X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcClassDcl.lhs;h=fb29e563bc2d4c893d630a7afa68204ebe0f2abb;hb=115f0fae2f782836550a9419f739fd29c09e4f1b;hp=08403bc52ac3c3ec6194db2756a56c789da94374;hpb=95581e0c3b2d4d6edd33fdd6e135aa3917072c4c;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcClassDcl.lhs b/ghc/compiler/typecheck/TcClassDcl.lhs index 08403bc..fb29e56 100644 --- a/ghc/compiler/typecheck/TcClassDcl.lhs +++ b/ghc/compiler/typecheck/TcClassDcl.lhs @@ -5,26 +5,26 @@ \begin{code} module TcClassDcl ( tcClassDecl1, tcClassDecls2, - tcMethodBind, mkMethodBind, badMethodErr + MethodSpec, tcMethodBind, mkMethodBind, badMethodErr ) where #include "HsVersions.h" import HsSyn ( TyClDecl(..), Sig(..), MonoBinds(..), - HsExpr(..), HsLit(..), + HsExpr(..), HsLit(..), Pat(WildPat), mkSimpleMatch, andMonoBinds, andMonoBindList, - isClassOpSig, isPragSig, - getClassDeclSysNames, placeHolderType + isClassOpSig, isPragSig, + placeHolderType ) import BasicTypes ( RecFlag(..), StrictnessMark(..) ) -import RnHsSyn ( RenamedTyClDecl, +import RnHsSyn ( RenamedTyClDecl, RenamedSig, RenamedClassOpSig, RenamedMonoBinds, maybeGenericMatch ) +import RnEnv ( lookupSysName ) import TcHsSyn ( TcMonoBinds ) -import Inst ( Inst, InstOrigin(..), LIE, emptyLIE, plusLIE, plusLIEs, - instToId, newDicts, newMethod ) +import Inst ( Inst, InstOrigin(..), instToId, newDicts, newMethod ) import TcEnv ( TyThingDetails(..), tcLookupClass, tcExtendTyVarEnv2, tcExtendTyVarEnv @@ -33,29 +33,36 @@ import TcBinds ( tcMonoBinds ) import TcMonoType ( TcSigInfo(..), tcHsType, tcHsTheta, mkTcSig ) import TcSimplify ( tcSimplifyCheck ) import TcUnify ( checkSigTyVars, sigCtxt ) -import TcMType ( tcInstTyVars, checkValidTheta, checkValidType, SourceTyCtxt(..), UserTypeCtxt(..) ) +import TcMType ( tcInstTyVars ) import TcType ( Type, TyVarDetails(..), TcType, TcThetaType, TcTyVar, - mkTyVarTys, mkPredTys, mkClassPred, - tcIsTyVarTy, tcSplitTyConApp_maybe, tcSplitSigmaTy + mkTyVarTys, mkPredTys, mkClassPred, tcSplitSigmaTy, tcSplitFunTys, + tcIsTyVarTy, tcSplitTyConApp_maybe, tcSplitForAllTys, tcSplitPhiTy, + getClassPredTys_maybe, mkPhiTy ) -import TcMonad +import TcRnMonad import Generics ( mkGenericRhs ) import PrelInfo ( nO_METHOD_BINDING_ERROR_ID ) -import Class ( classTyVars, classBigSig, classTyCon, className, +import Class ( classTyVars, classBigSig, classTyCon, Class, ClassOpItem, DefMeth (..) ) +import TyCon ( tyConGenInfo ) +import Subst ( substTyWith ) import MkId ( mkDictSelId, mkDataConId, mkDataConWrapId, mkDefaultMethodId ) import DataCon ( mkDataCon ) -import Id ( Id, idType, idName, setIdLocalExported ) -import Module ( Module ) +import Id ( Id, idType, idName, mkUserLocal, setIdLocalExported, setInlinePragma ) import Name ( Name, NamedThing(..) ) import NameEnv ( NameEnv, lookupNameEnv, emptyNameEnv, unitNameEnv, plusNameEnv ) -import NameSet ( emptyNameSet ) +import NameSet ( emptyNameSet, unitNameSet ) +import OccName ( mkClassTyConOcc, mkClassDataConOcc, mkWorkerOcc, + mkSuperDictSelOcc, reportIfUnused ) import Outputable import Var ( TyVar ) import CmdLineOpts +import UnicodeUtil ( stringToUtf8 ) import ErrUtils ( dumpIfSet ) -import Util ( count, isSingleton, lengthIs, equalLength ) -import Maybes ( seqMaybe, maybeToBool ) +import Util ( count, lengthIs, isSingleton ) +import Maybes ( seqMaybe ) +import Maybe ( isJust ) +import FastString \end{code} @@ -105,30 +112,40 @@ tcClassDecl1 :: RenamedTyClDecl -> TcM (Name, TyThingDetails) tcClassDecl1 (ClassDecl {tcdCtxt = context, tcdName = class_name, tcdTyVars = tyvar_names, tcdFDs = fundeps, tcdSigs = class_sigs, tcdMeths = def_methods, - tcdSysNames = sys_names, tcdLoc = src_loc}) + tcdLoc = src_loc}) = -- LOOK THINGS UP IN THE ENVIRONMENT - tcLookupClass class_name `thenTc` \ clas -> + tcLookupClass class_name `thenM` \ clas -> let - tyvars = classTyVars clas - op_sigs = filter isClassOpSig class_sigs - op_names = [n | ClassOpSig n _ _ _ <- op_sigs] - (_, datacon_name, datacon_wkr_name, sc_sel_names) = getClassDeclSysNames sys_names + tyvars = classTyVars clas + op_sigs = filter isClassOpSig class_sigs + op_names = [n | ClassOpSig n _ _ _ <- op_sigs] in tcExtendTyVarEnv tyvars $ - checkDefaultBinds clas op_names def_methods `thenTc` \ mb_dm_env -> + checkDefaultBinds clas op_names def_methods `thenM` \ mb_dm_env -> -- CHECK THE CONTEXT -- The renamer has already checked that the context mentions -- only the type variable of the class decl. -- Context is already kind-checked - ASSERT( equalLength context sc_sel_names ) - tcHsTheta context `thenTc` \ sc_theta -> + tcHsTheta context `thenM` \ sc_theta -> -- CHECK THE CLASS SIGNATURES, - mapTc (tcClassSig clas tyvars mb_dm_env) op_sigs `thenTc` \ sig_stuff -> + mappM (tcClassSig clas tyvars mb_dm_env) op_sigs `thenM` \ sig_stuff -> -- MAKE THE CLASS DETAILS + lookupSysName class_name mkClassDataConOcc `thenM` \ datacon_name -> + lookupSysName datacon_name mkWorkerOcc `thenM` \ datacon_wkr_name -> + mapM (lookupSysName class_name . mkSuperDictSelOcc) + [1..length context] `thenM` \ sc_sel_names -> + -- We number off the superclass selectors, 1, 2, 3 etc so that we + -- can construct names for the selectors. Thus + -- class (C a, C b) => D a b where ... + -- gives superclass selectors + -- D_sc1, D_sc2 + -- (We used to call them D_C, but now we can have two different + -- superclasses both called C!) + lookupSysName class_name mkClassTyConOcc `thenM` \ tycon_name -> let (op_tys, op_items) = unzip sig_stuff sc_tys = mkPredTys sc_theta @@ -148,7 +165,7 @@ tcClassDecl1 (ClassDecl {tcdCtxt = context, tcdName = class_name, dict_con_id = mkDataConId datacon_wkr_name dict_con dict_wrap_id = mkDataConWrapId dict_con in - returnTc (class_name, ClassDetails sc_theta sc_sel_ids op_items dict_con) + returnM (class_name, ClassDetails sc_theta sc_sel_ids op_items dict_con tycon_name) \end{code} \begin{code} @@ -167,31 +184,31 @@ checkDefaultBinds :: Class -> [Name] -> Maybe RenamedMonoBinds -- But do all this only for source binds checkDefaultBinds clas ops Nothing - = returnTc Nothing + = returnM Nothing checkDefaultBinds clas ops (Just mbs) - = go mbs `thenTc` \ dm_env -> - returnTc (Just dm_env) + = go mbs `thenM` \ dm_env -> + returnM (Just dm_env) where - go EmptyMonoBinds = returnTc emptyNameEnv + go EmptyMonoBinds = returnM emptyNameEnv go (AndMonoBinds b1 b2) - = go b1 `thenTc` \ dm_info1 -> - go b2 `thenTc` \ dm_info2 -> - returnTc (dm_info1 `plusNameEnv` dm_info2) + = go b1 `thenM` \ dm_info1 -> + go b2 `thenM` \ dm_info2 -> + returnM (dm_info1 `plusNameEnv` dm_info2) go (FunMonoBind op _ matches loc) - = tcAddSrcLoc loc $ + = addSrcLoc loc $ -- Check that the op is