X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcInstDcls.lhs;h=1a38a133db4253914953acb490f9848caa094513;hb=d455d8a0f37aba8b7da6250519368a48a9386cca;hp=134ce6e1db28f7cf476ead06931797a628fb6ae8;hpb=710e207487929c4a5977b5ee3bc6e539091953db;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcInstDcls.lhs b/ghc/compiler/typecheck/TcInstDcls.lhs index 134ce6e..1a38a13 100644 --- a/ghc/compiler/typecheck/TcInstDcls.lhs +++ b/ghc/compiler/typecheck/TcInstDcls.lhs @@ -9,74 +9,74 @@ module TcInstDcls ( tcInstDecls1, tcInstDecls2, tcAddDeclCtxt ) where #include "HsVersions.h" -import CmdLineOpts ( opt_GlasgowExts, opt_AllowUndecidableInstances, opt_D_dump_deriv ) +import CmdLineOpts ( DynFlag(..), dopt ) -import HsSyn ( HsDecl(..), InstDecl(..), TyClDecl(..), - MonoBinds(..), HsExpr(..), HsLit(..), Sig(..), +import HsSyn ( HsDecl(..), InstDecl(..), TyClDecl(..), HsType(..), + MonoBinds(..), HsExpr(..), HsLit(..), Sig(..), andMonoBindList, collectMonoBinders, isClassDecl ) -import HsTypes ( HsType (..), HsTyVarBndr(..), toHsTyVar ) -import HsPat ( InPat (..) ) -import HsMatches ( Match (..) ) -import RnHsSyn ( RenamedHsBinds, RenamedInstDecl, RenamedHsDecl, extractHsTyVars ) +import RnHsSyn ( RenamedHsBinds, RenamedInstDecl, RenamedHsDecl, + RenamedMonoBinds, RenamedTyClDecl, RenamedHsType, + extractHsTyVars, maybeGenericMatch + ) import TcHsSyn ( TcMonoBinds, mkHsConApp ) import TcBinds ( tcSpecSigs ) import TcClassDcl ( tcMethodBind, badMethodErr ) import TcMonad -import RnMonad ( RnNameSupply, FixityEnv ) +import TcType ( tcInstType ) import Inst ( InstOrigin(..), - newDicts, newClassDicts, - LIE, emptyLIE, plusLIE, plusLIEs ) + newDicts, instToId, + LIE, mkLIE, emptyLIE, plusLIE, plusLIEs ) import TcDeriv ( tcDeriving ) -import TcEnv ( ValueEnv, tcExtendGlobalValEnv, - tcExtendTyVarEnvForMeths, TyThing (..), - tcAddImportedIdInfo, tcInstId, tcLookupTy, - newDFunName, tcExtendTyVarEnv +import TcEnv ( TcEnv, tcExtendGlobalValEnv, + tcExtendTyVarEnvForMeths, + tcAddImportedIdInfo, tcLookupClass, + InstInfo(..), pprInstInfo, simpleInstInfoTyCon, + simpleInstInfoTy, newDFunName, tcExtendTyVarEnv, + isLocalThing, ) -import TcInstUtil ( InstInfo(..), pprInstInfo, classDataCon, simpleInstInfoTyCon, simpleInstInfoTy ) -import TcMonoType ( tcTyVars, tcHsSigType, tcHsType, kcHsSigType ) -import TcSimplify ( tcSimplifyAndCheck ) -import TcType ( zonkTcSigTyVars ) - -import Bag ( emptyBag, unitBag, unionBags, unionManyBags, - foldBag, Bag, listToBag +import InstEnv ( InstEnv, extendInstEnv ) +import TcMonoType ( tcTyVars, tcHsSigType, kcHsSigType, checkSigTyVars ) +import TcSimplify ( tcSimplifyCheck ) +import HscTypes ( HomeSymbolTable, DFunId, + ModDetails(..), PackageInstEnv, PersistentRenamerState ) + +import DataCon ( classDataCon ) import Class ( Class, DefMeth(..), classBigSig ) import Var ( idName, idType ) -import Maybes ( maybeToBool, expectJust ) +import VarSet ( emptyVarSet ) +import Maybes ( maybeToBool ) import MkId ( mkDictFunId ) +import FunDeps ( checkInstFDs ) import Generics ( validGenericInstanceType ) -import Module ( Module ) -import Name ( isLocallyDefined ) -import NameSet ( emptyNameSet, nameSetToList ) +import Module ( Module, foldModuleEnv ) +import Name ( getSrcLoc ) +import NameSet ( emptyNameSet, mkNameSet, nameSetToList ) import PrelInfo ( eRROR_ID ) -import PprType ( pprConstraint, pprPred ) -import TyCon ( isSynTyCon, tyConDerivings ) -import Type ( mkTyVarTys, splitSigmaTy, isTyVarTy, - splitTyConApp_maybe, splitDictTy_maybe, - splitAlgTyConApp_maybe, classesToPreds, classesOfPreds, - unUsgTy, tyVarsOfTypes, mkClassPred, mkTyVarTy, - getClassTys_maybe +import PprType ( pprClassPred, pprPred ) +import TyCon ( TyCon, isSynTyCon ) +import Type ( splitDFunTy, isTyVarTy, + splitTyConApp_maybe, splitDictTy, + splitForAllTys, + tyVarsOfTypes, mkClassPred, mkTyVarTy, + isTyVarClassPred, inheritablePred ) -import Subst ( mkTopTyVarSubst, substClasses, substTheta ) -import VarSet ( mkVarSet, varSetElems ) -import TysWiredIn ( genericTyCons, isFFIArgumentTy, isFFIResultTy ) +import Subst ( mkTopTyVarSubst, substTheta ) +import VarSet ( varSetElems ) +import TysWiredIn ( genericTyCons, isFFIArgumentTy, isFFIImportResultTy ) import PrelNames ( cCallableClassKey, cReturnableClassKey, hasKey ) -import Name ( Name, NameEnv, extendNameEnv_C, emptyNameEnv, - plusNameEnv_C, nameEnvElts ) -import FiniteMap ( mapFM ) +import Name ( Name ) import SrcLoc ( SrcLoc ) -import RnHsSyn -- ( RenamedMonoBinds ) import VarSet ( varSetElems ) -import UniqFM ( mapUFM ) import Unique ( Uniquable(..) ) -import BasicTypes ( NewOrData(..) ) -import ErrUtils ( dumpIfSet ) +import BasicTypes ( NewOrData(..), Fixity ) +import ErrUtils ( dumpIfSet_dyn ) import ListSetOps ( Assoc, emptyAssoc, plusAssoc_C, mapAssoc, assocElts, extendAssoc_C, equivClassesByUniq, minusList ) -import List ( intersect, (\\) ) +import List ( partition ) import Outputable \end{code} @@ -163,57 +163,88 @@ and $dbinds_super$ bind the superclass dictionaries sd1 \ldots sdm. Gather up the instance declarations from their various sources \begin{code} -tcInstDecls1 :: ValueEnv -- Contains IdInfo for dfun ids - -> [RenamedHsDecl] +tcInstDecls1 :: PackageInstEnv + -> PersistentRenamerState + -> HomeSymbolTable -- Contains instances + -> TcEnv -- Contains IdInfo for dfun ids + -> (Name -> Maybe Fixity) -- for deriving Show and Read -> Module -- Module for deriving - -> FixityEnv -- For derivings - -> RnNameSupply -- For renaming derivings - -> TcM s (Bag InstInfo, - RenamedHsBinds) - -tcInstDecls1 unf_env decls mod fixs rn_name_supply - = -- (1) Do the ordinary instance declarations - mapNF_Tc (tcInstDecl1 mod unf_env) - [inst_decl | InstD inst_decl <- decls] `thenNF_Tc` \ inst_info_bags -> - let - decl_inst_info = unionManyBags inst_info_bags - in - -- (2) Instances from "deriving" clauses; note that we only do derivings - -- for things in this module; we ignore deriving decls from - -- interfaces! - tcDeriving mod fixs rn_name_supply decl_inst_info `thenTc` \ (deriv_inst_info, deriv_binds) -> + -> [RenamedHsDecl] + -> TcM (PackageInstEnv, InstEnv, [InstInfo], RenamedHsBinds) - -- (3) Instances from generic class declarations - mapTc (getGenericInstances mod) - [cl_decl | TyClD cl_decl <- decls, isClassDecl cl_decl] `thenTc` \ cls_inst_info -> +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 + in + -- (1) Do the ordinary instance declarations + mapNF_Tc tcInstDecl1 inst_decls `thenNF_Tc` \ inst_infos -> + + -- (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) pcs_insts