HscEnv ->HsParsedModule ->TcGblEnv {- from local sig -}->ModIface ->IO(Messages ,MaybeTcGblEnv )tcRnMergeSignatures hsc_env hpm orig_tcg_env iface =withTiming (puredflags )(text "Signature merging"<+> brackets (ppr this_mod ))(const())$initTc hsc_env HsigFile Falsethis_mod real_loc $mergeSignatures hpm orig_tcg_env iface wheredflags =hsc_dflagshsc_env this_mod =mi_moduleiface real_loc =tcg_top_locorig_tcg_env thinModIface::[AvailInfo ]->ModIface ->ModIface thinModIface avails iface =iface {mi_exports=avails ,-- mi_fixities = ...,-- mi_warns = ...,-- mi_anns = ...,-- TODO: The use of nameOccName here is a bit dodgy, because-- perhaps there might be two IfaceTopBndr that are the same-- OccName but different Name. Requires better understanding-- of invariants here.mi_decls=exported_decls ++non_exported_decls ++dfun_decls -- mi_insts = ...,-- mi_fam_insts = ...,}wheredecl_pred occs decl =nameOccName (ifNamedecl )`elemOccSet `occs filter_decls occs =filter(decl_pred occs .snd)(mi_declsiface )exported_occs =mkOccSet [occName n |a <-avails ,n <-availNames a ]exported_decls =filter_decls exported_occs non_exported_occs =mkOccSet [occName n |(_,d )<-exported_decls ,n <-ifaceDeclNeverExportedRefs d ]non_exported_decls =filter_decls non_exported_occs dfun_pred IfaceId {ifIdDetails=IfDFunId }=Truedfun_pred_=Falsedfun_decls =filter(dfun_pred .snd)(mi_declsiface )-- | The list of 'Name's of *non-exported* 'IfaceDecl's which this-- 'IfaceDecl' may refer to. A non-exported 'IfaceDecl' should be kept-- after thinning if an *exported* 'IfaceDecl' (or 'mi_insts', perhaps)-- refers to it; we can't decide to keep it by looking at the exports-- of a module after thinning. Keep this synchronized with-- 'rnIfaceDecl'.ifaceDeclNeverExportedRefs::IfaceDecl ->[Name ]ifaceDeclNeverExportedRefs d @IfaceFamily {}=caseifFamFlavd ofIfaceClosedSynFamilyTyCon (Just(n ,_))->[n ]_->[]ifaceDeclNeverExportedRefs_=[]-- Note [Blank hsigs for all requirements]-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~-- One invariant that a client of GHC must uphold is that there-- must be an hsig file for every requirement (according to-- @-this-unit-id@); this ensures that for every interface-- file (hi), there is a source file (hsig), which helps grease-- the wheels of recompilation avoidance which assumes that-- source files always exist.{-
inheritedSigPvpWarning :: WarningTxt
inheritedSigPvpWarning =
 WarningTxt (noLoc NoSourceText) [noLoc (StringLiteral NoSourceText (fsLit msg))]
 where
 msg = "Inherited requirements from non-signature libraries (libraries " ++
 "with modules) should not be used, as this mode of use is not " ++
 "compatible with PVP-style version bounds. Instead, copy the " ++
 "declaration to the local hsig file or move the signature to a " ++
 "library of its own and add that library as a dependency."
