3 % (c) The University of Glasgow 2006
4 % (c) The GRASP/AQUA Project, Glasgow University, 1993-1998
7 A ``lint'' pass to check for Core correctness
13 showPass, endPass, endPassIf, endIteration
16 #include "HsVersions.h"
47 %************************************************************************
51 %************************************************************************
53 @showPass@ and @endPass@ don't really belong here, but it makes a convenient
54 place for them. They print out stuff before and after core passes,
55 and do Core Lint when necessary.
58 endPass :: DynFlags -> String -> DynFlag -> [CoreBind] -> IO [CoreBind]
59 endPass = dumpAndLint dumpIfSet_core
61 endPassIf :: Bool -> DynFlags -> String -> DynFlag -> [CoreBind] -> IO [CoreBind]
62 endPassIf cond = dumpAndLint (dumpIf_core cond)
64 endIteration :: DynFlags -> String -> DynFlag -> [CoreBind] -> IO [CoreBind]
65 endIteration = dumpAndLint dumpIfSet_dyn
67 dumpAndLint :: (DynFlags -> DynFlag -> String -> SDoc -> IO ())
68 -> DynFlags -> String -> DynFlag -> [CoreBind] -> IO [CoreBind]
69 dumpAndLint dump dflags pass_name dump_flag binds
71 -- Report result size if required
72 -- This has the side effect of forcing the intermediate to be evaluated
73 debugTraceMsg dflags 2 $
74 (text " Result size =" <+> int (coreBindsSize binds))
76 -- Report verbosely, if required
77 dump dflags dump_flag pass_name (pprCoreBindings binds)
80 lintCoreBindings dflags pass_name binds
86 %************************************************************************
88 \subsection[lintCoreBindings]{@lintCoreBindings@: Top-level interface}
90 %************************************************************************
92 Checks that a set of core bindings is well-formed. The PprStyle and String
93 just control what we print in the event of an error. The Bool value
94 indicates whether we have done any specialisation yet (in which case we do
99 (b) Out-of-scope type variables
100 (c) Out-of-scope local variables
103 If we have done specialisation the we check that there are
104 (a) No top-level bindings of primitive (unboxed type)
109 -- Things are *not* OK if:
111 -- * Unsaturated type app before specialisation has been done;
113 -- * Oversaturated type app after specialisation (eta reduction
114 -- may well be happening...);
119 In the desugarer, it's very very convenient to be able to say (in effect)
120 let a = Int in <body>
121 That is, use a type let. (See notes just below for why we want this.)
123 We don't have type lets in Core, so the desugarer uses type lambda
125 However, in the lambda form, we'd get lint errors from:
126 (/\a. let x::a = 4 in <body>) Int
127 because (x::a) doesn't look compatible with (4::Int).
129 So (HACK ALERT) the Lint phase does type-beta reduction "on the fly",
130 as it were. It carries a type substitution (in this example [a -> Int])
131 and applies this substitution before comparing types. The functin
132 lintTy :: Type -> LintM Type
133 returns a substituted type; that's the only reason it returns anything.
135 When we encounter a binder (like x::a) we must apply the substitution
136 to the type of the binding variable. lintBinders does this.
138 For Ids, the type-substituted Id is added to the in_scope set (which
139 itself is part of the TvSubst we are carrying down), and when we
140 find an occurence of an Id, we fetch it from the in-scope set.
145 It's needed when dealing with desugarer output for GADTs. Consider
146 data T = forall a. T a (a->Int) Bool
148 f (T x f True) = <e1>
149 f (T y g False) = <e2>
150 After desugaring we get
152 T a (x::a) (f::a->Int) (b:Bool) ->
155 False -> (/\b. let y=x; g=f in <e2>) a
156 And for a reason I now forget, the ...<e2>... can mention a; so
157 we want Lint to know that b=a. Ugh.
