X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcClassDcl.lhs;h=be9a07384505d5351da0f11091abc5d64d4df7ae;hb=438596897ebbe25a07e1c82085cfbc5bdb00f09e;hp=ad927a1d9075ea22b255f8cbebc2aa7dc581809c;hpb=995d6dbff24982c0a57c3befb01d733a7da613f1;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcClassDcl.lhs b/ghc/compiler/typecheck/TcClassDcl.lhs index ad927a1..be9a073 100644 --- a/ghc/compiler/typecheck/TcClassDcl.lhs +++ b/ghc/compiler/typecheck/TcClassDcl.lhs @@ -1,73 +1,68 @@ % -% (c) The GRASP/AQUA Project, Glasgow University, 1992-1995 +% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 % \section[TcClassDcl]{Typechecking class declarations} \begin{code} -#include "HsVersions.h" - -module TcClassDcl ( tcClassDecl1, tcClassDecls2 ) where +module TcClassDcl ( tcClassDecl1, tcClassDecls2, tcMethodBind, badMethodErr ) where -IMP_Ubiq() +#include "HsVersions.h" -import HsSyn ( HsDecl(..), ClassDecl(..), HsBinds(..), MonoBinds(..), - Match(..), GRHSsAndBinds(..), GRHS(..), HsExpr(..), - DefaultDecl, TyDecl, InstDecl, IfaceSig, Fixity, - HsLit(..), OutPat(..), Sig(..), HsType(..), HsTyVar, - SYN_IE(RecFlag), nonRecursive, andMonoBinds, - Stmt, DoOrListComp, ArithSeqInfo, InPat, Fake ) -import HsTypes ( getTyVarName ) +import HsSyn ( HsDecl(..), ClassDecl(..), Sig(..), MonoBinds(..), + InPat(..), HsBinds(..), GRHSsAndBinds(..), + HsExpr(..), HsLit(..), HsType(..), pprClassAssertion, + unguardedRHS, andMonoBinds, andMonoBindList, getTyVarName + ) import HsPragmas ( ClassPragmas(..) ) -import RnHsSyn ( RenamedClassDecl(..), RenamedClassPragmas(..), - RenamedClassOpSig(..), SYN_IE(RenamedMonoBinds), - RenamedGenPragmas(..), RenamedContext(..), SYN_IE(RenamedHsDecl) +import BasicTypes ( NewOrData(..), TopLevelFlag(..), RecFlag(..), StrictnessMark(..) ) +import RnHsSyn ( RenamedClassDecl, RenamedClassPragmas, + RenamedClassOpSig, RenamedMonoBinds, + RenamedContext, RenamedHsDecl, RenamedSig + ) +import TcHsSyn ( TcMonoBinds ) + +import Inst ( Inst, InstOrigin(..), LIE, emptyLIE, plusLIE, newDicts, newMethod ) +import TcEnv ( TcIdOcc(..), GlobalValueEnv, tcAddImportedIdInfo, + tcLookupClass, tcLookupTyVar, + tcExtendGlobalTyVars, tcExtendLocalValEnv ) -import TcHsSyn ( TcIdOcc(..), SYN_IE(TcHsBinds), SYN_IE(TcMonoBinds), SYN_IE(TcExpr), - mkHsTyApp, mkHsTyLam, mkHsDictApp, mkHsDictLam, tcIdType ) - -import Inst ( Inst, InstOrigin(..), SYN_IE(LIE), emptyLIE, plusLIE, newDicts, newMethod ) -import TcEnv ( tcLookupClass, tcLookupTyVar, tcLookupTyCon, newLocalIds, tcAddImportedIdInfo, - tcExtendGlobalTyVars ) -import TcInstDcls ( tcMethodBind ) -import TcKind ( unifyKind, TcKind ) +import TcBinds ( tcBindWithSigs, tcPragmaSigs ) +import TcUnify ( unifyKinds ) import TcMonad -import TcMonoType ( tcHsType, tcContext ) -import TcSimplify ( tcSimplifyAndCheck ) -import TcType ( SYN_IE(TcType), SYN_IE(TcTyVar), tcInstType, tcInstSigTyVars, tcInstSigType ) - -import Bag ( foldBag, unionManyBags ) -import Class ( GenClass, GenClassOp, mkClass, mkClassOp, classBigSig, - classOps, classOpString, classOpLocalType, classDefaultMethodId, - classOpTagByOccName, SYN_IE(ClassOp), SYN_IE(Class) +import TcMonoType ( tcHsType, tcContext, checkSigTyVars, sigCtxt, mkTcSig ) +import TcSimplify ( tcSimplifyAndCheck, bindInstsOfLocalFuns ) +import TcType ( TcType, TcTyVar, tcInstTyVars, zonkTcTyVarBndr ) +import PrelVals ( nO_METHOD_BINDING_ERROR_ID ) +import FieldLabel ( firstFieldLabelTag ) +import Bag ( unionManyBags ) +import Class ( mkClass, classBigSig, Class ) +import CmdLineOpts ( opt_GlasgowExts, opt_WarnMissingMethods ) +import MkId ( mkSuperDictSelId, mkDataConId, + mkMethodSelId, mkDefaultMethodId ) -import Id ( GenId, mkSuperDictSelId, mkMethodSelId, - mkDefaultMethodId, getIdUnfolding, - idType, SYN_IE(Id) +import DataCon ( mkDataCon ) +import Id ( Id, + getIdUnfolding, idType, idName ) import CoreUnfold ( getUnfoldingTemplate ) import IdInfo -import Name ( Name, isLocallyDefined, moduleString, - modAndOcc, nameString, NamedThing(..) ) +import Name ( Name, isLocallyDefined, NamedThing(..) ) import Outputable -import PrelVals ( nO_DEFAULT_METHOD_ERROR_ID ) -import PprStyle -import Pretty -import PprType ( GenClass, GenType, GenTyVar, GenClassOp ) -import SpecEnv ( SpecEnv ) -import SrcLoc ( mkGeneratedSrcLoc ) import Type ( mkFunTy, mkTyVarTy, mkTyVarTys, mkDictTy, - mkForAllTy, mkSigmaTy, splitSigmaTy, SYN_IE(Type) + mkSigmaTy, mkForAllTys, Type, ThetaType, + boxedTypeKind, mkArrowKind ) -import TysWiredIn ( stringTy ) -import TyVar ( unitTyVarSet, GenTyVar, SYN_IE(TyVar) ) -import Unique ( Unique ) -import UniqFM ( Uniquable(..) ) +import Var ( tyVarKind, TyVar ) +import VarSet ( mkVarSet ) +import TyCon ( mkAlgTyCon ) +import Unique ( Unique, Uniquable(..) ) import Util +import Maybes ( seqMaybe ) -- import TcPragmas ( tcGenPragmas, tcClassOpPragmas ) tcGenPragmas ty id ps = returnNF_Tc noIdInfo -tcClassOpPragmas ty sel def spec ps = returnNF_Tc (noIdInfo `addSpecInfo` spec, +tcClassOpPragmas ty sel def spec ps = returnNF_Tc (spec `setSpecInfo` noIdInfo, noIdInfo) \end{code} @@ -107,116 +102,141 @@ Death to "ExpandingDicts". \begin{code} -tcClassDecl1 rec_inst_mapper +tcClassDecl1 rec_env rec_inst_mapper (ClassDecl context class_name - tyvar_name class_sigs def_methods pragmas src_loc) + tyvar_names class_sigs def_methods pragmas + tycon_name datacon_name src_loc) = tcAddSrcLoc src_loc $ tcAddErrCtxt (classDeclCtxt class_name) $ + -- CHECK ARITY 1 FOR HASKELL 1.4 + checkTc (opt_GlasgowExts || length tyvar_names == 1) + (classArityErr class_name) `thenTc_` + -- LOOK THINGS UP IN THE ENVIRONMENT - tcLookupClass class_name `thenTc` \ (class_kind, rec_class) -> - tcLookupTyVar (getTyVarName tyvar_name) `thenNF_Tc` \ (tyvar_kind, rec_tyvar) -> - let - (rec_class_inst_env, rec_class_op_inst_fn) = rec_inst_mapper rec_class - in + tcLookupClass class_name `thenTc` \ (class_kinds, rec_class) -> + mapAndUnzipNF_Tc (tcLookupTyVar . getTyVarName) tyvar_names + `thenNF_Tc` \ (tyvar_kinds, rec_tyvars) -> -- FORCE THE CLASS AND ITS TYVAR TO HAVE SAME KIND - unifyKind class_kind tyvar_kind `thenTc_` + unifyKinds class_kinds tyvar_kinds `thenTc_` -- CHECK THE CONTEXT - tcClassContext rec_class rec_tyvar context pragmas - `thenTc` \ (scs, sc_sel_ids) -> + tcClassContext class_name rec_class rec_tyvars context pragmas + `thenTc` \ (sc_theta, sc_tys, sc_sel_ids) -> -- CHECK