2 % (c) The GRASP/AQUA Project, Glasgow University, 1993-1998
4 \section[CoreLint]{A ``lint'' pass to check for Core correctness}
13 #include "HsVersions.h"
16 import CoreFVs ( idFreeVars )
17 import CoreUtils ( findDefault, exprOkForSpeculation, coreBindsSize )
19 import Literal ( literalType )
20 import DataCon ( dataConRepType, dataConTyCon, dataConWorkId )
21 import TysWiredIn ( tupleCon )
22 import Var ( Var, Id, TyVar, isCoVar, idType, tyVarKind,
23 mustHaveLocalBinding, setTyVarKind, setIdType )
24 import VarEnv ( lookupInScope )
26 import Name ( getSrcLoc )
28 import ErrUtils ( dumpIfSet_core, ghcExit, Message, showPass,
29 mkLocMessage, debugTraceMsg )
30 import SrcLoc ( SrcLoc, noSrcLoc, mkSrcSpan )
31 import Type ( Type, tyVarsOfType, coreEqType,
33 splitForAllTy_maybe, splitTyConApp_maybe,
34 isUnLiftedType, typeKind, mkForAllTy, mkFunTy,
35 isUnboxedTupleType, isSubKind,
36 substTyWith, emptyTvSubst, extendTvInScope,
38 extendTvSubst, substTyVarBndr, isInScope,
40 import Coercion ( coercionKind, coercionKindPredTy )
41 import TyCon ( isPrimTyCon, isNewTyCon )
42 import BasicTypes ( RecFlag(..), Boxity(..), isNonRec )
43 import StaticFlags ( opt_PprStyle_Debug )
44 import DynFlags ( DynFlags, DynFlag(..), dopt )
48 import Util ( notNull )
55 %************************************************************************
59 %************************************************************************
61 @showPass@ and @endPass@ don't really belong here, but it makes a convenient
62 place for them. They print out stuff before and after core passes,
63 and do Core Lint when necessary.
66 endPass :: DynFlags -> String -> DynFlag -> [CoreBind] -> IO [CoreBind]
67 endPass dflags pass_name dump_flag binds
69 -- Report result size if required
70 -- This has the side effect of forcing the intermediate to be evaluated
71 debugTraceMsg dflags 2 $
72 (text " Result size =" <+> int (coreBindsSize binds))
74 -- Report verbosely, if required
75 dumpIfSet_core dflags dump_flag pass_name (pprCoreBindings binds)
78 lintCoreBindings dflags pass_name binds
84 %************************************************************************
86 \subsection[lintCoreBindings]{@lintCoreBindings@: Top-level interface}
88 %************************************************************************
90 Checks that a set of core bindings is well-formed. The PprStyle and String
91 just control what we print in the event of an error. The Bool value
92 indicates whether we have done any specialisation yet (in which case we do
97 (b) Out-of-scope type variables
98 (c) Out-of-scope local variables
101 If we have done specialisation the we check that there are
102 (a) No top-level bindings of primitive (unboxed type)
107 -- Things are *not* OK if:
109 -- * Unsaturated type app before specialisation has been done;
111 -- * Oversaturated type app after specialisation (eta reduction
112 -- may well be happening...);
117 In the desugarer, it's very very convenient to be able to say (in effect)
118 let a = Int in <body>
119 That is, use a type let. (See notes just below for why we want this.)
121 We don't have type lets in Core, so the desugarer uses type lambda
123 However, in the lambda form, we'd get lint errors from:
124 (/\a. let x::a = 4 in <body>) Int
125 because (x::a) doesn't look compatible with (4::Int).
127 So (HACK ALERT) the Lint phase does type-beta reduction "on the fly",
128 as it were. It carries a type substitution (in this example [a -> Int])
129 and applies this substitution before comparing types. The functin
130 lintTy :: Type -> LintM Type
131 returns a substituted type; that's the only reason it returns anything.
133 When we encounter a binder (like x::a) we must apply the substitution
134 to the type of the binding variable. lintBinders does this.
136 For Ids, the type-substituted Id is added to the in_scope set (which
137 itself is part of the TvSubst we are carrying down), and when we
138 find an occurence of an Id, we fetch it from the in-scope set.
