X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcInstDcls.lhs;h=3787abd5fc83b5b9e1aa1bb7bd5552acb1f18533;hb=483817dd051f011218c3c7041809ef019a7ebd0d;hp=279a37eb7395133e2c2ea0c773104eae5348881b;hpb=438596897ebbe25a07e1c82085cfbc5bdb00f09e;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcInstDcls.lhs b/ghc/compiler/typecheck/TcInstDcls.lhs index 279a37e..3787abd 100644 --- a/ghc/compiler/typecheck/TcInstDcls.lhs +++ b/ghc/compiler/typecheck/TcInstDcls.lhs @@ -4,63 +4,74 @@ \section[TcInstDecls]{Typechecking instance declarations} \begin{code} -module TcInstDcls ( - tcInstDecls1, - tcInstDecls2 - ) where +module TcInstDcls ( tcInstDecls1, tcInstDecls2, tcAddDeclCtxt ) where #include "HsVersions.h" -import HsSyn ( HsDecl(..), InstDecl(..), - HsBinds(..), MonoBinds(..), GRHSsAndBinds(..), - HsExpr(..), InPat(..), HsLit(..), Sig(..), - collectMonoBinders, andMonoBindList + +import CmdLineOpts ( DynFlag(..) ) + +import HsSyn ( HsDecl(..), InstDecl(..), TyClDecl(..), HsType(..), + MonoBinds(..), HsExpr(..), HsLit(..), Sig(..), HsTyVarBndr(..), + andMonoBindList, collectMonoBinders, + isClassDecl, isIfaceInstDecl, toHsType ) -import RnHsSyn ( RenamedHsBinds, RenamedInstDecl, RenamedHsDecl ) -import TcHsSyn ( TcMonoBinds, TcIdOcc(..), - maybeBoxedPrimType, tcIdType +import RnHsSyn ( RenamedHsBinds, RenamedInstDecl, RenamedHsDecl, + RenamedMonoBinds, RenamedTyClDecl, RenamedHsType, + extractHsTyVars, maybeGenericMatch ) - -import TcBinds ( tcPragmaSigs ) +import TcHsSyn ( TcMonoBinds, mkHsConApp ) +import TcBinds ( tcSpecSigs ) import TcClassDcl ( tcMethodBind, badMethodErr ) -import TcMonad -import RnMonad ( RnNameSupply ) -import Inst ( Inst, InstOrigin(..), - newDicts, LIE, emptyLIE, plusLIE, plusLIEs ) +import TcMonad +import TcMType ( tcInstSigType, checkValidTheta, checkValidInstHead, instTypeErr, + UserTypeCtxt(..), SourceTyCtxt(..) ) +import TcType ( mkClassPred, mkTyVarTy, mkTyVarTys, tcSplitForAllTys, + tcSplitSigmaTy, getClassPredTys, tcSplitPredTy_maybe, + TyVarDetails(..) + ) +import Inst ( InstOrigin(..), newDicts, instToId, + LIE, mkLIE, emptyLIE, plusLIE, plusLIEs ) import TcDeriv ( tcDeriving ) -import TcEnv ( GlobalValueEnv, tcExtendGlobalValEnv, tcAddImportedIdInfo, tcInstId ) -import TcInstUtil ( InstInfo(..), classDataCon ) -import TcMonoType ( tcHsType ) -import TcSimplify ( tcSimplifyAndCheck ) -import TcType ( TcTyVar, zonkTcTyVarBndr ) - -import Bag ( emptyBag, unitBag, unionBags, unionManyBags, - foldBag, bagToList, Bag +import TcEnv ( TcEnv, tcExtendGlobalValEnv, isLocalThing, + tcExtendTyVarEnvForMeths, tcLookupId, tcLookupClass, + InstInfo(..), pprInstInfo, simpleInstInfoTyCon, + simpleInstInfoTy, newDFunName ) -import CmdLineOpts ( opt_GlasgowExts, opt_AllowUndecidableInstances ) -import Class ( classBigSig, Class ) -import Var ( setIdInfo, idName, Id, TyVar ) -import DataCon ( isNullaryDataCon, dataConArgTys, dataConId ) -import Maybes ( maybeToBool, catMaybes, expectJust ) -import MkId ( mkDictFunId ) -import Name ( nameOccName, isLocallyDefined, Module, - NamedThing(..) +import InstEnv ( InstEnv, extendInstEnv ) +import PprType ( pprClassPred ) +import TcMonoType ( tcHsTyVars, kcHsSigType, tcHsType, tcHsSigType ) +import TcUnify ( checkSigTyVars ) +import TcSimplify ( tcSimplifyCheck ) +import HscTypes ( HomeSymbolTable, DFunId, + ModDetails(..), PackageInstEnv, PersistentRenamerState ) -import PrelVals ( eRROR_ID ) -import PprType ( pprConstraint ) -import SrcLoc ( SrcLoc ) -import TyCon ( isSynTyCon, isDataTyCon, tyConDerivings ) -import Type ( Type, isUnLiftedType, mkTyVarTys, - splitSigmaTy, isTyVarTy, - splitTyConApp_maybe, splitDictTy_maybe, - splitAlgTyConApp_maybe, - tyVarsOfTypes, substFlexiTheta +import Subst ( substTy, substTheta ) +import DataCon ( classDataCon ) +import Class ( Class, classBigSig ) +import Var ( idName, idType ) +import VarSet ( emptyVarSet ) +import Id ( setIdLocalExported ) +import MkId ( mkDictFunId, unsafeCoerceId, eRROR_ID ) +import FunDeps ( checkInstFDs ) +import Generics ( validGenericInstanceType ) +import Module ( Module, foldModuleEnv ) +import Name ( getSrcLoc ) +import NameSet ( unitNameSet, emptyNameSet, nameSetToList ) +import TyCon ( TyCon ) +import Subst ( mkTopTyVarSubst, substTheta ) +import TysWiredIn ( genericTyCons ) +import Name ( Name ) +import SrcLoc ( SrcLoc ) +import Unique ( Uniquable(..) ) +import Util ( lengthExceeds, isSingleton ) +import BasicTypes ( NewOrData(..), Fixity ) +import ErrUtils ( dumpIfSet_dyn ) +import ListSetOps ( Assoc, emptyAssoc, plusAssoc_C, mapAssoc, + assocElts, extendAssoc_C, equivClassesByUniq, minusList ) -import VarEnv ( zipVarEnv ) -import VarSet ( mkVarSet, varSetElems ) -import TysPrim ( byteArrayPrimTyCon, mutableByteArrayPrimTyCon ) -import TysWiredIn ( stringTy ) -import Unique ( Unique, cCallableClassKey, cReturnableClassKey, Uniquable(..) ) +import Maybe ( catMaybes ) +import