159 I tried quite hard to make the necessity for this go away, by changing the
160 desugarer, but the fundamental problem is this:
162 T a (x::a) (y::Int) -> let fail::a = ...
163 in (/\b. ...(case ... of
167 Now the inner case look as though it has incompatible branches.
171 lintCoreBindings :: DynFlags -> String -> [CoreBind] -> IO ()
173 lintCoreBindings dflags _whoDunnit _binds
174 | not (dopt Opt_DoCoreLinting dflags)
177 lintCoreBindings dflags whoDunnit binds
178 = case (initL (lint_binds binds)) of
179 Nothing -> showPass dflags ("Core Linted result of " ++ whoDunnit)
180 Just bad_news -> printDump (display bad_news) >>
183 -- Put all the top-level binders in scope at the start
184 -- This is because transformation rules can bring something
185 -- into use 'unexpectedly'
186 lint_binds binds = addLoc TopLevelBindings $
187 addInScopeVars (bindersOfBinds binds) $
190 lint_bind (Rec prs) = mapM_ (lintSingleBinding TopLevel Recursive) prs
191 lint_bind (NonRec bndr rhs) = lintSingleBinding TopLevel NonRecursive (bndr,rhs)
194 = vcat [ text ("*** Core Lint Errors: in result of " ++ whoDunnit ++ " ***"),
196 ptext (sLit "*** Offending Program ***"),
197 pprCoreBindings binds,
198 ptext (sLit "*** End of Offense ***")
202 %************************************************************************
204 \subsection[lintUnfolding]{lintUnfolding}
206 %************************************************************************
208 We use this to check all unfoldings that come in from interfaces
209 (it is very painful to catch errors otherwise):
212 lintUnfolding :: SrcLoc
213 -> [Var] -- Treat these as in scope
215 -> Maybe Message -- Nothing => OK
217 lintUnfolding locn vars expr
218 = initL (addLoc (ImportedUnfolding locn) $
219 addInScopeVars vars $
223 %************************************************************************
225 \subsection[lintCoreBinding]{lintCoreBinding}
227 %************************************************************************
229 Check a core binding, returning the list of variables bound.
232 lintSingleBinding :: TopLevelFlag -> RecFlag -> (Id, CoreExpr) -> LintM ()
233 lintSingleBinding top_lvl_flag rec_flag (binder,rhs)
234 = addLoc (RhsOf binder) $
236 do { ty <- lintCoreExpr rhs
237 ; lintBinder binder -- Check match to RHS type
238 ; binder_ty <- applySubst binder_ty
239 ; checkTys binder_ty ty (mkRhsMsg binder ty)
240 -- Check (not isUnLiftedType) (also checks for bogus unboxed tuples)
241 ; checkL (not (isUnLiftedType binder_ty)
242 || (isNonRec rec_flag && exprOkForSpeculation rhs))
243 (mkRhsPrimMsg binder rhs)
244 -- Check that if the binder is top-level or recursive, it's not demanded
245 ; checkL (not (isStrictId binder)
246 || (isNonRec rec_flag && not (isTopLevel top_lvl_flag)))
248 -- Check whether binder's specialisations contain any out-of-scope variables
249 ; mapM_ (checkBndrIdInScope binder) bndr_vars
251 -- Check whether arity and demand type are consistent (only if demand analysis
253 ; checkL (case maybeDmdTy of
254 Just (StrictSig dmd_ty) -> idArity binder >= dmdTypeDepth dmd_ty || exprIsTrivial rhs
256 (mkArityMsg binder) }
258 -- We should check the unfolding, if any, but this is tricky because
259 -- the unfolding is a SimplifiableCoreExpr. Give up for now.