-}-- Note [Handling never-exported TyThings under Backpack]-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~-- DEFINITION: A "never-exported TyThing" is a TyThing whose 'Name' will-- never be mentioned in the export list of a module (mi_avails).-- Unlike implicit TyThings (Note [Implicit TyThings]), non-exported-- TyThings DO have a standalone IfaceDecl declaration in their-- interface file.---- Originally, Backpack was designed under the assumption that anything-- you could declare in a module could also be exported; thus, merging-- the export lists of two signatures is just merging the declarations-- of two signatures writ small. Of course, in GHC Haskell, there are a-- few important things which are not explicitly exported but still can-- be used: in particular, dictionary functions for instances, Typeable-- TyCon bindings, and coercion axioms for type families also count.---- When handling these non-exported things, there two primary things-- we need to watch out for:---- * Signature matching/merging is done by comparing each-- of the exported entities of a signature and a module. These exported-- entities may refer to non-exported TyThings which must be tested for-- consistency. For example, an instance (ClsInst) will refer to a-- non-exported DFunId. In this case, 'checkBootDeclM' directly compares the-- embedded 'DFunId' in 'is_dfun'.---- For this to work at all, we must ensure that pointers in 'is_dfun' refer-- to DISTINCT 'DFunId's, even though the 'Name's (may) be the same.-- Unfortunately, this is the OPPOSITE of how we treat most other references-- to 'Name's, so this case needs to be handled specially.---- The details are in the documentation for 'typecheckIfacesForMerging'.-- and the Note [Resolving never-exported Names in TcIface].---- * When we rename modules and signatures, we use the export lists to-- decide how the declarations should be renamed. However, this-- means we don't get any guidance for how to rename non-exported-- entities. Fortunately, we only need to rename these entities-- *consistently*, so that 'typecheckIfacesForMerging' can wire them-- up as needed.---- The details are in Note [rnIfaceNeverExported] in 'RnModIface'.---- The root cause for all of these complications is the fact that these-- logically "implicit" entities are defined indirectly in an interface-- file. #13151 gives a proposal to make these *truly* implicit.merge_msg::ModuleName ->[IndefModule ]->SDoc merge_msg mod_name []=text "while checking the local signature"<+> ppr mod_name <+> text "for consistency"merge_msgmod_name reqs =hang (text "while merging the signatures from"<> colon )2(vcat [bullet <+> ppr req |req <-reqs ]$$ bullet <+> text "...and the local signature for"<+> ppr mod_name )-- | Given a local 'ModIface', merge all inherited requirements-- from 'requirementMerges' into this signature, producing-- a final 'TcGblEnv' that matches the local signature and-- all required signatures.mergeSignatures::HsParsedModule ->TcGblEnv ->ModIface ->TcRn TcGblEnv mergeSignatures (HsParsedModule {hpm_module=L loc (HsModule {hsmodExports=mb_exports }),hpm_src_files=src_files })orig_tcg_env lcl_iface0 =setSrcSpan loc $do-- The lcl_iface0 is the ModIface for the local hsig-- file, which is guaranteed to exist, see-- Note [Blank hsigs for all requirements]hsc_env <-getTopEnv dflags <-getDynFlags -- Copy over some things from the original TcGblEnv that-- we want to preserveupdGblEnv (\env ->env {-- Renamed imports/declarations are often used-- by programs that use the GHC API, e.g., Haddock.-- These won't get filled by the merging process (since-- we don't actually rename the parsed module again) so-- we need to take them directly from the previous-- typechecking.