X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcDeriv.lhs;h=80dbea987d3ea2c49c3ff510babda96ffc25c1c5;hb=d8e9ec6f40f40d3d70273d38dfcddb80e58e1a76;hp=5d7741970847922b51280f901e3bbe123d80978d;hpb=0a7b8d872ebf93a1bfc8f87a8a60cce0097ecfc2;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcDeriv.lhs b/ghc/compiler/typecheck/TcDeriv.lhs index 5d77419..80dbea9 100644 --- a/ghc/compiler/typecheck/TcDeriv.lhs +++ b/ghc/compiler/typecheck/TcDeriv.lhs @@ -14,25 +14,25 @@ import HsSyn ( HsBinds(..), MonoBinds(..), TyClDecl(..), collectLocatedMonoBinders ) import RdrHsSyn ( RdrNameMonoBinds ) import RnHsSyn ( RenamedHsBinds, RenamedMonoBinds, RenamedTyClDecl, RenamedHsPred ) -import CmdLineOpts ( DynFlag(..), DynFlags ) +import CmdLineOpts ( DynFlag(..) ) import TcMonad import TcEnv ( tcSetInstEnv, newDFunName, InstInfo(..), pprInstInfo, - tcLookupClass, tcLookupTyCon, tcExtendTyVarEnv + tcLookupTyCon, tcExtendTyVarEnv ) import TcGenDeriv -- Deriv stuff import InstEnv ( InstEnv, simpleDFunClassTyCon, extendInstEnv ) import TcMonoType ( tcHsPred ) -import TcSimplify ( tcSimplifyThetas ) +import TcSimplify ( tcSimplifyDeriv ) import RnBinds ( rnMethodBinds, rnTopMonoBinds ) import RnEnv ( bindLocatedLocalsRn ) import RnMonad ( renameDerivedCode, thenRn, mapRn, returnRn ) -import HscTypes ( DFunId, PersistentRenamerState ) +import HscTypes ( DFunId, PersistentRenamerState, FixityEnv ) -import BasicTypes ( Fixity, NewOrData(..) ) +import BasicTypes ( NewOrData(..) ) import Class ( className, classKey, classTyVars, Class ) -import ErrUtils ( dumpIfSet_dyn, Message ) +import ErrUtils ( dumpIfSet_dyn ) import MkId ( mkDictFunId ) import DataCon ( dataConRepArgTys, isNullaryDataCon, isExistentialDataCon ) import PrelInfo ( needsDataDeclCtxtClassKeys ) @@ -43,7 +43,7 @@ import RdrName ( RdrName ) import TyCon ( tyConTyVars, tyConDataCons, tyConArity, newTyConRep, tyConTheta, maybeTyConSingleCon, isDataTyCon, - isEnumerationTyCon, TyCon + isEnumerationTyCon, isRecursiveTyCon, TyCon ) import TcType ( TcType, ThetaType, mkTyVarTys, mkTyConApp, getClassPredTys_maybe, isUnLiftedType, mkClassPred, tyVarsOfTypes, tcSplitFunTys, @@ -51,12 +51,10 @@ import TcType ( TcType, ThetaType, mkTyVarTys, mkTyConApp, getClassPredTys_mayb import Var ( TyVar, tyVarKind ) import VarSet ( mkVarSet, subVarSet ) import PrelNames -import Util ( zipWithEqual, sortLt ) +import Util ( zipWithEqual, sortLt, notNull ) import ListSetOps ( removeDups, assoc ) import Outputable import Maybe ( isJust ) -import List ( nub ) -import FastString ( FastString ) \end{code} %************************************************************************ @@ -148,6 +146,9 @@ type DerivEqn = (Name, Class, TyCon, [TyVar], DerivRhs) -- The Name is the name for the DFun we'll build -- The tyvars bind all the variables in the RHS +pprDerivEqn (n,c,tc,tvs,rhs) + = parens (hsep [ppr n, ppr c, ppr tc, ppr tvs] <+> equals <+> ppr rhs) + type DerivRhs = ThetaType type DerivSoln = DerivRhs \end{code} @@ -176,6 +177,12 @@ context to the instance decl. The "offending classes" are Read, Enum? +FURTHER NOTE ADDED March 2002. In fact, Haskell98 now requires that +pattern matching against a constructor from a data type with a context +gives rise to the constraints for that context -- or at least the thinned +version. So now all classes are "offending". + + %************************************************************************ %* * @@ -187,25 +194,30 @@ context to the instance decl. The "offending classes" are tcDeriving :: PersistentRenamerState -> Module -- name of module under scrutiny -> InstEnv -- What we already know about instances - -> (Name -> Maybe Fixity) -- used in deriving Show and Read + -> FixityEnv -- used in deriving Show and Read -> [RenamedTyClDecl] -- All type constructors -> TcM ([InstInfo], -- The generated "instance decls". RenamedHsBinds) -- Extra generated bindings tcDeriving prs mod inst_env get_fixity tycl_decls = recoverTc (returnTc ([], EmptyBinds)) $ + getDOptsTc `thenNF_Tc` \ dflags -> -- Fish the "deriving"-related information out of the TcEnv -- and make the necessary "equations". - makeDerivEqns tycl_decls `thenTc` \ (ordinary_eqns, inst_info2) -> - - deriveOrdinaryStuff mod prs inst_env get_fixity - ordinary_eqns `thenTc` \ (inst_info1, binds) -> + makeDerivEqns tycl_decls `thenTc` \ (ordinary_eqns, newtype_inst_info) -> let - inst_info = inst_info2 ++ inst_info1 -- info2 usually empty + -- Add the newtype-derived instances to the inst env + -- before tacking the "ordinary" ones + inst_env1 = extend_inst_env dflags inst_env + (map iDFunId newtype_inst_info) + in + deriveOrdinaryStuff mod prs inst_env1 get_fixity + ordinary_eqns `thenTc` \ (ordinary_inst_info, binds) -> + let + inst_info = newtype_inst_info ++ ordinary_inst_info in - getDOptsTc `thenNF_Tc` \ dflags -> ioToTc (dumpIfSet_dyn dflags Opt_D_dump_deriv "Derived instances" (ddump_deriving inst_info binds)) `thenTc_` @@ -214,8 +226,11 @@ tcDeriving prs mod inst_env get_fixity tycl_decls where ddump_deriving :: [InstInfo] -> RenamedHsBinds -> SDoc ddump_deriving inst_infos extra_binds - = vcat (map pprInstInfo inst_infos) $$ ppr extra_binds + = vcat (map ppr_info inst_infos) $$ ppr extra_binds + ppr_info inst_info = pprInstInfo inst_info $$ + nest 4 (ppr (iBinds inst_info)) + -- pprInstInfo doesn't print much: only the type ----------------------------------------- deriveOrdinaryStuff mod prs inst_env_in get_fixity [] -- Short cut @@ -313,7 +328,7 @@ makeDerivEqns tycl_decls mk_eqn (new_or_data, tycon_name, pred) = tcLookupTyCon tycon_name `thenNF_Tc` \ tycon -> tcAddSrcLoc (getSrcLoc tycon) $ - tcAddErrCtxt (derivCtxt tycon) $ + tcAddErrCtxt (derivCtxt Nothing tycon) $ tcExtendTyVarEnv (tyConTyVars tycon) $ -- Deriving preds may (now) mention -- the type variables for the type constructor tcHsPred pred `thenTc` \ pred' -> @@ -341,12 +356,12 @@ makeDerivEqns tycl_decls not (isUnLiftedType arg_ty) -- No constraints for unlifted types? ] - -- "extra_constraints": see notes above about contexts on data decls - extra_constraints | offensive_class = tyConTheta tycon - | otherwise = [] - - offensive_class = classKey clas `elem` needsDataDeclCtxtClassKeys + extra_constraints = tyConTheta tycon + + -- | offensive_class = tyConTheta tycon + -- | otherwise = [] + -- offensive_class = classKey clas `elem` needsDataDeclCtxtClassKeys mk_eqn_help NewType tycon clas tys @@ -411,6 +426,10 @@ makeDerivEqns tycl_decls && n_args_to_keep >= 0 -- Well kinded: -- eg not: newtype T a = T Int deriving( Monad ) && eta_ok -- Eta reduction works + && not (isRecursiveTyCon tycon) -- Does not work for recursive tycons: + -- newtype A = MkA [A] + -- Don't want + -- instance Eq [A] => Eq A !! -- Check that eta reduction is OK -- (a) the