261 binder_ty = idType binder
262 maybeDmdTy = idNewStrictness_maybe binder
263 bndr_vars = varSetElems (idFreeVars binder)
264 lintBinder var | isId var = lintIdBndr var $ \_ -> (return ())
265 | otherwise = return ()
268 %************************************************************************
270 \subsection[lintCoreExpr]{lintCoreExpr}
272 %************************************************************************
275 type InType = Type -- Substitution not yet applied
276 type OutType = Type -- Substitution has been applied to this
278 lintCoreExpr :: CoreExpr -> LintM OutType
279 -- The returned type has the substitution from the monad
280 -- already applied to it:
281 -- lintCoreExpr e subst = exprType (subst e)
283 lintCoreExpr (Var var)
284 = do { checkL (not (var == oneTupleDataConId))
285 (ptext (sLit "Illegal one-tuple"))
286 ; var' <- lookupIdInScope var
287 ; return (idType var')
290 lintCoreExpr (Lit lit)
291 = return (literalType lit)
293 --lintCoreExpr (Note (Coerce to_ty from_ty) expr)
294 -- = do { expr_ty <- lintCoreExpr expr
295 -- ; to_ty <- lintTy to_ty
296 -- ; from_ty <- lintTy from_ty
297 -- ; checkTys from_ty expr_ty (mkCoerceErr from_ty expr_ty)
300 lintCoreExpr (Cast expr co)
301 = do { expr_ty <- lintCoreExpr expr
303 ; let (from_ty, to_ty) = coercionKind co'
304 ; checkTys from_ty expr_ty (mkCastErr from_ty expr_ty)
307 lintCoreExpr (Note _ expr)
310 lintCoreExpr (Let (NonRec bndr rhs) body)
311 = do { lintSingleBinding NotTopLevel NonRecursive (bndr,rhs)
312 ; addLoc (BodyOfLetRec [bndr])
313 (lintAndScopeId bndr $ \_ -> (lintCoreExpr body)) }
315 lintCoreExpr (Let (Rec pairs) body)
316 = lintAndScopeIds bndrs $ \_ ->
317 do { mapM (lintSingleBinding NotTopLevel Recursive) pairs
318 ; addLoc (BodyOfLetRec bndrs) (lintCoreExpr body) }
320 bndrs = map fst pairs
322 lintCoreExpr e@(App fun (Type ty))
323 -- See Note [Type let] above
324 = addLoc (AnExpr e) $
327 go (App fun (Type ty)) tys
328 = do { go fun (ty:tys) }
329 go (Lam tv body) (ty:tys)
330 = do { checkL (isTyVar tv) (mkKindErrMsg tv ty) -- Not quite accurate
332 ; let kind = tyVarKind tv
333 ; kind' <- lintTy kind
334 ; let tv' = setTyVarKind tv kind'
336 -- Now extend the substitution so we
337 -- take advantage of it in the body
338 ; addInScopeVars [tv'] $
339 extendSubstL tv' ty' $
342 = do { fun_ty <- lintCoreExpr fun
343 ; lintCoreArgs fun_ty (map Type tys) }
345 lintCoreExpr e@(App fun arg)
346 = do { fun_ty <- lintCoreExpr fun
347 ; addLoc (AnExpr e) $
348 lintCoreArg fun_ty arg }
350 lintCoreExpr (Lam var expr)
351 = addLoc (LambdaBodyOf var) $
352 lintBinders [var] $ \[var'] ->
353 do { body_ty <- lintCoreExpr expr
355 return (mkFunTy (idType var') body_ty)
357 return (mkForAllTy var' body_ty)
359 -- The applySubst is needed to apply the subst to var
361 lintCoreExpr e@(Case scrut var alt_ty alts) =
362 -- Check the scrutinee
363 do { scrut_ty <- lintCoreExpr scrut
364 ; alt_ty <- lintTy alt_ty
365 ; var_ty <- lintTy (idType var)
367 ; let mb_tc_app = splitTyConApp_maybe (idType var)
372 null (tyConDataCons tycon) ->
373 pprTrace "case binder's type has no constructors" (ppr e)
375 _otherwise -> return ()
377 -- Don't use lintIdBndr on var, because unboxed tuple is legitimate
379 ; subst <- getTvSubst
380 ; checkTys var_ty scrut_ty (mkScrutMsg var var_ty scrut_ty subst)
382 -- If the binder is an unboxed tuple type, don't put it in scope
383 ; let scope = if (isUnboxedTupleType (idType var)) then
385 else lintAndScopeId var
387 do { -- Check the alternatives
388 mapM (lintCoreAlt scrut_ty alt_ty) alts
389 ; checkCaseAlts e scrut_ty alts
394 lintCoreExpr e@(Type _)
395 = addErrL (mkStrangeTyMsg e)
398 %************************************************************************
400 \subsection[lintCoreArgs]{lintCoreArgs}
402 %************************************************************************
404 The basic version of these functions checks that the argument is a
405 subtype of the required type, as one would expect.