---- NB: the export declarations aren't in their final-- form yet. We'll fill those in when we reprocess-- the export declarations.tcg_rn_imports=tcg_rn_importsorig_tcg_env ,tcg_rn_decls=tcg_rn_declsorig_tcg_env ,-- Annotationstcg_ann_env=tcg_ann_envorig_tcg_env ,-- Documentation headertcg_doc_hdr=tcg_doc_hdrorig_tcg_env -- tcg_dus?-- tcg_th_used = tcg_th_used orig_tcg_env,-- tcg_th_splice_used = tcg_th_splice_used orig_tcg_env-- tcg_th_top_level_locs = tcg_th_top_level_locs orig_tcg_env})$dotcg_env <-getGblEnv letouter_mod =tcg_modtcg_env inner_mod =tcg_semantic_modtcg_env mod_name =moduleName(tcg_modtcg_env )-- STEP 1: Figure out all of the external signature interfaces-- we are going to merge in.letreqs =requirementMerges dflags mod_name addErrCtxt (merge_msg mod_name reqs )$do-- STEP 2: Read in the RAW forms of all of these interfacesireq_ifaces0 <-forMreqs $\(IndefModule iuid mod_name )->letm =mkModule (IndefiniteUnitId iuid )mod_name im =fst(splitModuleInsts m )infmapfst.withException $findAndReadIface (text "mergeSignatures")im m False-- STEP 3: Get the unrenamed exports of all these interfaces,-- thin it according to the export list, and do shaping on them.letextend_ns nsubst as=liftIO$extendNameShape hsc_env nsubst as-- This function gets run on every inherited interface, and-- it's responsible for:---- 1. Merging the exports of the interface into @nsubst@,-- 2. Adding these exports to the "OK to import" set (@oks@)-- if they came from a package with no exposed modules-- (this means we won't report a PVP error in this case), and-- 3. Thinning the interface according to an explicit export-- list.--gen_subst (nsubst ,oks ,ifaces )(imod @(IndefModule iuid _),ireq_iface )=doletinsts =indefUnitIdInstsiuid isFromSignaturePackage =letinst_uid =fst(splitUnitIdInsts (IndefiniteUnitId iuid ))pkg =getInstalledPackageDetails dflags inst_uid innull(exposedModulespkg )-- 3(a). Rename the exports according to how the dependency-- was instantiated. The resulting export list will be accurate-- except for exports *from the signature itself* (which may-- be subsequently updated by exports from other signatures in-- the merge.as1 <-tcRnModExports insts ireq_iface -- 3(b). Thin the interface if it comes from a signature package.(thinned_iface ,as2 )<-casemb_exports ofJust(L loc _)-- Check if the package containing this signature is-- a signature package (i.e., does not expose any-- modules.) If so, we can thin it.|isFromSignaturePackage ->setSrcSpan loc $do-- Suppress missing errors; they might be used to refer-- to entities from other signatures we are merging in.-- If an identifier truly doesn't exist in any of the-- signatures that are merged in, we will discover this-- when we run exports_from_avail on the final merged-- export list.(msgs ,mb_r )<-tryTc $do-- Suppose that we have written in a signature:-- signature A ( module A ) where {- empty -}-- If I am also inheriting a signature from a-- signature package, does 'module A' scope over-- all of its exports?---- There are two possible interpretations:---- 1. For non self-reexports, a module reexport-- is interpreted only in terms of the local-- signature module, and not any of the inherited-- ones. The reason for this is because after-- typechecking, module exports are completely-- erased from the interface of a file, so we-- have no way of "interpreting" a module reexport.-- Thus, it's only useful for the local signature-- module (where we have a useful GlobalRdrEnv.)---- 2. On the other hand, a common idiom when-- you want to "export everything, plus a reexport"-- in modules is to say module A ( module A, reex ).-- This applies to signature modules too; and in-- particular, you probably still want the entities-- from the inherited signatures to be preserved-- too.