143 It's needed when dealing with desugarer output for GADTs. Consider
144 data T = forall a. T a (a->Int) Bool
146 f (T x f True) = <e1>
147 f (T y g False) = <e2>
148 After desugaring we get
150 T a (x::a) (f::a->Int) (b:Bool) ->
153 False -> (/\b. let y=x; g=f in <e2>) a
154 And for a reason I now forget, the ...<e2>... can mention a; so
155 we want Lint to know that b=a. Ugh.
157 I tried quite hard to make the necessity for this go away, by changing the
158 desugarer, but the fundamental problem is this:
160 T a (x::a) (y::Int) -> let fail::a = ...
161 in (/\b. ...(case ... of
165 Now the inner case look as though it has incompatible branches.
169 lintCoreBindings :: DynFlags -> String -> [CoreBind] -> IO ()
171 lintCoreBindings dflags whoDunnit binds
172 | not (dopt Opt_DoCoreLinting dflags)
175 lintCoreBindings dflags whoDunnit binds
176 = case (initL (lint_binds binds)) of
177 Nothing -> showPass dflags ("Core Linted result of " ++ whoDunnit)
178 Just bad_news -> printDump (display bad_news) >>
181 -- Put all the top-level binders in scope at the start
182 -- This is because transformation rules can bring something
183 -- into use 'unexpectedly'
184 lint_binds binds = addInScopeVars (bindersOfBinds binds) $
187 lint_bind (Rec prs) = mapM_ (lintSingleBinding Recursive) prs
188 lint_bind (NonRec bndr rhs) = lintSingleBinding NonRecursive (bndr,rhs)
191 = vcat [ text ("*** Core Lint Errors: in result of " ++ whoDunnit ++ " ***"),
193 ptext SLIT("*** Offending Program ***"),
194 pprCoreBindings binds,
195 ptext SLIT("*** End of Offense ***")
199 %************************************************************************
201 \subsection[lintUnfolding]{lintUnfolding}
203 %************************************************************************
205 We use this to check all unfoldings that come in from interfaces
206 (it is very painful to catch errors otherwise):
209 lintUnfolding :: SrcLoc
210 -> [Var] -- Treat these as in scope
212 -> Maybe Message -- Nothing => OK
214 lintUnfolding locn vars expr
215 = initL (addLoc (ImportedUnfolding locn) $
216 addInScopeVars vars $
220 %************************************************************************
222 \subsection[lintCoreBinding]{lintCoreBinding}
224 %************************************************************************
226 Check a core binding, returning the list of variables bound.
229 lintSingleBinding rec_flag (binder,rhs)
230 = addLoc (RhsOf binder) $
232 do { ty <- lintCoreExpr rhs
233 ; lintBinder binder -- Check match to RHS type
234 ; binder_ty <- applySubst binder_ty
235 ; checkTys binder_ty ty (mkRhsMsg binder ty)
236 -- Check (not isUnLiftedType) (also checks for bogus unboxed tuples)
237 ; checkL (not (isUnLiftedType binder_ty)
238 || (isNonRec rec_flag && exprOkForSpeculation rhs))
239 (mkRhsPrimMsg binder rhs)
240 -- Check whether binder's specialisations contain any out-of-scope variables
241 ; mapM_ (checkBndrIdInScope binder) bndr_vars }
243 -- We should check the unfolding, if any, but this is tricky because
244 -- the unfolding is a SimplifiableCoreExpr. Give up for now.