408 lintCoreArgs :: OutType -> [CoreArg] -> LintM OutType
409 lintCoreArg :: OutType -> CoreArg -> LintM OutType
410 -- First argument has already had substitution applied to it
414 lintCoreArgs ty [] = return ty
415 lintCoreArgs ty (a : args) =
416 do { res <- lintCoreArg ty a
417 ; lintCoreArgs res args }
419 lintCoreArg fun_ty (Type arg_ty) =
420 do { arg_ty <- lintTy arg_ty
421 ; lintTyApp fun_ty arg_ty }
423 lintCoreArg fun_ty arg =
424 -- Make sure function type matches argument
425 do { arg_ty <- lintCoreExpr arg
426 ; let err1 = mkAppMsg fun_ty arg_ty arg
427 err2 = mkNonFunAppMsg fun_ty arg_ty arg
428 ; case splitFunTy_maybe fun_ty of
430 do { checkTys arg arg_ty err1
436 -- Both args have had substitution applied
437 lintTyApp :: OutType -> OutType -> LintM OutType
439 = case splitForAllTy_maybe ty of
440 Nothing -> addErrL (mkTyAppMsg ty arg_ty)
443 -> do { checkL (isTyVar tyvar) (mkTyAppMsg ty arg_ty)
444 ; checkKinds tyvar arg_ty
445 ; return (substTyWith [tyvar] [arg_ty] body) }
447 checkKinds :: Var -> Type -> LintM ()
448 checkKinds tyvar arg_ty
449 -- Arg type might be boxed for a function with an uncommitted
450 -- tyvar; notably this is used so that we can give
451 -- error :: forall a:*. String -> a
452 -- and then apply it to both boxed and unboxed types.
453 = checkL (arg_kind `isSubKind` tyvar_kind)
454 (mkKindErrMsg tyvar arg_ty)
456 tyvar_kind = tyVarKind tyvar
457 arg_kind | isCoVar tyvar = coercionKindPredTy arg_ty
458 | otherwise = typeKind arg_ty
462 %************************************************************************
464 \subsection[lintCoreAlts]{lintCoreAlts}
466 %************************************************************************
469 checkCaseAlts :: CoreExpr -> OutType -> [CoreAlt] -> LintM ()
470 -- a) Check that the alts are non-empty
471 -- b1) Check that the DEFAULT comes first, if it exists
472 -- b2) Check that the others are in increasing order
473 -- c) Check that there's a default for infinite types
474 -- NB: Algebraic cases are not necessarily exhaustive, because
475 -- the simplifer correctly eliminates case that can't
479 = addErrL (mkNullAltsMsg e)
481 checkCaseAlts e ty alts =
482 do { checkL (all non_deflt con_alts) (mkNonDefltMsg e)
483 ; checkL (increasing_tag con_alts) (mkNonIncreasingAltsMsg e)
484 ; checkL (isJust maybe_deflt || not is_infinite_ty)
485 (nonExhaustiveAltsMsg e) }
487 (con_alts, maybe_deflt) = findDefault alts
489 -- Check that successive alternatives have increasing tags
490 increasing_tag (alt1 : rest@( alt2 : _)) = alt1 `ltAlt` alt2 && increasing_tag rest
491 increasing_tag _ = True
493 non_deflt (DEFAULT, _, _) = False
496 is_infinite_ty = case splitTyConApp_maybe ty of
498 Just (tycon, _) -> isPrimTyCon tycon
502 checkAltExpr :: CoreExpr -> OutType -> LintM ()
503 checkAltExpr expr ann_ty
504 = do { actual_ty <- lintCoreExpr expr
505 ; checkTys actual_ty ann_ty (mkCaseAltMsg expr actual_ty ann_ty) }
507 lintCoreAlt :: OutType -- Type of scrutinee
508 -> OutType -- Type of the alternative
512 lintCoreAlt _ alt_ty (DEFAULT, args, rhs) =
513 do { checkL (null args) (mkDefaultArgsMsg args)
514 ; checkAltExpr rhs alt_ty }
516 lintCoreAlt scrut_ty alt_ty (LitAlt lit, args, rhs) =
517 do { checkL (null args) (mkDefaultArgsMsg args)
518 ; checkTys lit_ty scrut_ty (mkBadPatMsg lit_ty scrut_ty)
519 ; checkAltExpr rhs alt_ty }
521 lit_ty = literalType lit
523 lintCoreAlt scrut_ty alt_ty alt@(DataAlt con, args, rhs)
524 | isNewTyCon (dataConTyCon con) = addErrL (mkNewTyDataConAltMsg scrut_ty alt)
525 | Just (tycon, tycon_arg_tys) <- splitTyConApp_maybe scrut_ty
526 = addLoc (CaseAlt alt) $ do
527 { -- First instantiate the universally quantified
528 -- type variables of the data constructor
529 -- We've already check
530 checkL (tycon == dataConTyCon con) (mkBadConMsg tycon con)
531 ; let con_payload_ty = applyTys (dataConRepType con) tycon_arg_tys
533 -- And now bring the new binders into scope
534 ; lintBinders args $ \ args -> do
535 { addLoc (CasePat alt) $ do
536 { -- Check the pattern
537 -- Scrutinee type must be a tycon applicn; checked by caller
538 -- This code is remarkably compact considering what it does!
