X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcInstDcls.lhs;h=3fec58dd0a402b6d98daa0bc0e4f6b5518ca10e8;hb=1cdafe99abae1628f34ca8c064e3a8c0fcdbd079;hp=f3e350a5b63dd2eb0540e358edda4b73f51b7ed4;hpb=7c3d4a1f2b2529ce300b8acc1d26ad98312b9e96;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcInstDcls.lhs b/ghc/compiler/typecheck/TcInstDcls.lhs index f3e350a..3fec58d 100644 --- a/ghc/compiler/typecheck/TcInstDcls.lhs +++ b/ghc/compiler/typecheck/TcInstDcls.lhs @@ -8,47 +8,40 @@ module TcInstDcls ( tcInstDecls1, tcInstDecls2 ) where #include "HsVersions.h" -import HsSyn ( InstDecl(..), HsType(..), - MonoBinds(..), HsExpr(..), HsLit(..), Sig(..), - andMonoBindList, collectMonoBinders, - isClassDecl - ) -import RnHsSyn ( RenamedHsBinds, RenamedInstDecl, RenamedTyClDecl ) -import TcHsSyn ( TcMonoBinds, mkHsConApp ) -import TcBinds ( tcSpecSigs ) +import HsSyn +import TcBinds ( mkPragFun, tcPrags, badBootDeclErr ) import TcClassDcl ( tcMethodBind, mkMethodBind, badMethodErr, tcClassDecl2, getGenericInstances ) import TcRnMonad -import TcMType ( tcInstType, checkValidTheta, checkValidInstHead, instTypeErr, +import TcMType ( tcSkolSigType, checkValidTheta, checkValidInstHead, + checkInstTermination, instTypeErr, checkAmbiguity, SourceTyCtxt(..) ) -import TcType ( mkClassPred, tcSplitForAllTys, tyVarsOfType, - tcSplitSigmaTy, getClassPredTys, tcSplitPredTy_maybe, mkTyVarTys, - TyVarDetails(..), tcSplitDFunTy - ) -import Inst ( InstOrigin(..), tcInstClassOp, newDicts, instToId, - showLIE, tcExtendLocalInstEnv ) +import TcType ( mkClassPred, tyVarsOfType, + tcSplitSigmaTy, tcSplitDFunHead, mkTyVarTys, + SkolemInfo(InstSkol), tcSplitDFunTy, pprClassPred ) +import Inst ( tcInstClassOp, newDicts, instToId, showLIE, + getOverlapFlag, tcExtendLocalInstEnv ) +import InstEnv ( mkLocalInstance, instanceDFunId ) import TcDeriv ( tcDeriving ) -import TcEnv ( tcExtendGlobalValEnv, tcExtendTyVarEnv2, - InstInfo(..), InstBindings(..), - newDFunName, tcExtendLocalValEnv +import TcEnv ( InstInfo(..), InstBindings(..), + newDFunName, tcExtendIdEnv ) -import PprType ( pprClassPred ) import TcHsType ( kcHsSigType, tcHsKindedType ) import TcUnify ( checkSigTyVars ) -import TcSimplify ( tcSimplifyCheck, tcSimplifyTop ) -import Subst ( mkTyVarSubst, substTheta, substTy ) +import TcSimplify ( tcSimplifyCheck, tcSimplifySuperClasses ) +import Type ( zipOpenTvSubst, substTheta, substTys ) import DataCon ( classDataCon ) import Class ( classBigSig ) -import Var ( idName, idType ) -import NameSet +import Var ( Id, idName, idType ) import MkId ( mkDictFunId, rUNTIME_ERROR_ID ) import FunDeps ( checkInstFDs ) -import Name ( getSrcLoc ) -import NameSet ( unitNameSet, emptyNameSet, nameSetToList ) -import UnicodeUtil ( stringToUtf8 ) +import Name ( Name, getSrcLoc ) import Maybe ( catMaybes ) +import SrcLoc ( srcLocSpan, unLoc, noLoc, Located(..), srcSpanStart ) import ListSetOps ( minusList ) import Outputable +import Bag +import BasicTypes ( Activation( AlwaysActive ), InlineSpec(..) ) import FastString \end{code} @@ -136,12 +129,12 @@ Gather up the instance declarations from their various sources \begin{code} tcInstDecls1 -- Deal with both source-code and imported instance decls - :: [RenamedTyClDecl] -- For deriving stuff - -> [RenamedInstDecl] -- Source code instance decls + :: [LTyClDecl Name] -- For deriving stuff + -> [LInstDecl Name] -- Source code instance decls -> TcM (TcGblEnv, -- The full inst env [InstInfo], -- Source-code instance decls to process; -- contains all dfuns for this module - RenamedHsBinds) -- Supporting bindings for derived instances + HsValBinds Name) -- Supporting bindings for derived instances tcInstDecls1 tycl_decls inst_decls = checkNoErrs $ @@ -153,10 +146,10 @@ tcInstDecls1 tycl_decls inst_decls let local_inst_info = catMaybes local_inst_infos - clas_decls = filter isClassDecl tycl_decls + clas_decls = filter (isClassDecl.unLoc) tycl_decls in -- (2) Instances from generic class declarations - getGenericInstances clas_decls `thenM` \ generic_inst_info -> + getGenericInstances clas_decls `thenM` \ generic_inst_info -> -- Next, construct the instance environment so far, consisting of -- a) local instance decls @@ -167,34 +160,30 @@ tcInstDecls1 tycl_decls inst_decls -- (3) Compute instances from "deriving" clauses; -- This stuff computes a context for the derived instance decl, so it -- needs to know about all the instances possible; hence inst_env4 - tcDeriving tycl_decls `thenM` \ (deriv_inst_info, deriv_binds, keep_alive) -> + tcDeriving tycl_decls `thenM` \ (deriv_inst_info, deriv_binds) -> addInsts deriv_inst_info $ getGblEnv `thenM` \ gbl_env -> - returnM (gbl_env { tcg_keep = tcg_keep gbl_env `unionNameSets` keep_alive }, + returnM (gbl_env, generic_inst_info ++ deriv_inst_info ++ local_inst_info, deriv_binds) addInsts :: [InstInfo] -> TcM a -> TcM a addInsts infos thing_inside - = tcExtendLocalInstEnv (map iDFunId infos) thing_inside + = tcExtendLocalInstEnv (map iSpec infos) thing_inside \end{code} \begin{code} -tcLocalInstDecl1 :: RenamedInstDecl +tcLocalInstDecl1 :: LInstDecl Name -> TcM (Maybe InstInfo) -- Nothing if there was an error -- A source-file instance declaration -- Type-check all the stuff before the "where" -- -- We 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] -tcLocalInstDecl1 decl@(InstDecl poly_ty binds uprags src_loc) +tcLocalInstDecl1 decl@(L loc (InstDecl poly_ty binds uprags)) = -- Prime error recovery, set source location recoverM (returnM Nothing) $ - addSrcLoc src_loc $ + setSrcSpan loc $ addErrCtxt (instDeclCtxt1 poly_ty) $ -- Typecheck the instance type itself. We can't use @@ -207,11 +196,20 @@ tcLocalInstDecl1 decl@(InstDecl poly_ty binds uprags src_loc) checkValidTheta InstThetaCtxt theta `thenM_` checkAmbiguity tyvars theta (tyVarsOfType tau) `thenM_` checkValidInstHead tau `thenM` \ (clas,inst_tys) -> + checkInstTermination theta inst_tys `thenM_` checkTc (checkInstFDs theta clas inst_tys) (instTypeErr (pprClassPred clas inst_tys) msg) `thenM_` - newDFunName clas inst_tys src_loc `thenM` \ dfun_name -> - returnM (Just (InstInfo { iDFunId = mkDictFunId dfun_name tyvars theta clas inst_tys, - iBinds = VanillaInst binds uprags })) + newDFunName clas inst_tys (srcSpanStart