X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2FcoreSyn%2FCoreLint.lhs;h=be323be8faa25721e970c006189a926930488792;hb=fe108ff1b0d4b52679ba6deddadf5d2fb3fa8f22;hp=73520976c4289e0e1d0bca75fc313b7dd451c300;hpb=83817d01dff687643eee23218435b968ba358a25;p=ghc-hetmet.git diff --git a/ghc/compiler/coreSyn/CoreLint.lhs b/ghc/compiler/coreSyn/CoreLint.lhs index 7352097..be323be 100644 --- a/ghc/compiler/coreSyn/CoreLint.lhs +++ b/ghc/compiler/coreSyn/CoreLint.lhs @@ -1,54 +1,84 @@ % -% (c) The GRASP/AQUA Project, Glasgow University, 1993-1996 +% (c) The GRASP/AQUA Project, Glasgow University, 1993-1998 % \section[CoreLint]{A ``lint'' pass to check for Core correctness} \begin{code} module CoreLint ( lintCoreBindings, - lintUnfolding + lintUnfolding, + showPass, endPass ) where #include "HsVersions.h" -import IO ( hPutStr, stderr ) - -import CmdLineOpts ( opt_D_show_passes, opt_DoCoreLinting ) import CoreSyn - +import CoreFVs ( idFreeVars ) +import CoreUtils ( findDefault, exprOkForSpeculation, coreBindsSize ) +import Unify ( coreRefineTys ) import Bag -import Kind ( hasMoreBoxityInfo, Kind{-instance-} ) -import Literal ( literalType, Literal{-instance-} ) -import Id ( idType, isBottomingId, dataConRepType, isDataCon, isAlgCon, - dataConArgTys, GenId{-instances-}, - emptyIdSet, mkIdSet, - unionIdSets, elementOfIdSet, IdSet, - Id - ) -import Maybes ( catMaybes ) -import Name ( isLocallyDefined, getSrcLoc, Name{-instance NamedThing-}, - NamedThing(..) - ) +import Literal ( literalType ) +import DataCon ( dataConRepType, isVanillaDataCon, dataConTyCon, dataConWorkId ) +import TysWiredIn ( tupleCon ) +import Var ( Var, Id, TyVar, idType, tyVarKind, mustHaveLocalBinding ) +import VarSet +import Name ( getSrcLoc ) import PprCore -import ErrUtils ( doIfSet, ghcExit ) -import PrimOp ( primOpType ) -import PrimRep ( PrimRep(..) ) -import SrcLoc ( SrcLoc ) -import Type ( mkFunTy, splitFunTy_maybe, mkForAllTy, - splitForAllTy_maybe, - isUnpointedType, typeKind, instantiateTy, - splitAlgTyConApp_maybe, Type - ) -import TyCon ( TyCon, isPrimTyCon, isDataTyCon ) -import TyVar ( TyVar, tyVarKind, mkTyVarEnv ) -import ErrUtils ( ErrMsg ) -import Unique ( Unique ) -import Util ( zipEqual ) +import ErrUtils ( dumpIfSet_core, ghcExit, Message, showPass, + mkLocMessage, debugTraceMsg ) +import SrcLoc ( SrcLoc, noSrcLoc, mkSrcSpan ) +import Type ( Type, tyVarsOfType, coreEqType, + splitFunTy_maybe, mkTyVarTys, + splitForAllTy_maybe, splitTyConApp_maybe, + isUnLiftedType, typeKind, mkForAllTy, mkFunTy, + isUnboxedTupleType, isSubKind, + substTyWith, emptyTvSubst, extendTvInScope, + TvSubst, TvSubstEnv, mkTvSubst, setTvSubstEnv, substTy, + extendTvSubst, composeTvSubst, isInScope, + getTvSubstEnv, getTvInScope ) +import TyCon ( isPrimTyCon ) +import BasicTypes ( RecFlag(..), Boxity(..), isNonRec ) +import StaticFlags ( opt_PprStyle_Debug ) +import DynFlags ( DynFlags, DynFlag(..), dopt ) import Outputable -infixr 9 `thenL`, `seqL`, `thenMaybeL` +#ifdef DEBUG +import Util ( notNull ) +#endif + +import Maybe + +\end{code} + +%************************************************************************ +%* * +\subsection{End pass} +%* * +%************************************************************************ + +@showPass@ and @endPass@ don't really belong here, but it makes a convenient +place for them. They print out stuff before and after core passes, +and do Core Lint when necessary. + +\begin{code} +endPass :: DynFlags -> String -> DynFlag -> [CoreBind] -> IO [CoreBind] +endPass dflags pass_name dump_flag binds + = do + -- Report result size if required + -- This has the side effect of forcing the intermediate to be evaluated + debugTraceMsg dflags 2 $ + (text " Result size =" <+> int (coreBindsSize binds)) + + -- Report verbosely, if required + dumpIfSet_core dflags dump_flag pass_name (pprCoreBindings binds) + + -- Type check + lintCoreBindings dflags pass_name binds + + return binds \end{code} + %************************************************************************ %* * \subsection[lintCoreBindings]{@lintCoreBindings@: Top-level interface} @@ -74,37 +104,35 @@ Outstanding issues: -- -- Things are *not* OK if: -- - -- * Unsaturated type app before specialisation has been done; + -- * Unsaturated type app before specialisation has been done; -- - -- * Oversaturated type app after specialisation (eta reduction + -- * Oversaturated type app after specialisation (eta reduction -- may well be happening...); - -- - -- Note: checkTyApp is usually followed by a call to checkSpecTyApp. - -- \begin{code} -lintCoreBindings :: String -> Bool -> [CoreBinding] -> IO () +lintCoreBindings :: DynFlags -> String -> [CoreBind] -> IO () -lintCoreBindings whoDunnit spec_done binds - | not opt_DoCoreLinting +lintCoreBindings dflags whoDunnit binds + | not (dopt Opt_DoCoreLinting dflags) = return () -lintCoreBindings whoDunnit spec_done binds - = case (initL (lint_binds binds) spec_done) of - Nothing -> doIfSet opt_D_show_passes - (hPutStr stderr ("*** Core Linted result of " ++ whoDunnit ++ "\n")) - +lintCoreBindings dflags whoDunnit binds + = case (initL (lint_binds binds)) of + Nothing -> showPass dflags ("Core Linted result of " ++ whoDunnit) Just bad_news -> printDump (display bad_news) >> - ghcExit 1 + ghcExit dflags 1 where - lint_binds [] = returnL () - lint_binds (bind:binds) - = lintCoreBinding bind `thenL` \binders -> - addInScopeVars binders (lint_binds binds) + -- Put all the top-level binders in scope at the start + -- This is because transformation rules can bring something + -- into use 'unexpectedly' + lint_binds binds = addInScopeVars (bindersOfBinds binds) $ + mapM lint_bind binds + + lint_bind (Rec prs) = mapM_ (lintSingleBinding Recursive) prs + lint_bind (NonRec bndr rhs) = lintSingleBinding NonRecursive (bndr,rhs) display bad_news - = vcat [ - text ("*** Core Lint Errors: in result of " ++ whoDunnit ++ " ***"), + = vcat [ text ("*** Core Lint Errors: in result of " ++ whoDunnit ++ " ***"), bad_news, ptext SLIT("*** Offending Program ***"), pprCoreBindings binds, @@ -122,21 +150,15 @@ We use this to check all unfoldings that come in from interfaces (it is very painful to catch errors otherwise): \begin{code} -lintUnfolding :: SrcLoc -> CoreExpr -> Maybe CoreExpr - -lintUnfolding locn expr - = case - (initL (addLoc (ImportedUnfolding locn) (lintCoreExpr expr)) - True{-pretend spec done-}) - of - Nothing -> Just expr - Just msg -> - pprTrace "WARNING: Discarded bad unfolding from interface:\n" - (vcat [msg, - ptext SLIT("*** Bad unfolding ***"), - ppr expr, - ptext SLIT("*** End unfolding ***")]) - Nothing +lintUnfolding :: SrcLoc + -> [Var] -- Treat these as in scope + -> CoreExpr + -> Maybe Message -- Nothing => OK + +lintUnfolding locn vars expr + = initL (addLoc (ImportedUnfolding locn) $ + addInScopeVars vars $ + lintCoreExpr expr) \end{code} %************************************************************************ @@ -148,37 +170,25 @@ lintUnfolding locn expr Check a core binding, returning the list of variables bound. \begin{code} -lintCoreBinding :: CoreBinding -> LintM [Id] - -lintCoreBinding (NonRec binder rhs) - = lintSingleBinding (binder,rhs) `seqL` returnL [binder] - -lintCoreBinding (Rec pairs) - = addInScopeVars binders ( - mapL lintSingleBinding pairs `seqL` returnL binders - ) - where - binders = [b | (b,_) <- pairs] - -lintSingleBinding (binder,rhs) - = addLoc (RhsOf binder) ( - -- Check the rhs - lintCoreExpr rhs - - `thenL` \maybe_ty -> - -- Check match to RHS type - (case maybe_ty of - Nothing -> returnL () - Just ty -> checkTys (idType binder) ty (mkRhsMsg binder ty)) - - `seqL` - -- Check (not isUnpointedType) - checkIfSpecDoneL (not (isUnpointedType (idType binder))) - (mkRhsPrimMsg binder rhs) - +lintSingleBinding rec_flag (binder,rhs) + = addLoc (RhsOf binder) $ + -- Check the rhs + do { ty <- lintCoreExpr rhs + ; lintBinder binder -- Check match to RHS type + ; binder_ty <- applySubst binder_ty + ; checkTys binder_ty ty (mkRhsMsg binder ty) + -- Check (not isUnLiftedType) (also checks for bogus unboxed tuples) + ; checkL (not (isUnLiftedType binder_ty) + || (isNonRec rec_flag && exprOkForSpeculation rhs)) + (mkRhsPrimMsg binder rhs) + -- Check whether binder's specialisations contain any out-of-scope variables + ; mapM_ (checkBndrIdInScope binder) bndr_vars } + -- We should check the unfolding, if any, but this is tricky because -- the unfolding is a SimplifiableCoreExpr. Give up for now. - ) + where + binder_ty = idType binder + bndr_vars = varSetElems (idFreeVars binder) \end{code} %************************************************************************ @@ -188,73 +198,122 @@ lintSingleBinding (binder,rhs) %************************************************************************ \begin{code} -lintCoreExpr :: CoreExpr -> LintM (Maybe Type) -- Nothing if error found +type InType = Type -- Substitution not yet applied +type OutType = Type -- Substitution has been applied to this -lintCoreExpr (Var var) - | isAlgCon var = returnL (Just (idType var)) - -- Micro-hack here... Class decls generate applications of their - -- dictionary constructor, but don't generate a binding for the - -- constructor (since it would never be used). After a single round - -- of simplification, these dictionary constructors have been - -- inlined (from their UnfoldInfo) to CoCons. Just between - -- desugaring and simplfication, though, they appear as naked, unbound - -- variables as the function in an application. - -- The hack here simply doesn't check for out-of-scope-ness for - -- data constructors (at least, in a function position). +lintCoreExpr :: CoreExpr -> LintM OutType +-- The returned type has the substitution from the monad +-- already applied to it: +-- lintCoreExpr e subst = exprType (subst e) - | otherwise = checkInScope var `seqL` returnL (Just (idType var)) +lintCoreExpr (Var var) + = do { checkIdInScope var + ; applySubst (idType var) } -lintCoreExpr (Lit lit) = returnL (Just (literalType lit)) +lintCoreExpr (Lit lit) + = return (literalType lit) lintCoreExpr (Note (Coerce to_ty from_ty) expr) - = lintCoreExpr expr `thenMaybeL` \ expr_ty -> - lintTy to_ty `seqL` - lintTy from_ty `seqL` - checkTys from_ty expr_ty (mkCoerceErr from_ty expr_ty) `seqL` - returnL (Just