246 binder_ty = idType binder
247 bndr_vars = varSetElems (idFreeVars binder)
248 lintBinder var | isId var = lintIdBndr var $ \_ -> (return ())
249 | otherwise = return ()
252 %************************************************************************
254 \subsection[lintCoreExpr]{lintCoreExpr}
256 %************************************************************************
259 type InType = Type -- Substitution not yet applied
260 type OutType = Type -- Substitution has been applied to this
262 lintCoreExpr :: CoreExpr -> LintM OutType
263 -- The returned type has the substitution from the monad
264 -- already applied to it:
265 -- lintCoreExpr e subst = exprType (subst e)
267 lintCoreExpr (Var var)
268 = do { checkL (not (var == oneTupleDataConId))
269 (ptext SLIT("Illegal one-tuple"))
270 ; var' <- lookupIdInScope var
271 ; return (idType var')
274 lintCoreExpr (Lit lit)
275 = return (literalType lit)
277 --lintCoreExpr (Note (Coerce to_ty from_ty) expr)
278 -- = do { expr_ty <- lintCoreExpr expr
279 -- ; to_ty <- lintTy to_ty
280 -- ; from_ty <- lintTy from_ty
281 -- ; checkTys from_ty expr_ty (mkCoerceErr from_ty expr_ty)
284 lintCoreExpr (Cast expr co)
285 = do { expr_ty <- lintCoreExpr expr
287 ; let (from_ty, to_ty) = coercionKind co'
288 ; checkTys from_ty expr_ty (mkCastErr from_ty expr_ty)
291 lintCoreExpr (Note other_note expr)
294 lintCoreExpr (Let (NonRec bndr rhs) body)
295 = do { lintSingleBinding NonRecursive (bndr,rhs)
296 ; addLoc (BodyOfLetRec [bndr])
297 (lintAndScopeId bndr $ \_ -> (lintCoreExpr body)) }
299 lintCoreExpr (Let (Rec pairs) body)
300 = lintAndScopeIds bndrs $ \_ ->
301 do { mapM (lintSingleBinding Recursive) pairs
302 ; addLoc (BodyOfLetRec bndrs) (lintCoreExpr body) }
304 bndrs = map fst pairs
306 lintCoreExpr e@(App fun (Type ty))
307 -- See Note [Type let] above
308 = addLoc (AnExpr e) $
311 go (App fun (Type ty)) tys
312 = do { go fun (ty:tys) }
313 go (Lam tv body) (ty:tys)
314 = do { checkL (isTyVar tv) (mkKindErrMsg tv ty) -- Not quite accurate
316 ; let kind = tyVarKind tv
317 ; kind' <- lintTy kind
318 ; let tv' = setTyVarKind tv kind'
320 -- Now extend the substitution so we
321 -- take advantage of it in the body
322 ; addInScopeVars [tv'] $
323 extendSubstL tv' ty' $
326 = do { fun_ty <- lintCoreExpr fun
327 ; lintCoreArgs fun_ty (map Type tys) }
329 lintCoreExpr e@(App fun arg)
330 = do { fun_ty <- lintCoreExpr fun
331 ; addLoc (AnExpr e) $
332 lintCoreArg fun_ty arg }
334 lintCoreExpr (Lam var expr)
335 = addLoc (LambdaBodyOf var) $
336 lintBinders [var] $ \[var'] ->
337 do { body_ty <- lintCoreExpr expr
339 return (mkFunTy (idType var') body_ty)
341 return (mkForAllTy var' body_ty)
343 -- The applySubst is needed to apply the subst to var
345 lintCoreExpr e@(Case scrut var alt_ty alts) =
346 -- Check the scrutinee
347 do { scrut_ty <- lintCoreExpr scrut
348 ; alt_ty <- lintTy alt_ty
349 ; var_ty <- lintTy (idType var)
350 -- Don't use lintIdBndr on var, because unboxed tuple is legitimate
352 ; subst <- getTvSubst
353 ; checkTys var_ty scrut_ty (mkScrutMsg var var_ty scrut_ty subst)
355 -- If the binder is an unboxed tuple type, don't put it in scope
356 ; let scope = if (isUnboxedTupleType (idType var)) then
358 else lintAndScopeId var
360 do { -- Check the alternatives
361 checkCaseAlts e scrut_ty alts
362 ; mapM (lintCoreAlt scrut_ty alt_ty) alts
367 lintCoreExpr e@(Type ty)
368 = addErrL (mkStrangeTyMsg e)
371 %************************************************************************
373 \subsection[lintCoreArgs]{lintCoreArgs}
375 %************************************************************************
377 The basic version of these functions checks that the argument is a
378 subtype of the required type, as one would expect.