539 -- NB: args must be in scope here so that the lintCoreArgs
541 -- NB: relies on existential type args coming *after*
542 -- ordinary type args
543 ; con_result_ty <- lintCoreArgs con_payload_ty (varsToCoreExprs args)
544 ; checkTys con_result_ty scrut_ty (mkBadPatMsg con_result_ty scrut_ty)
547 ; checkAltExpr rhs alt_ty } }
549 | otherwise -- Scrut-ty is wrong shape
550 = addErrL (mkBadAltMsg scrut_ty alt)
553 %************************************************************************
555 \subsection[lint-types]{Types}
557 %************************************************************************
560 -- When we lint binders, we (one at a time and in order):
561 -- 1. Lint var types or kinds (possibly substituting)
562 -- 2. Add the binder to the in scope set, and if its a coercion var,
563 -- we may extend the substitution to reflect its (possibly) new kind
564 lintBinders :: [Var] -> ([Var] -> LintM a) -> LintM a
565 lintBinders [] linterF = linterF []
566 lintBinders (var:vars) linterF = lintBinder var $ \var' ->
567 lintBinders vars $ \ vars' ->
570 lintBinder :: Var -> (Var -> LintM a) -> LintM a
571 lintBinder var linterF
572 | isTyVar var = lint_ty_bndr
573 | otherwise = lintIdBndr var linterF
575 lint_ty_bndr = do { lintTy (tyVarKind var)
576 ; subst <- getTvSubst
577 ; let (subst', tv') = substTyVarBndr subst var
578 ; updateTvSubst subst' (linterF tv') }
580 lintIdBndr :: Var -> (Var -> LintM a) -> LintM a
581 -- Do substitution on the type of a binder and add the var with this
582 -- new type to the in-scope set of the second argument
583 -- ToDo: lint its rules
584 lintIdBndr id linterF
585 = do { checkL (not (isUnboxedTupleType (idType id)))
586 (mkUnboxedTupleMsg id)
587 -- No variable can be bound to an unboxed tuple.
588 ; lintAndScopeId id $ \id' -> linterF id'
591 lintAndScopeIds :: [Var] -> ([Var] -> LintM a) -> LintM a
592 lintAndScopeIds ids linterF
596 go (id:ids) = do { lintAndScopeId id $ \id ->
597 lintAndScopeIds ids $ \ids ->
600 lintAndScopeId :: Var -> (Var -> LintM a) -> LintM a
601 lintAndScopeId id linterF
602 = do { ty <- lintTy (idType id)
603 ; let id' = Var.setIdType id ty
604 ; addInScopeVars [id'] $ (linterF id')
607 lintTy :: InType -> LintM OutType
608 -- Check the type, and apply the substitution to it
609 -- ToDo: check the kind structure of the type
611 = do { ty' <- applySubst ty
612 ; mapM_ checkTyVarInScope (varSetElems (tyVarsOfType ty'))
617 %************************************************************************
619 \subsection[lint-monad]{The Lint monad}
621 %************************************************************************
626 [LintLocInfo] -> -- Locations
627 TvSubst -> -- Current type substitution; we also use this
628 -- to keep track of all the variables in scope,
629 -- both Ids and TyVars
630 Bag Message -> -- Error messages so far
631 (Maybe a, Bag Message) } -- Result and error messages (if any)
633 {- Note [Type substitution]
634 ~~~~~~~~~~~~~~~~~~~~~~~~
635 Why do we need a type substitution? Consider
636 /\(a:*). \(x:a). /\(a:*). id a x
637 This is ill typed, because (renaming variables) it is really
638 /\(a:*). \(x:a). /\(b:*). id b x
639 Hence, when checking an application, we can't naively compare x's type
640 (at its binding site) with its expected type (at a use site). So we
641 rename type binders as we go, maintaining a substitution.