to_ty) + = do { expr_ty <- lintCoreExpr expr + ; to_ty <- lintTy to_ty + ; from_ty <- lintTy from_ty + ; checkTys from_ty expr_ty (mkCoerceErr from_ty expr_ty) + ; return to_ty } lintCoreExpr (Note other_note expr) = lintCoreExpr expr -lintCoreExpr (Let binds body) - = lintCoreBinding binds `thenL` \binders -> - if (null binders) then - lintCoreExpr body -- Can't add a new source location - else - addLoc (BodyOfLetRec binders) - (addInScopeVars binders (lintCoreExpr body)) - -lintCoreExpr e@(Con con args) - = checkL (isDataCon con) (mkConErrMsg e) `seqL` - lintCoreArgs {-False-} e (dataConRepType con) args - -- Note: we don't check for primitive types in these arguments +lintCoreExpr (Let (NonRec bndr rhs) body) + = do { lintSingleBinding NonRecursive (bndr,rhs) + ; addLoc (BodyOfLetRec [bndr]) + (addInScopeVars [bndr] (lintCoreExpr body)) } -lintCoreExpr e@(Prim op args) - = lintCoreArgs {-True-} e (primOpType op) args - -- Note: we do check for primitive types in these arguments - -lintCoreExpr e@(App fun@(Var v) arg) | isBottomingId v - = lintCoreExpr fun `thenMaybeL` \ ty -> lintCoreArg {-False-} e ty arg - -- Note: we don't check for primitive types in argument to 'error' +lintCoreExpr (Let (Rec pairs) body) + = addInScopeVars bndrs $ + do { mapM (lintSingleBinding Recursive) pairs + ; addLoc (BodyOfLetRec bndrs) (lintCoreExpr body) } + where + bndrs = map fst pairs + +lintCoreExpr e@(App fun (Type ty)) +-- This is like 'let' for types +-- It's needed when dealing with desugarer output for GADTs. Consider +-- data T = forall a. T a (a->Int) Bool +-- f :: T -> ... -> +-- f (T x f True) = +-- f (T y g False) = +-- After desugaring we get +-- f t b = case t of +-- T a (x::a) (f::a->Int) (b:Bool) -> +-- case b of +-- True -> +-- False -> (/\b. let y=x; g=f in ) a +-- And for a reason I now forget, the ...... can mention a; so +-- we want Lint to know that b=a. Ugh. +-- +-- I tried quite hard to make the necessity for this go away, by changing the +-- desugarer, but the fundamental problem is this: +-- +-- T a (x::a) (y::Int) -> let fail::a = ... +-- in (/\b. ...(case ... of +-- True -> x::b +-- False -> fail) +-- ) a +-- Now the inner case look as though it has incompatible branches. + = addLoc (AnExpr e) $ + go fun [ty] + where + go (App fun (Type ty)) tys + = do { go fun (ty:tys) } + go (Lam tv body) (ty:tys) + = do { checkL (isTyVar tv) (mkKindErrMsg tv ty) -- Not quite accurate + ; ty' <- lintTy ty; + ; checkKinds tv ty' + -- Now extend the substitution so we + -- take advantage of it in the body + ; addInScopeVars [tv] $ + extendSubstL tv ty' $ + go body tys } + go fun tys + = do { fun_ty <- lintCoreExpr fun + ; lintCoreArgs fun_ty (map Type tys) } lintCoreExpr e@(App fun arg) - = lintCoreExpr fun `thenMaybeL` \ty -> lintCoreArg {-True-} e ty arg - -- Note: we do check for primitive types in this argument - -lintCoreExpr (Lam (ValBinder var) expr) - = addLoc (LambdaBodyOf var) - (addInScopeVars [var] - (lintCoreExpr expr `thenMaybeL` \ty -> - returnL (Just (mkFunTy (idType var) ty)))) - -lintCoreExpr (Lam (TyBinder tyvar) expr) - = lintCoreExpr expr `thenMaybeL` \ty -> - returnL (Just(mkForAllTy tyvar ty)) - -- ToDo: Should add in-scope type variable at this point - -lintCoreExpr e@(Case scrut alts) - = lintCoreExpr scrut `thenMaybeL` \ty -> - lintCoreAlts alts ty + = do { fun_ty <- lintCoreExpr fun + ; addLoc (AnExpr e) $ + lintCoreArg fun_ty arg } + +lintCoreExpr (Lam var expr) + = addLoc (LambdaBodyOf var) $ + do { body_ty <- addInScopeVars [var] $ + lintCoreExpr expr + ; if isId var then do + { var_ty <- lintId var + ; return (mkFunTy var_ty body_ty) } + else + return (mkForAllTy var body_ty) + } + -- The applySubst is needed to apply the subst to var + +lintCoreExpr e@(Case scrut var alt_ty alts) = + -- Check the scrutinee + do { scrut_ty <- lintCoreExpr scrut + ; alt_ty <- lintTy alt_ty + ; var_ty <- lintTy (idType var) + -- Don't use lintId on var, because unboxed tuple is legitimate + + ; checkTys var_ty scrut_ty (mkScrutMsg var scrut_ty) + + -- If the binder is an unboxed tuple type, don't put it in scope + ; let vars = if (isUnboxedTupleType (idType var)) then [] else [var] + ; addInScopeVars vars $ + do { -- Check the alternatives + checkCaseAlts e scrut_ty alts + ; mapM (lintCoreAlt scrut_ty alt_ty) alts + ; return alt_ty } } + +lintCoreExpr e@(Type ty) + = addErrL (mkStrangeTyMsg e) \end{code} %************************************************************************ @@ -263,68 +322,66 @@ lintCoreExpr e@(Case scrut alts) %* * %************************************************************************ -The boolean argument indicates whether we should flag type -applications to primitive types as being errors. +The basic version of these functions checks that the argument is a +subtype of the required type, as one would expect. \begin{code} -lintCoreArgs :: {-Bool ->-} CoreExpr -> Type -> [CoreArg] -> LintM (Maybe Type) - -lintCoreArgs _ ty [] = returnL (Just ty) -lintCoreArgs e ty (a : args) - = lintCoreArg e ty a `thenMaybeL` \ res -> - lintCoreArgs e res args +lintCoreArgs :: Type -> [CoreArg] -> LintM Type +lintCoreArg :: Type -> CoreArg -> LintM Type +-- First argument has already had substitution applied to it \end{code} -%************************************************************************ -%* * -\subsection[lintCoreArg]{lintCoreArg} -%* * -%************************************************************************ - \begin{code} -lintCoreArg :: {-Bool ->-} CoreExpr -> Type -> CoreArg -> LintM (Maybe Type) - -lintCoreArg e ty (LitArg lit) - = -- Make sure function type matches argument - case (splitFunTy_maybe ty) of - Just (arg,res) | (lit_ty == arg) -> returnL(Just res) - _ -> addErrL (mkAppMsg ty lit_ty e) `seqL` returnL Nothing - where - lit_ty = literalType lit +lintCoreArgs ty [] = return ty +lintCoreArgs ty (a : args) = + do { res <- lintCoreArg ty a + ; lintCoreArgs res args } + +lintCoreArg fun_ty a@(Type arg_ty) = + do { arg_ty <- lintTy arg_ty + ; lintTyApp fun_ty arg_ty } + +lintCoreArg fun_ty arg = + -- Make sure function type matches argument + do { arg_ty <- lintCoreExpr arg + ; let err = mkAppMsg fun_ty arg_ty arg + ; case splitFunTy_maybe fun_ty of + Just (arg,res) -> + do { checkTys arg arg_ty err + ; return res } + _ -> addErrL err } +\end{code} -lintCoreArg e ty (VarArg v) - = -- Make sure variable is bound - checkInScope v `seqL` - -- Make sure function type matches argument - case (splitFunTy_maybe ty) of - Just (arg,res) | (var_ty == arg) -> returnL(Just res) - _ -> addErrL (mkAppMsg ty var_ty e) `seqL` returnL Nothing +\begin{code} +-- Both args have had substitution applied +lintTyApp ty arg_ty + = case splitForAllTy_maybe ty of + Nothing -> addErrL (mkTyAppMsg ty arg_ty) + + Just (tyvar,body) + -> do { checkL (isTyVar tyvar) (mkTyAppMsg ty arg_ty) + ; checkKinds tyvar arg_ty + ; return (substTyWith [tyvar] [arg_ty] body) } + +lintTyApps fun_ty [] = return fun_ty + +lintTyApps fun_ty (arg_ty : arg_tys) = + do { fun_ty' <- lintTyApp fun_ty arg_ty + ; lintTyApps fun_ty' arg_tys } + +checkKinds tyvar arg_ty + -- Arg type might be boxed for a function with an uncommitted + -- tyvar; notably this is used so that we can give + -- error :: forall a:*. String -> a + -- and then apply it to both boxed and unboxed types. + = checkL (argty_kind `isSubKind` tyvar_kind) + (mkKindErrMsg tyvar arg_ty) where - var_ty = idType v - -lintCoreArg e ty a@(TyArg arg_ty) - = lintTy arg_ty `seqL` - - case (splitForAllTy_maybe ty) of - Nothing -> addErrL (mkTyAppMsg SLIT("Illegal") ty arg_ty e) `seqL` returnL Nothing - - Just (tyvar,body) -> - let - tyvar_kind = tyVarKind tyvar - argty_kind = typeKind arg_ty - in - if argty_kind `hasMoreBoxityInfo` tyvar_kind - -- Arg type might be boxed for a function with an uncommitted - -- tyvar; notably this is used so that we can give - -- error :: forall a:*. String -> a - -- and then apply it to both boxed and unboxed types. - then - returnL(Just(instantiateTy (mkTyVarEnv [(tyvar,arg_ty)]) body)) - else - pprTrace "lintCoreArg:kinds:" (hsep [ppr tyvar_kind, ppr argty_kind]) $ - addErrL (mkKindErrMsg tyvar arg_ty e) `seqL` returnL Nothing + tyvar_kind = tyVarKind tyvar + argty_kind = typeKind arg_ty \end{code} + %************************************************************************ %* * \subsection[lintCoreAlts]{lintCoreAlts} @@ -332,83 +389,108 @@ lintCoreArg e ty a@(TyArg arg_ty) %************************************************************************ \begin{code} -lintCoreAlts :: CoreCaseAlts - -> Type -- Type of scrutinee --- -> TyCon -- TyCon pinned on the case - -> LintM (Maybe Type) -- Type of alternatives - -lintCoreAlts whole_alts@(AlgAlts alts deflt) ty --tycon - = -- Check tycon is not a primitive tycon --- addErrIfL (isPrimTyCon tycon) (mkCasePrimMsg tycon) --- `seqL` - -- Check we are scrutinising a proper datatype - -- (ToDo: robustify) --- addErrIfL (not (tyConFamilySize tycon >= 1)) (mkCaseAbstractMsg tycon) --- `seqL` - lintDeflt deflt ty - `thenL` \maybe_deflt_ty -> - mapL (lintAlgAlt ty {-tycon-}) alts - `thenL` \maybe_alt_tys -> - -- Check the result types - case catMaybes (maybe_deflt_ty : maybe_alt_tys) of - [] -> returnL Nothing - - (first_ty:tys) -> mapL check tys `seqL` - returnL (Just first_ty) - where - check ty = checkTys first_ty ty (mkCaseAltMsg whole_alts) - -lintCoreAlts whole_alts@(PrimAlts alts deflt) ty --tycon - = -- Check tycon is a primitive tycon --- addErrIfL (not (isPrimTyCon tycon)) (mkCaseNotPrimMsg tycon) --- `seqL` - mapL (lintPrimAlt ty) alts - `thenL` \maybe_alt_tys -> - lintDeflt deflt ty - `thenL` \maybe_deflt_ty -> - -- Check the result types - case catMaybes (maybe_deflt_ty : maybe_alt_tys) of - [] -> returnL Nothing - - (first_ty:tys) -> mapL check tys `seqL` - returnL (Just first_ty) - where - check ty = checkTys first_ty ty (mkCaseAltMsg whole_alts) - -lintAlgAlt scrut_ty (con,args,rhs) - = (case splitAlgTyConApp_maybe scrut_ty of - Just (tycon, tys_applied, cons) | isDataTyCon tycon -> - let - arg_tys = dataConArgTys con tys_applied - in - checkL (con `elem` cons) (mkAlgAltMsg2 scrut_ty con) `seqL` - checkL (length arg_tys == length args) (mkAlgAltMsg3 con args) - `seqL` - mapL check (zipEqual "lintAlgAlt" arg_tys args) `seqL` - returnL () - - other -> addErrL (mkAlgAltMsg1 scrut_ty) - ) `seqL` - addInScopeVars args ( - lintCoreExpr rhs - ) +checkCaseAlts :: CoreExpr -> OutType -> [CoreAlt] -> LintM () +-- a) Check that the alts are non-empty +-- b1) Check that the DEFAULT comes first, if it exists +-- b2) Check that the others are in increasing order +-- c) Check that there's a default for infinite types +-- NB: Algebraic cases are not necessarily exhaustive, because +-- the simplifer correctly eliminates case that can't +-- possibly match. + +checkCaseAlts e ty [] + = addErrL (mkNullAltsMsg e) + +checkCaseAlts e ty alts = + do { checkL (all non_deflt con_alts) (mkNonDefltMsg e) + ; checkL (increasing_tag con_alts) (mkNonIncreasingAltsMsg e) + ; checkL (isJust maybe_deflt || not is_infinite_ty) + (nonExhaustiveAltsMsg e) } + where + (con_alts, maybe_deflt) = findDefault alts + + -- Check that successive alternatives have increasing tags + increasing_tag (alt1 : rest@( alt2 : _)) = alt1 `ltAlt` alt2 && increasing_tag rest + increasing_tag other = True + + non_deflt (DEFAULT, _, _) = False + non_deflt alt = True + + is_infinite_ty = case splitTyConApp_maybe ty of + Nothing -> False + Just (tycon, tycon_arg_tys) -> isPrimTyCon tycon +\end{code} + +\begin{code} +checkAltExpr :: CoreExpr -> OutType -> LintM () +checkAltExpr expr ann_ty + = do { actual_ty <- lintCoreExpr expr + ; checkTys actual_ty ann_ty (mkCaseAltMsg expr actual_ty ann_ty) } + +lintCoreAlt :: OutType -- Type of scrutinee + -> OutType -- Type of the alternative + -> CoreAlt + -> LintM () + +lintCoreAlt scrut_ty alt_ty alt@(DEFAULT, args, rhs) = + do { checkL (null args) (mkDefaultArgsMsg args) + ; checkAltExpr rhs alt_ty } + +lintCoreAlt scrut_ty alt_ty alt@(LitAlt lit, args, rhs) = + do { checkL (null args) (mkDefaultArgsMsg args) + ; checkTys lit_ty scrut_ty (mkBadPatMsg lit_ty scrut_ty) + ; checkAltExpr rhs alt_ty } where - check (ty, arg) = checkTys ty (idType arg) (mkAlgAltMsg4 ty arg) - - -- elem: yes, the elem-list here can sometimes be long-ish, - -- but as it's use-once, probably not worth doing anything different - -- We give it its own copy, so it isn't overloaded. - elem _ [] = False - elem x (y:ys) = x==y || elem x ys - -lintPrimAlt ty alt@(lit,rhs) - = checkTys (literalType lit) ty (mkPrimAltMsg alt) `seqL` - lintCoreExpr rhs - -lintDeflt NoDefault _ = returnL Nothing -lintDeflt deflt@(BindDefault binder rhs) ty - = checkTys (idType binder) ty (mkDefltMsg deflt) `seqL` - addInScopeVars [binder] (lintCoreExpr rhs) + lit_ty = literalType lit + +lintCoreAlt scrut_ty alt_ty alt@(DataAlt con, args, rhs) + | Just (tycon, tycon_arg_tys) <- splitTyConApp_maybe scrut_ty, + tycon == dataConTyCon con + = addLoc (CaseAlt alt) $ + addInScopeVars args $ -- Put the args in scope before lintBinder, + -- because the Ids mention the type variables + if isVanillaDataCon con then + do { addLoc (CasePat alt) $ do + { mapM lintBinder args + -- FIX! Add check that all args are Ids. + -- Check the pattern + -- Scrutinee type must be a tycon applicn; checked by caller + -- This code is remarkably compact considering what it does! + -- NB: args must be in scope here so that the lintCoreArgs line works. + -- NB: relies on existential type args coming *after* ordinary type args + + ; con_type <- lintTyApps (dataConRepType con) tycon_arg_tys + -- Can just map Var as we know that this is a vanilla datacon + ; con_result_ty <- lintCoreArgs con_type (map Var args) + ; checkTys con_result_ty scrut_ty (mkBadPatMsg con_result_ty scrut_ty) + } + -- Check the RHS + ; checkAltExpr rhs alt_ty } + + else -- GADT + do { let (tvs,ids) = span isTyVar args + ; subst <- getTvSubst + ; let in_scope = getTvInScope subst + subst_env = getTvSubstEnv subst + ; case coreRefineTys in_scope con tvs scrut_ty of { + Nothing -> return () ; -- Alternative is dead code + Just (refine, _) -> updateTvSubstEnv (composeTvSubst in_scope refine subst_env) $ + do { addLoc (CasePat alt) $ do + { tvs' <- mapM lintTy (mkTyVarTys tvs) + ; con_type <- lintTyApps (dataConRepType con) tvs' + ; mapM lintBinder ids -- Lint Ids in the refined world + ; lintCoreArgs con_type (map Var ids) + } + + ; let refined_alt_ty = substTy (mkTvSubst in_scope refine) alt_ty + -- alt_ty is already an OutType, so don't re-apply + -- the current substitution. But we must apply the + -- refinement so that the check in checkAltExpr is ok + ; checkAltExpr rhs refined_alt_ty + } } } + + | otherwise -- Scrut-ty is wrong shape + = addErrL (mkBadAltMsg scrut_ty alt) \end{code} %************************************************************************ @@ -418,9 +500,25 @@ lintDeflt deflt@(BindDefault binder rhs) ty %************************************************************************ \begin{code} -lintTy :: Type -> LintM () -lintTy ty = returnL () --- ToDo: Check that ty is well-kinded and has no unbound tyvars +lintBinder :: Var -> LintM () +lintBinder var | isId var = lintId var >> return () + | otherwise = return () + +lintId :: Var -> LintM OutType +-- ToDo: lint its rules +lintId id + = do { checkL (not (isUnboxedTupleType (idType id))) + (mkUnboxedTupleMsg id) + -- No variable can be bound to