loc) `thenM` \ dfun_name -> + getOverlapFlag `thenM` \ overlap_flag -> + let dfun = mkDictFunId dfun_name tyvars theta clas inst_tys + ispec = mkLocalInstance dfun overlap_flag + in + + tcIsHsBoot `thenM` \ is_boot -> + checkTc (not is_boot || (isEmptyLHsBinds binds && null uprags)) + badBootDeclErr `thenM_` + + returnM (Just (InstInfo { iSpec = ispec, iBinds = VanillaInst binds uprags })) where msg = parens (ptext SLIT("the instance types do not agree with the functional dependencies of the class")) \end{code} @@ -224,8 +222,8 @@ tcLocalInstDecl1 decl@(InstDecl poly_ty binds uprags src_loc) %************************************************************************ \begin{code} -tcInstDecls2 :: [RenamedTyClDecl] -> [InstInfo] - -> TcM (TcLclEnv, TcMonoBinds) +tcInstDecls2 :: [LTyClDecl Name] -> [InstInfo] + -> TcM (LHsBinds Id, TcLclEnv) -- (a) From each class declaration, -- generate any default-method bindings -- (b) From each instance decl @@ -234,16 +232,17 @@ tcInstDecls2 :: [RenamedTyClDecl] -> [InstInfo] tcInstDecls2 tycl_decls inst_decls = do { -- (a) Default methods from class decls (dm_binds_s, dm_ids_s) <- mapAndUnzipM tcClassDecl2 $ - filter isClassDecl tycl_decls - ; tcExtendLocalValEnv (concat dm_ids_s) $ do + filter (isClassDecl.unLoc) tycl_decls + ; tcExtendIdEnv (concat dm_ids_s) $ do -- (b) instance declarations ; inst_binds_s <- mappM tcInstDecl2 inst_decls -- Done - ; tcl_env <- getLclEnv - ; returnM (tcl_env, andMonoBindList dm_binds_s `AndMonoBinds` - andMonoBindList inst_binds_s) } + ; let binds = unionManyBags dm_binds_s `unionBags` + unionManyBags inst_binds_s + ; tcl_env <- getLclEnv -- Default method Ids in here + ; returnM (binds, tcl_env) } \end{code} ======= New documentation starts here (Sept 92) ============== @@ -314,74 +313,74 @@ First comes the easy case of a non-local instance decl. \begin{code} -tcInstDecl2 :: InstInfo -> TcM TcMonoBinds +tcInstDecl2 :: InstInfo -> TcM (LHsBinds Id) -tcInstDecl2 (InstInfo { iDFunId = dfun_id, iBinds = binds }) - = -- Prime error recovery - recoverM (returnM EmptyMonoBinds) $ - addSrcLoc (getSrcLoc dfun_id) $ +tcInstDecl2 (InstInfo { iSpec = ispec, iBinds = binds }) + = let + dfun_id = instanceDFunId ispec + rigid_info = InstSkol dfun_id + inst_ty = idType dfun_id + in + -- Prime error recovery + recoverM (returnM emptyLHsBinds) $ + setSrcSpan (srcLocSpan (getSrcLoc dfun_id)) $ addErrCtxt (instDeclCtxt2 (idType dfun_id)) $ - let - inst_ty = idType dfun_id - (inst_tyvars, _) = tcSplitForAllTys inst_ty - -- The tyvars of the instance decl scope over the 'where' part + + -- Instantiate the instance decl with skolem constants + tcSkolSigType rigid_info inst_ty `thenM` \ (inst_tyvars', dfun_theta', inst_head') -> + -- These inst_tyvars' scope over the 'where' part -- Those tyvars are inside the dfun_id's type, which is a bit -- bizarre, but OK so long as you realise it! - in - - -- Instantiate the instance decl with tc-style type variables - tcInstType InstTv inst_ty `thenM` \ (inst_tyvars', dfun_theta', inst_head') -> let - Just pred = tcSplitPredTy_maybe inst_head' - (clas, inst_tys') = getClassPredTys