THE CLASS SIGNATURES, - mapTc (tcClassSig rec_class rec_tyvar rec_class_op_inst_fn) class_sigs - `thenTc` \ sig_stuff -> + mapTc (tcClassSig rec_env rec_class rec_tyvars) class_sigs + `thenTc` \ sig_stuff -> -- MAKE THE CLASS OBJECT ITSELF let - (ops, op_sel_ids, defm_ids) = unzip3 sig_stuff - clas = mkClass (uniqueOf class_name) (getName class_name) rec_tyvar - scs sc_sel_ids ops op_sel_ids defm_ids + (op_tys, op_sel_ids, defm_ids) = unzip3 sig_stuff + rec_class_inst_env = rec_inst_mapper rec_class + clas = mkClass (getName class_name) rec_tyvars + sc_theta sc_sel_ids op_sel_ids defm_ids + tycon rec_class_inst_env - in - returnTc clas -\end{code} - - let - clas_ty = mkTyVarTy clas_tyvar - dict_component_tys = [mkDictTy sc clas_ty | sc <- scs] ++ - [classOpLocalType op | op <- ops]) + dict_component_tys = sc_tys ++ op_tys new_or_data = case dict_component_tys of [_] -> NewType other -> DataType - dict_con_id = mkDataCon class_name - [NotMarkedStrict] + dict_con = mkDataCon datacon_name + [NotMarkedStrict | _ <- dict_component_tys] [{- No labelled fields -}] - [clas_tyvar] + rec_tyvars [{-No context-}] + [{-No existential tyvars-}] [{-Or context-}] dict_component_tys - tycon - - tycon = mkDataTyCon class_name - (tyVarKind rec_tyvar `mkArrowKind` mkBoxedTypeKind) - [rec_tyvar] - [{- Empty context -}] - [dict_con_id] - [{- No derived classes -}] + tycon dict_con_id + dict_con_id = mkDataConId dict_con + + tycon = mkAlgTyCon tycon_name + (foldr (mkArrowKind . tyVarKind) boxedTypeKind rec_tyvars) + rec_tyvars + [] -- No context + [dict_con] -- Constructors + [] -- No derivings + (Just clas) -- Yes! It's a dictionary new_or_data + NonRecursive in + returnTc clas +\end{code} \begin{code} -tcClassContext :: Class -> TyVar +tcClassContext :: Name -> Class -> [TyVar] -> RenamedContext -- class context -> RenamedClassPragmas -- pragmas for superclasses - -> TcM s ([Class], -- the superclasses - [Id]) -- superclass selector Ids + -> TcM s (ThetaType, -- the superclass context + [Type], -- types of the superclass dictionaries + [Id]) -- superclass selector Ids -tcClassContext rec_class rec_tyvar context pragmas +tcClassContext class_name rec_class rec_tyvars context pragmas = -- Check the context. -- The renamer has already checked that the context mentions -- only the type variable of the class decl. - tcContext context `thenTc` \ theta -> + + -- For std Haskell check that the context constrains only tyvars + (if opt_GlasgowExts then + returnTc [] + else + mapTc check_constraint context + ) `thenTc_` + + tcContext context `thenTc` \ sc_theta -> + let - super_classes = [ supers | (supers, _) <- theta ] + sc_tys = [mkDictTy sc tys | (sc,tys) <- sc_theta] in -- Make super-class selector ids - mapTc (mk_super_id rec_class) super_classes `thenTc` \ sc_sel_ids -> + -- We number them off, 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!) + mapTc mk_super_id (sc_theta `zip` [firstFieldLabelTag..]) `thenTc` \ sc_sel_ids -> -- Done - returnTc (super_classes, sc_sel_ids) + returnTc (sc_theta, sc_tys, sc_sel_ids) where - rec_tyvar_ty = mkTyVarTy rec_tyvar + rec_tyvar_tys = mkTyVarTys rec_tyvars - mk_super_id rec_class super_class + mk_super_id ((super_class, tys), index) = tcGetUnique `thenNF_Tc` \ uniq -> let - ty = mkForAllTy rec_tyvar $ - mkFunTy (mkDictTy rec_class rec_tyvar_ty) - (mkDictTy super_class rec_tyvar_ty) + ty = mkForAllTys rec_tyvars $ + mkFunTy (mkDictTy rec_class rec_tyvar_tys) (mkDictTy super_class tys) in - returnTc (mkSuperDictSelId uniq rec_class super_class ty) + returnTc (mkSuperDictSelId uniq rec_class index ty) + check_constraint (c, tys) = checkTc (all is_tyvar tys) + (superClassErr class_name (c, tys)) -tcClassSig :: Class -- Knot tying only! - -> TyVar -- The class type variable, used for error check only - -> (ClassOp -> SpecEnv) -- Ditto; the spec info for the class ops + is_tyvar (MonoTyVar _) = True + is_tyvar other = False + + +tcClassSig :: GlobalValueEnv -- Knot tying only! + -> Class -- ...ditto... + -> [TyVar] -- The class type variable, used for error check only -> RenamedClassOpSig - -> TcM s (ClassOp, -- class op + -> TcM s (Type, -- Type of the method Id, -- selector id - Id) -- default-method ids + Maybe Id) -- default-method ids -tcClassSig rec_clas rec_clas_tyvar rec_classop_spec_fn - (ClassOpSig op_name dm_name +tcClassSig rec_env rec_clas rec_clas_tyvars + (ClassOpSig op_name maybe_dm_name op_ty src_loc) = tcAddSrcLoc src_loc $ - fixTc ( \ ~(_, rec_sel_id, rec_defm_id) -> -- Knot for pragmas -- Check the type signature. NB that the envt *already has* -- bindings for the type variables; see comments in TcTyAndClassDcls. @@ -225,24 +245,22 @@ tcClassSig rec_clas rec_clas_tyvar rec_classop_spec_fn -- and that it is not constrained by theta tcHsType op_ty `thenTc` \ local_ty -> let - global_ty = mkSigmaTy [rec_clas_tyvar] - [(rec_clas, mkTyVarTy rec_clas_tyvar)] + global_ty = mkSigmaTy rec_clas_tyvars + [(rec_clas, mkTyVarTys rec_clas_tyvars)] local_ty - class_op_nm = getOccName op_name - class_op = mkClassOp class_op_nm - (classOpTagByOccName rec_clas{-yeeps!-} class_op_nm) - local_ty in -- Build the selector id and default method id let - sel_id = mkMethodSelId op_name rec_clas class_op global_ty - defm_id = mkDefaultMethodId dm_name rec_clas class_op False global_ty - -- ToDo: improve the "False" + sel_id = mkMethodSelId op_name rec_clas global_ty + maybe_dm_id = case maybe_dm_name of + Nothing -> Nothing + Just dm_name -> let + dm_id = mkDefaultMethodId dm_name rec_clas global_ty + in + Just (tcAddImportedIdInfo rec_env dm_id) in - tcAddImportedIdInfo defm_id `thenNF_Tc` \ final_defm_id -> - returnTc (class_op, sel_id, final_defm_id) - ) + returnTc (local_ty, sel_id, maybe_dm_id) \end{code} @@ -270,58 +288,54 @@ each local class decl. \begin{code} tcClassDecls2 :: [RenamedHsDecl] - -> NF_TcM s (LIE s, TcHsBinds s) + -> NF_TcM s (LIE s, TcMonoBinds s) tcClassDecls2 decls = foldr combine - (returnNF_Tc (emptyLIE, EmptyBinds)) + (returnNF_Tc (emptyLIE, EmptyMonoBinds)) [tcClassDecl2 cls_decl | ClD cls_decl <- decls] where combine tc1 tc2 = tc1 `thenNF_Tc` \ (lie1, binds1) -> tc2 `thenNF_Tc` \ (lie2, binds2) -> returnNF_Tc (lie1 `plusLIE` lie2, - binds1 `ThenBinds` binds2) + binds1 `AndMonoBinds` binds2) \end{code} @tcClassDecl2@ is the business end of things. \begin{code} tcClassDecl2 :: RenamedClassDecl -- The