X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2FcoreSyn%2FCoreLint.lhs;h=be323be8faa25721e970c006189a926930488792;hb=fe108ff1b0d4b52679ba6deddadf5d2fb3fa8f22;hp=02d6e87475185a831dea2e0275d9929059fb0b97;hpb=783e505e2d884f94d30ec8074e590507f2561c49;p=ghc-hetmet.git diff --git a/ghc/compiler/coreSyn/CoreLint.lhs b/ghc/compiler/coreSyn/CoreLint.lhs index 02d6e87..be323be 100644 --- a/ghc/compiler/coreSyn/CoreLint.lhs +++ b/ghc/compiler/coreSyn/CoreLint.lhs @@ -7,81 +7,73 @@ module CoreLint ( lintCoreBindings, lintUnfolding, - beginPass, endPass + showPass, endPass ) where #include "HsVersions.h" -import IO ( hPutStr, hPutStrLn, stderr, stdout ) - -import CmdLineOpts ( opt_D_show_passes, opt_DoCoreLinting, opt_PprStyle_Debug ) import CoreSyn import CoreFVs ( idFreeVars ) -import CoreUtils ( exprOkForSpeculation, coreBindsSize ) - +import CoreUtils ( findDefault, exprOkForSpeculation, coreBindsSize ) +import Unify ( coreRefineTys ) import Bag -import Literal ( Literal, literalType ) -import DataCon ( DataCon, dataConRepType ) -import Id ( mayHaveNoBinding, isDeadBinder ) -import Var ( Var, Id, TyVar, idType, tyVarKind, isTyVar, isId ) +import Literal ( literalType ) +import DataCon ( dataConRepType, isVanillaDataCon, dataConTyCon, dataConWorkId ) +import TysWiredIn ( tupleCon ) +import Var ( Var, Id, TyVar, idType, tyVarKind, mustHaveLocalBinding ) import VarSet -import Subst ( mkTyVarSubst, substTy ) -import Name ( isLocallyDefined, getSrcLoc ) +import Name ( getSrcLoc ) import PprCore -import ErrUtils ( doIfSet, dumpIfSet, ghcExit, Message, - ErrMsg, addErrLocHdrLine, pprBagOfErrors ) -import PrimRep ( PrimRep(..) ) -import SrcLoc ( SrcLoc, noSrcLoc, isNoSrcLoc ) -import Type ( Type, Kind, tyVarsOfType, - splitFunTy_maybe, mkPiType, mkTyVarTy, unUsgTy, +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, - splitAlgTyConApp_maybe, - isUnboxedTupleType, - hasMoreBoxityInfo - ) -import TyCon ( TyCon, isPrimTyCon, tyConDataCons ) -import BasicTypes ( RecFlag(..), isNonRec ) + 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` +#ifdef DEBUG +import Util ( notNull ) +#endif + +import Maybe + \end{code} %************************************************************************ %* * -\subsection{Start and end pass} +\subsection{End pass} %* * %************************************************************************ -@beginPass@ and @endPass@ don't really belong here, but it makes a convenient +@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} -beginPass :: String -> IO () -beginPass pass_name - | opt_D_show_passes - = hPutStrLn stderr ("*** " ++ pass_name) - | otherwise - = return () - - -endPass :: String -> Bool -> [CoreBind] -> IO [CoreBind] -endPass pass_name dump_flag binds +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 - if opt_D_show_passes then - hPutStrLn stdout (" Result size = " ++ show (coreBindsSize binds)) - else - return () + debugTraceMsg dflags 2 $ + (text " Result size =" <+> int (coreBindsSize binds)) -- Report verbosely, if required - dumpIfSet dump_flag pass_name - (pprCoreBindings binds) + dumpIfSet_core dflags dump_flag pass_name (pprCoreBindings binds) -- Type check - lintCoreBindings pass_name binds + lintCoreBindings dflags pass_name binds return binds \end{code} @@ -112,39 +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...); \begin{code} -lintCoreBindings :: String -> [CoreBind] -> IO () +lintCoreBindings :: DynFlags -> String -> [CoreBind] -> IO () -lintCoreBindings whoDunnit binds - | not opt_DoCoreLinting +lintCoreBindings dflags whoDunnit binds + | not (dopt Opt_DoCoreLinting dflags) = return () -lintCoreBindings whoDunnit binds +lintCoreBindings dflags whoDunnit binds = case (initL (lint_binds binds)) of - Nothing -> doIfSet opt_D_show_passes - (hPutStr stderr ("*** Core Linted result of " ++ whoDunnit ++ "\n")) - + Nothing -> showPass dflags ("Core