381 lintCoreArgs :: Type -> [CoreArg] -> LintM Type
382 lintCoreArg :: Type -> CoreArg -> LintM Type
383 -- First argument has already had substitution applied to it
387 lintCoreArgs ty [] = return ty
388 lintCoreArgs ty (a : args) =
389 do { res <- lintCoreArg ty a
390 ; lintCoreArgs res args }
392 lintCoreArg fun_ty a@(Type arg_ty) =
393 do { arg_ty <- lintTy arg_ty
394 ; lintTyApp fun_ty arg_ty }
396 lintCoreArg fun_ty arg =
397 -- Make sure function type matches argument
398 do { arg_ty <- lintCoreExpr arg
399 ; let err1 = mkAppMsg fun_ty arg_ty arg
400 err2 = mkNonFunAppMsg fun_ty arg_ty arg
401 ; case splitFunTy_maybe fun_ty of
403 do { checkTys arg arg_ty err1
409 -- Both args have had substitution applied
411 = case splitForAllTy_maybe ty of
412 Nothing -> addErrL (mkTyAppMsg ty arg_ty)
415 -> do { checkL (isTyVar tyvar) (mkTyAppMsg ty arg_ty)
416 ; checkKinds tyvar arg_ty
417 ; return (substTyWith [tyvar] [arg_ty] body) }
419 checkKinds tyvar arg_ty
420 -- Arg type might be boxed for a function with an uncommitted
421 -- tyvar; notably this is used so that we can give
422 -- error :: forall a:*. String -> a
423 -- and then apply it to both boxed and unboxed types.
424 = checkL (arg_kind `isSubKind` tyvar_kind)
425 (mkKindErrMsg tyvar arg_ty)
427 tyvar_kind = tyVarKind tyvar
428 arg_kind | isCoVar tyvar = coercionKindPredTy arg_ty
429 | otherwise = typeKind arg_ty
433 %************************************************************************
435 \subsection[lintCoreAlts]{lintCoreAlts}
437 %************************************************************************
440 checkCaseAlts :: CoreExpr -> OutType -> [CoreAlt] -> LintM ()
441 -- a) Check that the alts are non-empty
442 -- b1) Check that the DEFAULT comes first, if it exists
443 -- b2) Check that the others are in increasing order
444 -- c) Check that there's a default for infinite types
445 -- NB: Algebraic cases are not necessarily exhaustive, because
446 -- the simplifer correctly eliminates case that can't
449 checkCaseAlts e ty []
450 = addErrL (mkNullAltsMsg e)
452 checkCaseAlts e ty alts =
453 do { checkL (all non_deflt con_alts) (mkNonDefltMsg e)
454 ; checkL (increasing_tag con_alts) (mkNonIncreasingAltsMsg e)
455 ; checkL (isJust maybe_deflt || not is_infinite_ty)
456 (nonExhaustiveAltsMsg e) }
458 (con_alts, maybe_deflt) = findDefault alts
460 -- Check that successive alternatives have increasing tags
461 increasing_tag (alt1 : rest@( alt2 : _)) = alt1 `ltAlt` alt2 && increasing_tag rest
462 increasing_tag other = True
464 non_deflt (DEFAULT, _, _) = False
467 is_infinite_ty = case splitTyConApp_maybe ty of
469 Just (tycon, tycon_arg_tys) -> isPrimTyCon tycon
473 checkAltExpr :: CoreExpr -> OutType -> LintM ()
474 checkAltExpr expr ann_ty
475 = do { actual_ty <- lintCoreExpr expr
476 ; checkTys actual_ty ann_ty (mkCaseAltMsg expr actual_ty ann_ty) }
478 lintCoreAlt :: OutType -- Type of scrutinee
479 -> OutType -- Type of the alternative
483 lintCoreAlt scrut_ty alt_ty alt@(DEFAULT, args, rhs) =
484 do { checkL (null args) (mkDefaultArgsMsg args)
485 ; checkAltExpr rhs alt_ty }
487 lintCoreAlt scrut_ty alt_ty alt@(LitAlt lit, args, rhs) =
488 do { checkL (null args) (mkDefaultArgsMsg args)
489 ; checkTys lit_ty scrut_ty (mkBadPatMsg lit_ty scrut_ty)
490 ; checkAltExpr rhs alt_ty }
492 lit_ty = literalType lit
494 lintCoreAlt scrut_ty alt_ty alt@(DataAlt con, args, rhs)
495 | isNewTyCon (dataConTyCon con) = addErrL (mkNewTyDataConAltMsg scrut_ty alt)
496 | Just (tycon, tycon_arg_tys) <- splitTyConApp_maybe scrut_ty
497 = addLoc (CaseAlt alt) $ do
498 { -- First instantiate the universally quantified
499 -- type variables of the data constructor
500 con_payload_ty <- lintCoreArgs (dataConRepType con) (map Type tycon_arg_tys)
502 -- And now bring the new binders into scope
503 ; lintBinders args $ \ args -> do
504 { addLoc (CasePat alt) $ do
505 { -- Check the pattern
506 -- Scrutinee type must be a tycon applicn; checked by caller
507 -- This code is remarkably compact considering what it does!