class declaration - -> NF_TcM s (LIE s, TcHsBinds s) + -> NF_TcM s (LIE s, TcMonoBinds s) tcClassDecl2 (ClassDecl context class_name - tyvar_name class_sigs default_binds pragmas src_loc) + tyvar_names class_sigs default_binds pragmas _ _ src_loc) | not (isLocallyDefined class_name) - = returnNF_Tc (emptyLIE, EmptyBinds) + = returnNF_Tc (emptyLIE, EmptyMonoBinds) | otherwise -- It is locally defined - = recoverNF_Tc (returnNF_Tc (emptyLIE, EmptyBinds)) $ - tcAddSrcLoc src_loc $ + = recoverNF_Tc (returnNF_Tc (emptyLIE, EmptyMonoBinds)) $ + tcAddSrcLoc src_loc $ -- Get the relevant class tcLookupClass class_name `thenTc` \ (_, clas) -> let - (tyvar, scs, sc_sel_ids, ops, op_sel_ids, defm_ids) - = classBigSig clas + (tyvars, sc_theta, sc_sel_ids, op_sel_ids, defm_ids) = classBigSig clas -- The selector binds are already in the selector Id's unfoldings - sel_binds = [ CoreMonoBind (RealId sel_id) (getUnfoldingTemplate (getIdUnfolding sel_id)) - | sel_id <- sc_sel_ids ++ op_sel_ids, - isLocallyDefined sel_id - ] - - final_sel_binds = MonoBind (andMonoBinds sel_binds) [] nonRecursive +-- sel_binds = [ CoreMonoBind (RealId sel_id) (getUnfoldingTemplate (getIdUnfolding sel_id)) +-- | sel_id <- sc_sel_ids ++ op_sel_ids, +-- isLocallyDefined sel_id +-- ] +-- +-- final_sel_binds = andMonoBindList sel_binds in -- Generate bindings for the default methods - tcInstSigTyVars [tyvar] `thenNF_Tc` \ ([clas_tyvar], _, _) -> - mapAndUnzipTc (buildDefaultMethodBind clas clas_tyvar default_binds) - (op_sel_ids `zip` [0..]) - `thenTc` \ (const_insts_s, meth_binds) -> - - returnTc (unionManyBags const_insts_s, - final_sel_binds `ThenBinds` - MonoBind (andMonoBinds meth_binds) [] nonRecursive) + tcDefaultMethodBinds clas default_binds `thenTc` \ (const_insts, meth_binds) -> + + returnTc (const_insts, meth_binds) +-- final_sel_binds `AndMonoBinds` meth_binds) +-- Leave 'em out for now. They always get inlined anyway. SLPJ June '98 \end{code} %************************************************************************ @@ -398,54 +412,203 @@ dfun.Foo.List \end{verbatim} \begin{code} -buildDefaultMethodBind +tcDefaultMethodBinds :: Class - -> TcTyVar s -> RenamedMonoBinds - -> (Id, Int) -> TcM s (LIE s, TcMonoBinds s) -buildDefaultMethodBind clas clas_tyvar default_binds (sel_id, idx) - = newDicts origin [(clas,inst_ty)] `thenNF_Tc` \ (this_dict, [this_dict_id]) -> +tcDefaultMethodBinds clas default_binds + = -- Construct suitable signatures + tcInstTyVars tyvars `thenNF_Tc` \ (clas_tyvars, inst_tys, inst_env) -> + + -- Typecheck the default bindings + let + tc_dm sel_id_w_dm@(_, Just dm_id) + = tcMethodBind clas origin inst_tys clas_tyvars + default_binds [{-no prags-}] False + sel_id_w_dm `thenTc` \ (bind, insts, (_, local_dm_id)) -> + returnTc (bind, insts, (clas_tyvars, RealId dm_id, local_dm_id)) + in + mapAndUnzip3Tc tc_dm sel_ids_w_dms `thenTc` \ (defm_binds, insts_needed, abs_bind_stuff) -> + + -- Check the context + newDicts origin [(clas,inst_tys)] `thenNF_Tc` \ (this_dict, [this_dict_id]) -> let avail_insts = this_dict - defm_id = classDefaultMethodId clas idx in - tcExtendGlobalTyVars clas_tyvar_set ( - tcMethodBind noDefmExpr inst_ty