---- We think it's worth making a special case for-- self reexports to make use case (2) work. To-- do this, we take the exports of the inherited-- signature @as1@, and bundle them into a-- GlobalRdrEnv where we treat them as having come-- from the import @import A@. Thus, we will-- pick them up if they are referenced explicitly-- (@foo@) or even if we do a module reexport-- (@module A@).letispec =ImpSpec ImpDeclSpec {-- NB: This needs to be mod name-- of the local signature, not-- the (original) module name of-- the inherited signature,-- because we need module-- LocalSig (from the local-- export list) to match it!is_mod=mod_name ,is_as=mod_name ,is_qual=False,is_dloc=loc }ImpAll rdr_env =mkGlobalRdrEnv (gresFromAvails (Justispec )as1 )setGblEnv tcg_env {tcg_rdr_env=rdr_env }$exports_from_avail mb_exports rdr_env -- NB: tcg_imports is also empty!emptyImportAvails (tcg_semantic_modtcg_env )casemb_r ofJust(_,as2 )->return(thinModIface as2 ireq_iface ,as2 )Nothing->addMessages msgs >>failM -- We can't think signatures from non signature packages_->return(ireq_iface ,as1 )-- 3(c). Only identifiers from signature packages are "ok" to-- import (that is, they are safe from a PVP perspective.)-- (NB: This code is actually dead right now.)letoks' |isFromSignaturePackage =extendOccSetList oks (exportOccs as2 )|otherwise=oks -- 3(d). Extend the name substitution (performing shaping)mb_r <-extend_ns nsubst as2 casemb_r ofLefterr ->failWithTc err Rightnsubst' ->return(nsubst' ,oks' ,(imod ,thinned_iface ):ifaces )nsubst0 =mkNameShape (moduleNameinner_mod )(mi_exportslcl_iface0 )ok_to_use0 =mkOccSet (exportOccs (mi_exportslcl_iface0 ))-- Process each interface, getting the thinned interfaces as well as-- the final, full set of exports @nsubst@ and the exports which are-- "ok to use" (we won't attach 'inheritedSigPvpWarning' to them.)(nsubst ,ok_to_use ,rev_thinned_ifaces )<-foldMgen_subst (nsubst0 ,ok_to_use0 ,[])(zipreqs ireq_ifaces0 )letthinned_ifaces =reverserev_thinned_ifaces exports =nameShapeExports nsubst rdr_env =mkGlobalRdrEnv (gresFromAvails Nothingexports )_warn_occs =filter(not.(`elemOccSet `ok_to_use ))(exportOccs exports )warns =NoWarnings {-
 -- TODO: Warnings are transitive, but this is not what we want here:
 -- if a module reexports an entity from a signature, that should be OK.
 -- Not supported in current warning framework
 warns | null warn_occs = NoWarnings
 | otherwise = WarnSome $ map (\o -> (o, inheritedSigPvpWarning)) warn_occs
 -}setGblEnv tcg_env {-- The top-level GlobalRdrEnv is quite interesting. It consists-- of two components:-- 1. First, we reuse the GlobalRdrEnv of the local signature.-- This is very useful, because it means that if we have-- to print a message involving some entity that the local-- signature imported, we'll qualify it accordingly.-- 2. Second, we need to add all of the declarations we are-- going to merge in (as they need to be in scope for the-- final test of the export list.)tcg_rdr_env=rdr_env `plusGlobalRdrEnv `tcg_rdr_envorig_tcg_env ,-- Inherit imports from the local signature, so that module-- rexports are picked up correctlytcg_imports=tcg_importsorig_tcg_env ,tcg_exports=exports ,tcg_dus=usesOnly (availsToNameSetWithSelectors exports ),tcg_warns=warns }$dotcg_env <-getGblEnv -- Make sure we didn't refer to anything that doesn't actually exist-- pprTrace "mergeSignatures: exports_from_avail" (ppr exports) $ return ()(mb_lies ,_)<-exports_from_avail mb_exports rdr_env (tcg_importstcg_env )(tcg_semantic_modtcg_env ){- -- NB: This is commented out, because warns above is disabled.
 -- If you tried to explicitly export an identifier that has a warning
 -- attached to it, that's probably a mistake. Warn about it.
 case mb_lies of
 Nothing -> return ()
 Just lies ->
 forM_ (concatMap (\(L loc x) -> map (L loc) (ieNames x)) lies) $ \(L loc n) ->
 setSrcSpan loc $
 unless (nameOccName n `elemOccSet` ok_to_use) $
 addWarn NoReason $ vcat [
 text "Exported identifier" <+> quotes (ppr n) <+> text "will cause warnings if used.",
 parens (text "To suppress this warning, remove" <+> quotes (ppr n) <+> text "from the export list of this signature.")