an unboxed tuple. + ; lintTy (idType id) } + +lintTy :: InType -> LintM OutType +-- Check the type, and apply the substitution to it +-- ToDo: check the kind structure of the type +lintTy ty + = do { ty' <- applySubst ty + ; mapM_ checkIdInScope (varSetElems (tyVarsOfType ty')) + ; return ty' } \end{code} @@ -431,228 +529,232 @@ lintTy ty = returnL () %************************************************************************ \begin{code} -type LintM a = Bool -- True <=> specialisation has been done - -> [LintLocInfo] -- Locations - -> IdSet -- Local vars in scope - -> Bag ErrMsg -- Error messages so far - -> (a, Bag ErrMsg) -- Result and error messages (if any) +newtype LintM a = + LintM { unLintM :: + [LintLocInfo] -> -- Locations + TvSubst -> -- Current type substitution; we also use this + -- to keep track of all the variables in scope, + -- both Ids and TyVars + Bag Message -> -- Error messages so far + (Maybe a, Bag Message) } -- Result and error messages (if any) + +instance Monad LintM where + return x = LintM (\ loc subst errs -> (Just x, errs)) + fail err = LintM (\ loc subst errs -> (Nothing, addErr subst errs (text err) loc)) + m >>= k = LintM (\ loc subst errs -> + let (res, errs') = unLintM m loc subst errs in + case res of + Just r -> unLintM (k r) loc subst errs' + Nothing -> (Nothing, errs')) data LintLocInfo = RhsOf Id -- The variable bound | LambdaBodyOf Id -- The lambda-binder | BodyOfLetRec [Id] -- One of the binders + | CaseAlt CoreAlt -- Case alternative + | CasePat CoreAlt -- *Pattern* of the case alternative + | AnExpr CoreExpr -- Some expression | ImportedUnfolding SrcLoc -- Some imported unfolding (ToDo: say which) +\end{code} + + +\begin{code} +initL :: LintM a -> Maybe Message {- errors -} +initL m + = case unLintM m [] emptyTvSubst emptyBag of + (_, errs) | isEmptyBag errs -> Nothing + | otherwise -> Just (vcat (punctuate (text "") (bagToList errs))) +\end{code} + +\begin{code} +checkL :: Bool -> Message -> LintM () +checkL True msg = return () +checkL False msg = addErrL msg + +addErrL :: Message -> LintM a +addErrL msg = LintM (\ loc subst errs -> (Nothing, addErr subst errs msg loc)) + +addErr :: TvSubst -> Bag Message -> Message -> [LintLocInfo] -> Bag Message +addErr subst errs_so_far msg locs + = ASSERT( notNull locs ) + errs_so_far `snocBag` mk_msg msg + where + (loc, cxt1) = dumpLoc (head locs) + cxts = [snd (dumpLoc loc) | loc <- locs] + context | opt_PprStyle_Debug = vcat (reverse cxts) $$ cxt1 $$ + ptext SLIT("Substitution:") <+> ppr subst + | otherwise = cxt1 + + mk_msg msg = mkLocMessage (mkSrcSpan loc loc) (context $$ msg) -instance Outputable LintLocInfo where - ppr (RhsOf v) - = ppr (getSrcLoc v) <> colon <+> - brackets (ptext SLIT("RHS of") <+> pp_binders [v]) +addLoc :: LintLocInfo -> LintM a -> LintM a +addLoc extra_loc m = + LintM (\ loc subst errs -> unLintM m (extra_loc:loc) subst errs) - ppr (LambdaBodyOf b) - = ppr (getSrcLoc b) <> colon <+> - brackets (ptext SLIT("in body of lambda with binder") <+> pp_binder b) +addInScopeVars :: [Var] -> LintM a -> LintM a +addInScopeVars vars m = + LintM (\ loc subst errs -> unLintM m loc (extendTvInScope subst vars) errs) - ppr (BodyOfLetRec bs) - = ppr (getSrcLoc (head bs)) <> colon <+> - brackets (ptext SLIT("in body of letrec with binders") <+> pp_binders bs) +updateTvSubstEnv :: TvSubstEnv -> LintM a -> LintM a +updateTvSubstEnv substenv m = + LintM (\ loc subst errs -> unLintM m loc (setTvSubstEnv subst substenv) errs) - ppr (ImportedUnfolding locn) - = ppr locn <> colon <+> - brackets (ptext SLIT("in an imported unfolding")) +getTvSubst :: LintM TvSubst +getTvSubst = LintM (\ loc subst errs -> (Just subst, errs)) -pp_binders :: [Id] -> SDoc -pp_binders bs = sep (punctuate comma (map pp_binder bs)) +applySubst :: Type -> LintM Type +applySubst ty = do { subst <- getTvSubst; return (substTy subst ty) } -pp_binder :: Id -> SDoc -pp_binder b = hsep [ppr b, text "::", ppr (idType b)] +extendSubstL :: TyVar -> Type -> LintM a -> LintM a +extendSubstL tv ty m + = LintM (\ loc subst errs -> unLintM m loc (extendTvSubst subst tv ty) errs) \end{code} \begin{code} -initL :: LintM a -> Bool -> Maybe ErrMsg -initL m spec_done - = case (m spec_done [] emptyIdSet emptyBag) of { (_, errs) -> - if isEmptyBag errs then - Nothing - else - Just (vcat (bagToList errs)) - } - -returnL :: a -> LintM a -returnL r spec loc scope errs = (r, errs) - -thenL :: LintM a -> (a -> LintM b) -> LintM b -thenL m k spec loc scope errs - = case m spec loc scope errs of - (r, errs') -> k r spec loc scope errs' - -seqL :: LintM a -> LintM b -> LintM b -seqL m k spec loc scope errs - = case m spec loc scope errs of - (_, errs') -> k spec loc scope errs' - -thenMaybeL :: LintM (Maybe a) -> (a -> LintM (Maybe b)) -> LintM (Maybe b) -thenMaybeL m k spec loc scope errs - = case m spec loc scope errs of - (Nothing, errs2) -> (Nothing, errs2) - (Just r, errs2) -> k r spec loc scope errs2 - -mapL :: (a -> LintM b) -> [a] -> LintM [b] -mapL f [] = returnL [] -mapL f (x:xs) - = f x `thenL` \ r -> - mapL f xs `thenL` \ rs -> - returnL (r:rs) - -mapMaybeL :: (a -> LintM (Maybe b)) -> [a] -> LintM (Maybe [b]) - -- Returns Nothing if anything fails -mapMaybeL f [] = returnL (Just []) -mapMaybeL f (x:xs) - = f x `thenMaybeL` \ r -> - mapMaybeL f xs `thenMaybeL` \ rs -> - returnL (Just (r:rs)) +checkIdInScope :: Var -> LintM () +checkIdInScope id + = do { checkL (not (id == oneTupleDataConId)) + (ptext SLIT("Illegal one-tuple")) + ; checkInScope (ptext SLIT("is out of scope")) id } + +oneTupleDataConId :: Id -- Should not happen +oneTupleDataConId = dataConWorkId (tupleCon Boxed 1) + +checkBndrIdInScope :: Var -> Var -> LintM () +checkBndrIdInScope binder id + = checkInScope msg id + where + msg = ptext SLIT("is out of scope inside info for") <+> + ppr binder + +checkInScope :: SDoc -> Var -> LintM () +checkInScope loc_msg var = + do { subst <- getTvSubst + ; checkL (not (mustHaveLocalBinding var) || (var `isInScope` subst)) + (hsep [ppr var, loc_msg]) } + +checkTys :: Type -> Type -> Message -> LintM () +-- check ty2 is subtype of ty1 (ie, has same structure but usage +-- annotations need only be consistent, not equal) +-- Assumes ty1,ty2 are have alrady had the substitution applied +checkTys ty1 ty2 msg = checkL (ty1 `coreEqType` ty2) msg \end{code} +%************************************************************************ +%* * +\subsection{Error messages} +%* * +%************************************************************************ + \begin{code} -checkL :: Bool -> ErrMsg -> LintM () -checkL True msg spec loc scope errs = ((), errs) -checkL False msg spec loc scope errs = ((), addErr errs msg loc) +dumpLoc (RhsOf v) + = (getSrcLoc v, brackets (ptext SLIT("RHS of") <+> pp_binders [v])) -checkIfSpecDoneL :: Bool -> ErrMsg -> LintM () -checkIfSpecDoneL True msg spec loc scope errs = ((), errs) -checkIfSpecDoneL False msg True loc scope errs = ((), addErr errs msg loc) -checkIfSpecDoneL False msg False loc scope errs = ((), errs) +dumpLoc (LambdaBodyOf b) + = (getSrcLoc b, brackets (ptext SLIT("in body of lambda with binder") <+> pp_binder b)) -addErrL :: ErrMsg -> LintM () -addErrL msg spec loc scope errs = ((), addErr errs msg loc) +dumpLoc (BodyOfLetRec []) + = (noSrcLoc, brackets (ptext SLIT("In body of a letrec with no binders"))) -addErr :: Bag ErrMsg -> ErrMsg -> [LintLocInfo] -> Bag ErrMsg +dumpLoc (BodyOfLetRec bs@(_:_)) + = ( getSrcLoc (head bs), brackets (ptext SLIT("in body of letrec with binders") <+> pp_binders bs)) -addErr errs_so_far msg locs - = ASSERT (not (null locs)) - errs_so_far `snocBag` (hang (ppr (head locs)) 4 msg) +dumpLoc (AnExpr e) + = (noSrcLoc, text "In the expression:" <+> ppr e) -addLoc :: LintLocInfo -> LintM a -> LintM a -addLoc extra_loc m spec loc scope errs - = m spec (extra_loc:loc) scope errs - -addInScopeVars :: [Id] -> LintM a -> LintM a -addInScopeVars ids m spec loc scope errs - = -- We check if these "new" ids are already - -- in scope, i.e., we have *shadowing* going on. - -- For now, it's just a "trace"; we may make - -- a real error out of it... - let - new_set = mkIdSet ids - --- shadowed = scope `intersectIdSets` new_set - in --- After adding -fliberate-case, Simon decided he likes shadowed --- names after all. WDP 94/07 --- (if isEmptyUniqSet shadowed --- then id --- else pprTrace "Shadowed vars:" (ppr (uniqSetToList shadowed))) ( - m spec loc (scope `unionIdSets` new_set) errs --- ) -\end{code} +dumpLoc (CaseAlt (con, args, rhs)) + = (noSrcLoc, text "In a case alternative:" <+> parens (ppr con <+> pp_binders args)) -\begin{code} -checkInScope :: Id -> LintM () -checkInScope id spec loc scope errs - = let - id_name = getName id - in - if isLocallyDefined id_name && not (id `elementOfIdSet` scope) then - ((), addErr errs (hsep [ppr id, ptext SLIT("is out of scope")]) loc) - else - ((),errs) - -checkTys :: Type -> Type -> ErrMsg -> LintM () -checkTys ty1 ty2 msg spec loc scope errs - = if ty1 == ty2 then ((), errs) else ((), addErr errs msg loc) -\end{code} +dumpLoc (CasePat (con, args, rhs)) + = (noSrcLoc, text "In the pattern of a case alternative:" <+> parens (ppr con <+> pp_binders args)) -\begin{code} -mkConErrMsg e - = ($$) (ptext SLIT("Application of newtype constructor:")) - (ppr e) +dumpLoc (ImportedUnfolding locn) + = (locn, brackets (ptext SLIT("in an imported unfolding"))) + +pp_binders :: [Var] -> SDoc +pp_binders bs = sep (punctuate comma (map pp_binder bs)) +pp_binder :: Var -> SDoc +pp_binder b | isId b = hsep [ppr b, dcolon, ppr (idType b)] + | isTyVar b = hsep [ppr b, dcolon, ppr (tyVarKind b)] +\end{code} -mkCaseAltMsg :: CoreCaseAlts -> ErrMsg -mkCaseAltMsg alts - = ($$) (ptext SLIT("Type of case alternatives not the same:")) - (ppr alts) +\begin{code} +------------------------------------------------------ +-- Messages for case expressions + +mkNullAltsMsg :: CoreExpr -> Message +mkNullAltsMsg e + = hang (text "Case expression with no alternatives:") + 4 (ppr e) + +mkDefaultArgsMsg :: [Var] -> Message +mkDefaultArgsMsg args + = hang (text "DEFAULT case with binders") + 4 (ppr args) + +mkCaseAltMsg :: CoreExpr -> Type -> Type -> Message +mkCaseAltMsg e ty1 ty2 + = hang (text "Type of case alternatives not the same as the annotation on case:") + 4 (vcat [ppr