from this class - checkTc (op `elem` ops) (badMethodErr clas op) `thenTc_` + checkTc (op `elem` ops) (badMethodErr clas op) `thenM_` -- Check that all the defns ar generic, or none are - checkTc (all_generic || none_generic) (mixedGenericErr op) `thenTc_` + checkTc (all_generic || none_generic) (mixedGenericErr op) `thenM_` - returnTc (unitNameEnv op all_generic) + returnM (unitNameEnv op all_generic) where - n_generic = count (maybeToBool . maybeGenericMatch) matches + n_generic = count (isJust . maybeGenericMatch) matches none_generic = n_generic == 0 all_generic = matches `lengthIs` n_generic \end{code} @@ -213,11 +230,11 @@ tcClassSig :: Class -- ...ditto... tcClassSig clas clas_tyvars maybe_dm_env (ClassOpSig op_name sig_dm op_ty src_loc) - = tcAddSrcLoc src_loc $ + = addSrcLoc src_loc $ -- Check the type signature. NB that the envt *already has* -- bindings for the type variables; see comments in TcTyAndClassDcls. - tcHsType op_ty `thenTc` \ local_ty -> + tcHsType op_ty `thenM` \ local_ty -> let theta = [mkClassPred clas (mkTyVarTys clas_tyvars)] @@ -235,7 +252,7 @@ tcClassSig clas clas_tyvars maybe_dm_env Just True -> GenDefMeth Just False -> DefMeth dm_name in - returnTc (local_ty, (sel_id, dm_info)) + returnM (local_ty, (sel_id, dm_info)) \end{code} @@ -304,19 +321,18 @@ The function @tcClassDecls2@ just arranges to apply @tcClassDecl2@ to each local class decl. \begin{code} -tcClassDecls2 :: Module -> [RenamedTyClDecl] -> NF_TcM (LIE, TcMonoBinds, [Id]) +tcClassDecls2 :: [RenamedTyClDecl] -> TcM (TcMonoBinds, [Id]) -tcClassDecls2 this_mod decls +tcClassDecls2 decls = foldr combine - (returnNF_Tc (emptyLIE, EmptyMonoBinds, [])) + (returnM (EmptyMonoBinds, [])) [tcClassDecl2 cls_decl | cls_decl@(ClassDecl {tcdMeths = Just _}) <- decls] -- The 'Just' picks out source ClassDecls where - combine tc1 tc2 = tc1 `thenNF_Tc` \ (lie1, binds1, ids1) -> - tc2 `thenNF_Tc` \ (lie2, binds2, ids2) -> - returnNF_Tc (lie1 `plusLIE` lie2, - binds1 `AndMonoBinds` binds2, - ids1 ++ ids2) + combine tc1 tc2 = tc1 `thenM` \ (binds1, ids1) -> + tc2 `thenM` \ (binds2, ids2) -> + returnM (binds1 `AndMonoBinds` binds2, + ids1 ++ ids2) \end{code} @tcClassDecl2@ generates bindings for polymorphic default methods @@ -324,14 +340,14 @@ tcClassDecls2 this_mod decls \begin{code} tcClassDecl2 :: RenamedTyClDecl -- The class declaration - -> NF_TcM (LIE, TcMonoBinds, [Id]) + -> TcM (TcMonoBinds, [Id]) tcClassDecl2 (ClassDecl {tcdName = class_name, tcdSigs = sigs, tcdMeths = Just default_binds, tcdLoc = src_loc}) = -- The 'Just' picks out source ClassDecls - recoverNF_Tc (returnNF_Tc (emptyLIE, EmptyMonoBinds, [])) $ - tcAddSrcLoc src_loc $ - tcLookupClass class_name `thenNF_Tc` \ clas -> + recoverM (returnM (EmptyMonoBinds, [])) $ + addSrcLoc src_loc $ + tcLookupClass class_name `thenM` \ clas -> -- We make a separate binding for each default method. -- At one time I used a single AbsBinds for all of them, thus @@ -346,13 +362,13 @@ tcClassDecl2 (ClassDecl {tcdName = class_name, tcdSigs = sigs, prags = filter isPragSig sigs tc_dm = tcDefMeth clas tyvars default_binds prags in - mapAndUnzip3Tc tc_dm op_items `thenTc` \ (defm_binds, const_lies, dm_ids_s) -> + mapAndUnzipM tc_dm op_items `thenM` \ (defm_binds, dm_ids_s) -> - returnTc (plusLIEs const_lies, andMonoBindList defm_binds, concat dm_ids_s) + returnM (andMonoBindList defm_binds, concat dm_ids_s) -tcDefMeth clas tyvars binds_in prags (_, NoDefMeth) = returnTc (EmptyMonoBinds, emptyLIE, []) -tcDefMeth clas tyvars binds_in prags (_, GenDefMeth) = returnTc (EmptyMonoBinds, emptyLIE, []) +tcDefMeth clas tyvars binds_in prags (_, NoDefMeth) = returnM (EmptyMonoBinds, []) +tcDefMeth clas tyvars binds_in prags (_, GenDefMeth) = returnM (EmptyMonoBinds, []) -- Generate code for polymorphic default methods only -- (Generic default methods have turned into instance decls by now.) -- This is incompatible with Hugs, which expects a polymorphic @@ -361,7 +377,7 @@ tcDefMeth clas tyvars binds_in prags (_, GenDefMeth) = returnTc (EmptyMonoBinds, -- (If necessary we can fix that, but we don't have a convenient Id to hand.) tcDefMeth clas tyvars binds_in prags op_item@(sel_id, DefMeth dm_name) - = tcInstTyVars ClsTv tyvars `thenNF_Tc` \ (clas_tyvars, inst_tys, _) -> + = tcInstTyVars ClsTv tyvars `thenM` \ (clas_tyvars, inst_tys, _) -> let dm_ty = idType sel_id -- Same as dict selector! -- The default method's type should really come from the @@ -372,38 +388,37 @@ tcDefMeth clas tyvars binds_in prags op_item@(sel_id, DefMeth dm_name) -- TyGenNever (in MkId). Ugh! KSW 1999-09. theta = [mkClassPred clas inst_tys] - dm_id = mkDefaultMethodId dm_name dm_ty - local_dm_id = setIdLocalExported dm_id - -- Reason for setIdLocalExported: see notes with MkId.mkDictFunId - xtve = tyvars `zip` clas_tyvars + local_dm_id = mkDefaultMethodId dm_name dm_ty + xtve = tyvars `zip` clas_tyvars in - newDicts origin theta `thenNF_Tc` \ [this_dict] -> + newDicts origin theta `thenM` \ [this_dict] -> - mkMethodBind origin clas inst_tys binds_in op_item `thenTc` \ (dm_inst, meth_info) -> - tcMethodBind xtve clas_tyvars theta - [this_dict] meth_info `thenTc` \ (defm_bind, insts_needed) -> + mkMethodBind origin clas inst_tys binds_in op_item `thenM` \ (_, meth_info) -> + getLIE (tcMethodBind xtve clas_tyvars theta + [this_dict] prags meth_info) `thenM` \ (defm_bind, insts_needed) -> - tcAddErrCtxt (defltMethCtxt clas) $ + addErrCtxt (defltMethCtxt clas) $ -- Check the context tcSimplifyCheck (ptext SLIT("class") <+> ppr clas) clas_tyvars [this_dict] - insts_needed `thenTc` \ (const_lie, dict_binds) -> + insts_needed `thenM` \ dict_binds -> -- Simplification can do unification - checkSigTyVars clas_tyvars `thenTc` \ clas_tyvars' -> + checkSigTyVars clas_tyvars `thenM` \ clas_tyvars' -> let + (_,dm_inst_id,_) = meth_info full_bind = AbsBinds clas_tyvars' [instToId this_dict] - [(clas_tyvars', local_dm_id, instToId dm_inst)] + [(clas_tyvars', local_dm_id, dm_inst_id)] emptyNameSet -- No inlines (yet) (dict_binds `andMonoBinds` defm_bind) in - returnTc (full_bind, const_lie, [dm_id]) + returnM (full_bind, [local_dm_id]) where origin = ClassDeclOrigin \end{code} @@ -422,6 +437,10 @@ time, because their signatures may have different contexts and tyvar sets. \begin{code} +type MethodSpec = (Id, -- Global selector Id + Id, -- Local Id (class tyvars instantiated) + RenamedMonoBinds) -- Binding for the method + tcMethodBind :: [(TyVar,TcTyVar)] -- Bindings for type environment -> [TcTyVar] -- Instantiated type variables for the @@ -432,18 +451,20 @@ tcMethodBind -> TcThetaType -- Available theta; it's just used for the error message -> [Inst] -- Available from context, used