List ( partition ) import Outputable \end{code} @@ -137,64 +148,294 @@ Here, Bop1 \ldots Bopn bind the methods op1 \ldots opn, and $dbinds_super$ bind the superclass dictionaries sd1 \ldots sdm. \end{enumerate} + +%************************************************************************ +%* * +\subsection{Extracting instance decls} +%* * +%************************************************************************ + +Gather up the instance declarations from their various sources + \begin{code} -tcInstDecls1 :: GlobalValueEnv -- Contains IdInfo for dfun ids - -> [RenamedHsDecl] - -> Module -- module name for deriving - -> RnNameSupply -- for renaming derivings - -> TcM s (Bag InstInfo, - RenamedHsBinds, - SDoc) - -tcInstDecls1 unf_env decls mod_name rn_name_supply - = -- Do the ordinary instance declarations - mapNF_Tc (tcInstDecl1 unf_env mod_name) - [inst_decl | InstD inst_decl <- decls] `thenNF_Tc` \ inst_info_bags -> +tcInstDecls1 + :: PackageInstEnv + -> PersistentRenamerState + -> HomeSymbolTable -- Contains instances + -> TcEnv -- Contains IdInfo for dfun ids + -> (Name -> Maybe Fixity) -- for deriving Show and Read + -> Module -- Module for deriving + -> [RenamedHsDecl] + -> TcM (PackageInstEnv, -- cached package inst env + InstEnv, -- the full inst env + [InstInfo], -- instance decls to process + [DFunId], -- instances from this module, for its iface + RenamedHsBinds) -- derived instances + +tcInstDecls1 inst_env0 prs hst unf_env get_fixity this_mod decls + = let + inst_decls = [inst_decl | InstD inst_decl <- decls] + tycl_decls = [decl | TyClD decl <- decls] + clas_decls = filter isClassDecl tycl_decls + (iface_inst_ds, local_inst_ds) = partition isIfaceInstDecl inst_decls + in + -- (1) Do the ordinary instance declarations + mapNF_Tc tcLocalInstDecl1 local_inst_ds `thenNF_Tc` \ local_inst_infos -> + mapNF_Tc tcImportedInstDecl1 iface_inst_ds `thenNF_Tc` \ iface_dfuns -> + + -- (2) Instances from generic class declarations + getGenericInstances clas_decls `thenTc` \ generic_inst_info -> + + -- Next, construct the instance environment so far, consisting of + -- a) cached non-home-package InstEnv (gotten from pcs) inst_env0 + -- b) imported instance decls (not in the home package) inst_env1 + -- c) other modules in this package (gotten from hst) inst_env2 + -- d) imported instance decls (from this module) inst_env3 + -- e) local instance decls inst_env4 + -- f) generic instances inst_env5 + -- The result of (b) replaces the cached InstEnv in the PCS + -- + -- Note that iface_dfuns may contain not only insts that we + -- demand-loaded from interface files, but also instances from + -- the current module in the case where we are loading this + -- module's interface file in GHCi, so we partition the + -- iface_dfuns into non-local and local instances so that we + -- don't end up with home package instances in the PCS. + -- + -- There can't be any instance declarations from the home + -- package other than from the current module (with the + -- compilation manager) because they are loaded explicitly by + -- the compilation manager. let - decl_inst_info = unionManyBags inst_info_bags + local_inst_info = catMaybes local_inst_infos + (local_iface_dfuns, pkg_iface_dfuns) + = partition (isLocalThing this_mod) iface_dfuns + hst_dfuns = foldModuleEnv ((++) . md_insts) [] hst + in + +-- pprTrace "tcInstDecls" (vcat [ppr imported_dfuns, ppr hst_dfuns]) $ + + addInstDFuns inst_env0 pkg_iface_dfuns `thenNF_Tc` \ inst_env1 -> + addInstDFuns inst_env1 hst_dfuns `thenNF_Tc` \ inst_env2 -> + addInstDFuns inst_env2 local_iface_dfuns `thenNF_Tc` \ inst_env3 -> + addInstInfos inst_env3 local_inst_info `thenNF_Tc` \ inst_env4 -> + addInstInfos inst_env4 generic_inst_info `thenNF_Tc` \ inst_env5 -> + + -- (3) Compute instances from "deriving" clauses; + -- note that we only do derivings for things in this module; + -- we ignore deriving decls from interfaces! + -- This stuff computes a context for the derived instance decl, so it + -- needs to know about all the instances possible; hence inst_env5 + tcDeriving prs this_mod inst_env5 get_fixity tycl_decls + `thenTc` \ (deriv_inst_info, deriv_binds) -> + addInstInfos inst_env5 deriv_inst_info `thenNF_Tc` \ final_inst_env -> + let inst_info = generic_inst_info ++ deriv_inst_info ++ local_inst_info in + + returnTc (inst_env1, + final_inst_env, + inst_info, + local_iface_dfuns ++ map iDFunId inst_info, + deriv_binds) + +addInstInfos :: InstEnv -> [InstInfo] -> NF_TcM InstEnv +addInstInfos inst_env infos = addInstDFuns inst_env (map iDFunId infos) + +addInstDFuns :: InstEnv -> [DFunId] -> NF_TcM InstEnv +addInstDFuns inst_env dfuns + = getDOptsTc `thenNF_Tc` \ dflags -> + let + (inst_env', errs) = extendInstEnv dflags inst_env dfuns in - -- Handle "derived" instances; note that we only do derivings - -- for things in this module; we ignore deriving decls from - -- interfaces! - tcDeriving mod_name rn_name_supply decl_inst_info - `thenTc` \ (deriv_inst_info, deriv_binds, ddump_deriv) -> + addErrsTc errs `thenNF_Tc_` + traceTc (text "Adding instances:" <+> vcat (map pp dfuns)) `thenTc_` + returnTc inst_env' + where + pp dfun = ppr dfun <+> dcolon <+> ppr (idType dfun) +\end{code} + +\begin{code} +tcImportedInstDecl1 :: RenamedInstDecl -> NF_TcM DFunId + -- An interface-file instance declaration + -- Should be in scope by now, because we should + -- have sucked in its interface-file definition + -- So it will be replete with its unfolding etc +tcImportedInstDecl1 decl@(InstDecl poly_ty binds uprags (Just dfun_name) src_loc) + = tcLookupId dfun_name + + +tcLocalInstDecl1 :: RenamedInstDecl + -> NF_TcM (Maybe InstInfo) -- Nothing if there was an error + -- A source-file instance declaration + -- Type-check all the stuff before the "where" + -- + -- We check for respectable instance type, and context + -- but only do this for non-imported instance decls. + -- Imported ones should have been checked already, and may indeed + -- contain something illegal in normal Haskell, notably + -- instance CCallable [Char] +tcLocalInstDecl1 decl@(InstDecl poly_ty binds uprags Nothing src_loc) + = -- Prime error recovery, set source location + recoverNF_Tc (returnNF_Tc Nothing) $ + tcAddSrcLoc src_loc $ + tcAddErrCtxt (instDeclCtxt poly_ty) $ + -- Typecheck the instance type itself. We can't use + -- tcHsSigType, because it's not a valid user type. + kcHsSigType poly_ty `thenTc_` + tcHsType poly_ty `thenTc` \ poly_ty' -> let - full_inst_info = deriv_inst_info `unionBags` decl_inst_info + (tyvars, theta, tau) = tcSplitSigmaTy poly_ty' in - returnTc (full_inst_info, deriv_binds, ddump_deriv) + checkValidTheta InstThetaCtxt theta `thenTc_` + checkValidInstHead tau `thenTc` \ (clas,inst_tys) -> + checkTc (checkInstFDs theta clas inst_tys) + (instTypeErr (pprClassPred clas inst_tys) msg) `thenTc_` + newDFunName clas inst_tys src_loc `thenNF_Tc` \ dfun_name -> + returnTc (Just (InstInfo { iDFunId = mkDictFunId dfun_name clas tyvars inst_tys theta, + iBinds = binds, iPrags = uprags })) + where + msg = parens (ptext SLIT("the instance types do not agree with the functional dependencies of the class")) +\end{code} -tcInstDecl1 :: GlobalValueEnv -> Module -> RenamedInstDecl -> NF_TcM s (Bag InstInfo) +%************************************************************************ +%* * +\subsection{Extracting generic instance declaration from class declarations} +%* * +%************************************************************************ -tcInstDecl1 unf_env mod_name (InstDecl poly_ty binds uprags (Just dfun_name) src_loc) - = -- Prime error recovery, set source location - recoverNF_Tc (returnNF_Tc emptyBag) $ - tcAddSrcLoc src_loc $ +@getGenericInstances@ extracts the generic instance declarations from a class +declaration. For exmaple - -- Type-check all the stuff before the "where" - tcHsType poly_ty `thenTc` \ poly_ty' -> + class C a where + op :: a -> a + + op{ x+y } (Inl v) = ... + op{ x+y } (Inr v) = ... + op{ x*y } (v :*: w) = ... + op{ 1 } Unit = ... + +gives rise to the instance declarations + + instance C (x+y) where + op (Inl v) = ... + op (Inr v) = ... + + instance C (x*y) where + op (v :*: w) = ... + + instance C 1 where + op Unit = ... + + +\begin{code} +getGenericInstances :: [RenamedTyClDecl] -> TcM [InstInfo] +getGenericInstances class_decls + = mapTc get_generics class_decls `thenTc` \ gen_inst_infos -> let - (tyvars, theta, dict_ty) = splitSigmaTy poly_ty' - (clas, inst_tys) = case splitDictTy_maybe dict_ty of - Nothing -> pprPanic "tcInstDecl1" (ppr poly_ty) - Just pair -> pair + gen_inst_info = concat gen_inst_infos in + if null gen_inst_info then + returnTc [] + else + getDOptsTc `thenNF_Tc` \ dflags -> + ioToTc (dumpIfSet_dyn dflags Opt_D_dump_deriv "Generic instances" + (vcat (map pprInstInfo gen_inst_info))) + `thenNF_Tc_` + returnTc gen_inst_info + +get_generics decl@(ClassDecl {tcdMeths = Nothing}) + = returnTc [] -- Imported class decls + +get_generics decl@(ClassDecl {tcdName = class_name, tcdMeths = Just def_methods, tcdLoc = loc}) + | null groups + = returnTc [] -- The comon case: no generic default methods + + | otherwise -- A source class decl with generic default methods + = recoverNF_Tc (returnNF_Tc []) $ + tcAddDeclCtxt decl $ + tcLookupClass class_name `thenTc` \ clas -> + + -- Make an InstInfo out of each group + mapTc (mkGenericInstance clas loc) groups `thenTc` \ inst_infos -> + + -- Check that there is only one InstInfo for each type constructor + -- The main way this can fail is if you write + -- f {| a+b |} ... = ... + -- f {| x+y |} ... = ... + -- Then at this point we'll have an InstInfo for each + let + tc_inst_infos :: [(TyCon, InstInfo)] + tc_inst_infos = [(simpleInstInfoTyCon i, i) | i <- inst_infos] + + bad_groups = [group | group <- equivClassesByUniq