X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcInstDcls.lhs;h=8005b0b7a7b39a10f7446fef9919912dbedc1cdc;hb=87e57c1ff5df3a5c3d5f67a9805f7300e7932ba3;hp=32a9c3ab23e143240e3e93be10567968e925eed6;hpb=c29022c49449b7d8862dcc2259e16cafe9461945;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcInstDcls.lhs b/ghc/compiler/typecheck/TcInstDcls.lhs index 32a9c3a..8005b0b 100644 --- a/ghc/compiler/typecheck/TcInstDcls.lhs +++ b/ghc/compiler/typecheck/TcInstDcls.lhs @@ -1,5 +1,5 @@ % -% (c) The GRASP/AQUA Project, Glasgow University, 1992-1996 +% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 % \section[TcInstDecls]{Typechecking instance declarations} @@ -12,58 +12,54 @@ module TcInstDcls ( #include "HsVersions.h" import HsSyn ( HsDecl(..), InstDecl(..), - HsBinds(..), MonoBinds(..), GRHSsAndBinds(..), GRHS(..), - HsExpr(..), InPat(..), HsLit(..), - unguardedRHS, - collectMonoBinders, andMonoBinds + HsBinds(..), MonoBinds(..), + HsExpr(..), InPat(..), HsLit(..), Sig(..), + collectMonoBinders, andMonoBindList ) -import RnHsSyn ( RenamedHsBinds, RenamedMonoBinds, - RenamedInstDecl, RenamedHsExpr, - RenamedSig, RenamedHsDecl +import RnHsSyn ( RenamedHsBinds, RenamedInstDecl, RenamedHsDecl ) +import TcHsSyn ( TcMonoBinds, + maybeBoxedPrimType ) -import TcHsSyn ( TcMonoBinds, TcIdOcc(..), TcIdBndr, - maybeBoxedPrimType, mkHsTyLam, mkHsTyApp, - ) -import TcBinds ( tcPragmaSigs, sigThetaCtxt ) +import TcBinds ( tcPragmaSigs ) import TcClassDcl ( tcMethodBind, badMethodErr ) import TcMonad import RnMonad ( RnNameSupply ) import Inst ( Inst, InstOrigin(..), - newDicts, LIE, emptyLIE, plusLIE ) -import PragmaInfo ( PragmaInfo(..) ) + newDicts, LIE, emptyLIE, plusLIE, plusLIEs ) import TcDeriv ( tcDeriving ) -import TcEnv ( tcExtendGlobalValEnv, tcAddImportedIdInfo ) -import TcInstUtil ( InstInfo(..), mkInstanceRelatedIds, classDataCon ) -import TcKind ( TcKind, unifyKind ) -import TcMonoType ( tcHsType ) -import TcSimplify ( tcSimplifyAndCheck ) -import TcType ( TcType, TcTyVar, TcTyVarSet, - zonkSigTyVar, tcInstSigTyVars, tcInstType, tcInstTheta +import TcEnv ( ValueEnv, tcExtendGlobalValEnv, tcExtendTyVarEnvForMeths, + tcAddImportedIdInfo, tcInstId ) +import TcInstUtil ( InstInfo(..), classDataCon ) +import TcMonoType ( tcHsTopType ) +import TcSimplify ( tcSimplifyAndCheck ) +import TcType ( TcTyVar, zonkTcTyVarBndr ) import Bag ( emptyBag, unitBag, unionBags, unionManyBags, foldBag, bagToList, Bag ) -import CmdLineOpts ( opt_GlasgowExts, opt_WarnMissingMethods ) +import CmdLineOpts ( opt_GlasgowExts, opt_AllowUndecidableInstances ) import Class ( classBigSig, Class ) -import Id ( idType, isNullaryDataCon, dataConArgTys, Id ) -import Maybes ( maybeToBool, seqMaybe, catMaybes ) -import Name ( nameOccName, mkLocalName, - isLocallyDefined, Module, +import Var ( setIdInfo, idName, idType, Id, TyVar ) +import DataCon ( isNullaryDataCon, dataConArgTys, dataConId ) +import Maybes ( maybeToBool, catMaybes, expectJust ) +import MkId ( mkDictFunId ) +import Name ( nameOccName, isLocallyDefined, Module, NamedThing(..) ) -import PrelVals ( nO_METHOD_BINDING_ERROR_ID ) -import PprType ( pprParendGenType, pprConstraint ) -import SrcLoc ( SrcLoc, noSrcLoc ) +import PrelVals ( eRROR_ID ) +import PprType ( pprConstraint ) +import SrcLoc ( SrcLoc ) import TyCon ( isSynTyCon, isDataTyCon, tyConDerivings ) -import Type ( Type, ThetaType, isUnpointedType, - splitSigmaTy, isTyVarTy, mkSigmaTy, +import Type ( Type, isUnLiftedType, mkTyVarTys, + splitSigmaTy, isTyVarTy, splitTyConApp_maybe, splitDictTy_maybe, - splitAlgTyConApp_maybe, splitRhoTy, - tyVarsOfTypes + splitAlgTyConApp_maybe, + tyVarsOfTypes, substTopTheta ) -import TyVar ( zipTyVarEnv, mkTyVarSet, tyVarSetToList, TyVar ) +import VarEnv ( zipVarEnv ) +import VarSet ( mkVarSet, varSetElems ) import TysPrim ( byteArrayPrimTyCon, mutableByteArrayPrimTyCon ) import TysWiredIn ( stringTy ) import Unique ( Unique, cCallableClassKey, cReturnableClassKey, Uniquable(..) ) @@ -144,13 +140,12 @@ and $dbinds_super$ bind the superclass dictionaries sd1 \ldots sdm. \end{enumerate} \begin{code} -tcInstDecls1 :: TcEnv s -- Contains IdInfo for dfun ids +tcInstDecls1 :: ValueEnv -- Contains IdInfo for dfun ids -> [RenamedHsDecl] -> Module -- module name for deriving -> RnNameSupply -- for renaming derivings -> TcM s (Bag InstInfo, - RenamedHsBinds, - SDoc) + RenamedHsBinds) tcInstDecls1 unf_env decls mod_name rn_name_supply = -- Do the ordinary instance declarations @@ -163,15 +158,15 @@ tcInstDecls1 unf_env decls mod_name rn_name_supply -- 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) -> + `thenTc` \ (deriv_inst_info, deriv_binds) -> let full_inst_info = deriv_inst_info `unionBags` decl_inst_info in - returnTc (full_inst_info, deriv_binds, ddump_deriv) + returnTc (full_inst_info, deriv_binds) -tcInstDecl1 :: TcEnv s -> Module -> RenamedInstDecl -> NF_TcM s (Bag InstInfo) +tcInstDecl1 :: ValueEnv -> Module -> RenamedInstDecl -> NF_TcM s (Bag InstInfo) tcInstDecl1 unf_env mod_name (InstDecl poly_ty binds uprags (Just dfun_name) src_loc) = -- Prime error recovery, set source location @@ -179,7 +174,7 @@ tcInstDecl1 unf_env mod_name (InstDecl poly_ty binds uprags (Just dfun_name) src tcAddSrcLoc src_loc $ -- Type-check all the stuff before the "where" - tcHsType poly_ty `thenTc` \ poly_ty' -> + tcHsTopType poly_ty `thenTc` \ poly_ty' -> let (tyvars, theta, dict_ty) = splitSigmaTy poly_ty' (clas, inst_tys) = case splitDictTy_maybe dict_ty of @@ -187,18 +182,27 @@ tcInstDecl1 unf_env mod_name (InstDecl poly_ty binds uprags (Just dfun_name) src Just pair -> pair in - -- Check for respectable instance type - scrutiniseInstanceType clas inst_tys `thenTc_` + -- 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] + (if isLocallyDefined dfun_name then + scrutiniseInstanceHead clas inst_tys `thenNF_Tc_` + mapNF_Tc scrutiniseInstanceConstraint theta + else + returnNF_Tc [] + ) `thenNF_Tc_` -- Make the dfun id and constant-method ids let - (dfun_id, dfun_theta) = mkInstanceRelatedIds dfun_name - clas tyvars inst_tys theta + dfun_id = mkDictFunId dfun_name clas tyvars inst_tys theta + -- Add info from interface file final_dfun_id = tcAddImportedIdInfo unf_env dfun_id in returnTc (unitBag (InstInfo clas tyvars inst_tys theta - dfun_theta final_dfun_id + final_dfun_id binds src_loc uprags)) \end{code} @@ -211,7 +215,7 @@ 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) + -> NF_TcM s (LIE, TcMonoBinds) tcInstDecls2 inst_decls = foldBag combine tcInstDecl2 (returnNF_Tc (emptyLIE, EmptyMonoBinds)) inst_decls @@ -290,10 +294,10 @@ 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 -> NF_TcM s (LIE, TcMonoBinds) tcInstDecl2 (InstInfo clas inst_tyvars inst_tys - inst_decl_theta dfun_theta + inst_decl_theta dfun_id monobinds locn uprags) | not (isLocallyDefined dfun_id) @@ -315,34 +319,30 @@ tcInstDecl2 (InstInfo clas inst_tyvars inst_tys recoverNF_Tc (returnNF_Tc (emptyLIE, EmptyMonoBinds)) $ tcAddSrcLoc locn $ - -- Get the class signature - let - origin = InstanceDeclOrigin + -- Instantiate the instance decl with tc-style type variables + tcInstId dfun_id `thenNF_Tc` \ (inst_tyvars', dfun_theta', dict_ty') -> + let + (clas, inst_tys') = expectJust "tcInstDecl2" (splitDictTy_maybe dict_ty') + + origin = InstanceDeclOrigin + (class_tyvars, sc_theta, sc_sel_ids, - op_sel_ids, defm_ids) = classBigSig clas - in - - -- Instantiate the instance decl with tc-style type variables - tcInstSigTyVars inst_tyvars `thenNF_Tc` \ (inst_tyvars', _, tenv) -> - mapNF_Tc (tcInstType tenv) inst_tys `thenNF_Tc` \ inst_tys' -> - tcInstTheta tenv dfun_theta `thenNF_Tc` \ dfun_theta' -> - tcInstTheta tenv inst_decl_theta `thenNF_Tc` \ inst_decl_theta' -> + op_sel_ids, defm_ids) = classBigSig clas - -- Instantiate the super-class context with inst_tys - - tcInstTheta (zipTyVarEnv class_tyvars inst_tys') sc_theta `thenNF_Tc` \ sc_theta' -> + -- Instantiate the theta found in the original instance decl + inst_decl_theta' = substTopTheta (zipVarEnv inst_tyvars (mkTyVarTys inst_tyvars')) + inst_decl_theta + -- Instantiate the super-class context with inst_tys + sc_theta' = substTopTheta (zipVarEnv class_tyvars inst_tys') sc_theta + 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]) -> - -- Now process any INLINE or SPECIALIZE pragmas for the methods - -- ...[NB May 97; all ignored except INLINE] - tcPragmaSigs uprags `thenTc` \ (prag_fn, spec_binds, spec_lie) -> - -- Check that all the method bindings come from this class let check_from_this_class (bndr, loc) @@ -354,18 +354,31 @@ tcInstDecl2 (InstInfo clas inst_tyvars inst_tys in mapNF_Tc check_from_this_class bndrs `thenNF_Tc_` - tcExtendGlobalValEnv (catMaybes defm_ids) ( - + tcExtendTyVarEnvForMeths inst_tyvars inst_tyvars' ( + tcExtendGlobalValEnv (catMaybes defm_ids) ( -- Default-method Ids may be mentioned in synthesised RHSs - mapAndUnzip3Tc (tcInstMethodBind clas inst_tys' inst_tyvars' monobinds) + + mapAndUnzip3Tc (tcMethodBind clas origin inst_tyvars' inst_tys' inst_decl_theta' + monobinds uprags True) (op_sel_ids `zip` defm_ids) - ) `thenTc` \ (method_binds_s, insts_needed_s, meth_lies_w_ids) -> + )) `thenTc` \ (method_binds_s, insts_needed_s, meth_lies_w_ids) -> + + -- Deal with SPECIALISE instance pragmas + let + dfun_prags = [Sig (idName dfun_id) ty loc | SpecInstSig ty loc <- uprags] + in + tcExtendGlobalValEnv [dfun_id] ( + tcPragmaSigs dfun_prags + ) `thenTc` \ (prag_info_fn, prag_binds, prag_lie) -> -- Check the overloading constraints of the methods and superclasses - mapNF_Tc zonkSigTyVar inst_tyvars' `thenNF_Tc` \ zonked_inst_tyvars -> + -- 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 = mkTyVarSet zonked_inst_tyvars + inst_tyvars_set = mkVarSet zonked_inst_tyvars (meth_lies, meth_ids) = unzip meth_lies_w_ids @@ -374,279 +387,102 @@ tcInstDecl2 (InstInfo clas inst_tyvars inst_tys dfun_arg_dicts `plusLIE` sc_dicts `plusLIE` unionManyBags meth_lies + + methods_lie = plusLIEs insts_needed_s in - tcAddErrCtxt superClassCtxt $ - tcAddErrCtxtM (sigThetaCtxt sc_dicts) $ - - -- Deal with the LIE arising from