643 The same substitution also supports let-type, current expressed as
645 Here we substitute 'ty' for 'a' in 'body', on the fly.
648 instance Monad LintM where
649 return x = LintM (\ _ _ errs -> (Just x, errs))
650 fail err = LintM (\ loc subst errs -> (Nothing, addErr subst errs (text err) loc))
651 m >>= k = LintM (\ loc subst errs ->
652 let (res, errs') = unLintM m loc subst errs in
654 Just r -> unLintM (k r) loc subst errs'
655 Nothing -> (Nothing, errs'))
658 = RhsOf Id -- The variable bound
659 | LambdaBodyOf Id -- The lambda-binder
660 | BodyOfLetRec [Id] -- One of the binders
661 | CaseAlt CoreAlt -- Case alternative
662 | CasePat CoreAlt -- *Pattern* of the case alternative
663 | AnExpr CoreExpr -- Some expression
664 | ImportedUnfolding SrcLoc -- Some imported unfolding (ToDo: say which)
670 initL :: LintM a -> Maybe Message {- errors -}
672 = case unLintM m [] emptyTvSubst emptyBag of
673 (_, errs) | isEmptyBag errs -> Nothing
674 | otherwise -> Just (vcat (punctuate (text "") (bagToList errs)))
678 checkL :: Bool -> Message -> LintM ()
679 checkL True _ = return ()
680 checkL False msg = addErrL msg
682 addErrL :: Message -> LintM a
683 addErrL msg = LintM (\ loc subst errs -> (Nothing, addErr subst errs msg loc))
685 addErr :: TvSubst -> Bag Message -> Message -> [LintLocInfo] -> Bag Message
686 addErr subst errs_so_far msg locs
687 = ASSERT( notNull locs )
688 errs_so_far `snocBag` mk_msg msg
690 (loc, cxt1) = dumpLoc (head locs)
691 cxts = [snd (dumpLoc loc) | loc <- locs]
692 context | opt_PprStyle_Debug = vcat (reverse cxts) $$ cxt1 $$
693 ptext (sLit "Substitution:") <+> ppr subst
696 mk_msg msg = mkLocMessage (mkSrcSpan loc loc) (context $$ msg)
698 addLoc :: LintLocInfo -> LintM a -> LintM a
700 LintM (\ loc subst errs -> unLintM m (extra_loc:loc) subst errs)
702 addInScopeVars :: [Var] -> LintM a -> LintM a
703 addInScopeVars vars m
705 = LintM (\ loc subst errs -> unLintM m loc (extendTvInScope subst vars) errs)
707 = addErrL (dupVars dups)
709 (_, dups) = removeDups compare vars
711 updateTvSubst :: TvSubst -> LintM a -> LintM a
712 updateTvSubst subst' m =
713 LintM (\ loc _ errs -> unLintM m loc subst' errs)
715 getTvSubst :: LintM TvSubst
716 getTvSubst = LintM (\ _ subst errs -> (Just subst, errs))
718 applySubst :: Type -> LintM Type
719 applySubst ty = do { subst <- getTvSubst; return (substTy subst ty) }
721 extendSubstL :: TyVar -> Type -> LintM a -> LintM a
723 = LintM (\ loc subst errs -> unLintM m loc (extendTvSubst subst tv ty) errs)
727 lookupIdInScope :: Id -> LintM Id
729 | not (mustHaveLocalBinding id)
730 = return id -- An imported Id
732 = do { subst <- getTvSubst
733 ; case lookupInScope (getTvInScope subst) id of
735 Nothing -> do { addErrL out_of_scope
738 out_of_scope = ppr id <+> ptext (sLit "is out of scope")
741 oneTupleDataConId :: Id -- Should not happen
742 oneTupleDataConId = dataConWorkId (tupleCon Boxed 1)
744 checkBndrIdInScope :: Var -> Var -> LintM ()
745 checkBndrIdInScope binder id
746 = checkInScope msg id
748 msg = ptext (sLit "is out of scope inside info for") <+>
751 checkTyVarInScope :: TyVar -> LintM ()
752 checkTyVarInScope tv = checkInScope (ptext (sLit "is out of scope")) tv
754 checkInScope :: SDoc -> Var -> LintM ()
755 checkInScope loc_msg var =
756 do { subst <- getTvSubst
757 ; checkL (not (mustHaveLocalBinding var) || (var `isInScope` subst))
758 (hsep [ppr var, loc_msg]) }