Linted result of " ++ whoDunnit) Just bad_news -> printDump (display bad_news) >> - ghcExit 1 + ghcExit dflags 1 where -- 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) $ - mapL lint_bind binds + mapM lint_bind binds - lint_bind (Rec prs) = mapL (lintSingleBinding Recursive) prs `seqL` - returnL () + 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, @@ -165,16 +153,12 @@ We use this to check all unfoldings that come in from interfaces lintUnfolding :: SrcLoc -> [Var] -- Treat these as in scope -> CoreExpr - -> Maybe Message -- Nothing => OK + -> Maybe Message -- Nothing => OK lintUnfolding locn vars expr - | not opt_DoCoreLinting - = Nothing - - | otherwise = initL (addLoc (ImportedUnfolding locn) $ - addInScopeVars vars $ - lintCoreExpr expr) + addInScopeVars vars $ + lintCoreExpr expr) \end{code} %************************************************************************ @@ -188,21 +172,17 @@ Check a core binding, returning the list of variables bound. \begin{code} lintSingleBinding rec_flag (binder,rhs) = addLoc (RhsOf binder) $ - - -- Check the rhs - lintCoreExpr rhs `thenL` \ ty -> - - -- Check match to RHS type - lintBinder binder `seqL` - checkTys binder_ty ty (mkRhsMsg binder ty) `seqL` - - -- Check (not isUnLiftedType) (also checks for bogus unboxed tuples) - checkL (not (isUnLiftedType binder_ty) || (isNonRec rec_flag && exprOkForSpeculation rhs)) - (mkRhsPrimMsg binder rhs) `seqL` - + -- 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 - mapL (checkBndrIdInScope binder) bndr_vars `seqL` - returnL () + ; 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. @@ -218,71 +198,119 @@ lintSingleBinding rec_flag (binder,rhs) %************************************************************************ \begin{code} -lintCoreExpr :: CoreExpr -> LintM Type +type InType = Type -- Substitution not yet applied +type OutType = Type -- Substitution has been applied to this + +lintCoreExpr :: CoreExpr -> LintM OutType +-- The returned type has the substitution from the monad +-- already applied to it: +-- lintCoreExpr e subst = exprType (subst e) -lintCoreExpr (Var var) = checkIdInScope var `seqL` returnL (idType var) -lintCoreExpr (Lit lit) = returnL (literalType lit) +lintCoreExpr (Var var) + = do { checkIdInScope var + ; applySubst (idType var) } + +lintCoreExpr (Lit lit) + = return (literalType lit) lintCoreExpr (Note (Coerce to_ty from_ty) expr) - = lintCoreExpr expr `thenL` \ expr_ty -> - lintTy to_ty `seqL` - lintTy from_ty `seqL` - checkTys from_ty (unUsgTy expr_ty) (mkCoerceErr from_ty expr_ty) `seqL` - returnL 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 (NonRec bndr rhs) body) - = lintSingleBinding NonRecursive (bndr,rhs) `seqL` - addLoc (BodyOfLetRec [bndr]) - (addInScopeVars [bndr] (lintCoreExpr body)) + = do { lintSingleBinding NonRecursive (bndr,rhs) + ; addLoc (BodyOfLetRec [bndr]) + (addInScopeVars [bndr] (lintCoreExpr body)) } -lintCoreExpr (Let (Rec pairs) body) +lintCoreExpr (Let (Rec pairs) body) = addInScopeVars bndrs $ - mapL (lintSingleBinding Recursive) pairs `seqL` - addLoc (BodyOfLetRec bndrs) (lintCoreExpr body) + 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 `thenL` \ ty -> - addLoc (AnExpr e) $ - lintCoreArg ty arg + = do { fun_ty <- lintCoreExpr fun + ; addLoc (AnExpr e) $ + lintCoreArg fun_ty arg } lintCoreExpr (Lam var expr) - = addLoc (LambdaBodyOf var) $ - checkL (not (isUnboxedTupleType (idType var))) (mkUnboxedTupleMsg var) - `seqL` - (addInScopeVars [var] $ - lintCoreExpr expr `thenL` \ ty -> - returnL (mkPiType var ty)) - -lintCoreExpr e@(Case scrut var alts) - = -- Check the scrutinee - lintCoreExpr scrut `thenL` \ scrut_ty -> - - -- Check the binder - lintBinder var `seqL` - - -- If this is an unboxed tuple case, then the binder must be dead - {- - checkL (if isUnboxedTupleType (idType var) - then isDeadBinder var - else True) (mkUnboxedTupleMsg