508 -- NB: args must be in scope here so that the lintCoreArgs line works.
509 -- NB: relies on existential type args coming *after* ordinary type args
511 ; con_result_ty <- lintCoreArgs con_payload_ty (varsToCoreExprs args)
512 ; checkTys con_result_ty scrut_ty (mkBadPatMsg con_result_ty scrut_ty)
515 ; checkAltExpr rhs alt_ty } }
517 | otherwise -- Scrut-ty is wrong shape
518 = addErrL (mkBadAltMsg scrut_ty alt)
521 %************************************************************************
523 \subsection[lint-types]{Types}
525 %************************************************************************
528 -- When we lint binders, we (one at a time and in order):
529 -- 1. Lint var types or kinds (possibly substituting)
530 -- 2. Add the binder to the in scope set, and if its a coercion var,
531 -- we may extend the substitution to reflect its (possibly) new kind
532 lintBinders :: [Var] -> ([Var] -> LintM a) -> LintM a
533 lintBinders [] linterF = linterF []
534 lintBinders (var:vars) linterF = lintBinder var $ \var' ->
535 lintBinders vars $ \ vars' ->
538 lintBinder :: Var -> (Var -> LintM a) -> LintM a
539 lintBinder var linterF
540 | isTyVar var = lint_ty_bndr
541 | otherwise = lintIdBndr var linterF
543 lint_ty_bndr = do { lintTy (tyVarKind var)
544 ; subst <- getTvSubst
545 ; let (subst', tv') = substTyVarBndr subst var
546 ; updateTvSubst subst' (linterF tv') }
548 lintIdBndr :: Var -> (Var -> LintM a) -> LintM a
549 -- Do substitution on the type of a binder and add the var with this
550 -- new type to the in-scope set of the second argument
551 -- ToDo: lint its rules
552 lintIdBndr id linterF
553 = do { checkL (not (isUnboxedTupleType (idType id)))
554 (mkUnboxedTupleMsg id)
555 -- No variable can be bound to an unboxed tuple.
556 ; lintAndScopeId id $ \id' -> linterF id'
559 lintAndScopeIds :: [Var] -> ([Var] -> LintM a) -> LintM a
560 lintAndScopeIds ids linterF
564 go (id:ids) = do { lintAndScopeId id $ \id ->
565 lintAndScopeIds ids $ \ids ->
568 lintAndScopeId :: Var -> (Var -> LintM a) -> LintM a
569 lintAndScopeId id linterF
570 = do { ty <- lintTy (idType id)
571 ; let id' = setIdType id ty
572 ; addInScopeVars [id'] $ (linterF id')
575 lintTy :: InType -> LintM OutType
576 -- Check the type, and apply the substitution to it
577 -- ToDo: check the kind structure of the type
579 = do { ty' <- applySubst ty
580 ; mapM_ checkTyVarInScope (varSetElems (tyVarsOfType ty'))
585 %************************************************************************
587 \subsection[lint-monad]{The Lint monad}
589 %************************************************************************
594 [LintLocInfo] -> -- Locations
595 TvSubst -> -- Current type substitution; we also use this
596 -- to keep track of all the variables in scope,
597 -- both Ids and TyVars
598 Bag Message -> -- Error messages so far
599 (Maybe a, Bag Message) } -- Result and error messages (if any)
601 {- Note [Type substitution]
602 ~~~~~~~~~~~~~~~~~~~~~~~~
603 Why do we need a type substitution? Consider
604 /\(a:*). \(x:a). /\(a:*). id a x
605 This is ill typed, because (renaming variables) it is really
606 /\(a:*). \(x:a). /\(b:*). id b x
607 Hence, when checking an application, we can't naively compare x's type
608 (at its binding site) with its expected type (at a use site). So we
609 rename type binders as we go, maintaining a substitution.