dropped-off args are identical @@ -420,15 +439,14 @@ makeDerivEqns tycl_decls && (tyVarsOfTypes args_to_keep `subVarSet` mkVarSet tyvars_to_keep) cant_derive_err = derivingThingErr clas tys tycon tyvars_to_keep - SLIT("too hard for cunning newtype deriving") - + (ptext SLIT("too hard for cunning newtype deriving")) bale_out err = addErrTc err `thenNF_Tc_` returnNF_Tc (Nothing, Nothing) ------------------------------------------------------------------ - chk_out :: Class -> TyCon -> [TcType] -> Maybe FastString + chk_out :: Class -> TyCon -> [TcType] -> Maybe SDoc chk_out clas tycon tys - | not (null tys) = Just non_std_why + | notNull tys = Just non_std_why | not (getUnique clas `elem` derivableClassKeys) = Just non_std_why | clas `hasKey` enumClassKey && not is_enumeration = Just nullary_why | clas `hasKey` boundedClassKey && not is_enumeration_or_single = Just single_nullary_why @@ -442,11 +460,11 @@ makeDerivEqns tycl_decls is_single_con = maybeToBool (maybeTyConSingleCon tycon) is_enumeration_or_single = is_enumeration || is_single_con - single_nullary_why = SLIT("one constructor data type or type with all nullary constructors expected") - nullary_why = SLIT("data type with all nullary constructors expected") - no_cons_why = SLIT("type has no data constructors") - non_std_why = SLIT("not a derivable class") - existential_why = SLIT("it has existentially-quantified constructor(s)") + single_nullary_why = ptext SLIT("one constructor data type or type with all nullary constructors expected") + nullary_why = ptext SLIT("data type with all nullary constructors expected") + no_cons_why = ptext SLIT("type has no data constructors") + non_std_why = ptext SLIT("not a derivable class") + existential_why = ptext SLIT("it has existentially-quantified constructor(s)") new_dfun_name clas tycon -- Just a simple wrapper = newDFunName clas [mkTyConApp tycon []] (getSrcLoc tycon) @@ -481,7 +499,7 @@ solveDerivEqns :: InstEnv -- This bunch is Absolutely minimal... solveDerivEqns inst_env_in orig_eqns - = iterateDeriv initial_solutions + = iterateDeriv 1 initial_solutions where -- The initial solutions for the equations claim that each -- instance has an empty context; this solution is certainly @@ -494,58 +512,52 @@ solveDerivEqns inst_env_in orig_eqns -- compares it with the current one; finishes if they are the -- same, otherwise recurses with the new solutions. -- It fails if any iteration fails - iterateDeriv :: [DerivSoln] ->TcM [DFunId] - iterateDeriv current_solns - = checkNoErrsTc (iterateOnce current_solns) - `thenTc` \ (new_dfuns, new_solns) -> + iterateDeriv :: Int -> [DerivSoln] ->TcM [DFunId] + iterateDeriv n current_solns + | n > 20 -- Looks as if we are in an infinite loop + -- This can happen if we have -fallow-undecidable-instances + -- (See TcSimplify.tcSimplifyDeriv.) + = pprPanic "solveDerivEqns: probable loop" + (vcat (map pprDerivEqn orig_eqns) $$ ppr current_solns) + | otherwise + = getDOptsTc `thenNF_Tc` \ dflags -> + let + dfuns = zipWithEqual "add_solns" mk_deriv_dfun orig_eqns current_solns + inst_env = extend_inst_env dflags inst_env_in dfuns + in + checkNoErrsTc ( + -- Extend the inst info from the explicit instance decls + -- with the current set of solutions, and simplify each RHS + tcSetInstEnv inst_env $ + mapTc gen_soln orig_eqns + ) `thenTc` \ new_solns -> if (current_solns == new_solns) then - returnTc new_dfuns + returnTc dfuns else - iterateDeriv new_solns + iterateDeriv (n+1) new_solns ------------------------------------------------------------------ - iterateOnce current_solns - = -- Extend the inst info from the explicit instance decls - -- with the current set of solutions, giving a - getDOptsTc `thenNF_Tc` \ dflags -> - let (new_dfuns, inst_env) = - add_solns dflags inst_env_in orig_eqns current_solns - in - -- Simplify each RHS - tcSetInstEnv inst_env ( - listTc [ tcAddSrcLoc (getSrcLoc tc) $ - tcAddErrCtxt (derivCtxt tc) $ - tcSimplifyThetas deriv_rhs - | (_, _,tc,_,deriv_rhs) <- orig_eqns ] - ) `thenTc` \ next_solns -> - - -- Canonicalise the solutions, so they compare nicely - let canonicalised_next_solns = [ sortLt (<) next_soln | next_soln <- next_solns ] - in - returnTc (new_dfuns, canonicalised_next_solns) + + gen_soln (_, clas, tc,tyvars,deriv_rhs) + = tcAddSrcLoc (getSrcLoc tc) $ + tcAddErrCtxt (derivCtxt (Just clas) tc) $ + tcSimplifyDeriv tyvars deriv_rhs `thenTc` \ theta -> + returnTc (sortLt (<) theta) -- Canonicalise before returning the soluction \end{code} \begin{code} -add_solns :: DynFlags - -> InstEnv -- The global, non-derived ones - -> [DerivEqn] -> [DerivSoln] - -> ([DFunId], InstEnv) - -- the eqns and solns move "in lockstep"; we have the eqns - -- because we need the LHS info for addClassInstance. - -add_solns dflags inst_env_in eqns solns - = (new_dfuns, inst_env) - where - new_dfuns = zipWithEqual "add_solns" mk_deriv_dfun eqns solns - (inst_env, _) = extendInstEnv dflags inst_env_in new_dfuns +extend_inst_env dflags inst_env new_dfuns + = new_inst_env + where + (new_inst_env, _errs) = extendInstEnv dflags inst_env new_dfuns -- Ignore the errors about duplicate instances. -- We don't want repeated error messages -- They'll appear later, when we do the top-level extendInstEnvs - mk_deriv_dfun (dfun_name, clas, tycon, tyvars, _) theta - = mkDictFunId dfun_name clas tyvars - [mkTyConApp tycon (mkTyVarTys tyvars)] - theta +mk_deriv_dfun (dfun_name, clas, tycon, tyvars, _) theta + = mkDictFunId dfun_name clas tyvars + [mkTyConApp tycon (mkTyVarTys tyvars)] + theta \end{code} %************************************************************************ @@ -614,7 +626,7 @@ the renamer. What a great hack! -- Generate the method bindings for the required instance -- (paired with class name, as we need that when renaming -- the method binds) -gen_bind :: (Name -> Maybe Fixity) -> DFunId -> (Name, RdrNameMonoBinds) +gen_bind :: FixityEnv -> DFunId -> (Name, RdrNameMonoBinds) gen_bind get_fixity dfun = (cls_nm, binds) where @@ -718,13 +730,18 @@ gen_taggery_Names dfuns \begin{code} derivingThingErr clas tys tycon tyvars why = sep [hsep [ptext SLIT("Can't make a derived instance of"), quotes (ppr pred)], - parens (ptext why)] + parens why] where pred = mkClassPred clas (tys ++ [mkTyConApp tycon (mkTyVarTys tyvars)]) malformedPredErr tycon pred = ptext SLIT("Illegal deriving item") <+> ppr pred -derivCtxt tycon - = ptext SLIT("When deriving classes for") <+> quotes (ppr tycon) +derivCtxt :: Maybe Class -> TyCon -> SDoc +derivCtxt maybe_cls tycon + = ptext SLIT("When deriving") <+> cls <+> ptext SLIT("for type") <+> quotes (ppr tycon) + where + cls = case maybe_cls of + Nothing -> ptext SLIT("instances") + Just c -> ptext SLIT("the") <+> quotes (ppr c) <+> ptext SLIT("instance") \end{code}