 ]
 -}failIfErrsM -- Save the exportssetGblEnv tcg_env {tcg_rn_exports=mb_lies }$dotcg_env <-getGblEnv -- STEP 4: Rename the interfacesext_ifaces <-forMthinned_ifaces $\((IndefModule iuid _),ireq_iface )->tcRnModIface (indefUnitIdInstsiuid )(Justnsubst )ireq_iface lcl_iface <-tcRnModIface (thisUnitIdInsts dflags )(Justnsubst )lcl_iface0 letifaces =lcl_iface :ext_ifaces -- STEP 4.1: Merge fixities (we'll verify shortly) tcg_fix_envletfix_env =mkNameEnv [(gre_namerdr_elt ,FixItem occ f )|(occ ,f )<-concatMapmi_fixitiesifaces ,rdr_elt <-lookupGlobalRdrEnv rdr_env occ ]-- STEP 5: Typecheck the interfaceslettype_env_var =tcg_type_env_vartcg_env -- typecheckIfacesForMerging does two things:-- 1. It merges the all of the ifaces together, and typechecks the-- result to type_env.-- 2. It typechecks each iface individually, but with their 'Name's-- resolving to the merged type_env from (1).-- See typecheckIfacesForMerging for more details.(type_env ,detailss )<-initIfaceTcRn $typecheckIfacesForMerging inner_mod ifaces type_env_var letinfos =zipifaces detailss -- Test for cyclescheckSynCycles (thisPackage dflags )(typeEnvTyCons type_env )[]-- NB on type_env: it contains NO dfuns. DFuns are recorded inside-- detailss, and given a Name that doesn't correspond to anything real. See-- also Note [Signature merging DFuns]-- Add the merged type_env to TcGblEnv, so that it gets serialized-- out when we finally write out the interface.---- NB: Why do we set tcg_tcs/tcg_patsyns/tcg_type_env directly,-- rather than use tcExtendGlobalEnv (the normal method to add newly-- defined types to TcGblEnv?) tcExtendGlobalEnv adds these-- TyThings to 'tcg_type_env_var', which is consulted when-- we read in interfaces to tie the knot. But *these TyThings themselves-- come from interface*, so that would result in deadlock. Don't-- update it!setGblEnv tcg_env {tcg_tcs=typeEnvTyCons type_env ,tcg_patsyns=typeEnvPatSyns type_env ,tcg_type_env=type_env ,tcg_fix_env=fix_env }$dotcg_env <-getGblEnv -- STEP 6: Check for compatibility/merge thingstcg_env <-(\x ->foldMx tcg_env infos )$\tcg_env (iface ,details )->doletcheck_export name |Justsig_thing <-lookupTypeEnv (md_typesdetails )name =caselookupTypeEnv type_env (getName sig_thing )ofJustthing ->checkHsigDeclM iface sig_thing thing Nothing->panic "mergeSignatures: check_export"-- Oops! We're looking for this export but it's-- not actually in the type environment of the signature's-- ModDetails.---- NB: This case happens because the we're iterating-- over the union of all exports, so some interfaces-- won't have everything. Note that md_exports is nonsense-- (it's the same as exports); maybe we should fix this-- eventually.|otherwise=return()mapM_check_export (mapavailName exports )-- Note [Signature merging instances]-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~-- Merge instances into the global environment. The algorithm here is-- dumb and simple: if an instance has exactly the same DFun type-- (tested by 'memberInstEnv') as an existing instance, we drop it;-- otherwise, we add it even, even if this would cause overlap.---- Why don't we deduplicate instances with identical heads? There's no-- good choice if they have premises:---- instance K1 a => K (T a)-- instance K2 a => K (T a)---- Why not eagerly error in this case? The overlapping head does not-- necessarily mean that the instances are unimplementable: in fact,-- they may be implemented without overlap (if, for example, the-- implementing module has 'instance K (T a)'; both are implemented in-- this case.) The implements test just checks that the wanteds are-- derivable assuming the givens.