get_uniq tc_inst_infos, + group `lengthExceeds` 1] + get_uniq (tc,_) = getUnique tc + in + mapTc (addErrTc . dupGenericInsts) bad_groups `thenTc_` + + -- Check that there is an InstInfo for each generic type constructor + let + missing = genericTyCons `minusList` [tc | (tc,_) <- tc_inst_infos] + in + checkTc (null missing) (missingGenericInstances missing) `thenTc_` + + returnTc inst_infos + + where + -- Group the declarations by type pattern + groups :: [(RenamedHsType, RenamedMonoBinds)] + groups = assocElts (getGenericBinds def_methods) + - -- Check for respectable instance type, and context - scrutiniseInstanceHead clas inst_tys `thenNF_Tc_` - mapNF_Tc scrutiniseInstanceConstraint theta `thenNF_Tc_` +--------------------------------- +getGenericBinds :: RenamedMonoBinds -> Assoc RenamedHsType RenamedMonoBinds + -- Takes a group of method bindings, finds the generic ones, and returns + -- them in finite map indexed by the type parameter in the definition. - -- Make the dfun id and constant-method ids +getGenericBinds EmptyMonoBinds = emptyAssoc +getGenericBinds (AndMonoBinds m1 m2) + = plusAssoc_C AndMonoBinds (getGenericBinds m1) (getGenericBinds m2) + +getGenericBinds (FunMonoBind id infixop matches loc) + = mapAssoc wrap (foldl add emptyAssoc matches) + -- Using foldl not foldr is vital, else + -- we reverse the order of the bindings! + where + add env match = case maybeGenericMatch match of + Nothing -> env + Just (ty, match') -> extendAssoc_C (++) env (ty, [match']) + + wrap ms = FunMonoBind id infixop ms loc + +--------------------------------- +mkGenericInstance :: Class -> SrcLoc + -> (RenamedHsType, RenamedMonoBinds) + -> TcM InstInfo + +mkGenericInstance clas loc (hs_ty, binds) + -- Make a generic instance declaration + -- For example: instance (C a, C b) => C (a+b) where { binds } + + = -- Extract the universally quantified type variables let - dfun_id = mkDictFunId dfun_name clas tyvars inst_tys theta + sig_tvs = map UserTyVar (nameSetToList (extractHsTyVars hs_ty)) + in + tcHsTyVars sig_tvs (kcHsSigType hs_ty) $ \ tyvars -> + + -- Type-check the instance type, and check its form + tcHsSigType GenPatCtxt hs_ty `thenTc` \ inst_ty -> + checkTc (validGenericInstanceType inst_ty) + (badGenericInstanceType binds) `thenTc_` - -- Add info from interface file - final_dfun_id = tcAddImportedIdInfo unf_env dfun_id + -- Make the dictionary function. + newDFunName clas [inst_ty] loc `thenNF_Tc` \ dfun_name -> + let + inst_theta = [mkClassPred clas [mkTyVarTy tv] | tv <- tyvars] + dfun_id = mkDictFunId dfun_name clas tyvars [inst_ty] inst_theta in - returnTc (unitBag (InstInfo clas tyvars inst_tys theta - final_dfun_id - binds src_loc uprags)) + + returnTc (InstInfo { iDFunId = dfun_id, iBinds = binds, iPrags = [] }) \end{code} @@ -205,11 +446,13 @@ tcInstDecl1 unf_env mod_name (InstDecl poly_ty binds uprags (Just dfun_name) src %************************************************************************ \begin{code} -tcInstDecls2 :: Bag InstInfo - -> NF_TcM s (LIE s, TcMonoBinds s) +tcInstDecls2 :: [InstInfo] + -> NF_TcM (LIE, TcMonoBinds) tcInstDecls2 inst_decls - = foldBag combine tcInstDecl2 (returnNF_Tc (emptyLIE, EmptyMonoBinds)) inst_decls +-- = foldBag combine tcInstDecl2 (returnNF_Tc (emptyLIE, EmptyMonoBinds)) inst_decls + = foldr combine (returnNF_Tc (emptyLIE, EmptyMonoBinds)) + (map tcInstDecl2 inst_decls) where combine tc1 tc2 = tc1 `thenNF_Tc` \ (lie1, binds1) -> tc2 `thenNF_Tc` \ (lie2, binds2) -> @@ -217,7 +460,6 @@ tcInstDecls2 inst_decls binds1 `AndMonoBinds` binds2) \end{code} - ======= New documentation starts here (Sept 92) ============== The main purpose of @tcInstDecl2@ is to return a @HsBinds@ which defines @@ -284,162 +526,151 @@ is the @dfun_theta@ below. First comes the easy case of a non-local instance decl. + \begin{code} -tcInstDecl2 :: InstInfo -> NF_TcM s (LIE s, TcMonoBinds s) - -tcInstDecl2 (InstInfo clas inst_tyvars inst_tys - inst_decl_theta - dfun_id monobinds - locn uprags) - | not (isLocallyDefined dfun_id) - = returnNF_Tc (emptyLIE, EmptyMonoBinds) - -{- - -- I deleted this "optimisation" because when importing these - -- instance decls the renamer would look for the dfun bindings and they weren't there. - -- This would be fixable, but it seems simpler just to produce a tiny void binding instead, - -- even though it's never used. - - -- This case deals with CCallable etc, which don't need any bindings - | isNoDictClass clas - = returnNF_Tc (emptyLIE, EmptyBinds) --} - - | otherwise +tcInstDecl2 :: InstInfo -> TcM (LIE, TcMonoBinds) + +tcInstDecl2 (NewTypeDerived { iDFunId = dfun_id }) + = tcInstSigType InstTv (idType dfun_id) `thenNF_Tc` \ (inst_tyvars', dfun_theta', inst_head') -> + newDicts InstanceDeclOrigin dfun_theta' `thenNF_Tc` \ rep_dicts -> + let + rep_dict_id = ASSERT( isSingleton rep_dicts ) + instToId (head rep_dicts) -- Derived newtypes have