X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcInstDcls.lhs;h=e3efa78ecccba6452afbffec3660750ac1a72a7e;hb=b117679aefcfabd2f8b34a9f495ede8508d7f88d;hp=900d97f78bde0d35b3c75a7c06a02182eebc6c1a;hpb=28139aea50376444d56f43f0914291348a51a7e7;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcInstDcls.lhs b/ghc/compiler/typecheck/TcInstDcls.lhs index 900d97f..e3efa78 100644 --- a/ghc/compiler/typecheck/TcInstDcls.lhs +++ b/ghc/compiler/typecheck/TcInstDcls.lhs @@ -11,77 +11,62 @@ module TcInstDcls ( #include "HsVersions.h" -import HsSyn ( HsDecl(..), InstDecl(..), HsType(..), +import HsSyn ( HsDecl(..), InstDecl(..), HsBinds(..), MonoBinds(..), GRHSsAndBinds(..), GRHS(..), - HsExpr(..), InPat(..), HsLit(..), + HsExpr(..), InPat(..), HsLit(..), Sig(..), unguardedRHS, collectMonoBinders, andMonoBinds ) +import HsBinds ( sigsForMe ) import RnHsSyn ( RenamedHsBinds, RenamedMonoBinds, - RenamedInstDecl, RenamedFixityDecl, RenamedHsExpr, - RenamedSig, RenamedSpecInstSig, RenamedHsDecl + RenamedInstDecl, RenamedHsExpr, + RenamedSig, RenamedHsDecl + ) +import TcHsSyn ( TcMonoBinds, TcIdOcc(..), TcIdBndr, + maybeBoxedPrimType, tcIdType ) -import TcHsSyn ( TcHsBinds, - TcMonoBinds, TcExpr, TcIdOcc(..), TcIdBndr, - tcIdType, maybeBoxedPrimType, - mkHsTyLam, mkHsTyApp, - mkHsDictLam, mkHsDictApp ) -import TcBinds ( tcPragmaSigs, sigThetaCtxt ) +import TcBinds ( tcPragmaSigs ) import TcClassDcl ( tcMethodBind, badMethodErr ) import TcMonad import RnMonad ( RnNameSupply ) -import Inst ( Inst, InstOrigin(..), InstanceMapper, - instToId, newDicts, newMethod, LIE, emptyLIE, plusLIE ) -import PragmaInfo ( PragmaInfo(..) ) +import Inst ( Inst, InstOrigin(..), + newDicts, LIE, emptyLIE, plusLIE, plusLIEs ) import TcDeriv ( tcDeriving ) -import TcEnv ( tcLookupClass, newLocalId, tcGetGlobalTyVars, - tcExtendGlobalValEnv, tcAddImportedIdInfo - ) -import TcInstUtil ( InstInfo(..), mkInstanceRelatedIds, buildInstanceEnvs, classDataCon ) +import TcEnv ( GlobalValueEnv, tcExtendGlobalValEnv, tcAddImportedIdInfo ) +import TcInstUtil ( InstInfo(..), mkInstanceRelatedIds, classDataCon ) import TcKind ( TcKind, unifyKind ) -import TcMatches ( tcMatchesFun ) -import TcMonoType ( tcTyVarScope, tcContext, tcHsTypeKind, tcHsType ) +import TcMonoType ( tcHsType ) import TcSimplify ( tcSimplifyAndCheck ) import TcType ( TcType, TcTyVar, TcTyVarSet, - zonkSigTyVar, - tcInstSigTyVars, tcInstType, tcInstSigTcType, - tcInstTheta, tcInstTcType + zonkSigTyVar, tcInstSigType, tcInstTheta ) -import Unify ( unifyTauTy, unifyTauTyLists ) - import Bag ( emptyBag, unitBag, unionBags, unionManyBags, - concatBag, foldBag, bagToList, listToBag, - Bag + foldBag, bagToList, Bag ) -import CmdLineOpts ( opt_GlasgowExts, - opt_SpecialiseOverloaded, opt_WarnMissingMethods - ) -import Class ( classBigSig, classTyCon, Class ) -import Id ( idType, replacePragmaInfo, - isNullaryDataCon, dataConArgTys, Id ) -import ListSetOps ( minusList ) -import Maybes ( maybeToBool, expectJust, seqMaybe, catMaybes ) -import Name ( nameOccName, getSrcLoc, mkLocalName, +import CmdLineOpts ( opt_GlasgowExts ) +import Class ( classBigSig, Class ) +import Id ( isNullaryDataCon, dataConArgTys, replaceIdInfo, idName, idType, Id ) +import Maybes ( maybeToBool, seqMaybe, catMaybes, expectJust ) +import Name ( nameOccName, mkLocalName, isLocallyDefined, Module, NamedThing(..) ) -import PrelVals ( nO_METHOD_BINDING_ERROR_ID ) -import PprType ( pprParendGenType, pprConstraint ) +import PrelVals ( eRROR_ID ) +import PprType ( pprParendType, pprConstraint ) import SrcLoc ( SrcLoc, noSrcLoc ) -import TyCon ( tyConDataCons, isSynTyCon, isDataTyCon, tyConDerivings ) -import Type ( Type, ThetaType, mkTyVarTys, isUnpointedType, - splitSigmaTy, splitAppTys, isTyVarTy, matchTy, mkSigmaTy, - splitTyConApp_maybe, getTyVar, splitDictTy_maybe, - splitAlgTyConApp_maybe, splitRhoTy, isSynTy, - tyVarsOfTypes +import TyCon ( isSynTyCon, isDataTyCon, tyConDerivings ) +import Type ( Type, ThetaType, isUnpointedType, + splitSigmaTy, isTyVarTy, mkSigmaTy, + splitTyConApp_maybe, splitDictTy_maybe, + splitAlgTyConApp_maybe, splitRhoTy, + tyVarsOfTypes, mkTyVarTys, ) import TyVar ( zipTyVarEnv, mkTyVarSet, tyVarSetToList, TyVar ) import TysPrim ( byteArrayPrimTyCon, mutableByteArrayPrimTyCon ) import TysWiredIn ( stringTy ) import Unique ( Unique, cCallableClassKey, cReturnableClassKey, Uniquable(..) ) -import Util ( zipEqual, removeDups ) import Outputable \end{code} @@ -159,7 +144,7 @@ and $dbinds_super$ bind the superclass dictionaries sd1 \ldots sdm. \end{enumerate} \begin{code} -tcInstDecls1 :: TcEnv s -- Contains IdInfo for dfun ids +tcInstDecls1 :: GlobalValueEnv -- Contains IdInfo for dfun ids -> [RenamedHsDecl] -> Module -- module name for deriving -> RnNameSupply -- for renaming derivings @@ -186,7 +171,7 @@ tcInstDecls1 unf_env decls mod_name rn_name_supply returnTc (full_inst_info, deriv_binds, ddump_deriv) -tcInstDecl1 :: TcEnv s -> Module -> RenamedInstDecl -> NF_TcM s (Bag InstInfo) +tcInstDecl1 :: GlobalValueEnv -> 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 @@ -202,8 +187,9 @@ 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 + scrutiniseInstanceHead clas inst_tys `thenNF_Tc_` + mapNF_Tc scrutiniseInstanceConstraint theta `thenNF_Tc_` -- Make the dfun id and constant-method ids let @@ -330,23 +316,26 @@ 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 + tcInstSigType (idType dfun_id) `thenNF_Tc` \ dfun_ty' -> + let + (inst_tyvars', + dfun_theta', dict_ty') = splitSigmaTy dfun_ty' + + (clas, inst_tys') = expectJust "tcInstDecl2" (splitDictTy_maybe dict_ty') + (class_tyvars, sc_theta, sc_sel_ids, - op_sel_ids, defm_ids) = classBigSig clas + op_sel_ids, defm_ids) = classBigSig clas + + origin = InstanceDeclOrigin 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' -> + -- Instantiate the theta found in the original instance decl + tcInstTheta (zipTyVarEnv inst_tyvars (mkTyVarTys inst_tyvars')) + inst_decl_theta `thenNF_Tc` \ inst_decl_theta' -> - -- Instantiate the super-class context with inst_tys - - tcInstTheta (zipTyVarEnv class_tyvars inst_tys') sc_theta `thenNF_Tc` \ sc_theta' -> + -- Instantiate the super-class context with the instance types + tcInstTheta (zipTyVarEnv class_tyvars inst_tys') sc_theta `thenNF_Tc` \ sc_theta' -> -- Create dictionary Ids from the specified instance contexts. newDicts origin sc_theta' `thenNF_Tc` \ (sc_dicts, sc_dict_ids) -> @@ -354,10 +343,6 @@ tcInstDecl2 (InstInfo clas inst_tyvars inst_tys 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) @@ -372,10 +357,18 @@ tcInstDecl2 (InstInfo clas inst_tyvars inst_tys 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_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 + 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 -> @@ -389,279 +382,96 @@ 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 (RealId eRROR_ID)) [tcIdType this_dict_id]) + (HsLitOut (HsString msg) stringTy) + + | otherwise -- The common case + = HsCon 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 + -- just generate the saturated constructor directly + where + msg = _PK_ ("Compiler error: bad dictionary " ++ showSDoc (ppr clas)) - dict_bind = VarMonoBind this_dict_id con_app + dict_bind = VarMonoBind this_dict_id dict_rhs method_binds = andMonoBinds method_binds_s + final_dfun_id = replaceIdInfo 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', RealId 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) -\end{code} - - -%************************************************************************ -%* * -\subsection{Processing each method} -%* * -%************************************************************************ - -\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 ]) - + returnTc (const_lie1 `plusLIE` const_lie2 `plusLIE` prag_lie, + main_bind `AndMonoBinds` prag_binds) \end{code} - %************************************************************************ %* * -\subsection{Type-checking specialise instance pragmas} +\subsection{Checking for a decent instance type} %* * %************************************************************************ -\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@ @@ -671,7 +481,11 @@ 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 = 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) @@ -679,54 +493,56 @@ 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) + (uniqueOf clas == cCallableClassKey || uniqueOf 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) + = 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")) - -- WITH HASKELL 1.4, MUST HAVE C (T a b c) - | not opt_GlasgowExts + | not opt_GlasgowExts && not (length inst_taus == 1 && - maybeToBool tyconapp_maybe && - not (isSynTyCon inst_tycon) && - all isTyVarTy arg_tys && + 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 (tyVarSetToList (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. @@ -759,15 +575,17 @@ 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), @@ -779,10 +597,6 @@ 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 @@ -796,19 +610,6 @@ 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}