the method bindings - tcSimplifyAndCheck (text "inst decl1a") + -- Ditto method bindings + tcAddErrCtxt methodCtxt ( + tcSimplifyAndCheck + (ptext SLIT("instance declaration context")) inst_tyvars_set -- Local tyvars avail_insts - (unionManyBags insts_needed_s) -- Need to get defns for all these - `thenTc` \ (const_lie1, op_binds) -> + 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. + 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. - -- Deal with the super-class bindings - -- Ignore errors because they come from the *next* tcSimplify + -- 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 (text "inst decl1b") + tcSimplifyAndCheck + (ptext SLIT("instance declaration context")) inst_tyvars_set 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, sc_binds) -> + ) `thenTc` \ (const_lie2, lie_binds2) -> - -- 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. - tcSimplifyAndCheck (text "inst decl1c") - 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. - -- Create the result bindings let - const_lie = const_lie1 `plusLIE` const_lie2 - lie_binds = op_binds `AndMonoBinds` sc_binds - - dict_constr = classDataCon clas - - con_app = foldl HsApp (TyApp (HsVar (RealId dict_constr)) inst_tys') - (map HsVar (sc_dict_ids ++ meth_ids)) + dict_constr = classDataCon clas + scs_and_meths = sc_dict_ids ++ meth_ids + + dict_rhs + | null scs_and_meths + = -- 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 eRROR_ID) [idType this_dict_id]) + (HsLitOut (HsString msg) stringTy) + + | otherwise -- The common case + = foldl HsApp (TyApp (HsVar (dataConId dict_constr)) inst_tys') + (map HsVar (sc_dict_ids ++ meth_ids)) -- 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 + -- than needing to be repeated here. + + where + msg = _PK_ ("Compiler error: bad dictionary " ++ showSDoc (ppr clas)) - dict_bind = VarMonoBind this_dict_id con_app - method_binds = andMonoBinds method_binds_s + 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 dfun_id, this_dict_id)] - (lie_binds `AndMonoBinds` + [(inst_tyvars', final_dfun_id, this_dict_id)] + (lie_binds1 `AndMonoBinds` + lie_binds2 `AndMonoBinds` method_binds `AndMonoBinds` dict_bind) in - returnTc (const_lie `plusLIE` spec_lie, - main_bind `AndMonoBinds` spec_binds) + returnTc (const_lie1 `plusLIE` const_lie2 `plusLIE` prag_lie, + main_bind `AndMonoBinds` prag_binds) \end{code} %************************************************************************ %* * -\subsection{Processing each method} +\subsection{Checking for a decent instance type} %* * %************************************************************************ -\begin{code} -tcInstMethodBind - :: Class - -> [TcType s] -- Instance types - -> [TcTyVar s] -- and their free (sig) tyvars - -> RenamedMonoBinds -- Method binding - -> (Id, Maybe Id) -- Selector id and default-method id - -> TcM s (TcMonoBinds s, LIE s, (LIE s, TcIdOcc s)) - -tcInstMethodBind clas inst_tys inst_tyvars meth_binds (sel_id, maybe_dm_id) - = tcGetSrcLoc `thenNF_Tc` \ loc -> - tcGetUnique `thenNF_Tc` \ uniq -> - let - meth_occ = getOccName sel_id - default_meth_name = mkLocalName uniq meth_occ loc - maybe_meth_bind = find meth_occ meth_binds - the_meth_bind = case maybe_meth_bind of - Just stuff -> stuff - Nothing -> mk_default_bind default_meth_name loc - in - - -- Warn if no method binding, only if -fwarn-missing-methods - - warnTc (opt_WarnMissingMethods && - not (maybeToBool maybe_meth_bind) && - not (maybeToBool maybe_dm_id)) - (omittedMethodWarn sel_id clas) `thenNF_Tc_` - - -- Typecheck the method binding - tcMethodBind clas origin inst_tys inst_tyvars sel_id the_meth_bind - where - origin = InstanceDeclOrigin -- Poor - - find occ EmptyMonoBinds = Nothing - find occ (AndMonoBinds b1 b2) = find occ b1 `seqMaybe` find occ b2 - - find occ b@(FunMonoBind op_name _ _ _) | nameOccName op_name == occ = Just b - | otherwise = Nothing - find occ b@(PatMonoBind (VarPatIn op_name) _ _) | nameOccName op_name == occ = Just b - | otherwise = Nothing - find occ other = panic "Urk! Bad instance method binding" - - - mk_default_bind local_meth_name loc - = PatMonoBind (VarPatIn local_meth_name) - (GRHSsAndBindsIn (unguardedRHS (default_expr loc) loc) EmptyBinds) - loc - - default_expr loc - = case maybe_dm_id of - Just dm_id -> HsVar (getName dm_id) -- There's a default method - Nothing -> error_expr loc -- No default method - - error_expr loc - = HsApp (HsVar (getName nO_METHOD_BINDING_ERROR_ID)) - (HsLit (HsString (_PK_ (error_msg loc)))) - - error_msg loc = showSDoc (hcat [ppr loc, text "|", ppr sel_id ]) - -\end{code} - - - -%************************************************************************ -%* * -\subsection{Type-checking specialise instance pragmas} -%* * -%************************************************************************ - -\begin{code} -{- LATER -tcSpecInstSigs :: E -> CE -> TCE - -> Bag InstInfo -- inst decls seen (declared and derived) - -> [RenamedSpecInstSig] -- specialise instance upragmas - -> TcM (Bag InstInfo) -- new, overlapped, inst decls - -tcSpecInstSigs e ce tce inst_infos [] - = returnTc emptyBag - -tcSpecInstSigs e ce tce inst_infos sigs - = buildInstanceEnvs inst_infos `thenTc` \ inst_mapper -> - tc_inst_spec_sigs inst_mapper sigs `thenNF_Tc` \ spec_inst_infos -> - returnTc spec_inst_infos - where - tc_inst_spec_sigs inst_mapper [] - = returnNF_Tc emptyBag - tc_inst_spec_sigs inst_mapper (sig:sigs) - = tcSpecInstSig e ce tce inst_infos inst_mapper sig `thenNF_Tc` \ info_sig -> - tc_inst_spec_sigs inst_mapper sigs `thenNF_Tc` \ info_sigs -> - returnNF_Tc (info_sig `unionBags` info_sigs) - -tcSpecInstSig :: E -> CE -> TCE - -> Bag InstInfo - -> InstanceMapper - -> RenamedSpecInstSig - -> NF_TcM (Bag InstInfo) - -tcSpecInstSig e ce tce inst_infos inst_mapper (SpecInstSig class_name ty src_loc) - = recoverTc emptyBag ( - tcAddSrcLoc src_loc ( - let - clas = lookupCE ce class_name -- Renamer ensures this can't fail - - -- Make some new type variables, named as in the specialised instance type - ty_names = extractHsTyNames ???is_tyvarish_name??? ty - (tmpl_e,inst_tmpls,inst_tmpl_tys) = mkTVE ty_names - in - babyTcMtoTcM (tcInstanceType ce tce tmpl_e True src_loc ty) - `thenTc` \ inst_ty -> - let - maybe_tycon = case splitAlgTyConApp_maybe inst_ty of - Just (tc,_,_) -> Just tc - Nothing -> Nothing - - maybe_unspec_inst = lookup_unspec_inst clas maybe_tycon inst_infos - in - -- Check that we have a local instance declaration to specialise - checkMaybeTc maybe_unspec_inst - (specInstUnspecInstNotFoundErr clas inst_ty src_loc) `thenTc_` - - -- Create tvs to substitute for tmpls while simplifying the context - copyTyVars inst_tmpls `thenNF_Tc` \ (tv_e, inst_tvs, inst_tv_tys) -> - let - Just (InstInfo _ unspec_tyvars unspec_inst_ty unspec_theta - _ _ binds _ uprag) = maybe_unspec_inst - - subst = case matchTy unspec_inst_ty inst_ty of - Just subst -> subst - Nothing -> panic "tcSpecInstSig:matchTy" - - subst_theta = instantiateThetaTy subst unspec_theta - subst_tv_theta = instantiateThetaTy tv_e subst_theta - - mk_spec_origin clas ty - = InstanceSpecOrigin inst_mapper clas ty src_loc - -- I'm VERY SUSPICIOUS ABOUT THIS - -- the inst-mapper is in a knot at this point so it's no good - -- looking at it in tcSimplify... - in - tcSimplifyThetas mk_spec_origin subst_tv_theta - `thenTc` \ simpl_tv_theta -> - let - simpl_theta = [ (clas, tv_to_tmpl tv) | (clas, tv) <- simpl_tv_theta ] - - tv_tmpl_map = zipEqual "tcSpecInstSig" inst_tv_tys inst_tmpl_tys - tv_to_tmpl tv = assoc "tcSpecInstSig" tv_tmpl_map tv - in - mkInstanceRelatedIds clas inst_tmpls inst_ty simpl_theta uprag - `thenNF_Tc` \ (dfun_id, dfun_theta, const_meth_ids) -> - - getSwitchCheckerTc `thenNF_Tc` \ sw_chkr -> - (if sw_chkr SpecialiseTrace then - pprTrace "Specialised Instance: " - (vcat [hsep [if null simpl_theta then empty else ppr simpl_theta, - if null simpl_theta then empty else ptext SLIT("=>"), - ppr clas, - pprParendGenType inst_ty], - hsep [ptext SLIT(" derived from:"), - if null unspec_theta then empty else ppr unspec_theta, - if null unspec_theta then empty else ptext SLIT("=>"), - ppr clas, - pprParendGenType unspec_inst_ty]]) - else id) ( - - returnTc (unitBag (InstInfo clas inst_tmpls inst_ty simpl_theta - dfun_theta dfun_id - binds src_loc uprag)) - ))) - - -lookup_unspec_inst clas maybe_tycon inst_infos - = case filter (match_info match_inst_ty) (bagToList inst_infos) of - [] -> Nothing - (info:_) -> Just info - where - match_info match_ty (InstInfo inst_clas _ inst_ty _ _ _ _ _ from_here _ _ _) - = from_here && clas == inst_clas && - match_ty inst_ty && is_plain_instance inst_ty - - match_inst_ty = case maybe_tycon of - Just tycon -> match_tycon tycon - Nothing -> match_fun - - match_tycon tycon inst_ty = case (splitAlgTyConApp_maybe inst_ty) of - Just (inst_tc,_,_) -> tycon == inst_tc - Nothing -> False - - match_fun inst_ty = isFunType inst_ty - - -is_plain_instance inst_ty - = case (splitAlgTyConApp_maybe inst_ty) of - Just (_,tys,_) -> all isTyVarTemplateTy tys - Nothing -> case maybeUnpackFunTy inst_ty of - Just (arg, res) -> isTyVarTemplateTy arg && isTyVarTemplateTy res - Nothing -> error "TcInstDecls:is_plain_instance" --} -\end{code} - - -Checking for a decent instance type -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -@scrutiniseInstanceType@ checks the type {\em and} its syntactic constraints: +@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@ @@ -656,7 +492,12 @@ compiled elsewhere). In these cases, we let them go through anyway. We can also have instances for functions: @instance Foo (a -> b) ...