760 checkTys :: Type -> Type -> Message -> LintM ()
761 -- check ty2 is subtype of ty1 (ie, has same structure but usage
762 -- annotations need only be consistent, not equal)
763 -- Assumes ty1,ty2 are have alrady had the substitution applied
764 checkTys ty1 ty2 msg = checkL (ty1 `coreEqType` ty2) msg
767 %************************************************************************
769 \subsection{Error messages}
771 %************************************************************************
774 dumpLoc :: LintLocInfo -> (SrcLoc, SDoc)
777 = (getSrcLoc v, brackets (ptext (sLit "RHS of") <+> pp_binders [v]))
779 dumpLoc (LambdaBodyOf b)
780 = (getSrcLoc b, brackets (ptext (sLit "in body of lambda with binder") <+> pp_binder b))
782 dumpLoc (BodyOfLetRec [])
783 = (noSrcLoc, brackets (ptext (sLit "In body of a letrec with no binders")))
785 dumpLoc (BodyOfLetRec bs@(_:_))
786 = ( getSrcLoc (head bs), brackets (ptext (sLit "in body of letrec with binders") <+> pp_binders bs))
789 = (noSrcLoc, text "In the expression:" <+> ppr e)
791 dumpLoc (CaseAlt (con, args, _))
792 = (noSrcLoc, text "In a case alternative:" <+> parens (ppr con <+> pp_binders args))
794 dumpLoc (CasePat (con, args, _))
795 = (noSrcLoc, text "In the pattern of a case alternative:" <+> parens (ppr con <+> pp_binders args))
797 dumpLoc (ImportedUnfolding locn)
798 = (locn, brackets (ptext (sLit "in an imported unfolding")))
799 dumpLoc TopLevelBindings
802 pp_binders :: [Var] -> SDoc
803 pp_binders bs = sep (punctuate comma (map pp_binder bs))
805 pp_binder :: Var -> SDoc
806 pp_binder b | isId b = hsep [ppr b, dcolon, ppr (idType b)]
807 | otherwise = hsep [ppr b, dcolon, ppr (tyVarKind b)]
811 ------------------------------------------------------
812 -- Messages for case expressions
814 mkNullAltsMsg :: CoreExpr -> Message
816 = hang (text "Case expression with no alternatives:")
819 mkDefaultArgsMsg :: [Var] -> Message
820 mkDefaultArgsMsg args
821 = hang (text "DEFAULT case with binders")
824 mkCaseAltMsg :: CoreExpr -> Type -> Type -> Message
825 mkCaseAltMsg e ty1 ty2
826 = hang (text "Type of case alternatives not the same as the annotation on case:")
827 4 (vcat [ppr ty1, ppr ty2, ppr e])
829 mkScrutMsg :: Id -> Type -> Type -> TvSubst -> Message
830 mkScrutMsg var var_ty scrut_ty subst
831 = vcat [text "Result binder in case doesn't match scrutinee:" <+> ppr var,
832 text "Result binder type:" <+> ppr var_ty,--(idType var),
833 text "Scrutinee type:" <+> ppr scrut_ty,
834 hsep [ptext (sLit "Current TV subst"), ppr subst]]
836 mkNonDefltMsg, mkNonIncreasingAltsMsg :: CoreExpr -> Message
838 = hang (text "Case expression with DEFAULT not at the beginnning") 4 (ppr e)
839 mkNonIncreasingAltsMsg e
840 = hang (text "Case expression with badly-ordered alternatives") 4 (ppr e)
842 nonExhaustiveAltsMsg :: CoreExpr -> Message
843 nonExhaustiveAltsMsg e
844 = hang (text "Case expression with non-exhaustive alternatives") 4 (ppr e)
846 mkBadConMsg :: TyCon -> DataCon -> Message
847 mkBadConMsg tycon datacon
849 text "In a case alternative, data constructor isn't in scrutinee type:",
850 text "Scrutinee type constructor:" <+> ppr tycon,
851 text "Data con:" <+> ppr datacon
854 mkBadPatMsg :: Type -> Type -> Message
855 mkBadPatMsg con_result_ty scrut_ty
857 text "In a case alternative, pattern result type doesn't match scrutinee type:",
858 text "Pattern result type:" <+> ppr con_result_ty,
859 text "Scrutinee type:" <+> ppr scrut_ty
