X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcInstDcls.lhs;h=987d1d53d37ee96c792c9631ee57fa51c6985733;hb=1b91b7e5adb10bb9d9c6bfe6112f3ef03ab47e31;hp=9d36640dd2bf9bf77b415a664656954bcd000340;hpb=fcfa1c6f92dcb9d0e1fbe0563944c76739259612;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcInstDcls.lhs b/ghc/compiler/typecheck/TcInstDcls.lhs index 9d36640..987d1d5 100644 --- a/ghc/compiler/typecheck/TcInstDcls.lhs +++ b/ghc/compiler/typecheck/TcInstDcls.lhs @@ -1,105 +1,87 @@ % -% (c) The GRASP/AQUA Project, Glasgow University, 1992-1996 +% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 % \section[TcInstDecls]{Typechecking instance declarations} \begin{code} -#include "HsVersions.h" +module TcInstDcls ( tcInstDecls1, tcInstDecls2, tcAddDeclCtxt ) where -module TcInstDcls ( - tcInstDecls1, - tcInstDecls2, - tcMethodBind - ) where +#include "HsVersions.h" -IMP_Ubiq() +import CmdLineOpts ( DynFlag(..), dopt ) -import HsSyn ( HsDecl(..), InstDecl(..), TyDecl, ClassDecl, DefaultDecl, - FixityDecl, IfaceSig, Sig(..), - SpecInstSig(..), HsBinds(..), - MonoBinds(..), GRHSsAndBinds(..), GRHS(..), Match, - InPat(..), OutPat(..), HsExpr(..), HsLit(..), - Stmt, DoOrListComp, ArithSeqInfo, Fake, Fixity, - HsType(..), HsTyVar, - SYN_IE(RecFlag), recursive, nonRecursive, collectMonoBinders, - andMonoBinds - ) -import RnHsSyn ( SYN_IE(RenamedHsBinds), SYN_IE(RenamedMonoBinds), - SYN_IE(RenamedInstDecl), SYN_IE(RenamedFixityDecl), SYN_IE(RenamedHsExpr), - SYN_IE(RenamedSig), SYN_IE(RenamedSpecInstSig), SYN_IE(RenamedHsDecl) +import HsSyn ( HsDecl(..), InstDecl(..), TyClDecl(..), + MonoBinds(..), HsExpr(..), HsLit(..), Sig(..), + andMonoBindList, collectMonoBinders, isClassDecl ) -import TcHsSyn ( TcIdOcc(..), SYN_IE(TcIdBndr), SYN_IE(TcHsBinds), - SYN_IE(TcMonoBinds), SYN_IE(TcExpr), tcIdType, - mkHsTyLam, mkHsTyApp, - mkHsDictLam, mkHsDictApp ) - -import TcBinds ( tcBindWithSigs, TcSigInfo(..) ) -import TcMonad -import RnMonad ( SYN_IE(RnNameSupply) ) -import Inst ( Inst, InstOrigin(..), SYN_IE(InstanceMapper), - instToId, newDicts, newMethod, SYN_IE(LIE), emptyLIE, plusLIE ) -import TcBinds ( tcPragmaSigs, checkSigTyVars ) -import PragmaInfo ( PragmaInfo(..) ) +import HsTypes ( HsType (..), HsTyVarBndr(..), toHsTyVar ) +import HsPat ( InPat (..) ) +import HsMatches ( Match (..) ) +import RnHsSyn ( RenamedHsBinds, RenamedInstDecl, RenamedHsDecl, + extractHsTyVars ) +import TcHsSyn ( TcMonoBinds, mkHsConApp ) +import TcBinds ( tcSpecSigs ) +import TcClassDcl ( tcMethodBind, badMethodErr ) +import TcMonad +import Inst ( InstOrigin(..), + newDicts, newClassDicts, + LIE, emptyLIE, plusLIE, plusLIEs ) import TcDeriv ( tcDeriving ) -import TcEnv ( tcLookupClass, newLocalId, tcExtendGlobalTyVars, tcGetGlobalTyVars ) -import SpecEnv ( SpecEnv ) -import TcGRHSs ( tcGRHSsAndBinds ) -import TcInstUtil ( InstInfo(..), mkInstanceRelatedIds, buildInstanceEnvs ) -import TcKind ( TcKind, unifyKind ) -import TcMatches ( tcMatchesFun ) -import TcMonoType ( tcTyVarScope, tcContext, tcHsTypeKind ) -import TcSimplify ( tcSimplifyAndCheck ) -import TcType ( SYN_IE(TcType), SYN_IE(TcTyVar), SYN_IE(TcTyVarSet), - tcInstSigTyVars, tcInstType, tcInstSigTcType, - tcInstTheta, tcInstTcType, tcInstSigType +import TcEnv ( TcEnv, tcExtendGlobalValEnv, + tcExtendTyVarEnvForMeths, TyThing (..), + tcAddImportedIdInfo, tcInstId, tcLookupClass, + newDFunName, tcExtendTyVarEnv ) -import Unify ( unifyTauTy, unifyTauTyLists ) - +import TcInstUtil ( InstInfo(..), InstEnv, pprInstInfo, classDataCon, + simpleInstInfoTyCon, simpleInstInfoTy, isLocalInst, + extendInstEnv ) +import TcMonoType ( tcTyVars, tcHsSigType, tcHsType, kcHsSigType ) +import TcSimplify ( tcSimplifyAndCheck ) +import TcType ( zonkTcSigTyVars ) +import HscTypes ( PersistentCompilerState(..), HomeSymbolTable, DFunId, + ModDetails(..) ) import Bag ( emptyBag, unitBag, unionBags, unionManyBags, - concatBag, foldBag, bagToList, listToBag, - Bag ) -import CmdLineOpts ( opt_GlasgowExts, opt_CompilingGhcInternals, - opt_OmitDefaultInstanceMethods, - opt_SpecialiseOverloaded + foldBag, Bag, listToBag ) -import Class ( GenClass, GenClassOp, - classBigSig, classOps, classOpLocalType, - classDefaultMethodId, SYN_IE(Class) - ) -import Id ( GenId, idType, isDefaultMethodId_maybe, - isNullaryDataCon, dataConArgTys, SYN_IE(Id) ) -import ListSetOps ( minusList ) -import Maybes ( maybeToBool, expectJust, seqMaybe ) -import Name ( nameOccName, getOccString, occNameString, moduleString, getOccName, - isLocallyDefined, OccName, Name{--O only-}, SYN_IE(Module), - NamedThing(..) +import