var) `seqL` - -} - - checkTys (idType var) scrut_ty (mkScrutMsg var scrut_ty) `seqL` - - addInScopeVars [var] ( - - -- Check the alternatives - checkAllCasesCovered e scrut_ty alts `seqL` - mapL (lintCoreAlt scrut_ty) alts `thenL` \ (alt_ty : alt_tys) -> - mapL (check alt_ty) alt_tys `seqL` - returnL alt_ty) - where - check alt_ty1 alt_ty2 = checkTys alt_ty1 alt_ty2 (mkCaseAltMsg e) + = 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) @@ -294,61 +322,64 @@ lintCoreExpr e@(Type ty) %* * %************************************************************************ -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 :: Type -> [CoreArg] -> LintM Type - -lintCoreArgs ty [] = returnL ty -lintCoreArgs ty (a : args) - = lintCoreArg ty a `thenL` \ res -> - lintCoreArgs res args +lintCoreArg :: Type -> CoreArg -> LintM Type +-- First argument has already had substitution applied to it \end{code} \begin{code} -lintCoreArg :: Type -> CoreArg -> LintM Type - -lintCoreArg ty a@(Type arg_ty) - = lintTy arg_ty `seqL` - lintTyApp ty arg_ty - -lintCoreArg fun_ty arg - = -- Make sure function type matches argument - lintCoreExpr arg `thenL` \ arg_ty -> - case (splitFunTy_maybe fun_ty) of - Just (arg,res) | (arg_ty == arg) -> returnL res - _ -> addErrL (mkAppMsg fun_ty arg_ty) +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} \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) -> - 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 (substTy (mkTyVarSubst [tyvar] [arg_ty]) body) - else - addErrL (mkKindErrMsg tyvar arg_ty) - -lintTyApps fun_ty [] - = returnL fun_ty - -lintTyApps fun_ty (arg_ty : arg_tys) - = lintTyApp fun_ty arg_ty `thenL` \ fun_ty' -> - lintTyApps fun_ty' arg_tys -\end{code} + 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 + tyvar_kind = tyVarKind tyvar + argty_kind = typeKind arg_ty +\end{code} %************************************************************************ @@ -358,87 +389,108 @@ lintTyApps fun_ty (arg_ty : arg_tys) %************************************************************************ \begin{code} -checkAllCasesCovered e ty [] = addErrL (mkNullAltsMsg e) - -checkAllCasesCovered e ty [(DEFAULT,_,_)] = nopL +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 -checkAllCasesCovered e scrut_ty alts - = case splitTyConApp_maybe scrut_ty of { - Nothing -> addErrL (badAltsMsg e); - Just (tycon, tycon_arg_tys) -> + -- Check that successive alternatives have increasing tags + increasing_tag (alt1 : rest@( alt2 : _)) = alt1 `ltAlt` alt2 && increasing_tag rest + increasing_tag other = True - if isPrimTyCon tycon then - checkL (hasDefault alts) (nonExhaustiveAltsMsg e) - else -{- No longer needed -#ifdef DEBUG - -- Algebraic cases are not necessarily exhaustive, because - -- the simplifer correctly eliminates case that can't - -- possibly match. - -- This code just emits a message to say so - let - missing_cons = filter not_in_alts (tyConDataCons tycon) - not_in_alts con = all (not_in_alt con) alts - not_in_alt con (DataCon con', _, _) = con /= con' - not_in_alt con other = True - - case_bndr = case e of { Case _ bndr alts -> bndr } - in - if not (hasDefault alts || null missing_cons) then - pprTrace "Exciting (but not a problem)! Non-exhaustive case:" - (ppr case_bndr <+> ppr missing_cons) - nopL - else -#endif --} - nopL } + non_deflt (DEFAULT, _, _) = False + non_deflt alt = True -hasDefault [] = False -hasDefault ((DEFAULT,_,_) : alts) = True -hasDefault (alt : alts) = hasDefault alts + is_infinite_ty = case splitTyConApp_maybe ty of + Nothing -> False + Just (tycon, tycon_arg_tys) -> isPrimTyCon tycon \end{code} \begin{code} -lintCoreAlt :: Type -- Type of scrutinee +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 Type -- Type of alternatives + -> LintM () -lintCoreAlt scrut_ty alt@(DEFAULT, args, rhs) - = checkL (null args) (mkDefaultArgsMsg args) `seqL` - lintCoreExpr