862 mkBadAltMsg :: Type -> CoreAlt -> Message
863 mkBadAltMsg scrut_ty alt
864 = vcat [ text "Data alternative when scrutinee is not a tycon application",
865 text "Scrutinee type:" <+> ppr scrut_ty,
866 text "Alternative:" <+> pprCoreAlt alt ]
868 mkNewTyDataConAltMsg :: Type -> CoreAlt -> Message
869 mkNewTyDataConAltMsg scrut_ty alt
870 = vcat [ text "Data alternative for newtype datacon",
871 text "Scrutinee type:" <+> ppr scrut_ty,
872 text "Alternative:" <+> pprCoreAlt alt ]
875 ------------------------------------------------------
876 -- Other error messages
878 mkAppMsg :: Type -> Type -> CoreExpr -> Message
879 mkAppMsg fun_ty arg_ty arg
880 = vcat [ptext (sLit "Argument value doesn't match argument type:"),
881 hang (ptext (sLit "Fun type:")) 4 (ppr fun_ty),
882 hang (ptext (sLit "Arg type:")) 4 (ppr arg_ty),
883 hang (ptext (sLit "Arg:")) 4 (ppr arg)]
885 mkNonFunAppMsg :: Type -> Type -> CoreExpr -> Message
886 mkNonFunAppMsg fun_ty arg_ty arg
887 = vcat [ptext (sLit "Non-function type in function position"),
888 hang (ptext (sLit "Fun type:")) 4 (ppr fun_ty),
889 hang (ptext (sLit "Arg type:")) 4 (ppr arg_ty),
890 hang (ptext (sLit "Arg:")) 4 (ppr arg)]
892 mkKindErrMsg :: TyVar -> Type -> Message
893 mkKindErrMsg tyvar arg_ty
894 = vcat [ptext (sLit "Kinds don't match in type application:"),
895 hang (ptext (sLit "Type variable:"))
896 4 (ppr tyvar <+> dcolon <+> ppr (tyVarKind tyvar)),
897 hang (ptext (sLit "Arg type:"))
898 4 (ppr arg_ty <+> dcolon <+> ppr (typeKind arg_ty))]
900 mkTyAppMsg :: Type -> Type -> Message
902 = vcat [text "Illegal type application:",
903 hang (ptext (sLit "Exp type:"))
904 4 (ppr ty <+> dcolon <+> ppr (typeKind ty)),
905 hang (ptext (sLit "Arg type:"))
906 4 (ppr arg_ty <+> dcolon <+> ppr (typeKind arg_ty))]
908 mkRhsMsg :: Id -> Type -> Message
911 [hsep [ptext (sLit "The type of this binder doesn't match the type of its RHS:"),
913 hsep [ptext (sLit "Binder's type:"), ppr (idType binder)],
914 hsep [ptext (sLit "Rhs type:"), ppr ty]]
916 mkRhsPrimMsg :: Id -> CoreExpr -> Message
917 mkRhsPrimMsg binder _rhs
918 = vcat [hsep [ptext (sLit "The type of this binder is primitive:"),
920 hsep [ptext (sLit "Binder's type:"), ppr (idType binder)]
923 mkStrictMsg :: Id -> Message
925 = vcat [hsep [ptext (sLit "Recursive or top-level binder has strict demand info:"),
927 hsep [ptext (sLit "Binder's demand info:"), ppr (idNewDemandInfo binder)]
930 mkArityMsg :: Id -> Message
932 = vcat [hsep [ptext (sLit "Demand type has "),
933 ppr (dmdTypeDepth dmd_ty),
934 ptext (sLit " arguments, rhs has "),
935 ppr (idArity binder),
936 ptext (sLit "arguments, "),
938 hsep [ptext (sLit "Binder's strictness signature:"), ppr dmd_ty]
941 where (StrictSig dmd_ty) = idNewStrictness binder
943 mkUnboxedTupleMsg :: Id -> Message
944 mkUnboxedTupleMsg binder
945 = vcat [hsep [ptext (sLit "A variable has unboxed tuple type:"), ppr binder],
946 hsep [ptext (sLit "Binder's type:"), ppr (idType binder)]]
948 mkCastErr :: Type -> Type -> Message
949 mkCastErr from_ty expr_ty
950 = vcat [ptext (sLit "From-type of Cast differs from type of enclosed expression"),
951 ptext (sLit "From-type:") <+> ppr from_ty,
952 ptext (sLit "Type of enclosed expr:") <+> ppr expr_ty
955 dupVars :: [[Var]] -> Message
957 = hang (ptext (sLit "Duplicate variables brought into scope"))
960 mkStrangeTyMsg :: CoreExpr -> Message
962 = ptext (sLit "Type where expression expected:") <+> ppr e