pcs + -- b) imported instance decls (not in the home package) inst_env1 + -- c) other modules in this package (gotten from hst) inst_env2 + -- d) local instance decls inst_env3 + -- e) generic instances inst_env4 + -- The result of (b) replaces the cached InstEnv in the PCS + let + (local_inst_info, imported_inst_info) + = partition (isLocalThing this_mod . iDFunId) (concat inst_infos) + imported_dfuns = map (tcAddImportedIdInfo unf_env . iDFunId) + imported_inst_info + hst_dfuns = foldModuleEnv ((++) . md_insts) [] hst + in + addInstDFuns inst_env0 imported_dfuns `thenNF_Tc` \ inst_env1 -> + addInstDFuns inst_env1 hst_dfuns `thenNF_Tc` \ inst_env2 -> + addInstInfos inst_env2 local_inst_info `thenNF_Tc` \ inst_env3 -> + addInstInfos inst_env3 generic_inst_info `thenNF_Tc` \ inst_env4 -> + + -- (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; hecne inst_env4 + tcDeriving prs this_mod inst_env4 get_fixity tycl_decls + `thenTc` \ (deriv_inst_info, deriv_binds) -> + addInstInfos inst_env4 deriv_inst_info `thenNF_Tc` \ final_inst_env -> + + returnTc (inst_env1, + final_inst_env, + generic_inst_info ++ deriv_inst_info ++ local_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 dfuns infos + = getDOptsTc `thenTc` \ dflags -> let - generic_insts = concat cls_inst_info - full_inst_info = deriv_inst_info `unionBags` - unionManyBags inst_info_bags `unionBags` - (listToBag generic_insts) + (inst_env', errs) = extendInstEnv dflags dfuns infos in - ioToTc (dumpIfSet opt_D_dump_deriv "Generic instances" - (vcat (map pprInstInfo generic_insts))) `thenNF_Tc_` - - (returnTc (full_inst_info, deriv_binds)) + addErrsTc errs `thenNF_Tc_` + returnTc inst_env' \end{code} \begin{code} -tcInstDecl1 :: Module -> ValueEnv -> RenamedInstDecl -> NF_TcM s (Bag InstInfo) +tcInstDecl1 :: RenamedInstDecl -> NF_TcM [InstInfo] -- Deal with a single instance declaration -tcInstDecl1 mod unf_env (InstDecl poly_ty binds uprags maybe_dfun_name src_loc) +tcInstDecl1 decl@(InstDecl poly_ty binds uprags maybe_dfun_name src_loc) = -- Prime error recovery, set source location - recoverNF_Tc (returnNF_Tc emptyBag) $ + recoverNF_Tc (returnNF_Tc []) $ tcAddSrcLoc src_loc $ -- Type-check all the stuff before the "where" - tcHsSigType poly_ty `thenTc` \ poly_ty' -> + tcAddErrCtxt (instDeclCtxt poly_ty) ( + tcHsSigType poly_ty + ) `thenTc` \ poly_ty' -> let - (tyvars, theta, dict_ty) = splitSigmaTy poly_ty' - (clas, inst_tys) = case splitDictTy_maybe dict_ty of - Just ct -> ct - Nothing -> pprPanic "tcInstDecl1" (ppr poly_ty) + (tyvars, theta, clas, inst_tys) = splitDFunTy poly_ty' in (case maybe_dfun_name of @@ -224,22 +255,23 @@ tcInstDecl1 mod unf_env (InstDecl poly_ty binds uprags maybe_dfun_name src_loc) -- Imported ones should have been checked already, and may indeed -- contain something illegal in normal Haskell, notably -- instance CCallable [Char] - scrutiniseInstanceHead clas inst_tys `thenNF_Tc_` - mapNF_Tc scrutiniseInstanceConstraint theta `thenNF_Tc_` + getDOptsTc `thenTc` \ dflags -> + checkInstValidity dflags theta clas inst_tys `thenTc_` -- Make the dfun id and return it - newDFunName mod clas inst_tys src_loc `thenNF_Tc` \ dfun_name -> - returnNF_Tc (mkDictFunId dfun_name clas tyvars inst_tys theta) + newDFunName clas inst_tys src_loc `thenNF_Tc` \ dfun_name -> + returnNF_Tc (True, dfun_name) Just dfun_name -> -- An interface-file instance declaration - -- Make the dfun id and add info from interface file - let - dfun_id = mkDictFunId dfun_name clas tyvars inst_tys theta - in - returnNF_Tc (tcAddImportedIdInfo unf_env dfun_id) - ) `thenNF_Tc` \ dfun_id -> - - returnTc (unitBag (InstInfo clas tyvars inst_tys theta dfun_id binds src_loc uprags)) + -- Make the dfun id + returnNF_Tc (False, dfun_name) + ) `thenNF_Tc` \ (is_local, dfun_name) -> + + let + dfun_id = mkDictFunId dfun_name clas tyvars inst_tys theta + in + returnTc [InstInfo { iDFunId = dfun_id, + iBinds = binds, iPrags = uprags }] \end{code} @@ -274,20 +306,35 @@ gives rise to the instance declarations \begin{code} -getGenericInstances :: Module -> RenamedTyClDecl -> TcM s [InstInfo] -getGenericInstances mod decl@(ClassDecl context class_name tyvar_names - fundeps class_sigs def_methods pragmas - name_list loc) +getGenericInstances :: [RenamedTyClDecl] -> TcM [InstInfo] +getGenericInstances class_decls + = mapTc get_generics class_decls `thenTc` \ gen_inst_infos -> + let + gen_inst_info = concat gen_inst_infos + in + if null gen_inst_info then + returnTc [] + else + getDOptsTc `thenTc` \ 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 + = returnTc [] -- The comon case: no generic default methods - | otherwise + | otherwise -- A local class decl with generic default methods = recoverNF_Tc (returnNF_Tc []) $ tcAddDeclCtxt decl $ - tcLookupTy class_name `thenTc` \ (AClass clas) -> + tcLookupClass class_name `thenTc` \ clas -> -- Make an InstInfo out of each group - mapTc (mkGenericInstance mod clas loc) groups `thenTc` \ inst_infos -> + 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 @@ -295,15 +342,18 @@ getGenericInstances mod decl@(ClassDecl context class_name tyvar_names -- f {| x+y |} ... = ... -- Then at this point we'll have an InstInfo for each let - bad_groups = [group | group <- equivClassesByUniq get_uniq inst_infos, + tc_inst_infos :: [(TyCon, InstInfo)] + tc_inst_infos = [(simpleInstInfoTyCon i, i) | i <- inst_infos] + + bad_groups = [group | group <- equivClassesByUniq get_uniq tc_inst_infos, length group > 1] - get_uniq inst = getUnique (simpleInstInfoTyCon inst) + 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` map simpleInstInfoTyCon inst_infos + missing = genericTyCons `minusList` [tc | (tc,_) <- tc_inst_infos] in checkTc (null missing) (missingGenericInstances missing) `thenTc_` @@ -325,20 +375,22 @@ getGenericBinds (AndMonoBinds m1 m2) = plusAssoc_C AndMonoBinds (getGenericBinds m1) (getGenericBinds m2) getGenericBinds (FunMonoBind id infixop matches loc) - = mapAssoc wrap (foldr add emptyAssoc matches) + = mapAssoc wrap (foldl add emptyAssoc matches) + -- Using foldl not foldr is vital, else + -- we reverse the order of the bindings! where - add match env = case maybeGenericMatch match of + 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 :: Module -> Class -> SrcLoc +mkGenericInstance :: Class -> SrcLoc -> (RenamedHsType, RenamedMonoBinds) - -> TcM s InstInfo + -> TcM InstInfo -mkGenericInstance mod clas loc (hs_ty, binds) +mkGenericInstance clas loc (hs_ty, binds) -- Make a generic instance declaration -- For example: instance (C a, C b) => C (a+b) where { binds } @@ -353,15 +405,15 @@ mkGenericInstance mod clas loc (hs_ty, binds) (badGenericInstanceType binds) `thenTc_` -- Make the dictionary function. - newDFunName mod clas [inst_ty] loc `thenNF_Tc` \ dfun_name -> + newDFunName clas [inst_ty] loc `thenNF_Tc` \ dfun_name -> let inst_theta = [mkClassPred clas [mkTyVarTy tv] | tv <- tyvars] inst_tys = [inst_ty] dfun_id = mkDictFunId dfun_name clas tyvars inst_tys inst_theta in - returnTc (InstInfo clas tyvars inst_tys inst_theta dfun_id binds loc []) - -- The "[]" means "no pragmas" + returnTc (InstInfo { iDFunId = dfun_id, + iBinds = binds, iPrags = [] }) \end{code} @@ -372,11 +424,13 @@ mkGenericInstance mod clas loc (hs_ty, binds) %************************************************************************ \begin{code} -tcInstDecls2 :: Bag InstInfo - -> NF_TcM s (LIE, TcMonoBinds) +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) -> @@ -450,25 +504,21 @@ is the @dfun_theta@ below. First comes the easy case of a non-local instance decl. -\begin{code} -tcInstDecl2 :: InstInfo -> NF_TcM s (LIE, TcMonoBinds) -tcInstDecl2 (InstInfo clas inst_tyvars inst_tys - inst_decl_theta - dfun_id monobinds - locn uprags) - | not (isLocallyDefined dfun_id) - = returnNF_Tc (emptyLIE, EmptyMonoBinds) +\begin{code} +tcInstDecl2 :: InstInfo -> NF_TcM (LIE, TcMonoBinds) +-- tcInstDecl2 is called *only* on InstInfos - | otherwise +tcInstDecl2 (InstInfo { iDFunId = dfun_id, + iBinds = monobinds, iPrags = uprags }) = -- Prime error recovery recoverNF_Tc (returnNF_Tc (emptyLIE, EmptyMonoBinds)) $ - tcAddSrcLoc locn $ + tcAddSrcLoc (getSrcLoc dfun_id) $ -- Instantiate the instance decl with tc-style type variables - tcInstId dfun_id `thenNF_Tc` \ (inst_tyvars', dfun_theta', dict_ty') -> + tcInstType (idType dfun_id) `thenNF_Tc` \ (inst_tyvars', dfun_theta', dict_ty') -> let - (clas, inst_tys') = expectJust "tcInstDecl2" (splitDictTy_maybe dict_ty') + (clas, inst_tys') = splitDictTy dict_ty' origin = InstanceDeclOrigin (class_tyvars, sc_theta, _, op_items) = classBigSig clas @@ -476,34 +526,34 @@ tcInstDecl2 (InstInfo clas inst_tyvars inst_tys dm_ids = [dm_id | (_, DefMeth dm_id) <- op_items] sel_names = [idName sel_id | (sel_id, _) <- op_items] - -- Instantiate the theta found in the original instance decl - inst_decl_theta' = substTheta (mkTopTyVarSubst inst_tyvars (mkTyVarTys inst_tyvars')) - inst_decl_theta - -- Instantiate the super-class context with inst_tys - sc_theta' = substClasses (mkTopTyVarSubst class_tyvars inst_tys') sc_theta + sc_theta' = substTheta (mkTopTyVarSubst class_tyvars inst_tys') sc_theta -- Find any definitions in monobinds that aren't from the class bad_bndrs = collectMonoBinders monobinds `minusList` sel_names + + -- The type variable from the dict fun actually scope + -- over the bindings. They were gotten from + -- the original instance declaration + (inst_tyvars, _) = splitForAllTys (idType dfun_id) in -- Check that all the method bindings come from this class mapTc (addErrTc . badMethodErr clas) bad_bndrs `thenNF_Tc_` -- Create dictionary Ids from the specified instance contexts. - newClassDicts 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, _) -> - newClassDicts origin [(clas,inst_tys')] `thenNF_Tc` \ (this_dict, [this_dict_id]) -> + 