rhs +lintCoreAlt scrut_ty alt_ty alt@(DEFAULT, args, rhs) = + do { checkL (null args) (mkDefaultArgsMsg args) + ; checkAltExpr rhs alt_ty } -lintCoreAlt scrut_ty alt@(LitAlt lit, args, rhs) - = checkL (null args) (mkDefaultArgsMsg args) `seqL` - checkTys lit_ty scrut_ty - (mkBadPatMsg lit_ty scrut_ty) `seqL` - lintCoreExpr rhs +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 lit_ty = literalType lit -lintCoreAlt scrut_ty alt@(DataAlt con, args, rhs) - = addLoc (CaseAlt alt) ( - - mapL (\arg -> checkL (not (isUnboxedTupleType (idType arg))) - (mkUnboxedTupleMsg arg)) args `seqL` - - addInScopeVars args ( - - -- 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. - case splitTyConApp_maybe scrut_ty of { Just (tycon, tycon_arg_tys) -> - lintTyApps (dataConRepType con) tycon_arg_tys `thenL` \ con_type -> - lintCoreArgs con_type (map mk_arg args) `thenL` \ con_result_ty -> - checkTys con_result_ty scrut_ty (mkBadPatMsg con_result_ty scrut_ty) - } `seqL` - - -- Check the RHS - lintCoreExpr rhs - )) - where - mk_arg b | isTyVar b = Type (mkTyVarTy b) - | otherwise = Var b +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} %************************************************************************ @@ -449,13 +501,24 @@ lintCoreAlt scrut_ty alt@(DataAlt con, args, rhs) \begin{code} lintBinder :: Var -> LintM () -lintBinder v = nopL --- ToDo: lint its type - -lintTy :: Type -> LintM () -lintTy ty = mapL checkIdInScope (varSetElems (tyVarsOfType ty)) `seqL` - returnL () - -- ToDo: check the kind structure of the type +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} @@ -466,91 +529,96 @@ lintTy ty = mapL checkIdInScope (varSetElems (tyVarsOfType ty)) `seqL` %************************************************************************ \begin{code} -type LintM a = [LintLocInfo] -- Locations - -> IdSet -- Local vars in scope - -> Bag ErrMsg -- Error messages so far - -> (Maybe 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 -- Pattern of a case alternative + | 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 +initL :: LintM a -> Maybe Message {- errors -} initL m - = case (m [] emptyVarSet emptyBag) of { (_, errs) -> - if isEmptyBag errs then - Nothing - else - Just (pprBagOfErrors errs) - } - -returnL :: a -> LintM a -returnL r loc scope errs = (Just r, errs) - -nopL :: LintM a -nopL loc scope errs = (Nothing, errs) - -thenL :: LintM a -> (a -> LintM b) -> LintM b -thenL m k loc scope errs - = case m loc scope errs of - (Just r, errs') -> k r loc scope errs' - (Nothing, errs') -> (Nothing, errs') - -seqL :: LintM a -> LintM b -> LintM b -seqL m k loc scope errs - = case m loc scope errs of - (_, errs') -> k loc scope errs' - -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) + = 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 loc scope errs = (Nothing, errs) -checkL False msg loc scope errs = (Nothing, addErr errs msg loc) +checkL True msg = return () +checkL False msg = addErrL msg addErrL :: Message -> LintM a -addErrL msg loc scope errs = (Nothing, addErr errs msg loc) - -addErr :: Bag ErrMsg -> Message -> [LintLocInfo] -> Bag ErrMsg +addErrL msg = LintM (\ loc subst errs -> (Nothing, addErr subst errs msg loc)) -addErr errs_so_far msg locs - = ASSERT (not (null locs)) +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) $$ cxt1 + context | opt_PprStyle_Debug = vcat (reverse cxts) $$ cxt1 $$ + ptext SLIT("Substitution:") <+> ppr subst | otherwise = cxt1 - mk_msg msg - | isNoSrcLoc loc = (loc, hang context 4 msg) - | otherwise = addErrLocHdrLine loc context msg + mk_msg msg = mkLocMessage (mkSrcSpan loc loc) (context $$ msg) addLoc :: LintLocInfo -> LintM a -> LintM a -addLoc extra_loc m loc scope errs - = m (extra_loc:loc) scope errs +addLoc extra_loc m = + LintM (\ loc subst errs -> unLintM m (extra_loc:loc) subst errs) addInScopeVars :: [Var] -> LintM a -> LintM a -addInScopeVars