just one dict arg + + body = TyLam inst_tyvars' $ + DictLam [rep_dict_id] $ + (HsVar unsafeCoerceId `TyApp` [idType rep_dict_id, inst_head']) + `HsApp` + (HsVar rep_dict_id) + -- You might wonder why we have the 'coerce'. It's because the + -- type equality mechanism isn't clever enough; see comments with Type.eqType. + -- So Lint complains if we don't have this. + in + returnTc (emptyLIE, VarMonoBind dfun_id body) + +tcInstDecl2 (InstInfo { iDFunId = dfun_id, iBinds = monobinds, iPrags = uprags }) = -- Prime error recovery - recoverNF_Tc (returnNF_Tc (emptyLIE, EmptyMonoBinds)) $ - tcAddSrcLoc locn $ + recoverNF_Tc (returnNF_Tc (emptyLIE, EmptyMonoBinds)) $ + tcAddSrcLoc (getSrcLoc dfun_id) $ + tcAddErrCtxt (instDeclCtxt (toHsType (idType dfun_id))) $ -- Instantiate the instance decl with tc-style type variables - tcInstId dfun_id `thenNF_Tc` \ (inst_tyvars', dfun_theta', dict_ty') -> + tcInstSigType InstTv (idType dfun_id) `thenNF_Tc` \ (inst_tyvars', dfun_theta', inst_head') -> let - (clas, inst_tys') = expectJust "tcInstDecl2" (splitDictTy_maybe dict_ty') - - origin = InstanceDeclOrigin + Just pred = tcSplitPredTy_maybe inst_head' + (clas, inst_tys') = getClassPredTys pred + (class_tyvars, sc_theta, _, op_items) = classBigSig clas - (class_tyvars, - sc_theta, sc_sel_ids, - op_sel_ids, defm_ids) = classBigSig clas + sel_names = [idName sel_id | (sel_id, _) <- op_items] - -- Instantiate the theta found in the original instance decl - inst_decl_theta' = substFlexiTheta (zipVarEnv inst_tyvars (mkTyVarTys inst_tyvars')) - inst_decl_theta + -- Instantiate the super-class context with inst_tys + sc_theta' = substTheta (mkTopTyVarSubst class_tyvars inst_tys') sc_theta - -- Instantiate the super-class context with inst_tys - sc_theta' = substFlexiTheta (zipVarEnv class_tyvars inst_tys') sc_theta + -- Find any definitions in monobinds that aren't from the class + bad_bndrs = collectMonoBinders monobinds `minusList` sel_names + (inst_tyvars, _) = tcSplitForAllTys (idType dfun_id) + origin = InstanceDeclOrigin in - -- Create dictionary Ids from the specified instance contexts. - newDicts origin sc_theta' `thenNF_Tc` \ (sc_dicts, sc_dict_ids) -> - newDicts origin dfun_theta' `thenNF_Tc` \ (dfun_arg_dicts, dfun_arg_dicts_ids) -> - newDicts origin inst_decl_theta' `thenNF_Tc` \ (inst_decl_dicts, _) -> - newDicts origin [(clas,inst_tys')] `thenNF_Tc` \ (this_dict, [this_dict_id]) -> - -- Check that all the method bindings come from this class - let - check_from_this_class (bndr, loc) - | nameOccName bndr `elem` sel_names = returnNF_Tc () - | otherwise = tcAddSrcLoc loc $ - addErrTc (badMethodErr bndr clas) - sel_names = map getOccName op_sel_ids - bndrs = bagToList (collectMonoBinders monobinds) - in - mapNF_Tc check_from_this_class bndrs `thenNF_Tc_` + mapTc (addErrTc . badMethodErr clas) bad_bndrs `thenNF_Tc_` - tcExtendGlobalValEnv (catMaybes defm_ids) ( - - -- Default-method Ids may be mentioned in synthesised RHSs - mapAndUnzip3Tc (tcMethodBind clas origin inst_tys' inst_tyvars' monobinds uprags True) - (op_sel_ids `zip` defm_ids) - ) `thenTc` \ (method_binds_s, insts_needed_s, meth_lies_w_ids) -> - - -- Deal with SPECIALISE instance pragmas + -- Create dictionary Ids from the specified instance contexts. + newDicts origin sc_theta' `thenNF_Tc` \ sc_dicts -> + newDicts origin dfun_theta' `thenNF_Tc` \ dfun_arg_dicts -> + newDicts origin [mkClassPred clas inst_tys'] `thenNF_Tc` \ [this_dict] -> + + tcExtendTyVarEnvForMeths inst_tyvars inst_tyvars' ( + -- The type variable from the dict fun actually scope + -- over the bindings. They were gotten from + -- the original instance declaration + + -- Default-method Ids may be mentioned in synthesised RHSs, + -- but they'll already be in the environment. + + mapAndUnzip3Tc (tcMethodBind clas origin inst_tyvars' inst_tys' + dfun_theta' + monobinds uprags True) + op_items + ) `thenTc` \ (method_binds_s, insts_needed_s, meth_insts) -> + + -- Deal with SPECIALISE instance pragmas by making them + -- look like SPECIALISE pragmas for the dfun let - dfun_prags = [Sig (idName dfun_id) ty loc | SpecInstSig ty loc <- uprags] + dfun_prags = [SpecSig (idName dfun_id) ty loc | SpecInstSig ty loc <- uprags] in tcExtendGlobalValEnv [dfun_id] ( - tcPragmaSigs dfun_prags - ) `thenTc` \ (prag_info_fn, prag_binds, prag_lie) -> + tcSpecSigs dfun_prags + ) `thenTc` \ (prag_binds, prag_lie) -> -- Check the overloading constraints of the methods and superclasses - - -- tcMethodBind has checked that the class_tyvars havn't - -- been unified with each other or another type, but we must - -- still zonk them - mapNF_Tc zonkTcTyVarBndr inst_tyvars' `thenNF_Tc` \ zonked_inst_tyvars -> let - inst_tyvars_set = mkVarSet zonked_inst_tyvars - - (meth_lies, meth_ids) = unzip meth_lies_w_ids - -- These insts are in scope; quite a few, eh? - avail_insts = this_dict `plusLIE` - dfun_arg_dicts `plusLIE` - sc_dicts `plusLIE` - unionManyBags meth_lies + avail_insts = [this_dict] ++ + dfun_arg_dicts ++ + sc_dicts ++ + meth_insts - methods_lie = plusLIEs insts_needed_s + methods_lie = plusLIEs insts_needed_s in - -- Ditto method bindings + -- Simplify the constraints from methods tcAddErrCtxt methodCtxt ( - tcSimplifyAndCheck + tcSimplifyCheck (ptext SLIT("instance declaration context")) - inst_tyvars_set -- Local tyvars + inst_tyvars' avail_insts methods_lie ) `thenTc` \ (const_lie1, lie_binds1) -> - -- Check that we *could* construct the superclass dictionaries, - -- even though we are *actually* going to pass the superclass dicts in; - -- the check ensures that the caller will never have - --a problem building them. + -- Figure out bindings for the superclass context tcAddErrCtxt superClassCtxt ( - tcSimplifyAndCheck + tcSimplifyCheck (ptext SLIT("instance declaration context")) - inst_tyvars_set -- Local tyvars - inst_decl_dicts -- The instance dictionaries available - sc_dicts -- The superclass dicationaries reqd - ) `thenTc` \ _ -> - -- Ignore the result; we're only doing - -- this to make sure it can be done. - - -- Now do the simplification again, this time to get the - -- bindings; this time we use an enhanced "avails" - -- Ignore errors because they come from the *previous* tcSimplify - discardErrsTc ( - tcSimplifyAndCheck - (ptext SLIT("instance declaration context")) - inst_tyvars_set + inst_tyvars' dfun_arg_dicts -- NB! Don't include this_dict here, else the sc_dicts -- get bound by just selecting from this_dict!! - sc_dicts - ) `thenTc` \ (const_lie2, lie_binds2) -> - + (mkLIE sc_dicts) + ) `thenTc` \ (const_lie2, lie_binds2) -> + + checkSigTyVars inst_tyvars' emptyVarSet `thenNF_Tc` \ zonked_inst_tyvars -> -- Create the result bindings let + local_dfun_id = setIdLocalExported dfun_id + -- Reason for setIdLocalExported: see notes with MkId.mkDictFunId + dict_constr = classDataCon clas - scs_and_meths = sc_dict_ids ++ meth_ids + scs_and_meths = map instToId (sc_dicts ++ meth_insts) + this_dict_id = instToId this_dict + inlines | null dfun_arg_dicts = emptyNameSet + | otherwise = unitNameSet (idName dfun_id) + -- Always inline the dfun; this is an experimental decision + -- because it makes a big performance difference sometimes. + -- Often it means we can do the method selection, and then + -- inline the method as well. Marcin's idea; see comments below. + -- + -- BUT: don't inline it if it's a constant dictionary; + -- we'll get all the benefit without inlining, and we get + -- a **lot** of code duplication if we inline it dict_rhs | null scs_and_meths - = -- Blatant special case for CCallable, CReturnable [and Eval -- sof 5/98] + = -- Blatant special case for CCallable, CReturnable -- If the dictionary is empty then we should never -- select anything from it, so we make its RHS just -- emit an error message. This in turn means that we don't -- mention the constructor, which doesn't exist for CCallable, CReturnable -- Hardly beautiful, but only three extra lines. - HsApp (TyApp (HsVar (RealId eRROR_ID)) [tcIdType this_dict_id]) - (HsLitOut (HsString msg) stringTy) + HsApp (TyApp (HsVar eRROR_ID) [idType this_dict_id]) + (HsLit (HsString msg)) | otherwise -- The common case - = foldl HsApp (TyApp (HsVar (RealId (dataConId dict_constr))) inst_tys') - (map HsVar (sc_dict_ids ++ meth_ids)) + = mkHsConApp dict_constr inst_tys' (map HsVar scs_and_meths) -- We don't produce a binding for the dict_constr; instead we -- rely on the simplifier to unfold this saturated application -- We do this rather than generate an HsCon directly, because -- it means that the special cases (e.g. dictionary with only one - -- member) are dealt with by the common MkId.mkDataConId code rather + -- member) are dealt with by the common MkId.mkDataConWrapId code rather -- than needing to be repeated here. where @@ -448,13 +679,12 @@ tcInstDecl2 (InstInfo clas inst_tyvars inst_tys dict_bind = VarMonoBind this_dict_id dict_rhs method_binds = andMonoBindList method_binds_s - final_dfun_id = setIdInfo dfun_id (prag_info_fn (idName dfun_id)) - -- Pretty truesome main_bind = AbsBinds zonked_inst_tyvars - dfun_arg_dicts_ids - [(inst_tyvars', RealId final_dfun_id, this_dict_id)] + (map instToId dfun_arg_dicts) + [(inst_tyvars', local_dfun_id, this_dict_id)] + inlines (lie_binds1 `AndMonoBinds` lie_binds2 `AndMonoBinds` method_binds `AndMonoBinds` @@ -464,163 +694,142 @@ tcInstDecl2 (InstInfo clas inst_tyvars inst_tys main_bind `AndMonoBinds` prag_binds) \end{code} + ------------------------------ + Inlining dfuns unconditionally + ------------------------------ + +The code above unconditionally inlines dict funs. Here's why. +Consider this program: + + test :: Int -> Int -> Bool + test x y = (x,y) == (y,x) || test y x + -- Recursive to avoid making it inline. + +This needs the (Eq (Int,Int)) instance. If we inline that dfun +the code we end up with is good: + + Test.