611 The same substitution also supports let-type, current expressed as
613 Here we substitute 'ty' for 'a' in 'body', on the fly.
616 instance Monad LintM where
617 return x = LintM (\ loc subst errs -> (Just x, errs))
618 fail err = LintM (\ loc subst errs -> (Nothing, addErr subst errs (text err) loc))
619 m >>= k = LintM (\ loc subst errs ->
620 let (res, errs') = unLintM m loc subst errs in
622 Just r -> unLintM (k r) loc subst errs'
623 Nothing -> (Nothing, errs'))
626 = RhsOf Id -- The variable bound
627 | LambdaBodyOf Id -- The lambda-binder
628 | BodyOfLetRec [Id] -- One of the binders
629 | CaseAlt CoreAlt -- Case alternative
630 | CasePat CoreAlt -- *Pattern* of the case alternative
631 | AnExpr CoreExpr -- Some expression
632 | ImportedUnfolding SrcLoc -- Some imported unfolding (ToDo: say which)
637 initL :: LintM a -> Maybe Message {- errors -}
639 = case unLintM m [] emptyTvSubst emptyBag of
640 (_, errs) | isEmptyBag errs -> Nothing
641 | otherwise -> Just (vcat (punctuate (text "") (bagToList errs)))
645 checkL :: Bool -> Message -> LintM ()
646 checkL True msg = return ()
647 checkL False msg = addErrL msg
649 addErrL :: Message -> LintM a
650 addErrL msg = LintM (\ loc subst errs -> (Nothing, addErr subst errs msg loc))
652 addErr :: TvSubst -> Bag Message -> Message -> [LintLocInfo] -> Bag Message
653 addErr subst errs_so_far msg locs
654 = ASSERT( notNull locs )
655 errs_so_far `snocBag` mk_msg msg
657 (loc, cxt1) = dumpLoc (head locs)
658 cxts = [snd (dumpLoc loc) | loc <- locs]
659 context | opt_PprStyle_Debug = vcat (reverse cxts) $$ cxt1 $$
660 ptext SLIT("Substitution:") <+> ppr subst
663 mk_msg msg = mkLocMessage (mkSrcSpan loc loc) (context $$ msg)
665 addLoc :: LintLocInfo -> LintM a -> LintM a
667 LintM (\ loc subst errs -> unLintM m (extra_loc:loc) subst errs)
669 addInScopeVars :: [Var] -> LintM a -> LintM a
670 addInScopeVars vars m =
671 LintM (\ loc subst errs -> unLintM m loc (extendTvInScope subst vars) errs)
673 updateTvSubst :: TvSubst -> LintM a -> LintM a
674 updateTvSubst subst' m =
675 LintM (\ loc subst errs -> unLintM m loc subst' errs)
677 getTvSubst :: LintM TvSubst
678 getTvSubst = LintM (\ loc subst errs -> (Just subst, errs))
680 applySubst :: Type -> LintM Type
681 applySubst ty = do { subst <- getTvSubst; return (substTy subst ty) }
683 extendSubstL :: TyVar -> Type -> LintM a -> LintM a
685 = LintM (\ loc subst errs -> unLintM m loc (extendTvSubst subst tv ty) errs)
689 lookupIdInScope :: Id -> LintM Id
691 | not (mustHaveLocalBinding id)
692 = return id -- An imported Id
694 = do { subst <- getTvSubst
695 ; case lookupInScope (getTvInScope subst) id of
697 Nothing -> do { addErrL out_of_scope
700 out_of_scope = ppr id <+> ptext SLIT("is out of scope")
703 oneTupleDataConId :: Id -- Should not happen
704 oneTupleDataConId = dataConWorkId (tupleCon Boxed 1)
706 checkBndrIdInScope :: Var -> Var -> LintM ()
707 checkBndrIdInScope binder id
708 = checkInScope msg id
710 msg = ptext SLIT("is out of scope inside info for") <+>