Class ( Class, DefMeth(..), classBigSig ) +import Var ( idName, idType ) +import Maybes ( maybeToBool, expectJust ) +import MkId ( mkDictFunId ) +import Generics ( validGenericInstanceType ) +import Module ( Module, foldModuleEnv ) +import Name ( isLocallyDefined ) +import NameSet ( emptyNameSet, nameSetToList ) +import PrelInfo ( eRROR_ID ) +import PprType ( pprConstraint, pprPred ) +import TyCon ( TyCon, isSynTyCon, tyConDerivings ) +import Type ( mkTyVarTys, splitSigmaTy, isTyVarTy, + splitTyConApp_maybe, splitDictTy_maybe, + splitAlgTyConApp_maybe, classesToPreds, classesOfPreds, + unUsgTy, tyVarsOfTypes, mkClassPred, mkTyVarTy, + getClassTys_maybe ) -import PrelVals ( nO_EXPLICIT_METHOD_ERROR_ID ) -import PprType ( GenType, GenTyVar, GenClass, GenClassOp, TyCon, - pprParendGenType +import Subst ( mkTopTyVarSubst, substClasses, substTheta ) +import VarSet ( mkVarSet, varSetElems ) +import TysWiredIn ( genericTyCons, isFFIArgumentTy, isFFIResultTy ) +import PrelNames ( cCallableClassKey, cReturnableClassKey, hasKey ) +import Name ( Name, NameEnv, extendNameEnv_C, emptyNameEnv, + plusNameEnv_C, nameEnvElts ) +import FiniteMap ( mapFM ) +import SrcLoc ( SrcLoc ) +import RnHsSyn -- ( RenamedMonoBinds ) +import VarSet ( varSetElems ) +import UniqFM ( mapUFM ) +import Unique ( Uniquable(..) ) +import BasicTypes ( NewOrData(..) ) +import ErrUtils ( dumpIfSet_dyn ) +import ListSetOps ( Assoc, emptyAssoc, plusAssoc_C, mapAssoc, + assocElts, extendAssoc_C, + equivClassesByUniq, minusList ) +import List ( intersect, (\\), partition ) import Outputable -import SrcLoc ( SrcLoc, noSrcLoc ) -import Pretty -import TyCon ( isSynTyCon, isDataTyCon, derivedClasses ) -import Type ( GenType(..), SYN_IE(ThetaType), mkTyVarTys, isPrimType, - splitSigmaTy, splitAppTys, isTyVarTy, matchTy, mkSigmaTy, - getTyCon_maybe, maybeAppTyCon, SYN_IE(Type), - maybeBoxedPrimType, maybeAppDataTyCon, splitRhoTy, eqTy - ) -import TyVar ( GenTyVar, SYN_IE(GenTyVarSet), tyVarSetToList, - mkTyVarSet, unionTyVarSets, SYN_IE(TyVar) ) -import TysPrim ( byteArrayPrimTyCon, mutableByteArrayPrimTyCon ) -import TysWiredIn ( stringTy ) -import Unique ( Unique, cCallableClassKey, cReturnableClassKey ) -import UniqFM ( Uniquable(..) ) -import Util ( zipEqual, panic, pprPanic, pprTrace -#if __GLASGOW_HASKELL__ < 202 - , trace -#endif - ) \end{code} Typechecking instance declarations is done in two passes. The first @@ -175,71 +157,262 @@ Here, Bop1 \ldots Bopn bind the methods op1 \ldots opn, and $dbinds_super$ bind the superclass dictionaries sd1 \ldots sdm. \end{enumerate} + +%************************************************************************ +%* * +\subsection{Extracting instance decls} +%* * +%************************************************************************ + +Gather up the instance declarations from their various sources + \begin{code} -tcInstDecls1 :: [RenamedHsDecl] - -> Module -- module name for deriving - -> RnNameSupply -- for renaming derivings - -> TcM s (Bag InstInfo, - RenamedHsBinds, - PprStyle -> Doc) - -tcInstDecls1 decls mod_name rn_name_supply - = -- Do the ordinary instance declarations - mapNF_Tc (tcInstDecl1 mod_name) - [inst_decl | InstD inst_decl <- decls] `thenNF_Tc` \ inst_info_bags -> +tcInstDecls1 :: PersistentCompilerState + -> HomeSymbolTable -- Contains instances + -> TcEnv -- Contains IdInfo for dfun ids + -> Module -- Module for deriving + -> [TyCon] + -> [RenamedHsDecl] + -> TcM (PersistentCompilerState, InstEnv, [InstInfo], RenamedHsBinds) + +tcInstDecls1 pcs hst unf_env mod local_tycons decls + = let + inst_decls = [inst_decl | InstD inst_decl <- decls] + clas_decls = [clas_decl | TyClD clas_decl <- decls, isClassDecl clas_decl] + in + -- (1) Do the ordinary instance declarations + mapNF_Tc (tcInstDecl1 mod unf_env) inst_decls `thenNF_Tc` \ inst_infos -> + + -- (2) Instances from generic class declarations + getGenericInstances mod clas_decls `thenTc` \ generic_inst_info -> + + -- Next, construct the instance environment so far, consisting of + -- a) cached non-home-package InstEnv (gotten from pcs) pcs_insts pcs + -- b) imported instance decls (not in the home package) inst_env1 + -- c) other modules in this package (gotten from hst) inst_env2 + -- d) local instance decls inst_env3 + -- e) generic instances inst_env4 + -- The result of (b) replaces the cached InstEnv in the PCS let - decl_inst_info = unionManyBags inst_info_bags + (local_inst_info, imported_inst_info) + = partition isLocalInst (concat inst_infos) + + imported_dfuns = map (tcAddImportedIdInfo