$wtest = + \r -> case ==# [ww ww1] of wild { + PrelBase.False -> Test.$wtest ww1 ww; + PrelBase.True -> + case ==# [ww1 ww] of wild1 { + PrelBase.False -> Test.$wtest ww1 ww; + PrelBase.True -> PrelBase.True []; + }; + }; + Test.test = \r [w w1] + case w of w2 { + PrelBase.I# ww -> + case w1 of w3 { PrelBase.I# ww1 -> Test.$wtest ww ww1; }; + }; + +If we don't inline the dfun, the code is not nearly as good: + + (==) = case PrelTup.$fEq(,) PrelBase.$fEqInt PrelBase.$fEqInt of tpl { + PrelBase.:DEq tpl1 tpl2 -> tpl2; + }; + + Test.$wtest = + \r [ww ww1] + let { y = PrelBase.I#! [ww1]; } in + let { x = PrelBase.I#! [ww]; } in + let { sat_slx = PrelTup.(,)! [y x]; } in + let { sat_sly = PrelTup.(,)! [x y]; + } in + case == sat_sly sat_slx of wild { + PrelBase.False -> Test.$wtest ww1 ww; + PrelBase.True -> PrelBase.True []; + }; + + Test.test = + \r [w w1] + case w of w2 { + PrelBase.I# ww -> + case w1 of w3 { PrelBase.I# ww1 -> Test.$wtest ww ww1; }; + }; + +Why doesn't GHC inline $fEq? Because it looks big: + + PrelTup.zdfEqZ1T{-rcX-} + = \ @ a{-reT-} :: * @ b{-reS-} :: * + zddEq{-rf6-} _Ks :: {PrelBase.Eq{-23-} a{-reT-}} + zddEq1{-rf7-} _Ks :: {PrelBase.Eq{-23-} b{-reS-}} -> + let { + zeze{-rf0-} _Kl :: (b{-reS-} -> b{-reS-} -> PrelBase.Bool{-3c-}) + zeze{-rf0-} = PrelBase.zeze{-01L-}@ b{-reS-} zddEq1{-rf7-} } in + let { + zeze1{-rf3-} _Kl :: (a{-reT-} -> a{-reT-} -> PrelBase.Bool{-3c-}) + zeze1{-rf3-} = PrelBase.zeze{-01L-} @ a{-reT-} zddEq{-rf6-} } in + let { + zeze2{-reN-} :: ((a{-reT-}, b{-reS-}) -> (a{-reT-}, b{-reS-})-> PrelBase.Bool{-3c-}) + zeze2{-reN-} = \ ds{-rf5-} _Ks :: (a{-reT-}, b{-reS-}) + ds1{-rf4-} _Ks :: (a{-reT-}, b{-reS-}) -> + case ds{-rf5-} + of wild{-reW-} _Kd { (a1{-rf2-} _Ks, a2{-reZ-} _Ks) -> + case ds1{-rf4-} + of wild1{-reX-} _Kd { (b1{-rf1-} _Ks, b2{-reY-} _Ks) -> + PrelBase.zaza{-r4e-} + (zeze1{-rf3-} a1{-rf2-} b1{-rf1-}) + (zeze{-rf0-} a2{-reZ-} b2{-reY-}) + } + } } in + let { + a1{-reR-} :: ((a{-reT-}, b{-reS-})-> (a{-reT-}, b{-reS-})-> PrelBase.Bool{-3c-}) + a1{-reR-} = \ a2{-reV-} _Ks :: (a{-reT-}, b{-reS-}) + b1{-reU-} _Ks :: (a{-reT-}, b{-reS-}) -> + PrelBase.not{-r6I-} (zeze2{-reN-} a2{-reV-} b1{-reU-}) + } in + PrelBase.zdwZCDEq{-r8J-} @ (a{-reT-}, b{-reS-}) a1{-reR-} zeze2{-reN-}) + +and it's not as bad as it seems, because it's further dramatically +simplified: only zeze2 is extracted and its body is simplified. + %************************************************************************ %* * -\subsection{Checking for a decent instance type} +\subsection{Error messages} %* * %************************************************************************ -@scrutiniseInstanceHead@ checks the type {\em and} its syntactic constraints: -it must normally look like: @instance Foo (Tycon a b c ...) ...@ - -The exceptions to this syntactic checking: (1)~if the @GlasgowExts@ -flag is on, or (2)~the instance is imported (they must have been -compiled elsewhere). In these cases, we let them go through anyway. - -We can also have instances for functions: @instance Foo (a -> b) ...@. - \begin{code} -scrutiniseInstanceConstraint (clas, tys) - | all isTyVarTy tys - || opt_AllowUndecidableInstances = returnNF_Tc () - | otherwise = addErrTc (instConstraintErr clas tys) - -scrutiniseInstanceHead clas inst_taus - | -- CCALL CHECK (a).... urgh! - -- To verify that a user declaration of a CCallable/CReturnable - -- instance is OK, we must be able to see the constructor(s) - -- of the instance type (see next guard.) - -- - -- We flag this separately to give a more precise error msg. - -- - (getUnique clas == cCallableClassKey || getUnique clas == cReturnableClassKey) - && is_alg_tycon_app && not constructors_visible - = addErrTc (invisibleDataConPrimCCallErr clas first_inst_tau) - - | -- CCALL CHECK (b) - -- A user declaration of a CCallable/CReturnable instance - -- must be for a "boxed primitive" type. - (getUnique clas == cCallableClassKey && not (ccallable_type first_inst_tau)) || - (getUnique clas == cReturnableClassKey && not (creturnable_type first_inst_tau)) - = addErrTc (nonBoxedPrimCCallErr clas first_inst_tau) - - -- DERIVING CHECK - -- It is obviously illegal to have an explicit instance - -- for something that we are also planning to `derive' - | maybeToBool alg_tycon_app_maybe && clas `elem` (tyConDerivings alg_tycon) - = addErrTc (derivingWhenInstanceExistsErr clas first_inst_tau) - -- Kind check will have ensured inst_taus is of length 1 - - -- Allow anything for AllowUndecidableInstances - | opt_AllowUndecidableInstances - = returnNF_Tc () - - -- If GlasgowExts then check at least one isn't a type variable - | opt_GlasgowExts - = if all isTyVarTy inst_taus then - addErrTc (instTypeErr clas inst_taus (text "There must be at least one non-type-variable in the instance head")) - else - returnNF_Tc () - - -- WITH HASKELL 1.4, MUST HAVE