713 checkTyVarInScope :: TyVar -> LintM ()
714 checkTyVarInScope tv = checkInScope (ptext SLIT("is out of scope")) tv
716 checkInScope :: SDoc -> Var -> LintM ()
717 checkInScope loc_msg var =
718 do { subst <- getTvSubst
719 ; checkL (not (mustHaveLocalBinding var) || (var `isInScope` subst))
720 (hsep [ppr var, loc_msg]) }
722 checkTys :: Type -> Type -> Message -> LintM ()
723 -- check ty2 is subtype of ty1 (ie, has same structure but usage
724 -- annotations need only be consistent, not equal)
725 -- Assumes ty1,ty2 are have alrady had the substitution applied
726 checkTys ty1 ty2 msg = checkL (ty1 `coreEqType` ty2) msg
729 %************************************************************************
731 \subsection{Error messages}
733 %************************************************************************
737 = (getSrcLoc v, brackets (ptext SLIT("RHS of") <+> pp_binders [v]))
739 dumpLoc (LambdaBodyOf b)
740 = (getSrcLoc b, brackets (ptext SLIT("in body of lambda with binder") <+> pp_binder b))
742 dumpLoc (BodyOfLetRec [])
743 = (noSrcLoc, brackets (ptext SLIT("In body of a letrec with no binders")))
745 dumpLoc (BodyOfLetRec bs@(_:_))
746 = ( getSrcLoc (head bs), brackets (ptext SLIT("in body of letrec with binders") <+> pp_binders bs))
749 = (noSrcLoc, text "In the expression:" <+> ppr e)
751 dumpLoc (CaseAlt (con, args, rhs))
752 = (noSrcLoc, text "In a case alternative:" <+> parens (ppr con <+> pp_binders args))
754 dumpLoc (CasePat (con, args, rhs))
755 = (noSrcLoc, text "In the pattern of a case alternative:" <+> parens (ppr con <+> pp_binders args))
757 dumpLoc (ImportedUnfolding locn)
758 = (locn, brackets (ptext SLIT("in an imported unfolding")))
760 pp_binders :: [Var] -> SDoc
761 pp_binders bs = sep (punctuate comma (map pp_binder bs))
763 pp_binder :: Var -> SDoc
764 pp_binder b | isId b = hsep [ppr b, dcolon, ppr (idType b)]
765 | isTyVar b = hsep [ppr b, dcolon, ppr (tyVarKind b)]
769 ------------------------------------------------------
770 -- Messages for case expressions
772 mkNullAltsMsg :: CoreExpr -> Message
774 = hang (text "Case expression with no alternatives:")
777 mkDefaultArgsMsg :: [Var] -> Message
778 mkDefaultArgsMsg args
779 = hang (text "DEFAULT case with binders")
782 mkCaseAltMsg :: CoreExpr -> Type -> Type -> Message
783 mkCaseAltMsg e ty1 ty2
784 = hang (text "Type of case alternatives not the same as the annotation on case:")
785 4 (vcat [ppr ty1, ppr ty2, ppr e])
787 mkScrutMsg :: Id -> Type -> Type -> TvSubst -> Message
788 mkScrutMsg var var_ty scrut_ty subst
789 = vcat [text "Result binder in case doesn't match scrutinee:" <+> ppr var,
790 text "Result binder type:" <+> ppr var_ty,--(idType var),
791 text "Scrutinee type:" <+> ppr scrut_ty,
792 hsep [ptext SLIT("Current TV subst"), ppr subst]]
796 = hang (text "Case expression with DEFAULT not at the beginnning") 4 (ppr e)
797 mkNonIncreasingAltsMsg e
798 = hang (text "Case expression with badly-ordered alternatives") 4 (ppr e)
800 nonExhaustiveAltsMsg :: CoreExpr -> Message
801 nonExhaustiveAltsMsg e