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' ( tcExtendGlobalValEnv dm_ids ( -- Default-method Ids may be mentioned in synthesised RHSs mapAndUnzip3Tc (tcMethodBind clas origin inst_tyvars' inst_tys' - inst_decl_theta' + dfun_theta' monobinds uprags True) op_items - )) `thenTc` \ (method_binds_s, insts_needed_s, meth_lies_w_ids) -> + )) `thenTc` \ (method_binds_s, insts_needed_s, meth_insts) -> -- Deal with SPECIALISE instance pragmas by making them -- look like SPECIALISE pragmas for the dfun @@ -515,65 +565,43 @@ tcInstDecl2 (InstInfo clas inst_tyvars inst_tys ) `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 before passing them to tcSimplifyAndCheck - zonkTcSigTyVars 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 - (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 + tcSimplifyCheck (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 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 = mkNameSet [idName dfun_id | InlineInstSig _ _ <- uprags] dict_rhs | null scs_and_meths @@ -583,11 +611,11 @@ tcInstDecl2 (InstInfo clas inst_tyvars inst_tys -- 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 eRROR_ID) [(unUsgTy . idType) this_dict_id]) + HsApp (TyApp (HsVar eRROR_ID) [idType this_dict_id]) (HsLit (HsString msg)) | otherwise -- The common case - = mkHsConApp 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 @@ -604,9 +632,9 @@ tcInstDecl2 (InstInfo clas inst_tyvars inst_tys main_bind = AbsBinds zonked_inst_tyvars - dfun_arg_dicts_ids + (map instToId dfun_arg_dicts) [(inst_tyvars', dfun_id, this_dict_id)] - emptyNameSet -- No inlines (yet) + inlines (lie_binds1 `AndMonoBinds` lie_binds2 `AndMonoBinds` method_binds `AndMonoBinds` @@ -633,58 +661,55 @@ 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 pred - | opt_AllowUndecidableInstances - = returnNF_Tc () +checkInstValidity dflags theta clas inst_tys + | null errs = returnTc () + | otherwise = addErrsTc errs `thenNF_Tc_` failTc + where + errs = checkInstHead dflags theta clas inst_tys ++ + [err | pred <- theta, err <- checkInstConstraint dflags pred] + +checkInstConstraint dflags pred + -- Checks whether a predicate is legal in the + -- context of an instance declaration + | ok = [] + | otherwise = [instConstraintErr pred] + where + ok = inheritablePred pred && + (isTyVarClassPred pred || arbitrary_preds_ok) - | Just (clas,tys) <- getClassTys_maybe pred, - all isTyVarTy tys - = returnNF_Tc () + arbitrary_preds_ok = dopt Opt_AllowUndecidableInstances dflags - | otherwise - = addErrTc (instConstraintErr pred) -scrutiniseInstanceHead clas inst_taus +checkInstHead dflags theta clas inst_taus | -- CCALL CHECK -- A user declaration of a CCallable/CReturnable instance -- must be for a "boxed primitive" type. - (clas `hasKey` cCallableClassKey && not (ccallable_type first_inst_tau)) || - (clas `hasKey` 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 () + (clas `hasKey` cCallableClassKey + && not (ccallable_type dflags first_inst_tau)) + || + (clas `hasKey` cReturnableClassKey + && not (creturnable_type first_inst_tau)) + = [nonBoxedPrimCCallErr clas first_inst_tau] -- 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 () + | dopt Opt_GlasgowExts dflags + = -- GlasgowExts case + check_tyvars dflags clas inst_taus ++ check_fundeps dflags