---- Still, overlapping instances with hypotheses like above are going-- to be a bad deal, because instance resolution when we're typechecking-- against the merged signature is going to have a bad time when-- there are overlapping heads like this: we never backtrack, so it-- may be difficult to see that a wanted is derivable. For now,-- we hope that we get lucky / the overlapping instances never-- get used, but it is not a very good situation to be in.--letmerge_inst (insts ,inst_env )inst |memberInstEnv inst_env inst -- test DFun Type equality=(insts ,inst_env )|otherwise-- NB: is_dfun_name inst is still nonsense here,-- see Note [Signature merging DFuns]=(inst :insts ,extendInstEnv inst_env inst )(insts ,inst_env )=foldl'merge_inst (tcg_inststcg_env ,tcg_inst_envtcg_env )(md_instsdetails )-- This is a HACK to prevent calculateAvails from including imp_mod-- in the listing. We don't want it because a module is NOT-- supposed to include itself in its dep_orphs/dep_finsts. See #13214iface' =iface {mi_orphan=False,mi_finsts=False}avails =plusImportAvails (tcg_importstcg_env )$calculateAvails dflags iface' FalseFalseImportedBySystem returntcg_env {tcg_inst_env=inst_env ,tcg_insts=insts ,tcg_imports=avails ,tcg_merged=ifouter_mod ==mi_moduleiface -- Don't add ourselves!thentcg_mergedtcg_env else(mi_moduleiface ,mi_mod_hashiface ):tcg_mergedtcg_env }-- Note [Signature merging DFuns]-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~-- Once we know all of instances which will be defined by this merged-- signature, we go through each of the DFuns and rename them with a fresh,-- new, unique DFun Name, and add these DFuns to tcg_type_env (thus fixing-- up the "bogus" names that were setup in 'typecheckIfacesForMerging'.---- We can't do this fixup earlier, because we need a way to identify each-- source DFun (from each of the signatures we are merging in) so that-- when we have a ClsInst, we can pull up the correct DFun to check if-- the types match.---- See also Note [rnIfaceNeverExported] in RnModIfacedfun_insts <-forM(tcg_inststcg_env )$\inst ->don <-newDFunName (is_clsinst )(is_tysinst )(nameSrcSpan (is_dfun_nameinst ))letdfun =setVarName (is_dfuninst )n return(dfun ,inst {is_dfun_name=n ,is_dfun=dfun })tcg_env <-returntcg_env {tcg_insts=mapsnddfun_insts ,tcg_type_env=extendTypeEnvWithIds (tcg_type_envtcg_env )(mapfstdfun_insts )}addDependentFiles src_files returntcg_env -- | Top-level driver for signature instantiation (run when compiling-- an @hsig@ file.)tcRnInstantiateSignature::HscEnv ->Module ->RealSrcSpan ->IO(Messages ,MaybeTcGblEnv )tcRnInstantiateSignature hsc_env this_mod real_loc =withTiming (puredflags )(text "Signature instantiation"<+> brackets (ppr this_mod ))(const())$initTc hsc_env HsigFile Falsethis_mod real_loc $instantiateSignature wheredflags =hsc_dflagshsc_env exportOccs::[AvailInfo ]->[OccName ]exportOccs =concatMap(mapoccName .availNames )impl_msg::Module ->IndefModule ->SDoc impl_msg impl_mod (IndefModule req_uid req_mod_name )=text "while checking that"<+> ppr impl_mod <+> text "implements signature"<+> ppr req_mod_name <+> text "in"<+> ppr req_uid -- | Check if module implements a signature. (The signature is-- always un-hashed, which is why its components are specified-- explicitly.)checkImplements::Module ->IndefModule ->TcRn TcGblEnv checkImplements impl_mod req_mod @(IndefModule uid mod_name )=addErrCtxt (impl_msg impl_mod req_mod )$doletinsts =indefUnitIdInstsuid -- STEP 1: Load the implementing interface, and make a RdrEnv-- for its exports. Also, add its 'ImportAvails' to 'tcg_imports',-- so that we treat all orphan instances it provides as visible-- when we verify that all instances are checked (see #12945), and so that-- when