802 = hang (text "Case expression with non-exhaustive alternatives") 4 (ppr e)
804 mkBadPatMsg :: Type -> Type -> Message
805 mkBadPatMsg con_result_ty scrut_ty
807 text "In a case alternative, pattern result type doesn't match scrutinee type:",
808 text "Pattern result type:" <+> ppr con_result_ty,
809 text "Scrutinee type:" <+> ppr scrut_ty
812 mkBadAltMsg :: Type -> CoreAlt -> Message
813 mkBadAltMsg scrut_ty alt
814 = vcat [ text "Data alternative when scrutinee is not a tycon application",
815 text "Scrutinee type:" <+> ppr scrut_ty,
816 text "Alternative:" <+> pprCoreAlt alt ]
818 mkNewTyDataConAltMsg :: Type -> CoreAlt -> Message
819 mkNewTyDataConAltMsg scrut_ty alt
820 = vcat [ text "Data alternative for newtype datacon",
821 text "Scrutinee type:" <+> ppr scrut_ty,
822 text "Alternative:" <+> pprCoreAlt alt ]
825 ------------------------------------------------------
826 -- Other error messages
828 mkAppMsg :: Type -> Type -> CoreExpr -> Message
829 mkAppMsg fun_ty arg_ty arg
830 = vcat [ptext SLIT("Argument value doesn't match argument type:"),
831 hang (ptext SLIT("Fun type:")) 4 (ppr fun_ty),
832 hang (ptext SLIT("Arg type:")) 4 (ppr arg_ty),
833 hang (ptext SLIT("Arg:")) 4 (ppr arg)]
835 mkNonFunAppMsg :: Type -> Type -> CoreExpr -> Message
836 mkNonFunAppMsg fun_ty arg_ty arg
837 = vcat [ptext SLIT("Non-function type in function position"),
838 hang (ptext SLIT("Fun type:")) 4 (ppr fun_ty),
839 hang (ptext SLIT("Arg type:")) 4 (ppr arg_ty),
840 hang (ptext SLIT("Arg:")) 4 (ppr arg)]
842 mkKindErrMsg :: TyVar -> Type -> Message
843 mkKindErrMsg tyvar arg_ty
844 = vcat [ptext SLIT("Kinds don't match in type application:"),
845 hang (ptext SLIT("Type variable:"))
846 4 (ppr tyvar <+> dcolon <+> ppr (tyVarKind tyvar)),
847 hang (ptext SLIT("Arg type:"))
848 4 (ppr arg_ty <+> dcolon <+> ppr (typeKind arg_ty))]
850 mkTyAppMsg :: Type -> Type -> Message
852 = vcat [text "Illegal type application:",
853 hang (ptext SLIT("Exp type:"))
854 4 (ppr ty <+> dcolon <+> ppr (typeKind ty)),
855 hang (ptext SLIT("Arg type:"))
856 4 (ppr arg_ty <+> dcolon <+> ppr (typeKind arg_ty))]
858 mkRhsMsg :: Id -> Type -> Message
861 [hsep [ptext SLIT("The type of this binder doesn't match the type of its RHS:"),
863 hsep [ptext SLIT("Binder's type:"), ppr (idType binder)],
864 hsep [ptext SLIT("Rhs type:"), ppr ty]]
866 mkRhsPrimMsg :: Id -> CoreExpr -> Message
867 mkRhsPrimMsg binder rhs
868 = vcat [hsep [ptext SLIT("The type of this binder is primitive:"),
870 hsep [ptext SLIT("Binder's type:"), ppr (idType binder)]
873 mkUnboxedTupleMsg :: Id -> Message
874 mkUnboxedTupleMsg binder
875 = vcat [hsep [ptext SLIT("A variable has unboxed tuple type:"), ppr binder],
876 hsep [ptext SLIT("Binder's type:"), ppr (idType binder)]]
878 mkCastErr from_ty expr_ty
879 = vcat [ptext SLIT("From-type of Cast differs from type of enclosed expression"),
880 ptext SLIT("From-type:") <+> ppr from_ty,
881 ptext SLIT("Type of enclosed expr:") <+> ppr expr_ty
885 = ptext SLIT("Type where expression expected:") <+> ppr e