default_binds (sel_id, idx) - ) `thenTc` \ (defm_bind, insts_needed, (_, local_defm_id)) -> + tcAddErrCtxt (classDeclCtxt clas) $ + + -- 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 clas_tyvars `thenNF_Tc` \ clas_tyvars' -> - -- CHECK THE CONTEXT OF THE DEFAULT-METHOD BINDS tcSimplifyAndCheck - clas_tyvar_set + (ptext SLIT("class") <+> ppr clas) + (mkVarSet clas_tyvars') avail_insts - insts_needed `thenTc` \ (const_lie, dict_binds) -> + (unionManyBags insts_needed) `thenTc` \ (const_lie, dict_binds) -> let - defm_binds = AbsBinds - [clas_tyvar] + full_binds = AbsBinds + clas_tyvars' [this_dict_id] - [([clas_tyvar], RealId defm_id, local_defm_id)] - (dict_binds `AndMonoBinds` defm_bind) + abs_bind_stuff + (dict_binds `andMonoBinds` andMonoBindList defm_binds) in - returnTc (const_lie, defm_binds) + returnTc (const_lie, full_binds) where - clas_tyvar_set = unitTyVarSet clas_tyvar - inst_ty = mkTyVarTy clas_tyvar - origin = ClassDeclOrigin - noDefmExpr _ = HsApp (HsVar (getName nO_DEFAULT_METHOD_ERROR_ID)) - (HsLit (HsString (_PK_ error_msg))) - - error_msg = show (sep [text "Class", ppr PprForUser clas, - text "Method", ppr PprForUser sel_id]) + (tyvars, sc_theta, sc_sel_ids, op_sel_ids, defm_ids) = classBigSig clas + + sel_ids_w_dms = [pair | pair@(_, Just _) <- op_sel_ids `zip` defm_ids] + -- Just the ones for which there is an explicit + -- user default declaration + + origin = ClassDeclOrigin \end{code} +@tcMethodBind@ is used to type-check both default-method and +instance-decl method declarations. We must type-check methods one at a +time, because their signatures may have different contexts and +tyvar sets. +\begin{code} +tcMethodBind + :: Class + -> InstOrigin s + -> [TcType s] -- Instance types + -> [TcTyVar s] -- Free variables of those instance types + -- they'll be signature tyvars, and we + -- want to check that they don't bound + -> RenamedMonoBinds -- Method binding (pick the right one from in here) + -> [RenamedSig] -- Pramgas (just for this one) + -> Bool -- True <=> supply default decl if no explicit decl + -- This is true for instance decls, + -- false for class decls + -> (Id, Maybe Id) -- The method selector and default-method Id + -> TcM s (TcMonoBinds s, LIE s, (LIE s, TcIdOcc s)) + +tcMethodBind clas origin inst_tys inst_tyvars + meth_binds prags supply_default_bind + (sel_id, maybe_dm_id) + = tcGetSrcLoc `thenNF_Tc` \ loc -> + + newMethod origin (RealId sel_id) inst_tys `thenNF_Tc` \ meth@(_, TcId meth_id) -> + mkTcSig meth_id loc `thenNF_Tc` \ sig_info -> + + let + meth_name = idName meth_id + maybe_user_bind = find_bind meth_name meth_binds + + no_user_bind = case maybe_user_bind of {Nothing -> True; other -> False} + no_user_default = case maybe_dm_id of {Nothing -> True; other -> False} + + meth_bind = case maybe_user_bind of + Just bind -> bind + Nothing -> mk_default_bind meth_name loc + + meth_prags = find_prags meth_name prags + in + + -- Warn if no method binding, only if -fwarn-missing-methods + if no_user_bind && not supply_default_bind then + pprPanic "tcMethodBind" (ppr clas <+> ppr inst_tys) + else + warnTc (opt_WarnMissingMethods && no_user_bind && no_user_default) + (omittedMethodWarn