pred + (clas, inst_tys') = tcSplitDFunHead inst_head' (class_tyvars, sc_theta, _, op_items) = classBigSig clas -- Instantiate the super-class context with inst_tys - sc_theta' = substTheta (mkTyVarSubst class_tyvars inst_tys') sc_theta - origin = InstanceDeclOrigin + sc_theta' = substTheta (zipOpenTvSubst class_tyvars inst_tys') sc_theta + origin = SigOrigin rigid_info in -- Create dictionary Ids from the specified instance contexts. - newDicts origin sc_theta' `thenM` \ sc_dicts -> - newDicts origin dfun_theta' `thenM` \ dfun_arg_dicts -> - newDicts origin [pred] `thenM` \ [this_dict] -> + newDicts InstScOrigin sc_theta' `thenM` \ sc_dicts -> + newDicts origin dfun_theta' `thenM` \ dfun_arg_dicts -> + newDicts origin [mkClassPred clas inst_tys'] `thenM` \ [this_dict] -> -- Default-method Ids may be mentioned in synthesised RHSs, -- but they'll already be in the environment. - ------------------ -- Typecheck the methods let -- These insts are in scope; quite a few, eh? avail_insts = [this_dict] ++ dfun_arg_dicts ++ sc_dicts in - tcMethods clas inst_tyvars inst_tyvars' + tcMethods origin clas inst_tyvars' dfun_theta' inst_tys' avail_insts op_items binds `thenM` \ (meth_ids, meth_binds) -> -- Figure out bindings for the superclass context - tcSuperClasses inst_tyvars' dfun_arg_dicts sc_dicts - `thenM` \ (zonked_inst_tyvars, sc_binds_inner, sc_binds_outer) -> - - -- Deal with 'SPECIALISE instance' pragmas by making them - -- look like SPECIALISE pragmas for the dfun + -- Don't include this_dict in the 'givens', else + -- sc_dicts get bound by just selecting from this_dict!! + addErrCtxt superClassCtxt + (tcSimplifySuperClasses inst_tyvars' + dfun_arg_dicts + sc_dicts) `thenM` \ sc_binds -> + + -- It's possible that the superclass stuff might unified one + -- of the inst_tyavars' with something in the envt + checkSigTyVars inst_tyvars' `thenM_` + + -- Deal with 'SPECIALISE instance' pragmas let - uprags = case binds of - VanillaInst _ uprags -> uprags - other -> [] - spec_prags = [ SpecSig (idName dfun_id) ty loc - | SpecInstSig ty loc <- uprags ] - xtve = inst_tyvars `zip` inst_tyvars' + specs = case binds of + VanillaInst _ prags -> filter isSpecInstLSig prags + other -> [] in - tcExtendGlobalValEnv [dfun_id] ( - tcExtendTyVarEnv2 xtve $ - tcSpecSigs spec_prags - ) `thenM` \ prag_binds -> - + tcPrags dfun_id specs `thenM` \ prags -> + -- Create the result bindings let dict_constr = classDataCon clas scs_and_meths = map instToId sc_dicts ++ meth_ids this_dict_id = instToId this_dict - inlines | null dfun_arg_dicts = emptyNameSet - | otherwise = unitNameSet (idName dfun_id) + inline_prag | null dfun_arg_dicts = [] + | otherwise = [InlinePrag (Inline AlwaysActive True)] -- Always inline the dfun; this is an experimental decision -- because it makes a big performance difference sometimes. -- Often it means we can do the method selection, and then @@ -394,17 +393,6 @@ tcInstDecl2 (InstInfo { iDFunId = dfun_id, iBinds = binds }) -- See Note [Inline dfuns] below 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 rUNTIME_ERROR_ID) [idType this_dict_id]) - (HsLit (HsStringPrim (mkFastString (stringToUtf8 msg)))) - - | otherwise -- The common case = mkHsConApp dict_constr inst_tys' (map HsVar scs_and_meths) -- We don't produce a binding for the dict_constr; instead we -- rely on the simplifier to unfold this saturated application @@ -416,31 +404,32 @@ tcInstDecl2 (InstInfo { iDFunId = dfun_id, iBinds = binds }) where msg = "Compiler error: bad dictionary " ++ showSDoc (ppr clas) - dict_bind = VarMonoBind this_dict_id dict_rhs - all_binds = sc_binds_inner `AndMonoBinds` meth_binds `AndMonoBinds` dict_bind + dict_bind = noLoc (VarBind this_dict_id dict_rhs) + all_binds = dict_bind `consBag` (sc_binds `unionBags` meth_binds) - main_bind = AbsBinds - zonked_inst_tyvars - (map instToId dfun_arg_dicts) - [(inst_tyvars', dfun_id, this_dict_id)] - inlines all_binds + main_bind = noLoc $ AbsBinds + inst_tyvars' + (map instToId dfun_arg_dicts) + [(inst_tyvars', dfun_id, this_dict_id, + inline_prag ++ prags)] + all_binds in showLIE (text "instance") `thenM_` - returnM (main_bind `AndMonoBinds` prag_binds `AndMonoBinds` sc_binds_outer) + returnM (unitBag main_bind) -tcMethods clas inst_tyvars inst_tyvars' dfun_theta' inst_tys' +tcMethods origin clas inst_tyvars' dfun_theta' inst_tys' avail_insts op_items (VanillaInst monobinds uprags) = -- Check that all the method bindings come from this class let sel_names = [idName sel_id | (sel_id, _) <- op_items] - bad_bndrs = collectMonoBinders monobinds `minusList` sel_names + bad_bndrs = collectHsBindBinders monobinds `minusList` sel_names in mappM (addErrTc . badMethodErr clas) bad_bndrs `thenM_` -- Make the method bindings let - mk_method_bind = mkMethodBind InstanceDeclOrigin clas inst_tys' monobinds + mk_method_bind = mkMethodBind origin clas inst_tys' monobinds in mapAndUnzipM mk_method_bind op_items `thenM` \ (meth_insts, meth_infos) -> @@ -474,20 +463,21 @@ tcMethods clas inst_tyvars inst_tyvars' dfun_theta' inst_tys' -- The trouble is that the 'meth_inst' for op, which is 'available', also -- looks like 'op at Int'. But they are not the same. let + prag_fn = mkPragFun uprags all_insts = avail_insts ++ catMaybes meth_insts - xtve = inst_tyvars `zip` inst_tyvars' - tc_method_bind = tcMethodBind xtve inst_tyvars' dfun_theta' all_insts uprags + tc_method_bind = tcMethodBind inst_tyvars' dfun_theta' all_insts prag_fn + meth_ids = [meth_id | (_,meth_id,_) <- meth_infos] in + mapM tc_method_bind meth_infos `thenM` \ meth_binds_s -> - returnM ([meth_id | (_,meth_id,_) <- meth_infos], - andMonoBindList meth_binds_s) + returnM (meth_ids, unionManyBags meth_binds_s) -- Derived newtype instances -tcMethods clas inst_tyvars inst_tyvars' dfun_theta' inst_tys' +tcMethods origin clas inst_tyvars' dfun_theta' inst_tys' avail_insts op_items (NewTypeDerived rep_tys) - = getInstLoc InstanceDeclOrigin `thenM` \ inst_loc -> + = getInstLoc origin `thenM` \ inst_loc -> mapAndUnzip3M (do_one inst_loc) op_items `thenM` \ (meth_ids, meth_binds, rhs_insts) -> tcSimplifyCheck @@ -496,7 +486,7 @@ tcMethods clas inst_tyvars inst_tyvars' dfun_theta' inst_tys' -- I don't think we have to do the checkSigTyVars thing - returnM (meth_ids, lie_binds `AndMonoBinds` andMonoBindList meth_binds) + returnM (meth_ids, lie_binds `unionBags` listToBag meth_binds) where do_one inst_loc (sel_id, _) @@ -509,73 +499,14 @@ tcMethods clas inst_tyvars inst_tyvars' dfun_theta' inst_tys' let meth_id = instToId meth_inst in - return (meth_id, VarMonoBind meth_id (HsVar (instToId rhs_inst)), rhs_inst) + return (meth_id, noLoc (VarBind meth_id (nlHsVar (instToId rhs_inst))), rhs_inst) -- Instantiate rep_tys with the relevant type variables - rep_tys' = map (substTy subst) rep_tys - subst = mkTyVarSubst inst_tyvars (mkTyVarTys inst_tyvars') -\end{code} - -Note: [Superclass loops] -~~~~~~~~~~~~~~~~~~~~~~~~~ -We have to be very, very careful when generating superclasses, lest we -accidentally build a loop. Here's an example: - - class S a - - class S a => C a where { opc :: a -> a } - class S b => D b where { opd :: b -> b } - - instance C Int where - opc = opd - - instance D Int where - opd = opc - -From (instance C Int) we get the constraint set {ds1:S Int, dd:D Int} -Simplifying, we may well get: - $dfCInt = :C ds1 (opd dd) - dd = $dfDInt - ds1 = $p1 dd -Notice that we spot that we can extract ds1 from dd. - -Alas! Alack! We can do the same for (instance D Int): - - $dfDInt = :D ds2 (opc dc) - dc = $dfCInt - ds2 = $p1 dc - -And now we've defined the superclass in terms of itself. - - -Solution: treat the superclass context separately, and simplify it -all the way down to nothing on its own. Don't toss any 'free' parts -out to be simplified together with other bits of context. -Hence the tcSimplifyTop below. - -At a more basic level, don't include this_dict in the context wrt -which we simplify sc_dicts, else sc_dicts get bound by just selecting -from this_dict!! - -\begin{code} -tcSuperClasses inst_tyvars' dfun_arg_dicts sc_dicts - = addErrCtxt superClassCtxt $ - getLIE (tcSimplifyCheck doc inst_tyvars' - dfun_arg_dicts - sc_dicts) `thenM` \ (sc_binds1, sc_lie) -> - - -- It's possible that the superclass stuff might have done unification - checkSigTyVars inst_tyvars' `thenM` \ zonked_inst_tyvars -> - - -- We must simplify this all the way down - -- lest we build superclass loops - -- See Note [Superclass loops] above - tcSimplifyTop sc_lie `thenM` \ sc_binds2 -> - - returnM (zonked_inst_tyvars, sc_binds1, sc_binds2) - - where - doc = ptext SLIT("instance declaration superclass context") + -- This looks a bit odd, because inst_tyvars' are the skolemised version + -- of the type variables in the instance declaration; but rep_tys doesn't + -- have the skolemised version, so we substitute them in here + rep_tys' = substTys subst rep_tys + subst = zipOpenTvSubst inst_tyvars' (mkTyVarTys inst_tyvars') \end{code} @@ -678,8 +609,8 @@ simplified: only zeze2 is extracted and its body is simplified. \begin{code} instDeclCtxt1 hs_inst_ty - = inst_decl_ctxt (case hs_inst_ty of - HsForAllTy _ _ _ (HsPredTy pred) -> ppr pred + = inst_decl_ctxt (case unLoc hs_inst_ty of + HsForAllTy _ _ _ (L _ (HsPredTy pred)) -> ppr pred HsPredTy pred -> ppr pred other -> ppr hs_inst_ty) -- Don't expect this instDeclCtxt2 dfun_ty