C (T a b c) - | not (length inst_taus == 1 && - maybeToBool maybe_tycon_app && -- Yes, there's a type constuctor - not (isSynTyCon tycon) && -- ...but not a synonym - all isTyVarTy arg_tys && -- Applied to type variables - length (varSetElems (tyVarsOfTypes arg_tys)) == length arg_tys - -- This last condition checks that all the type variables are distinct - ) - = addErrTc (instTypeErr clas inst_taus - (text "the instance type must be of form (T a b c)" $$ - text "where T is not a synonym, and a,b,c are distinct type variables") - ) - - | otherwise - = returnNF_Tc () - +tcAddDeclCtxt decl thing_inside + = tcAddSrcLoc (tcdLoc decl) $ + tcAddErrCtxt ctxt $ + thing_inside where - (first_inst_tau : _) = inst_taus - - -- Stuff for algebraic or -> type - maybe_tycon_app = splitTyConApp_maybe first_inst_tau - Just (tycon, arg_tys) = maybe_tycon_app - - -- Stuff for an *algebraic* data type - alg_tycon_app_maybe = splitAlgTyConApp_maybe first_inst_tau - -- The "Alg" part looks through synonyms - is_alg_tycon_app = maybeToBool alg_tycon_app_maybe - Just (alg_tycon, _, data_cons) = alg_tycon_app_maybe - - constructors_visible = not (null data_cons) - - --- These conditions come directly from what the DsCCall is capable of. --- Totally grotesque. Green card should solve this. - -ccallable_type ty = isUnLiftedType ty || -- Allow CCallable Int# etc - maybeToBool (maybeBoxedPrimType ty) || -- Ditto Int etc - ty == stringTy || - byte_arr_thing - where - byte_arr_thing = case splitAlgTyConApp_maybe ty of - Just (tycon, ty_args, [data_con]) | isDataTyCon tycon -> - length data_con_arg_tys == 2 && - maybeToBool maybe_arg2_tycon && - (arg2_tycon == byteArrayPrimTyCon || - arg2_tycon == mutableByteArrayPrimTyCon) - where - data_con_arg_tys = dataConArgTys data_con ty_args - (data_con_arg_ty1 : data_con_arg_ty2 : _) = data_con_arg_tys - maybe_arg2_tycon = splitTyConApp_maybe data_con_arg_ty2 - Just (arg2_tycon,_) = maybe_arg2_tycon - - other -> False - -creturnable_type ty = maybeToBool (maybeBoxedPrimType ty) || - -- Or, a data type with a single nullary constructor - case (splitAlgTyConApp_maybe ty) of - Just (tycon, tys_applied, [data_con]) - -> isNullaryDataCon data_con - other -> False + thing = case decl of + ClassDecl {} -> "class" + TySynonym {} -> "type synonym" + TyData {tcdND = NewType} -> "newtype" + TyData {tcdND = DataType} -> "data type" + + ctxt = hsep [ptext SLIT("In the"), text thing, + ptext SLIT("declaration for"), quotes (ppr (tcdName decl))] + +instDeclCtxt inst_ty = ptext SLIT("In the instance declaration for") <+> quotes doc + where + doc = case inst_ty of + HsForAllTy _ _ (HsPredTy pred) -> ppr pred + HsPredTy pred -> ppr pred + other -> ppr inst_ty -- Don't expect this \end{code} \begin{code} -instConstraintErr clas tys - = hang (ptext SLIT("Illegal constaint") <+> - quotes (pprConstraint clas tys) <+> - ptext SLIT("in instance context")) - 4 (ptext SLIT("(Instance contexts must constrain only type variables)")) - -instTypeErr clas tys msg - = sep [ptext SLIT("Illegal instance declaration for") <+> quotes (pprConstraint clas tys), - nest 4 (parens msg) +badGenericInstanceType binds + = vcat [ptext SLIT("Illegal type pattern in the generic bindings"), + nest 4 (ppr binds)] + +missingGenericInstances missing + = ptext SLIT("Missing type patterns for") <+> pprQuotedList missing + +dupGenericInsts tc_inst_infos + = vcat [ptext SLIT("More than one type pattern for a single generic type constructor:"), + nest 4 (vcat (map ppr_inst_ty tc_inst_infos)), + ptext SLIT("All the type patterns for a generic type constructor must be identical") ] - -derivingWhenInstanceExistsErr clas tycon - = hang (hsep [ptext SLIT("Deriving class"), - quotes (ppr clas), - ptext SLIT("type"), quotes (ppr tycon)]) - 4 (ptext SLIT("when an explicit instance exists")) - -nonBoxedPrimCCallErr clas inst_ty - = hang (ptext SLIT("Unacceptable instance type for ccall-ish class")) - 4 (hsep [ ptext SLIT("class"), ppr clas, ptext SLIT("type"), - ppr inst_ty]) - -{- - Declaring CCallable & CReturnable instances in a module different - from where the type was defined. Caused by importing data type - abstractly (either programmatically or by the renamer being over-eager - in its pruning.) --} -invisibleDataConPrimCCallErr clas inst_ty - = hang (hsep [ptext SLIT("Constructors for"), quotes (ppr inst_ty), - ptext SLIT("not visible when checking"), - quotes (ppr clas), ptext SLIT("instance")]) - 4 (hsep [text "(Try either importing", ppr inst_ty, - text "non-abstractly or compile using -fno-prune-tydecls ..)"]) + where + ppr_inst_ty (tc,inst) = ppr (simpleInstInfoTy inst) methodCtxt = ptext SLIT("When checking the methods of an instance declaration") -superClassCtxt = ptext SLIT("When checking the superclasses of an instance declaration") +superClassCtxt = ptext SLIT("When checking the super-classes of an instance declaration") \end{code}