we eventually write out the interface we record appropriate-- dependency information.impl_iface <-initIfaceTcRn $loadSysInterface (text "checkImplements 1")impl_mod letimpl_gr =mkGlobalRdrEnv (gresFromAvails Nothing(mi_exportsimpl_iface ))nsubst =mkNameShape (moduleNameimpl_mod )(mi_exportsimpl_iface )-- Load all the orphans, so the subsequent 'checkHsigIface' sees-- all the instances it needs toloadModuleInterfaces (text "Loading orphan modules (from implementor of hsig)")(dep_orphs(mi_depsimpl_iface ))dflags <-getDynFlags letavails =calculateAvails dflags impl_iface False{- safe -}False{- boot -}ImportedBySystem fix_env =mkNameEnv [(gre_namerdr_elt ,FixItem occ f )|(occ ,f )<-mi_fixitiesimpl_iface ,rdr_elt <-lookupGlobalRdrEnv impl_gr occ ]updGblEnv (\tcg_env ->tcg_env {-- Setting tcg_rdr_env to treat all exported entities from-- the implementing module as in scope improves error messages,-- as it reduces the amount of qualification we need. Unfortunately,-- we still end up qualifying references to external modules-- (see bkpfail07 for an example); we'd need to record more-- information in ModIface to solve this.tcg_rdr_env=tcg_rdr_envtcg_env `plusGlobalRdrEnv `impl_gr ,tcg_imports=tcg_importstcg_env `plusImportAvails `avails ,-- This is here so that when we call 'lookupFixityRn' for something-- directly implemented by the module, we grab the right thingtcg_fix_env=fix_env })$do-- STEP 2: Load the *unrenamed, uninstantiated* interface for-- the ORIGINAL signature. We are going to eventually rename it,-- but we must proceed slowly, because it is NOT known if the-- instantiation is correct.letsig_mod =mkModule (IndefiniteUnitId uid )mod_name isig_mod =fst(splitModuleInsts sig_mod )mb_isig_iface <-findAndReadIface (text "checkImplements 2")isig_mod sig_mod Falseisig_iface <-casemb_isig_iface ofSucceeded (iface ,_)->returniface Failed err ->failWithTc $hang (text "Could not find hi interface for signature"<+> quotes (ppr isig_mod )<> colon )4err -- STEP 3: Check that the implementing interface exports everything-- we need. (Notice we IGNORE the Modules in the AvailInfos.)forM_(exportOccs (mi_exportsisig_iface ))$\occ ->caselookupGlobalRdrEnv impl_gr occ of[]->addErr $quotes (ppr occ )<+> text "is exported by the hsig file, but not"<+> text "exported by the implementing module"<+> quotes (ppr impl_mod )_->return()failIfErrsM -- STEP 4: Now that the export is complete, rename the interface...sig_iface <-tcRnModIface insts (Justnsubst )isig_iface -- STEP 5: ...and typecheck it. (Note that in both cases, the nsubst-- lets us determine how top-level identifiers should be handled.)sig_details <-initIfaceTcRn $typecheckIfaceForInstantiate nsubst sig_iface -- STEP 6: Check that it's sufficienttcg_env <-getGblEnv checkHsigIface tcg_env impl_gr sig_iface sig_details -- STEP 7: Return the updated 'TcGblEnv' with the signature exports,-- so we write them out.returntcg_env {tcg_exports=mi_exportssig_iface }-- | Given 'tcg_mod', instantiate a 'ModIface' from the indefinite-- library to use the actual implementations of the relevant entities,-- checking that the implementation matches the signature.instantiateSignature::TcRn TcGblEnv instantiateSignature =dotcg_env <-getGblEnv dflags <-getDynFlags letouter_mod =tcg_modtcg_env inner_mod =tcg_semantic_modtcg_env -- TODO: setup the local RdrEnv so the error messages look a little better.-- But this information isn't stored anywhere. Should we RETYPECHECK-- the local one just to get the information? Hmm...MASSERT(moduleUnitIdouter_mod==thisPackagedflags)inner_mod `checkImplements `IndefModule (newIndefUnitId (thisComponentId dflags )(thisUnitIdInsts dflags ))(moduleNameouter_mod )