ty1, ppr ty2, ppr e]) + +mkScrutMsg :: Id -> Type -> Message +mkScrutMsg var scrut_ty + = vcat [text "Result binder in case doesn't match scrutinee:" <+> ppr var, + text "Result binder type:" <+> ppr (idType var), + text "Scrutinee type:" <+> ppr scrut_ty] + + +mkNonDefltMsg e + = hang (text "Case expression with DEFAULT not at the beginnning") 4 (ppr e) +mkNonIncreasingAltsMsg e + = hang (text "Case expression with badly-ordered alternatives") 4 (ppr e) + +nonExhaustiveAltsMsg :: CoreExpr -> Message +nonExhaustiveAltsMsg e + = hang (text "Case expression with non-exhaustive alternatives") 4 (ppr e) + +mkBadPatMsg :: Type -> Type -> Message +mkBadPatMsg con_result_ty scrut_ty + = vcat [ + text "In a case alternative, pattern result type doesn't match scrutinee type:", + text "Pattern result type:" <+> ppr con_result_ty, + text "Scrutinee type:" <+> ppr scrut_ty + ] -mkCaseAbstractMsg :: TyCon -> ErrMsg -mkCaseAbstractMsg tycon - = ($$) (ptext SLIT("An algebraic case on some weird type:")) - (ppr tycon) +mkBadAltMsg :: Type -> CoreAlt -> Message +mkBadAltMsg scrut_ty alt + = vcat [ text "Data alternative when scrutinee is not a tycon application", + text "Scrutinee type:" <+> ppr scrut_ty, + text "Alternative:" <+> pprCoreAlt alt ] -mkDefltMsg :: CoreCaseDefault -> ErrMsg -mkDefltMsg deflt - = ($$) (ptext SLIT("Binder in case default doesn't match type of scrutinee:")) - (ppr deflt) +------------------------------------------------------ +-- Other error messages -mkAppMsg :: Type -> Type -> CoreExpr -> ErrMsg -mkAppMsg fun arg expr +mkAppMsg :: Type -> Type -> CoreExpr -> Message +mkAppMsg fun_ty arg_ty arg = vcat [ptext SLIT("Argument value doesn't match argument type:"), - hang (ptext SLIT("Fun type:")) 4 (ppr fun), - hang (ptext SLIT("Arg type:")) 4 (ppr arg), - hang (ptext SLIT("Expression:")) 4 (pprCoreExpr expr)] + hang (ptext SLIT("Fun type:")) 4 (ppr fun_ty), + hang (ptext SLIT("Arg type:")) 4 (ppr arg_ty), + hang (ptext SLIT("Arg:")) 4 (ppr arg)] -mkKindErrMsg :: TyVar -> Type -> CoreExpr -> ErrMsg -mkKindErrMsg tyvar arg_ty expr +mkKindErrMsg :: TyVar -> Type -> Message +mkKindErrMsg tyvar arg_ty = vcat [ptext SLIT("Kinds don't match in type application:"), hang (ptext SLIT("Type variable:")) - 4 (ppr tyvar <+> ptext SLIT("::") <+> ppr (tyVarKind tyvar)), + 4 (ppr tyvar <+> dcolon <+> ppr (tyVarKind tyvar)), hang (ptext SLIT("Arg type:")) - 4 (ppr arg_ty <+> ptext SLIT("::") <+> ppr (typeKind arg_ty)), - hang (ptext SLIT("Expression:")) 4 (pprCoreExpr expr)] + 4 (ppr arg_ty <+> dcolon <+> ppr (typeKind arg_ty))] -mkTyAppMsg :: FAST_STRING -> Type -> Type -> CoreExpr -> ErrMsg -mkTyAppMsg msg ty arg expr - = vcat [hsep [ptext msg, ptext SLIT("type application:")], +mkTyAppMsg :: Type -> Type -> Message +mkTyAppMsg ty arg_ty + = vcat [text "Illegal type application:", hang (ptext SLIT("Exp type:")) - 4 (ppr ty <+> ptext SLIT("::") <+> ppr (typeKind ty)), + 4 (ppr ty <+> dcolon <+> ppr (typeKind ty)), hang (ptext SLIT("Arg type:")) - 4 (ppr arg <+> ptext SLIT("::") <+> ppr (typeKind arg)), - hang (ptext SLIT("Expression:")) 4 (pprCoreExpr expr)] - -mkAlgAltMsg1 :: Type -> ErrMsg -mkAlgAltMsg1 ty - = ($$) (text "In some case statement, type of scrutinee is not a data type:") - (ppr ty) + 4 (ppr arg_ty <+> dcolon <+> ppr (typeKind arg_ty))] -mkAlgAltMsg2 :: Type -> Id -> ErrMsg -mkAlgAltMsg2 ty con - = vcat [ - text "In some algebraic case alternative, constructor is not a constructor of scrutinee type:", - ppr ty, - ppr con - ] - -mkAlgAltMsg3 :: Id -> [Id] -> ErrMsg -mkAlgAltMsg3 con alts - = vcat [ - text "In some algebraic case alternative, number of arguments doesn't match constructor:", - ppr con, - ppr alts - ] - -mkAlgAltMsg4 :: Type -> Id -> ErrMsg -mkAlgAltMsg4 ty arg - = vcat [ - text "In some algebraic case alternative, type of argument doesn't match data constructor:", - ppr ty, - ppr arg - ] - -mkPrimAltMsg :: (Literal, CoreExpr) -> ErrMsg -mkPrimAltMsg alt - = ($$) - (text "In a primitive case alternative, type of literal doesn't match type of scrutinee:") - (ppr alt) - -mkRhsMsg :: Id -> Type -> ErrMsg +mkRhsMsg :: Id -> Type -> Message mkRhsMsg binder ty = vcat [hsep [ptext SLIT("The type of this binder doesn't match the type of its RHS:"), @@ -660,16 +762,24 @@ mkRhsMsg binder ty hsep [ptext SLIT("Binder's type:"), ppr (idType binder)], hsep [ptext SLIT("Rhs type:"), ppr ty]] -mkRhsPrimMsg :: Id -> CoreExpr -> ErrMsg +mkRhsPrimMsg :: Id -> CoreExpr -> Message mkRhsPrimMsg binder rhs = vcat [hsep [ptext SLIT("The type of this binder is primitive:"), ppr binder], hsep [ptext SLIT("Binder's type:"), ppr (idType binder)] ] +mkUnboxedTupleMsg :: Id -> Message +mkUnboxedTupleMsg binder + = vcat [hsep [ptext SLIT("A variable has unboxed tuple type:"), ppr binder], + hsep [ptext SLIT("Binder's type:"), ppr (idType binder)]] + mkCoerceErr from_ty expr_ty = vcat [ptext SLIT("From-type of Coerce differs from type of enclosed expression"), ptext SLIT("From-type:") <+> ppr from_ty, ptext SLIT("Type of enclosed expr:") <+> ppr expr_ty ] + +mkStrangeTyMsg e + = ptext SLIT("Type where expression expected:") <+> ppr e \end{code}