unf_env . iDFunId) + imported_inst_info + hst_dfuns = foldModuleEnv ((++) . md_insts) [] hst in - -- Handle "derived" instances; note that we only do derivings - -- for things in this module; we ignore deriving decls from - -- interfaces! We pass fixities, because they may be used - -- in deriving Read and Show. - tcDeriving mod_name rn_name_supply decl_inst_info - `thenTc` \ (deriv_inst_info, deriv_binds, ddump_deriv) -> + addInstDFuns (pcs_insts pcs) imported_dfuns `thenNF_Tc` \ inst_env1 -> + addInstDFuns inst_env1 hst_dfuns `thenNF_Tc` \ inst_env2 -> + addInstInfos inst_env2 local_inst_info `thenNF_Tc` \ inst_env3 -> + addInstInfos inst_env3 generic_inst_info `thenNF_Tc` \ inst_env4 -> + + -- (3) Compute instances from "deriving" clauses; + -- note that we only do derivings for things in this module; + -- we ignore deriving decls from interfaces! + -- This stuff computes a context for the derived instance decl, so it + -- needs to know about all the instances possible; hecne inst_env4 + tcDeriving (pcs_PRS pcs) mod inst_env4 local_tycons + `thenTc` \ (deriv_inst_info, deriv_binds) -> + addInstInfos inst_env4 deriv_inst_info + `thenNF_Tc` \ final_inst_env -> + + returnTc (pcs { pcs_insts = inst_env1 }, + final_inst_env, + generic_inst_info ++ deriv_inst_info ++ local_inst_info, + deriv_binds) + +addInstInfos :: InstEnv -> [InstInfo] -> NF_TcM InstEnv +addInstInfos inst_env infos = addInstDFuns inst_env (map iDFunId infos) + +addInstDFuns :: InstEnv -> [DFunId] -> NF_TcM InstEnv +addInstDFuns dfuns infos + = getDOptsTc `thenTc` \ dflags -> + extendInstEnv dflags dfuns infos `bind` \ (inst_env', errs) -> + addErrsTc errs `thenNF_Tc_` + returnTc inst_env' + where + bind x f = f x + +\end{code} + +\begin{code} +tcInstDecl1 :: Module -> TcEnv -> RenamedInstDecl -> NF_TcM [InstInfo] +-- Deal with a single instance declaration +tcInstDecl1 mod unf_env (InstDecl poly_ty binds uprags maybe_dfun_name src_loc) + = -- Prime error recovery, set source location + recoverNF_Tc (returnNF_Tc []) $ + tcAddSrcLoc src_loc $ + -- Type-check all the stuff before the "where" + tcHsSigType poly_ty `thenTc` \ poly_ty' -> let - full_inst_info = deriv_inst_info `unionBags` decl_inst_info + (tyvars, theta, dict_ty) = splitSigmaTy poly_ty' + (clas, inst_tys) = case splitDictTy_maybe dict_ty of + Just ct -> ct + Nothing -> pprPanic "tcInstDecl1" (ppr poly_ty) in - returnTc (full_inst_info, deriv_binds, ddump_deriv) + (case maybe_dfun_name of + Nothing -> -- A source-file instance declaration + + -- 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] + scrutiniseInstanceHead clas inst_tys `thenNF_Tc_` + mapNF_Tc scrutiniseInstanceConstraint theta `thenNF_Tc_` + + -- Make the dfun id and return it + newDFunName mod clas inst_tys src_loc `thenNF_Tc` \ dfun_name -> + returnNF_Tc (True, mkDictFunId dfun_name clas tyvars inst_tys theta) + + Just dfun_name -> -- An interface-file instance declaration + -- Make the dfun id + returnNF_Tc (False, mkDictFunId dfun_name clas tyvars inst_tys theta) + ) `thenNF_Tc` \ (is_local, dfun_id) -> + + returnTc [InstInfo { iLocal = is_local, + iClass = clas, iTyVars = tyvars, iTys = inst_tys, + iTheta = theta, iDFunId = dfun_id, + iBinds = binds, iLoc = src_loc, iPrags = uprags }] +\end{code} -tcInstDecl1 :: Module -> RenamedInstDecl -> NF_TcM s (Bag InstInfo) -tcInstDecl1 mod_name (InstDecl poly_ty binds uprags (Just dfun_name) src_loc) - = -- Prime error recovery, set source location - recoverNF_Tc (returnNF_Tc emptyBag) $ - tcAddSrcLoc src_loc $ +%************************************************************************ +%* * +\subsection{Extracting generic instance declaration from class declarations} +%* * +%************************************************************************ - -- Look things up - tcLookupClass class_name `thenTc` \ (clas_kind, clas) -> - - -- Typecheck the context and instance type - tcTyVarScope tyvar_names (\ tyvars -> - tcContext context `thenTc` \ theta -> - tcHsTypeKind inst_ty `thenTc` \ (tau_kind, tau) -> - unifyKind clas_kind tau_kind `thenTc_` - returnTc (tyvars, theta, tau) - ) `thenTc` \ (inst_tyvars, inst_theta, inst_tau) -> - - -- Check for respectable instance type - scrutiniseInstanceType dfun_name clas inst_tau - `thenTc` \ (inst_tycon,arg_tys) -> - - -- Make the dfun id and constant-method ids - mkInstanceRelatedIds dfun_name - clas inst_tyvars inst_tau inst_theta - `thenNF_Tc` \ (dfun_id, dfun_theta) -> - - returnTc (unitBag (InstInfo clas inst_tyvars inst_tau inst_theta - dfun_theta dfun_id - binds src_loc uprags)) +@getGenericInstances@ extracts the generic instance declarations from a class +declaration. For exmaple + + class C a where + op :: a -> a + + op{ x+y } (Inl v) = ... + op{ x+y } (Inr v) = ... + op{ x*y } (v :*: w) = ... + op{ 1 } Unit = ... + +gives rise to the instance declarations + + instance C (x+y) where + op (Inl v) = ... + op (Inr v) = ... + + instance C (x*y) where + op (v :*: w) = ... + + instance C 1 where + op Unit = ... + + +\begin{code} +getGenericInstances :: Module -> [RenamedTyClDecl] -> TcM [InstInfo] +getGenericInstances mod class_decls + = mapTc (get_generics mod) class_decls `thenTc` \ gen_inst_infos -> + let + gen_inst_info = concat gen_inst_infos + in + getDOptsTc `thenTc` \ dflags -> + ioToTc (dumpIfSet_dyn dflags Opt_D_dump_deriv "Generic instances" + (vcat (map pprInstInfo gen_inst_info))) + `thenNF_Tc_` + returnTc gen_inst_info + +get_generics mod decl@(ClassDecl context class_name tyvar_names + fundeps class_sigs def_methods pragmas + name_list loc) + | null groups + = returnTc [] -- The comon case: + -- no generic default methods, or + -- its an imported class decl (=> has no methods at all) + + | otherwise -- A local class decl with generic default methods + = recoverNF_Tc (returnNF_Tc []) $ + tcAddDeclCtxt decl $ + tcLookupClass class_name `thenTc` \ clas -> + + -- Make an InstInfo out of each group + mapTc (mkGenericInstance mod clas loc) groups `thenTc` \ inst_infos -> + + -- Check that there is only one InstInfo for each type constructor + -- The main way this can fail is if you write + -- f {| a+b |} ... = ... + -- f {| x+y |} ... = ... + -- Then at this point we'll have an InstInfo for each + let + bad_groups = [group | group <- equivClassesByUniq get_uniq inst_infos, + length group > 1] + get_uniq inst = getUnique (simpleInstInfoTyCon inst) + in + mapTc (addErrTc . dupGenericInsts) bad_groups `thenTc_` + + -- Check that there is an InstInfo for each generic type constructor + let + missing = genericTyCons `minusList` map simpleInstInfoTyCon inst_infos + in + checkTc (null missing) (missingGenericInstances missing) `thenTc_` + + returnTc inst_infos + + where + -- Group the declarations by type pattern + groups :: [(RenamedHsType, RenamedMonoBinds)] + groups = assocElts (getGenericBinds def_methods) + + +--------------------------------- +getGenericBinds :: RenamedMonoBinds -> Assoc RenamedHsType RenamedMonoBinds + -- Takes a group of method bindings, finds the generic ones, and returns + -- them in finite map indexed by the type parameter in the definition. + +getGenericBinds EmptyMonoBinds = emptyAssoc +getGenericBinds (AndMonoBinds m1 m2) + = plusAssoc_C AndMonoBinds (getGenericBinds m1) (getGenericBinds m2) + +getGenericBinds (FunMonoBind id infixop matches loc) + = mapAssoc wrap (foldr add emptyAssoc matches) where - (tyvar_names, context, dict_ty) = case poly_ty of - HsForAllTy tvs cxt dict_ty -> (tvs, cxt, dict_ty) - other -> ([], [], poly_ty) - (class_name, inst_ty) = case dict_ty of - MonoDictTy cls ty -> (cls,ty) - other -> pprPanic "Malformed intance decl" (ppr PprDebug poly_ty) + add match env = case maybeGenericMatch match of + Nothing -> env + Just (ty, match') -> extendAssoc_C (++) env (ty, [match']) + + wrap ms = FunMonoBind id infixop ms loc + +--------------------------------- +mkGenericInstance :: Module -> Class -> SrcLoc + -> (RenamedHsType, RenamedMonoBinds) + -> TcM InstInfo + +mkGenericInstance mod clas loc (hs_ty, binds) + -- Make a generic instance declaration + -- For example: instance (C a, C b) => C (a+b) where { binds } + + = -- Extract the universally quantified type variables + tcTyVars (nameSetToList (extractHsTyVars hs_ty)) + (kcHsSigType hs_ty) `thenTc` \ tyvars -> + tcExtendTyVarEnv tyvars $ + + -- Type-check the instance type, and check its form + tcHsSigType hs_ty `thenTc` \ inst_ty -> + checkTc (validGenericInstanceType inst_ty) + (badGenericInstanceType binds) `thenTc_` + + -- Make the dictionary function. + newDFunName mod clas [inst_ty] loc `thenNF_Tc` \ dfun_name -> + let + inst_theta = [mkClassPred clas [mkTyVarTy tv] | tv <- tyvars] + inst_tys = [inst_ty] + dfun_id = mkDictFunId dfun_name clas tyvars inst_tys inst_theta + in + + returnTc (InstInfo { iLocal = True, + iClass = clas, iTyVars = tyvars, iTys = inst_tys, + iTheta = inst_theta, iDFunId = dfun_id, iBinds = binds, + iLoc = loc, iPrags = [] }) \end{code} @@ -250,19 +423,20 @@ tcInstDecl1 mod_name (InstDecl poly_ty binds uprags (Just dfun_name) src_loc) %************************************************************************ \begin{code} -tcInstDecls2 :: Bag InstInfo - -> NF_TcM s (LIE s, TcHsBinds s) +tcInstDecls2 :: [InstInfo] + -> NF_TcM (LIE, TcMonoBinds) tcInstDecls2 inst_decls - = foldBag combine tcInstDecl2 (returnNF_Tc (emptyLIE, EmptyBinds)) inst_decls +-- = foldBag combine tcInstDecl2 (returnNF_Tc (emptyLIE, EmptyMonoBinds)) inst_decls + = foldr combine (returnNF_Tc (emptyLIE, EmptyMonoBinds)) + (map tcInstDecl2 inst_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} - ======= New documentation starts here (Sept 92) ============== The main purpose of @tcInstDecl2@ is to return a @HsBinds@ which defines @@ -330,322 +504,178 @@ 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, TcHsBinds s) +tcInstDecl2 :: InstInfo -> NF_TcM (LIE, TcMonoBinds) -tcInstDecl2 (InstInfo clas inst_tyvars inst_ty - inst_decl_theta dfun_theta - dfun_id monobinds - locn uprags) +tcInstDecl2 (InstInfo { iClass = clas, iTyVars = inst_tyvars, iTys = inst_tys, + iTheta = inst_decl_theta, iDFunId = dfun_id, + iBinds = monobinds, iLoc = locn, iPrags = uprags }) | not (isLocallyDefined dfun_id) - = returnNF_Tc (emptyLIE, EmptyBinds) - -{- - -- I deleted this "optimisation" because when importing these - -- instance decls the renamer would look for the dfun bindings and they weren't there. - -- This would be fixable, but it seems simpler just to produce a tiny void binding instead, - -- even though it's never used. - - -- This case deals with CCallable etc, which don't need any bindings - | isNoDictClass clas - = returnNF_Tc (emptyLIE, EmptyBinds) --} + = returnNF_Tc (emptyLIE, EmptyMonoBinds) | otherwise = -- Prime error recovery - recoverNF_Tc (returnNF_Tc (emptyLIE, EmptyBinds)) $ - tcAddSrcLoc locn $ - - -- Get the class signature - tcInstSigTyVars inst_tyvars `thenNF_Tc` \ (inst_tyvars', _, tenv) -> - let - origin = InstanceDeclOrigin - (class_tyvar, - super_classes, sc_sel_ids, - class_ops, op_sel_ids, defm_ids) = classBigSig clas - in - tcInstType tenv inst_ty `thenNF_Tc` \ inst_ty' -> - tcInstTheta tenv dfun_theta `thenNF_Tc` \ dfun_theta' -> - tcInstTheta tenv inst_decl_theta `thenNF_Tc` \ inst_decl_theta' -> + recoverNF_Tc (returnNF_Tc (emptyLIE, EmptyMonoBinds)) $ + tcAddSrcLoc locn $ + + -- Instantiate the instance decl with tc-style type variables + tcInstId dfun_id `thenNF_Tc` \ (inst_tyvars', dfun_theta', dict_ty') -> let - sc_theta' = super_classes `zip` repeat inst_ty' + (clas, inst_tys') = expectJust "tcInstDecl2" (splitDictTy_maybe dict_ty') + origin = InstanceDeclOrigin + + (class_tyvars, sc_theta, _, op_items) = classBigSig clas + + dm_ids = [dm_id | (_, DefMeth dm_id) <- op_items] + sel_names = [idName sel_id | (sel_id, _) <- op_items] + + -- Instantiate the theta found in the original instance decl + inst_decl_theta' = substTheta (mkTopTyVarSubst inst_tyvars (mkTyVarTys inst_tyvars')) + inst_decl_theta + + -- Instantiate the super-class context with inst_tys + sc_theta' = substClasses (mkTopTyVarSubst class_tyvars inst_tys') sc_theta + + -- Find any definitions in monobinds that aren't from the class + bad_bndrs = collectMonoBinders monobinds `minusList` sel_names 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_ty')] `thenNF_Tc` \ (this_dict, [this_dict_id]) -> + -- Check that all the method bindings come from this class + mapTc (addErrTc . badMethodErr clas) bad_bndrs `thenNF_Tc_` - -- Check the method bindings + -- Create dictionary Ids from the specified instance contexts. + newClassDicts 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, _) -> + newClassDicts origin [(clas,inst_tys')] `thenNF_Tc` \ (this_dict, [this_dict_id]) -> + + tcExtendTyVarEnvForMeths inst_tyvars inst_tyvars' ( + tcExtendGlobalValEnv dm_ids ( + -- Default-method Ids may be mentioned in synthesised RHSs + + mapAndUnzip3Tc (tcMethodBind clas origin inst_tyvars' inst_tys' + inst_decl_theta' + monobinds uprags True) + op_items + )) `thenTc` \ (method_binds_s, insts_needed_s, meth_lies_w_ids) -> + + -- Deal with SPECIALISE instance pragmas by making them + -- look like SPECIALISE pragmas for the dfun let - inst_tyvars_set' = mkTyVarSet inst_tyvars' - check_from_this_class (bndr, loc) - | nameOccName bndr `elem` sel_names = returnTc () - | otherwise = recoverTc (returnTc ()) $ - tcAddSrcLoc loc $ - failTc (instBndrErr bndr clas) - sel_names = map getOccName op_sel_ids + dfun_prags = [SpecSig (idName dfun_id) ty loc | SpecInstSig ty loc <- uprags] in - mapTc check_from_this_class (bagToList (collectMonoBinders monobinds)) `thenTc_` - tcExtendGlobalTyVars inst_tyvars_set' ( - mapAndUnzip3Tc (tcMethodBind (getDefmRhs clas) inst_ty' monobinds) - (op_sel_ids `zip` [0..]) - ) `thenTc` \ (method_binds_s, insts_needed_s, meth_lies_w_ids) -> + tcExtendGlobalValEnv [dfun_id] ( + tcSpecSigs dfun_prags + ) `thenTc` \ (prag_binds, prag_lie) -> -- Check the overloading constraints of the methods and superclasses + + -- tcMethodBind has checked that the class_tyvars havn't + -- been unified with each other or another type, but we must + -- still zonk them before passing them to tcSimplifyAndCheck + zonkTcSigTyVars inst_tyvars' `thenNF_Tc` \ zonked_inst_tyvars -> let + inst_tyvars_set = mkVarSet zonked_inst_tyvars + (meth_lies, meth_ids) = unzip meth_lies_w_ids - avail_insts -- These insts are in scope; quite a few, eh? - = this_dict `plusLIE` dfun_arg_dicts `plusLIE` unionManyBags meth_lies + + -- These insts are in scope; quite a few, eh? + avail_insts = this_dict `plusLIE` + dfun_arg_dicts `plusLIE` + sc_dicts `plusLIE` + unionManyBags meth_lies + + methods_lie = plusLIEs insts_needed_s in - tcAddErrCtxt bindSigCtxt ( - tcSimplifyAndCheck - inst_tyvars_set' -- Local tyvars - avail_insts - (sc_dicts `unionBags` - unionManyBags insts_needed_s) -- Need to get defns for all these - ) `thenTc` \ (const_lie, super_binds) -> + -- Ditto method bindings + tcAddErrCtxt methodCtxt ( + tcSimplifyAndCheck + (ptext SLIT("instance declaration context")) + inst_tyvars_set -- Local tyvars + avail_insts + 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 superClassSigCtxt ( - tcSimplifyAndCheck - inst_tyvars_set' -- Local tyvars + -- 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 + ) `thenTc` \ _ -> + -- Ignore the result; we're only doing -- this to make sure it can be done. - -- Now process any SPECIALIZE pragmas for the methods - let - spec_sigs = [ s | s@(SpecSig _ _ _ _) <- uprags ] - in - tcPragmaSigs spec_sigs `thenTc` \ (_, spec_binds, spec_lie) -> + -- 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 + (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, lie_binds2) -> + -- Create the result bindings let - dict_bind = VarMonoBind this_dict_id (Dictionary sc_dict_ids meth_ids) - method_binds = andMonoBinds method_binds_s + 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) [(unUsgTy . idType) this_dict_id]) + (HsLit (HsString msg)) + + | otherwise -- The common case + = mkHsConApp 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.mkDataConWrapId code rather + -- than needing to be repeated here. + + where + msg = _PK_ ("Compiler error: bad dictionary " ++ showSDoc (ppr clas)) + + dict_bind = VarMonoBind this_dict_id dict_rhs + method_binds = andMonoBindList method_binds_s main_bind - = MonoBind ( - AbsBinds - inst_tyvars' + = AbsBinds + zonked_inst_tyvars dfun_arg_dicts_ids - [(inst_tyvars', RealId dfun_id, this_dict_id)] - (super_binds `AndMonoBinds` + [(inst_tyvars', dfun_id, this_dict_id)] + emptyNameSet -- No inlines (yet) + (lie_binds1 `AndMonoBinds` + lie_binds2 `AndMonoBinds` method_binds `AndMonoBinds` - dict_bind)) - [] recursive -- Recursive to play safe - in - returnTc (const_lie `plusLIE` spec_lie, - main_bind `ThenBinds` spec_binds) -\end{code} - -The next function looks for a method binding; if there isn't one it -manufactures one that just calls the global default method. - -See the notes under default decls in TcClassDcl.lhs. - -\begin{code} -getDefmRhs :: Class -> Int -> RenamedHsExpr -getDefmRhs clas idx = HsVar (getName (classDefaultMethodId clas idx)) -\end{code} - - -%************************************************************************ -%* * -\subsection{Processing each method} -%* * -%************************************************************************ - -\begin{code} -tcMethodBind - :: (Int -> RenamedHsExpr) -- Function mapping a tag to default RHS - -> TcType s -- Instance type - -> RenamedMonoBinds -- Method binding - -> (Id, Int) -- Selector ID (and its 0-indexed tag) - -- for which binding is wanted - -> TcM s (TcMonoBinds s, LIE s, (LIE s, TcIdOcc s)) - -tcMethodBind deflt_fn inst_ty meth_binds (sel_id, idx) - = newMethod origin (RealId sel_id) [inst_ty] `thenNF_Tc` \ meth@(_, TcId meth_id) -> - tcInstSigTcType (idType meth_id) `thenNF_Tc` \ (tyvars', rho_ty') -> - let - meth_name = getName meth_id - default_bind = PatMonoBind (VarPatIn meth_name) - (GRHSsAndBindsIn [OtherwiseGRHS (deflt_fn idx) noSrcLoc] EmptyBinds) - noSrcLoc - - (op_name, op_bind) = case go (getOccName sel_id) meth_binds of - Just stuff -> stuff - Nothing -> (meth_name, default_bind) - - (theta', tau') = splitRhoTy rho_ty' - sig_info = TySigInfo op_name meth_id tyvars' theta' tau' noSrcLoc + dict_bind) in - tcBindWithSigs [op_name] op_bind [sig_info] - nonRecursive (\_ -> NoPragmaInfo) `thenTc` \ (binds, insts, _) -> - - returnTc (binds, insts, meth) - where - origin = InstanceDeclOrigin -- Poor - - go occ EmptyMonoBinds = Nothing - go occ (AndMonoBinds b1 b2) = go occ b1 `seqMaybe` go occ b2 - - go occ b@(FunMonoBind op_name _ _ locn) | nameOccName op_name == occ = Just (op_name, b) - | otherwise = Nothing - go occ b@(PatMonoBind (VarPatIn op_name) _ locn) | nameOccName op_name == occ = Just (op_name, b) - | otherwise = Nothing - go occ other = panic "Urk! Bad instance method binding" + 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 maybeAppDataTyCon 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 PprDebug simpl_theta, - if null simpl_theta then empty else ptext SLIT("=>"), - ppr PprDebug clas, - pprParendGenType PprDebug inst_ty], - hsep [ptext SLIT(" derived from:"), - if null unspec_theta then empty else ppr PprDebug unspec_theta, - if null unspec_theta then empty else ptext SLIT("=>"), - ppr PprDebug clas, - pprParendGenType PprDebug 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 (maybeAppDataTyCon inst_ty) of - Just (inst_tc,_,_) -> tycon == inst_tc - Nothing -> False - - match_fun inst_ty = isFunType inst_ty - - -is_plain_instance inst_ty - = case (maybeAppDataTyCon 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@ @@ -655,130 +685,144 @@ 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 dfun_name clas inst_tau - -- TYCON CHECK - | not (maybeToBool inst_tycon_maybe) || isSynTyCon inst_tycon - = failTc (instTypeErr inst_tau) - - -- IMPORTED INSTANCES ARE OK (but see tcInstDecl1) - | not (isLocallyDefined dfun_name) - = returnTc (inst_tycon,arg_tys) - - -- TYVARS CHECK - | not (all isTyVarTy arg_tys || - opt_GlasgowExts) - = failTc (instTypeErr inst_tau) +scrutiniseInstanceConstraint pred + = getDOptsTc `thenTc` \ dflags -> case () of + () + | dopt Opt_AllowUndecidableInstances dflags + -> returnNF_Tc () + + | Just (clas,tys) <- getClassTys_maybe pred, + all isTyVarTy tys + -> returnNF_Tc () + + | otherwise + -> addErrTc (instConstraintErr pred) + +scrutiniseInstanceHead clas inst_taus + = getDOptsTc `thenTc` \ dflags -> case () of + () + | -- CCALL CHECK + -- A user declaration of a CCallable/CReturnable instance + -- must be for a "boxed primitive" type. + (clas `hasKey` cCallableClassKey + && not (ccallable_type dflags first_inst_tau)) + || + (clas `hasKey` 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' - -- Though we can have an explicit instance which is more - -- specific than the derived instance - | clas `elem` (derivedClasses inst_tycon) - && all isTyVarTy arg_tys - = failTc (derivingWhenInstanceExistsErr clas inst_tycon) - - | -- CCALL CHECK - -- A user declaration of a CCallable/CReturnable instance - -- must be for a "boxed primitive" type. - (uniqueOf clas == cCallableClassKey && not (ccallable_type inst_tau)) || - (uniqueOf clas == cReturnableClassKey && not (creturnable_type inst_tau)) - = failTc (nonBoxedPrimCCallErr clas inst_tau) - - | otherwise - = returnTc (inst_tycon,arg_tys) + | 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 + + -- Allow anything for AllowUndecidableInstances + | dopt Opt_AllowUndecidableInstances dflags + -> returnNF_Tc () + + -- If GlasgowExts then check at least one isn't a type variable + | dopt Opt_GlasgowExts dflags + -> 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 (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 + ) + -> 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 + -> returnNF_Tc () where - (possible_tycon, arg_tys) = splitAppTys inst_tau - inst_tycon_maybe = getTyCon_maybe possible_tycon - inst_tycon = expectJust "tcInstDecls1:inst_tycon" inst_tycon_maybe + (first_inst_tau : _) = inst_taus + + -- 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 + Just (alg_tycon, _, _) = alg_tycon_app_maybe + + ccallable_type dflags ty = isFFIArgumentTy dflags False {- Not safe call -} ty + creturnable_type ty = isFFIResultTy ty +\end{code} --- These conditions come directly from what the DsCCall is capable of. --- Totally grotesque. Green card should solve this. -ccallable_type ty = isPrimType ty || -- Allow CCallable Int# etc - maybeToBool (maybeBoxedPrimType ty) || -- Ditto Int etc - ty `eqTy` stringTy || - byte_arr_thing - where - byte_arr_thing = case maybeAppDataTyCon ty of - Just (tycon, ty_args, [data_con]) | isDataTyCon tycon -> - length data_con_arg_tys == 2 && - maybeToBool maybe_arg2_tycon && - (arg2_tycon == byteArrayPrimTyCon || - arg2_tycon == mutableByteArrayPrimTyCon) - where - data_con_arg_tys = dataConArgTys data_con ty_args - (data_con_arg_ty1 : data_con_arg_ty2 : _) = data_con_arg_tys - maybe_arg2_tycon = maybeAppTyCon data_con_arg_ty2 - Just (arg2_tycon,_) = maybe_arg2_tycon - - other -> False - -creturnable_type ty = maybeToBool (maybeBoxedPrimType ty) || - -- Or, a data type with a single nullary constructor - case (maybeAppDataTyCon ty) of - Just (tycon, tys_applied, [data_con]) - -> isNullaryDataCon data_con - other -> False -\end{code} +%************************************************************************ +%* * +\subsection{Error messages} +%* * +%************************************************************************ \begin{code} - -instTypeErr ty sty - = case ty of - SynTy tc _ _ -> hcat [ptext SLIT("The type synonym `"), ppr sty tc, rest_of_msg] - TyVarTy tv -> hcat [ptext SLIT("The type variable `"), ppr sty tv, rest_of_msg] - other -> hcat [ptext SLIT("The type `"), ppr sty ty, rest_of_msg] +tcAddDeclCtxt decl thing_inside + = tcAddSrcLoc loc $ + tcAddErrCtxt ctxt $ + thing_inside where - rest_of_msg = ptext SLIT("' cannot be used as an instance type.") - -instBndrErr bndr clas sty - = hsep [ptext SLIT("Class"), ppr sty clas, ptext SLIT("does not have a method"), ppr sty bndr] + (name, loc, thing) + = case decl of + (ClassDecl _ name _ _ _ _ _ _ loc) -> (name, loc, "class") + (TySynonym name _ _ loc) -> (name, loc, "type synonym") + (TyData NewType _ name _ _ _ _ _ loc _ _) -> (name, loc, "newtype") + (TyData DataType _ name _ _ _ _ _ loc _ _) -> (name, loc, "data type") + + ctxt = hsep [ptext SLIT("In the"), text thing, + ptext SLIT("declaration for"), quotes (ppr name)] +\end{code} -derivingWhenInstanceExistsErr clas tycon sty +\begin{code} +instConstraintErr pred + = hang (ptext SLIT("Illegal constraint") <+> + quotes (pprPred pred) <+> + ptext SLIT("in instance context")) + 4 (ptext SLIT("(Instance contexts must constrain only type variables)")) + +badGenericInstanceType binds + = vcat [ptext SLIT("Illegal type pattern in the generic bindings"), + nest 4 (ppr binds)] + +missingGenericInstances missing + = ptext SLIT("Missing type patterns for") <+> pprQuotedList missing + + + +dupGenericInsts inst_infos + = vcat [ptext SLIT("More than one type pattern for a single generic type constructor:"), + nest 4 (vcat (map (ppr . simpleInstInfoTy) inst_infos)), + ptext SLIT("All the type patterns for a generic type constructor must be identical") + ] + +instTypeErr clas tys msg + = sep [ptext SLIT("Illegal instance declaration for") <+> quotes (pprConstraint clas tys), + nest 4 (parens msg) + ] + +derivingWhenInstanceExistsErr clas tycon = hang (hsep [ptext SLIT("Deriving class"), - ppr sty clas, - ptext SLIT("type"), ppr sty tycon]) + quotes (ppr clas), + ptext SLIT("type"), quotes (ppr tycon)]) 4 (ptext SLIT("when an explicit instance exists")) -derivingWhenInstanceImportedErr inst_mod clas tycon sty - = hang (hsep [ptext SLIT("Deriving class"), - ppr sty clas, - ptext SLIT("type"), ppr sty tycon]) - 4 (hsep [ptext SLIT("when an instance declared in module"), - pp_mod, ptext SLIT("has been imported")]) - where - pp_mod = hsep [ptext SLIT("module"), ptext inst_mod] - -nonBoxedPrimCCallErr clas inst_ty sty +nonBoxedPrimCCallErr clas inst_ty = hang (ptext SLIT("Unacceptable instance type for ccall-ish class")) - 4 (hsep [ ptext SLIT("class"), ppr sty clas, ptext SLIT("type"), - ppr sty inst_ty]) - -omitDefaultMethodWarn clas_op clas_name inst_ty sty - = hsep [ptext SLIT("Warning: Omitted default method for"), - ppr sty clas_op, ptext SLIT("in instance"), - text clas_name, pprParendGenType sty inst_ty] - -instMethodNotInClassErr occ clas sty - = hang (ptext SLIT("Instance mentions a method not in the class")) - 4 (hsep [ptext SLIT("class"), ppr sty clas, ptext SLIT("method"), - ppr sty occ]) - -patMonoBindsCtxt pbind sty - = hang (ptext SLIT("In a pattern binding:")) - 4 (ppr sty pbind) - -methodSigCtxt name ty sty - = hang (hsep [ptext SLIT("When matching the definition of class method"), - ppr sty name, ptext SLIT("to its signature :") ]) - 4 (ppr sty ty) - -bindSigCtxt sty - = ptext SLIT("When checking methods of an instance declaration") - -superClassSigCtxt sty - = ptext SLIT("When checking superclass constraints of an instance declaration") + 4 (hsep [ ptext SLIT("class"), ppr clas, ptext SLIT("type"), + ppr inst_ty]) +methodCtxt = ptext SLIT("When checking the methods of an instance declaration") +superClassCtxt = ptext SLIT("When checking the superclasses of an instance declaration") \end{code}