@. \begin{code} -scrutiniseInstanceType clas inst_taus +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) @@ -664,59 +505,71 @@ scrutiniseInstanceType clas inst_taus -- -- We flag this separately to give a more precise error msg. -- - (uniqueOf clas == cCallableClassKey && not constructors_visible) || - (uniqueOf clas == cReturnableClassKey && not constructors_visible) - = failWithTc (invisibleDataConPrimCCallErr clas first_inst_tau) + (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. - (uniqueOf clas == cCallableClassKey && not (ccallable_type first_inst_tau)) || - (uniqueOf clas == cReturnableClassKey && not (creturnable_type first_inst_tau)) - = failWithTc (nonBoxedPrimCCallErr clas first_inst_tau) + (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' - | clas `elem` (tyConDerivings inst_tycon) - = failWithTc (derivingWhenInstanceExistsErr clas first_inst_tau) + | 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 - -- ALL TYPE VARIABLES => bad - | all isTyVarTy inst_taus - = failWithTc (instTypeErr clas inst_taus (text "all the instance types are type variables")) + -- 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 opt_GlasgowExts - && not (length inst_taus == 1 && - maybeToBool tyconapp_maybe && - not (isSynTyCon inst_tycon) && - all isTyVarTy arg_tys && - length (tyVarSetToList (tyVarsOfTypes arg_tys)) == length arg_tys + | 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 ) - = failWithTc (instTypeErr clas inst_taus + = 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 - = returnTc () + = returnNF_Tc () where - tyconapp_maybe = splitTyConApp_maybe first_inst_tau - Just (inst_tycon, arg_tys) = tyconapp_maybe (first_inst_tau : _) = inst_taus - constructors_visible = - case splitAlgTyConApp_maybe first_inst_tau of - Just (_,_,[]) -> False - everything_else -> True + -- 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 = isUnpointedType ty || -- Allow CCallable Int# etc +ccallable_type ty = isUnLiftedType ty || -- Allow CCallable Int# etc maybeToBool (maybeBoxedPrimType ty) || -- Ditto Int etc ty == stringTy || byte_arr_thing @@ -744,15 +597,17 @@ creturnable_type ty = maybeToBool (maybeBoxedPrimType ty) || \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) ] -instBndrErr bndr clas - = hsep [ptext SLIT("Class"), quotes (ppr clas), ptext SLIT("does not have a method"), quotes (ppr bndr)] - derivingWhenInstanceExistsErr clas tycon = hang (hsep [ptext SLIT("Deriving class"), quotes (ppr clas), @@ -764,10 +619,6 @@ nonBoxedPrimCCallErr clas inst_ty 4 (hsep [ ptext SLIT("class"), ppr clas, ptext SLIT("type"), ppr inst_ty]) -omittedMethodWarn sel_id clas - = sep [ptext SLIT("No explicit method nor default method for") <+> quotes (ppr sel_id), - ptext SLIT("in an instance declaration for") <+> quotes (ppr clas)] - {- Declaring CCallable & CReturnable instances in a module different from where the type was defined. Caused by importing data type @@ -781,19 +632,6 @@ invisibleDataConPrimCCallErr clas inst_ty 4 (hsep [text "(Try either importing", ppr inst_ty, text "non-abstractly or compile using -fno-prune-tydecls ..)"]) -instMethodNotInClassErr occ clas - = hang (ptext SLIT("Instance mentions a method not in the class")) - 4 (hsep [ptext SLIT("class") <+> quotes (ppr clas), - ptext SLIT("method") <+> quotes (ppr occ)]) - -patMonoBindsCtxt pbind - = hang (ptext SLIT("In a pattern binding:")) - 4 (ppr pbind) - -methodSigCtxt name ty - = hang (hsep [ptext SLIT("When matching the definition of class method"), - quotes (ppr name), ptext SLIT("to its signature :") ]) - 4 (ppr ty) - -superClassCtxt = ptext SLIT("From the superclasses of the instance declaration") +methodCtxt = ptext SLIT("When checking the methods of an instance declaration") +superClassCtxt = ptext SLIT("When checking the superclasses of an instance declaration") \end{code}