to simplify constraints -- from the method body - -> (Id, TcSigInfo, RenamedMonoBinds) -- Details of this method - -> TcM (TcMonoBinds, LIE) + -> [RenamedSig] -- Pragmas (e.g. inline pragmas) + -> MethodSpec -- Details of this method + -> TcM TcMonoBinds -tcMethodBind xtve inst_tyvars inst_theta avail_insts - (sel_id, meth_sig, meth_bind) - = - -- Check the bindings; first adding inst_tyvars to the envt +tcMethodBind xtve inst_tyvars inst_theta avail_insts prags + (sel_id, meth_id, meth_bind) + = -- Check the bindings; first adding inst_tyvars to the envt -- so that we don't quantify over them in nested places + mkTcSig meth_id `thenM` \ meth_sig -> + tcExtendTyVarEnv2 xtve ( - tcAddErrCtxt (methodCtxt sel_id) $ - tcMonoBinds meth_bind [meth_sig] NonRecursive - ) `thenTc` \ (meth_bind, meth_lie, _, _) -> + addErrCtxt (methodCtxt sel_id) $ + getLIE (tcMonoBinds meth_bind [meth_sig] NonRecursive) + ) `thenM` \ ((meth_bind, _, _), meth_lie) -> -- Now do context reduction. We simplify wrt both the local tyvars -- and the ones of the class/instance decl, so that there is @@ -456,78 +477,151 @@ tcMethodBind xtve inst_tyvars inst_theta avail_insts let TySigInfo meth_id meth_tvs meth_theta _ local_meth_id _ _ = meth_sig in - tcAddErrCtxtM (sigCtxt sel_id inst_tyvars inst_theta (idType meth_id)) $ - newDicts SignatureOrigin meth_theta `thenNF_Tc` \ meth_dicts -> + addErrCtxtM (sigCtxt sel_id inst_tyvars inst_theta (idType meth_id)) $ + newDicts SignatureOrigin meth_theta `thenM` \ meth_dicts -> let all_tyvars = meth_tvs ++ inst_tyvars all_insts = avail_insts ++ meth_dicts in tcSimplifyCheck (ptext SLIT("class or instance method") <+> quotes (ppr sel_id)) - all_tyvars all_insts meth_lie `thenTc` \ (lie, lie_binds) -> + all_tyvars all_insts meth_lie `thenM` \ lie_binds -> - checkSigTyVars all_tyvars `thenTc` \ all_tyvars' -> + checkSigTyVars all_tyvars `thenM` \ all_tyvars' -> let + -- Attach inline pragmas as appropriate + (final_meth_id, inlines) + | (InlineSig inl _ phase _ : _) <- filter is_inline prags + = (meth_id `setInlinePragma` phase, + if inl then unitNameSet (idName meth_id) else emptyNameSet) + | otherwise + = (meth_id, emptyNameSet) + + is_inline (InlineSig _ name _ _) = name == idName sel_id + is_inline other = False + meth_tvs' = take (length meth_tvs) all_tyvars' poly_meth_bind = AbsBinds meth_tvs' (map instToId meth_dicts) - [(meth_tvs', meth_id, local_meth_id)] - emptyNameSet -- Inlines? + [(meth_tvs', final_meth_id, local_meth_id)] + inlines (lie_binds `andMonoBinds` meth_bind) in - returnTc (poly_meth_bind, lie) + returnM poly_meth_bind mkMethodBind :: InstOrigin -> Class -> [TcType] -- Class and instance types -> RenamedMonoBinds -- Method binding (pick the right one from in here) -> ClassOpItem - -> TcM (Inst, -- Method inst - (Id, -- Global selector Id - TcSigInfo, -- Signature - RenamedMonoBinds)) -- Binding for the method + -> TcM (Maybe Inst, -- Method inst + MethodSpec) +-- Find the binding for the specified method, or make +-- up a suitable default method if it isn't there mkMethodBind origin clas inst_tys meth_binds (sel_id, dm_info) - = tcGetSrcLoc `thenNF_Tc` \ loc -> - newMethod origin sel_id inst_tys `thenNF_Tc` \ meth_inst -> + = mkMethId origin clas sel_id inst_tys `thenM` \ (mb_inst, meth_id) -> let - meth_id = instToId meth_inst meth_name = idName meth_id in -- Figure out what method binding to use -- If the user suppplied one, use it, else construct a default one + getSrcLocM `thenM` \ loc -> (case find_bind (idName sel_id) meth_name meth_binds of - Just user_bind -> returnTc user_bind - Nothing -> mkDefMethRhs origin clas inst_tys sel_id loc dm_info `thenTc` \ rhs -> - returnTc (FunMonoBind meth_name False -- Not infix decl - [mkSimpleMatch [] rhs placeHolderType loc] loc) - ) `thenTc` \ meth_bind -> - - mkTcSig meth_id loc `thenNF_Tc` \ meth_sig -> - - returnTc (meth_inst, (sel_id, meth_sig, meth_bind)) - + Just user_bind -> returnM user_bind + Nothing -> mkDefMethRhs origin clas inst_tys sel_id loc dm_info `thenM` \ rhs -> + returnM (FunMonoBind meth_name False -- Not infix decl + [mkSimpleMatch [] rhs placeHolderType loc] loc) + ) `thenM` \ meth_bind -> + + returnM (mb_inst, (sel_id, meth_id, meth_bind)) + +mkMethId :: InstOrigin -> Class + -> Id -> [TcType] -- Selector, and instance types + -> TcM (Maybe Inst, Id) + +-- mkMethId instantiates the selector Id at the specified types +-- THe +mkMethId origin clas sel_id inst_tys + = let + (tyvars,rho) = tcSplitForAllTys (idType sel_id) + rho_ty = ASSERT( length tyvars == length inst_tys ) + substTyWith tyvars inst_tys rho + (preds,tau) = tcSplitPhiTy rho_ty + first_pred = head preds + in + -- The first predicate should be of form (C a b) + -- where C is the class in question + ASSERT( not (null preds) && + case getClassPredTys_maybe first_pred of + { Just (clas1,tys) -> clas == clas1 ; Nothing -> False } + ) + if isSingleton preds then + -- If it's the only one, make a 'method' + getInstLoc origin `thenM` \ inst_loc -> + newMethod inst_loc sel_id inst_tys preds tau `thenM` \ meth_inst -> + returnM (Just meth_inst, instToId meth_inst) + else + -- If it's not the only one we need to be careful + -- For example, given 'op' defined thus: + -- class Foo a where + -- op :: (?x :: String) => a -> a + -- (mkMethId op T) should return an Inst with type + -- (?x :: String) => T -> T + -- That is, the class-op's context is still there. + -- BUT: it can't be a Method any more, because it breaks + -- INVARIANT 2 of methods. (See the data decl for Inst.) + newUnique `thenM` \ uniq -> + getSrcLocM `thenM` \ loc -> + let + real_tau = mkPhiTy (tail preds) tau + meth_id = mkUserLocal (getOccName sel_id) uniq real_tau loc + in + returnM (Nothing, meth_id) -- The user didn't supply a method binding, -- so we have to make up a default binding -- The RHS of a default method depends on the default-method info mkDefMethRhs origin clas inst_tys sel_id loc (DefMeth dm_name) = -- An polymorphic default method - returnTc (HsVar dm_name) + traceRn (text "mkDefMeth" <+> ppr dm_name) `thenM_` + returnM (HsVar dm_name) mkDefMethRhs origin clas inst_tys sel_id loc NoDefMeth = -- No default method -- Warn only if -fwarn-missing-methods - doptsTc Opt_WarnMissingMethods `thenNF_Tc` \ warn -> - warnTc (isInstDecl origin && warn) - (omittedMethodWarn sel_id) `thenNF_Tc_` - returnTc error_rhs + doptM Opt_WarnMissingMethods `thenM` \ warn -> + warnTc (isInstDecl origin + && warn + && reportIfUnused (getOccName sel_id)) + (omittedMethodWarn sel_id) `thenM_` + returnM error_rhs where - error_rhs = HsApp (HsVar (getName nO_METHOD_BINDING_ERROR_ID)) - (HsLit (HsString (_PK_ error_msg))) + error_rhs = HsLam (mkSimpleMatch wild_pats simple_rhs placeHolderType loc) + simple_rhs = HsApp (HsVar (getName nO_METHOD_BINDING_ERROR_ID)) + (HsLit (HsStringPrim (mkFastString (stringToUtf8 error_msg)))) error_msg = showSDoc (hcat [ppr loc, text "|", ppr sel_id ]) + -- When the type is of form t1 -> t2 -> t3 + -- make a default method like (\ _ _ -> noMethBind "blah") + -- rather than simply (noMethBind "blah") + -- Reason: if t1 or t2 are higher-ranked types we get n + -- silly ambiguity messages. + -- Example: f :: (forall a. Eq a => a -> a) -> Int + -- f = error "urk" + -- Here, tcSub tries to force (error "urk") to have the right type, + -- thus: f = \(x::forall a. Eq a => a->a) -> error "urk" (x t) + -- where 't' is fresh ty var. This leads directly to "ambiguous t". + -- + -- NB: technically this changes the meaning of the default-default + -- method slightly, because `seq` can see the lambdas. Oh well. + (_,_,tau1) = tcSplitSigmaTy (idType sel_id) + (_,_,tau2) = tcSplitSigmaTy tau1 + -- Need two splits because the selector can have a type like + -- forall a. Foo a => forall b. Eq b => ... + (arg_tys, _) = tcSplitFunTys tau2 + wild_pats = [WildPat placeHolderType | ty <- arg_tys] mkDefMethRhs origin clas inst_tys sel_id loc GenDefMeth = -- A generic default method @@ -535,11 +629,15 @@ mkDefMethRhs origin clas inst_tys sel_id loc GenDefMeth -- instance declaration is for a single-parameter type class with -- a type constructor applied to type arguments in the instance decl -- (checkTc, so False provokes the error) - checkTc (not (isInstDecl origin) || simple_inst) - (badGenericInstance sel_id) `thenTc_` + ASSERT( isInstDecl origin ) -- We never get here from a class decl + + checkTc (isJust maybe_tycon) + (badGenericInstance sel_id (notSimple inst_tys)) `thenM_` + checkTc (isJust (tyConGenInfo tycon)) + (badGenericInstance sel_id (notGeneric tycon)) `thenM_` - ioToTc (dumpIfSet opt_PprStyle_Debug "Generic RHS" stuff) `thenNF_Tc_` - returnTc rhs + ioToTcRn (dumpIfSet opt_PprStyle_Debug "Generic RHS" stuff) `thenM_` + returnM rhs where rhs = mkGenericRhs sel_id clas_tyvar tycon @@ -550,7 +648,6 @@ mkDefMethRhs origin clas inst_tys sel_id loc GenDefMeth -- case we require that the instance decl is for a single-parameter -- type class with type variable arguments: -- instance (...) => C (T a b) - simple_inst = maybeToBool maybe_tycon clas_tyvar = head (classTyVars clas) Just tycon = maybe_tycon maybe_tycon = case inst_tys of @@ -600,10 +697,18 @@ badMethodErr clas op omittedMethodWarn sel_id = ptext SLIT("No explicit method nor default method for") <+> quotes (ppr sel_id) -badGenericInstance sel_id +badGenericInstance sel_id because = sep [ptext SLIT("Can't derive generic code for") <+> quotes (ppr sel_id), - ptext SLIT("because the instance declaration is not for a simple type (T a b c)"), - ptext SLIT("(where T is a derivable type constructor)")] + because] + +notSimple inst_tys + = vcat [ptext SLIT("because the instance type(s)"), + nest 2 (ppr inst_tys), + ptext SLIT("is not a simple type of form (T a b c)")] + +notGeneric tycon + = vcat [ptext SLIT("because the instance type constructor") <+> quotes (ppr tycon) <+> + ptext SLIT("was not compiled with -fgenerics")] mixedGenericErr op = ptext SLIT("Can't mix generic and non-generic equations for class method") <+> quotes (ppr op)