theta clas inst_taus -- 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)" $$ - text "where T is not a synonym, and a,b,c are distinct type variables") - ) + | not (length inst_taus == 1 && + maybeToBool maybe_tycon_app && -- Yes, there's a type constuctor + not (isSynTyCon tycon) && -- ...but not a synonym + all isTyVarTy arg_tys && -- Applied to type variables + length (varSetElems (tyVarsOfTypes arg_tys)) == length arg_tys + -- This last condition checks that all the type variables are distinct + ) + = [instTypeErr clas inst_taus + (text "the instance type must be of form (T a b c)" $$ + text "where T is not a synonym, and a,b,c are distinct type variables")] | otherwise - = returnNF_Tc () + = [] where (first_inst_tau : _) = inst_taus @@ -693,13 +718,25 @@ scrutiniseInstanceHead clas inst_taus 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 - Just (alg_tycon, _, _) = alg_tycon_app_maybe - -ccallable_type ty = isFFIArgumentTy False {- Not safe call -} ty -creturnable_type ty = isFFIResultTy ty + ccallable_type dflags ty = isFFIArgumentTy dflags False {- Not safe call -} ty + creturnable_type ty = isFFIImportResultTy dflags ty + +check_tyvars dflags clas inst_taus + -- Check that at least one isn't a type variable + -- unless -fallow-undecideable-instances + | dopt Opt_AllowUndecidableInstances dflags = [] + | not (all isTyVarTy inst_taus) = [] + | otherwise = [the_err] + where + the_err = instTypeErr clas inst_taus msg + msg = ptext SLIT("There must be at least one non-type-variable in the instance head") + +check_fundeps dflags theta clas inst_taus + | checkInstFDs theta clas inst_taus = [] + | otherwise = [the_err] + where + the_err = instTypeErr clas inst_taus msg + msg = ptext SLIT("the instance types do not agree with the functional dependencies of the class") \end{code} @@ -711,19 +748,25 @@ creturnable_type ty = isFFIResultTy ty \begin{code} tcAddDeclCtxt decl thing_inside - = tcAddSrcLoc loc $ + = tcAddSrcLoc (tcdLoc decl) $ tcAddErrCtxt ctxt $ thing_inside where - (name, loc, thing) - = case decl of - (ClassDecl _ name _ _ _ _ _ _ loc) -> (name, loc, "class") - (TySynonym name _ _ loc) -> (name, loc, "type synonym") - (TyData NewType _ name _ _ _ _ _ loc _ _) -> (name, loc, "newtype") - (TyData DataType _ name _ _ _ _ _ loc _ _) -> (name, loc, "data type") + 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 name)] + 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} @@ -742,28 +785,24 @@ missingGenericInstances missing -dupGenericInsts inst_infos +dupGenericInsts tc_inst_infos = vcat [ptext SLIT("More than one type pattern for a single generic type constructor:"), - nest 4 (vcat (map (ppr . simpleInstInfoTy) inst_infos)), + nest 4 (vcat (map ppr_inst_ty tc_inst_infos)), ptext SLIT("All the type patterns for a generic type constructor must be identical") ] + where + ppr_inst_ty (tc,inst) = ppr (simpleInstInfoTy inst) instTypeErr clas tys msg - = sep [ptext SLIT("Illegal instance declaration for") <+> quotes (pprConstraint clas tys), + = sep [ptext SLIT("Illegal instance declaration for") <+> + quotes (pprClassPred clas tys), nest 4 (parens msg) ] -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]) + 4 (pprClassPred clas [inst_ty]) 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}