X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcInstDcls.lhs;h=fd70cffe4fcad247ef4eb2db0a7b1419e0f584ab;hb=20d1c20c49feae6b862c87504bbd9b8c483044f3;hp=571ebf7031e35d20751f8240544cdbcbfa63e24b;hpb=99073d876ea762016683fb0b22b9d343ff864eb4;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcInstDcls.lhs b/ghc/compiler/typecheck/TcInstDcls.lhs index 571ebf7..fd70cff 100644 --- a/ghc/compiler/typecheck/TcInstDcls.lhs +++ b/ghc/compiler/typecheck/TcInstDcls.lhs @@ -11,67 +11,64 @@ module TcInstDcls ( tcInstDecls1, tcInstDecls2, tcAddDeclCtxt ) where import CmdLineOpts ( DynFlag(..), dopt ) -import HsSyn ( HsDecl(..), InstDecl(..), TyClDecl(..), InPat(..), - MonoBinds(..), HsExpr(..), HsLit(..), Sig(..), Match(..), +import HsSyn ( HsDecl(..), InstDecl(..), TyClDecl(..), HsType(..), + MonoBinds(..), HsExpr(..), HsLit(..), Sig(..), andMonoBindList, collectMonoBinders, isClassDecl ) -import HsTypes ( HsType (..), HsTyVarBndr(..), toHsTyVar ) -import RnHsSyn ( RenamedHsBinds, RenamedInstDecl, RenamedHsDecl, RenamedMonoBinds, - RenamedTyClDecl, RenamedHsType, +import RnHsSyn ( RenamedHsBinds, RenamedInstDecl, RenamedHsDecl, + RenamedMonoBinds, RenamedTyClDecl, RenamedHsType, extractHsTyVars, maybeGenericMatch ) import TcHsSyn ( TcMonoBinds, mkHsConApp ) import TcBinds ( tcSpecSigs ) import TcClassDcl ( tcMethodBind, badMethodErr ) import TcMonad +import TcType ( tcInstType ) import Inst ( InstOrigin(..), - newDicts, newClassDicts, - LIE, emptyLIE, plusLIE, plusLIEs ) + newDicts, newClassDicts, instToId, + LIE, mkLIE, emptyLIE, plusLIE, plusLIEs ) import TcDeriv ( tcDeriving ) import TcEnv ( TcEnv, tcExtendGlobalValEnv, - tcExtendTyVarEnvForMeths, TyThing (..), - tcAddImportedIdInfo, tcInstId, tcLookupClass, - newDFunName, tcExtendTyVarEnv + tcExtendTyVarEnvForMeths, + tcAddImportedIdInfo, tcLookupClass, + InstInfo(..), pprInstInfo, simpleInstInfoTyCon, + simpleInstInfoTy, newDFunName, tcExtendTyVarEnv, + isLocalThing, ) -import InstEnv ( InstInfo(..), InstEnv, pprInstInfo, classDataCon, - simpleInstInfoTyCon, simpleInstInfoTy, isLocalInst, - extendInstEnv ) -import TcMonoType ( tcTyVars, tcHsSigType, tcHsType, kcHsSigType ) -import TcSimplify ( tcSimplifyAndCheck ) -import TcType ( zonkTcSigTyVars ) -import HscTypes ( PersistentCompilerState(..), HomeSymbolTable, DFunId, - ModDetails(..) ) - -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, foldModuleEnv ) -import Name ( isLocallyDefined ) +import Name ( getSrcLoc ) import NameSet ( emptyNameSet, nameSetToList ) import PrelInfo ( eRROR_ID ) -import PprType ( pprConstraint, pprPred ) -import TyCon ( TyCon, isSynTyCon, tyConDerivings ) -import Type ( mkTyVarTys, splitDFunTy, isTyVarTy, +import PprType ( pprClassPred, pprPred ) +import TyCon ( TyCon, isSynTyCon ) +import Type ( splitDFunTy, isTyVarTy, splitTyConApp_maybe, splitDictTy, - splitAlgTyConApp_maybe, classesToPreds, classesOfPreds, - unUsgTy, tyVarsOfTypes, mkClassPred, mkTyVarTy, + splitForAllTys, + tyVarsOfTypes, mkClassPred, mkTyVarTy, getClassTys_maybe ) -import Subst ( mkTopTyVarSubst, substClasses, substTheta ) -import VarSet ( mkVarSet, varSetElems ) -import TysWiredIn ( genericTyCons, isFFIArgumentTy, isFFIResultTy ) +import Subst ( mkTopTyVarSubst, substClasses ) +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 VarSet ( varSetElems ) -import UniqFM ( mapUFM ) import Unique ( Uniquable(..) ) import BasicTypes ( NewOrData(..), Fixity ) import ErrUtils ( dumpIfSet_dyn ) @@ -79,7 +76,7 @@ import ListSetOps ( Assoc, emptyAssoc, plusAssoc_C, mapAssoc, assocElts, extendAssoc_C, equivClassesByUniq, minusList ) -import List ( intersect, (\\), partition ) +import List ( partition ) import Outputable \end{code} @@ -166,25 +163,26 @@ and $dbinds_super$ bind the superclass dictionaries sd1 \ldots sdm. Gather up the instance declarations from their various sources \begin{code} -tcInstDecls1 :: PersistentCompilerState +tcInstDecls1 :: PackageInstEnv + -> PersistentRenamerState -> HomeSymbolTable -- Contains instances -> TcEnv -- Contains IdInfo for dfun ids -> (Name -> Maybe Fixity) -- for deriving Show and Read -> Module -- Module for deriving - -> [TyCon] -> [RenamedHsDecl] - -> TcM (PersistentCompilerState, InstEnv, [InstInfo], RenamedHsBinds) + -> TcM (PackageInstEnv, InstEnv, [InstInfo], RenamedHsBinds) -tcInstDecls1 pcs hst unf_env get_fixity mod local_tycons decls +tcInstDecls1 inst_env0 prs hst unf_env get_fixity this_mod decls = let - inst_decls = [inst_decl | InstD inst_decl <- decls] - clas_decls = [clas_decl | TyClD clas_decl <- decls, isClassDecl clas_decl] + 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 mod unf_env) inst_decls `thenNF_Tc` \ inst_infos -> + mapNF_Tc tcInstDecl1 inst_decls `thenNF_Tc` \ inst_infos -> -- (2) Instances from generic class declarations - getGenericInstances mod clas_decls `thenTc` \ generic_inst_info -> + 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 @@ -194,14 +192,14 @@ tcInstDecls1 pcs hst unf_env get_fixity mod local_tycons decls -- e) generic instances inst_env4 -- The result of (b) replaces the cached InstEnv in the PCS let - (local_inst_info, imported_inst_info) - = partition isLocalInst (concat inst_infos) + (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 (pcs_insts pcs) imported_dfuns `thenNF_Tc` \ inst_env1 -> + 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 -> @@ -211,12 +209,11 @@ tcInstDecls1 pcs hst unf_env get_fixity mod local_tycons decls -- 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 (pcs_PRS pcs) mod inst_env4 get_fixity local_tycons + 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 -> + addInstInfos inst_env4 deriv_inst_info `thenNF_Tc` \ final_inst_env -> - returnTc (pcs { pcs_insts = inst_env1 }, + returnTc (inst_env1, final_inst_env, generic_inst_info ++ deriv_inst_info ++ local_inst_info, deriv_binds) @@ -227,24 +224,25 @@ addInstInfos inst_env infos = addInstDFuns inst_env (map iDFunId infos) addInstDFuns :: InstEnv -> [DFunId] -> NF_TcM InstEnv addInstDFuns dfuns infos = getDOptsTc `thenTc` \ dflags -> - extendInstEnv dflags dfuns infos `bind` \ (inst_env', errs) -> + let + (inst_env', errs) = extendInstEnv dflags dfuns infos + in addErrsTc errs `thenNF_Tc_` returnTc inst_env' - where - bind x f = f x - \end{code} \begin{code} -tcInstDecl1 :: Module -> TcEnv -> RenamedInstDecl -> NF_TcM [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 []) $ 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, clas, inst_tys) = splitDFunTy poly_ty' in @@ -257,22 +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 (True, 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 - returnNF_Tc (False, mkDictFunId dfun_name clas tyvars inst_tys theta) - ) `thenNF_Tc` \ (is_local, dfun_id) -> + returnNF_Tc (False, dfun_name) + ) `thenNF_Tc` \ (is_local, dfun_name) -> - returnTc [InstInfo { iLocal = is_local, - iClass = clas, iTyVars = tyvars, iTys = inst_tys, - iTheta = theta, iDFunId = dfun_id, - iBinds = binds, iLoc = src_loc, iPrags = uprags }] + let + dfun_id = mkDictFunId dfun_name clas tyvars inst_tys theta + in + returnTc [InstInfo { iDFunId = dfun_id, + iBinds = binds, iPrags = uprags }] \end{code} @@ -307,9 +306,9 @@ gives rise to the instance declarations \begin{code} -getGenericInstances :: Module -> [RenamedTyClDecl] -> TcM [InstInfo] -getGenericInstances mod class_decls - = mapTc (get_generics mod) class_decls `thenTc` \ gen_inst_infos -> +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 @@ -319,13 +318,12 @@ getGenericInstances mod class_decls `thenNF_Tc_` returnTc gen_inst_info -get_generics mod decl@(ClassDecl context class_name tyvar_names - fundeps class_sigs def_methods - name_list loc) +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, or - -- its an imported class decl (=> has no methods at all) + = returnTc [] -- The comon case: no generic default methods | otherwise -- A local class decl with generic default methods = recoverNF_Tc (returnNF_Tc []) $ @@ -333,7 +331,7 @@ get_generics mod decl@(ClassDecl context class_name tyvar_names 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 @@ -341,15 +339,18 @@ get_generics 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_` @@ -371,20 +372,22 @@ 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 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 } @@ -399,17 +402,15 @@ 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 { iLocal = True, - iClass = clas, iTyVars = tyvars, iTys = inst_tys, - iTheta = inst_theta, iDFunId = dfun_id, iBinds = binds, - iLoc = loc, iPrags = [] }) + returnTc (InstInfo { iDFunId = dfun_id, + iBinds = binds, iPrags = [] }) \end{code} @@ -500,22 +501,19 @@ is the @dfun_theta@ below. First comes the easy case of a non-local instance decl. + \begin{code} tcInstDecl2 :: InstInfo -> NF_TcM (LIE, TcMonoBinds) +-- tcInstDecl2 is called *only* on InstInfos -tcInstDecl2 (InstInfo { iClass = clas, iTyVars = inst_tyvars, iTys = inst_tys, - iTheta = inst_decl_theta, iDFunId = dfun_id, - iBinds = monobinds, iLoc = locn, iPrags = uprags }) - | not (isLocallyDefined dfun_id) - = returnNF_Tc (emptyLIE, EmptyMonoBinds) - - | 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') = splitDictTy dict_ty' origin = InstanceDeclOrigin @@ -525,34 +523,34 @@ tcInstDecl2 (InstInfo { iClass = clas, iTyVars = inst_tyvars, iTys = 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 -- 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]) -> + newClassDicts origin sc_theta' `thenNF_Tc` \ sc_dicts -> + newDicts origin dfun_theta' `thenNF_Tc` \ dfun_arg_dicts -> + newClassDicts origin [(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 @@ -564,65 +562,42 @@ tcInstDecl2 (InstInfo { iClass = clas, iTyVars = inst_tyvars, iTys = 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 + 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 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 dict_rhs | null scs_and_meths @@ -632,11 +607,11 @@ tcInstDecl2 (InstInfo { iClass = clas, iTyVars = inst_tyvars, iTys = 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 @@ -653,7 +628,7 @@ tcInstDecl2 (InstInfo { iClass = clas, iTyVars = inst_tyvars, iTys = 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) (lie_binds1 `AndMonoBinds` @@ -682,23 +657,26 @@ 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 - = getDOptsTc `thenTc` \ dflags -> case () of - () - | dopt Opt_AllowUndecidableInstances dflags - -> returnNF_Tc () - - | Just (clas,tys) <- getClassTys_maybe pred, - all isTyVarTy tys - -> returnNF_Tc () - - | otherwise - -> addErrTc (instConstraintErr pred) - -scrutiniseInstanceHead clas inst_taus - = getDOptsTc `thenTc` \ dflags -> case () of - () - | -- CCALL CHECK +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 + | dopt Opt_AllowUndecidableInstances dflags + = [] + + | Just (clas,tys) <- getClassTys_maybe pred, + all isTyVarTy tys + = [] + + | otherwise + = [instConstraintErr pred] + +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 @@ -706,41 +684,27 @@ scrutiniseInstanceHead clas inst_taus || (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 - | dopt Opt_AllowUndecidableInstances dflags - -> returnNF_Tc () + = [nonBoxedPrimCCallErr clas first_inst_tau] -- If GlasgowExts then check at least one isn't a type variable - | dopt Opt_GlasgowExts dflags - -> 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)" $$ - text "where T is not a synonym, and a,b,c are distinct type variables") - ) - - | otherwise - -> returnNF_Tc () + | not (length inst_taus == 1 && + maybeToBool maybe_tycon_app && -- Yes, there's a type constuctor + not (isSynTyCon tycon) && -- ...but not a synonym + all isTyVarTy arg_tys && -- Applied to type variables + length (varSetElems (tyVarsOfTypes arg_tys)) == length arg_tys + -- This last condition checks that all the type variables are distinct + ) + = [instTypeErr clas inst_taus + (text "the instance type must be of form (T a b c)" $$ + text "where T is not a synonym, and a,b,c are distinct type variables")] + + | otherwise + = [] where (first_inst_tau : _) = inst_taus @@ -749,13 +713,25 @@ 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 dflags ty = isFFIArgumentTy dflags False {- Not safe call -} ty - creturnable_type ty = isFFIResultTy 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} @@ -767,19 +743,25 @@ scrutiniseInstanceHead clas inst_taus \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} @@ -798,28 +780,24 @@ 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}