sel_id clas) `thenNF_Tc_` + + -- Check the pragmas + tcExtendLocalValEnv [meth_name] [meth_id] ( + tcPragmaSigs meth_prags + ) `thenTc` \ (prag_info_fn, prag_binds1, prag_lie) -> + + -- Check the bindings + tcExtendGlobalTyVars (mkVarSet inst_tyvars) ( + tcAddErrCtxt (methodCtxt sel_id) $ + tcBindWithSigs NotTopLevel meth_bind [sig_info] + NonRecursive prag_info_fn + ) `thenTc` \ (binds, insts, _) -> + + + -- The prag_lie for a SPECIALISE pragma will mention the function + -- itself, so we have to simplify them away right now lest they float + -- outwards! + bindInstsOfLocalFuns prag_lie [meth_id] `thenTc` \ (prag_lie', prag_binds2) -> + + + -- Now check that the instance type variables + -- (or, in the case of a class decl, the class tyvars) + -- have not been unified with anything in the environment + tcAddErrCtxtM (sigCtxt (quotes (ppr sel_id)) (idType meth_id)) ( + checkSigTyVars inst_tyvars `thenTc_` + + returnTc (binds `AndMonoBinds` prag_binds1 `AndMonoBinds` prag_binds2, + insts `plusLIE` prag_lie', + meth)) + + where + sel_name = idName sel_id + + -- The renamer just puts the selector ID as the binder in the method binding + -- but we must use the method name; so we substitute it here. Crude but simple. + find_bind meth_name (FunMonoBind op_name fix matches loc) + | op_name == sel_name = Just (FunMonoBind meth_name fix matches loc) + find_bind meth_name (PatMonoBind (VarPatIn op_name) rhs loc) + | op_name == sel_name = Just (PatMonoBind (VarPatIn meth_name) rhs loc) + find_bind meth_name (AndMonoBinds b1 b2) + = find_bind meth_name b1 `seqMaybe` find_bind meth_name b2 + find_bind meth_name other = Nothing -- Default case + + + -- Find the prags for this method, and replace the + -- selector name with the method name + find_prags meth_name [] = [] + find_prags meth_name (SpecSig name ty spec loc : prags) + | name == sel_name = SpecSig meth_name ty spec loc : find_prags meth_name prags + find_prags meth_name (InlineSig name loc : prags) + | name == sel_name = InlineSig meth_name loc : find_prags meth_name prags + find_prags meth_name (NoInlineSig name loc : prags) + | name == sel_name = NoInlineSig meth_name loc : find_prags meth_name prags + find_prags meth_name (prag:prags) = find_prags meth_name prags + + 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} -Contexts -~~~~~~~~ +Contexts and errors +~~~~~~~~~~~~~~~~~~~ \begin{code} -classDeclCtxt class_name sty - = hsep [ptext SLIT("In the class declaration for"), ppr sty class_name] +classArityErr class_name + = ptext SLIT("Too many parameters for class") <+> quotes (ppr class_name) + +classDeclCtxt class_name + = ptext SLIT("In the class declaration for") <+> quotes (ppr class_name) + +superClassErr class_name sc + = ptext SLIT("Illegal superclass constraint") <+> quotes (pprClassAssertion sc) + <+> ptext SLIT("in declaration for class") <+> quotes (ppr class_name) + +methodCtxt sel_id + = ptext SLIT("In the definition for method") <+> quotes (ppr sel_id) + +badMethodErr bndr clas + = hsep [ptext SLIT("Class"), quotes (ppr clas), + ptext SLIT("does not have a method"), quotes (ppr bndr)] + +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)] \end{code}