ids m loc scope errs - = m loc (scope `unionVarSet` mkVarSet ids) errs +addInScopeVars vars m = + LintM (\ loc subst errs -> unLintM m loc (extendTvInScope subst vars) errs) + +updateTvSubstEnv :: TvSubstEnv -> LintM a -> LintM a +updateTvSubstEnv substenv m = + LintM (\ loc subst errs -> unLintM m loc (setTvSubstEnv subst substenv) errs) + +getTvSubst :: LintM TvSubst +getTvSubst = LintM (\ loc subst errs -> (Just subst, errs)) + +applySubst :: Type -> LintM Type +applySubst ty = do { subst <- getTvSubst; return (substTy subst ty) } + +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} checkIdInScope :: Var -> LintM () checkIdInScope id - = checkInScope (ptext SLIT("is out of scope")) 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 @@ -560,31 +628,18 @@ checkBndrIdInScope binder id ppr binder checkInScope :: SDoc -> Var -> LintM () -checkInScope loc_msg var loc scope errs - | isLocallyDefined var - && not (var `elemVarSet` scope) - && not (isId var && mayHaveNoBinding 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). - -- Ditto primitive Ids - = (Nothing, addErr errs (hsep [ppr var, loc_msg]) loc) - | otherwise - = (Nothing,errs) +checkInScope loc_msg var = + do { subst <- getTvSubst + ; checkL (not (mustHaveLocalBinding var) || (var `isInScope` subst)) + (hsep [ppr var, loc_msg]) } checkTys :: Type -> Type -> Message -> LintM () -checkTys ty1 ty2 msg loc scope errs - | ty1 == ty2 = (Nothing, errs) - | otherwise = (Nothing, addErr errs msg loc) +-- 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} @@ -598,23 +653,30 @@ dumpLoc (RhsOf v) dumpLoc (LambdaBodyOf b) = (getSrcLoc b, brackets (ptext SLIT("in body of lambda with binder") <+> pp_binder b)) -dumpLoc (BodyOfLetRec bs) +dumpLoc (BodyOfLetRec []) + = (noSrcLoc, brackets (ptext SLIT("In body of a letrec with no binders"))) + +dumpLoc (BodyOfLetRec bs@(_:_)) = ( getSrcLoc (head bs), brackets (ptext SLIT("in body of letrec with binders") <+> pp_binders bs)) dumpLoc (AnExpr e) = (noSrcLoc, text "In the expression:" <+> ppr e) dumpLoc (CaseAlt (con, args, rhs)) - = (noSrcLoc, text "In a case pattern:" <+> parens (ppr con <+> ppr args)) + = (noSrcLoc, text "In a case alternative:" <+> parens (ppr con <+> pp_binders args)) + +dumpLoc (CasePat (con, args, rhs)) + = (noSrcLoc, text "In the pattern of a case alternative:" <+> parens (ppr con <+> pp_binders args)) dumpLoc (ImportedUnfolding locn) = (locn, brackets (ptext SLIT("in an imported unfolding"))) -pp_binders :: [Id] -> SDoc +pp_binders :: [Var] -> SDoc pp_binders bs = sep (punctuate comma (map pp_binder bs)) -pp_binder :: Id -> SDoc -pp_binder b = hsep [ppr b, dcolon, ppr (idType b)] +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} \begin{code} @@ -631,10 +693,10 @@ mkDefaultArgsMsg args = hang (text "DEFAULT case with binders") 4 (ppr args) -mkCaseAltMsg :: CoreExpr -> Message -mkCaseAltMsg e - = hang (text "Type of case alternatives not the same:") - 4 (ppr e) +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 @@ -642,15 +704,15 @@ mkScrutMsg var scrut_ty text "Result binder type:" <+> ppr (idType var), text "Scrutinee type:" <+> ppr scrut_ty] -badAltsMsg :: CoreExpr -> Message -badAltsMsg e - = hang (text "Case statement scrutinee is not a data type:") - 4 (ppr e) + +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) + = hang (text "Case expression with non-exhaustive alternatives") 4 (ppr e) mkBadPatMsg :: Type -> Type -> Message mkBadPatMsg con_result_ty scrut_ty @@ -660,13 +722,21 @@ mkBadPatMsg con_result_ty scrut_ty text "Scrutinee type:" <+> ppr scrut_ty ] +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 ] + ------------------------------------------------------ -- Other error messages -mkAppMsg fun arg +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("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 -> Message mkKindErrMsg tyvar arg_ty