2 % (c) The GRASP/AQUA Project, Glasgow University, 1993-1998
4 \section[MkIface]{Print an interface for a module}
7 module MkIface ( writeIface ) where
9 #include "HsVersions.h"
11 import IO ( Handle, hPutStr, openFile,
12 hClose, hPutStrLn, IOMode(..) )
15 import HsCore ( HsIdInfo(..), toUfExpr )
16 import RdrHsSyn ( RdrNameRuleDecl )
17 import HsPragmas ( DataPragmas(..), ClassPragmas(..) )
18 import HsTypes ( toHsTyVars )
19 import BasicTypes ( Fixity(..), FixityDirection(..), NewOrData(..),
20 Version, bumpVersion, initialVersion, isLoopBreaker
24 import TcInstUtil ( InstInfo(..) )
27 import Id ( Id, idType, idInfo, omitIfaceSigForId, isUserExportedId, hasNoBinding,
32 import DataCon ( StrictnessMark(..), dataConSig, dataConFieldLabels, dataConStrictMarks )
33 import IdInfo ( IdInfo, StrictnessInfo(..), ArityInfo(..), InlinePragInfo(..),
34 CprInfo(..), CafInfo(..),
35 inlinePragInfo, arityInfo, arityLowerBound,
36 strictnessInfo, isBottomingStrictness,
37 cafInfo, specInfo, cprInfo,
38 occInfo, isNeverInlinePrag,
39 workerExists, workerInfo, WorkerInfo(..)
41 import CoreSyn ( CoreExpr, CoreBind, Bind(..), isBuiltinRule, rulesRules, rulesRhsFreeVars )
42 import CoreFVs ( exprSomeFreeVars, ruleSomeLhsFreeVars, ruleSomeFreeVars )
43 import CoreUnfold ( okToUnfoldInHiFile, couldBeSmallEnoughToInline )
44 import Module ( moduleString, pprModule, pprModuleName, moduleUserString )
45 import Name ( isLocallyDefined, isWiredInName, toRdrName, nameModule,
48 import OccName ( OccName, pprOccName )
49 import TyCon ( TyCon, getSynTyConDefn, isSynTyCon, isNewTyCon, isAlgTyCon,
50 tyConTheta, tyConTyVars, tyConDataCons, tyConFamilySize
52 import Class ( Class, classExtraBigSig )
53 import FieldLabel ( fieldLabelName, fieldLabelType )
54 import Type ( mkSigmaTy, splitSigmaTy, mkDictTy, tidyTopType,
55 deNoteType, classesToPreds,
56 Type, ThetaType, PredType(..), ClassContext
60 import Rules ( pprProtoCoreRule, ProtoCoreRule(..) )
62 import Bag ( bagToList, isEmptyBag )
63 import Maybes ( catMaybes, maybeToBool )
64 import UniqFM ( lookupUFM, listToUFM )
65 import Util ( sortLt, mapAccumL )
66 import SrcLoc ( noSrcLoc )
69 import ErrUtils ( dumpIfSet )
71 import Maybe ( isNothing )
72 import List ( partition )
77 %************************************************************************
79 \subsection{Write a new interface file}
81 %************************************************************************
84 writeIface this_mod old_iface new_iface
85 local_tycons local_classes inst_info
86 final_ids tidy_binds tidy_orphan_rules
88 if isNothing opt_HiDir && isNothing opt_HiFile
89 then return () -- not producing any .hi file
93 hi_suf = case opt_HiSuf of { Nothing -> "hi"; Just suf -> suf }
94 filename = case opt_HiFile of {
98 Just dir -> dir ++ '/':moduleUserString this_mod
100 Nothing -> panic "writeIface"
104 do maybe_final_iface <- checkIface old_iface full_new_iface
105 case maybe_final_iface of {
106 Nothing -> when opt_D_dump_rn_trace $
107 putStrLn "Interface file unchanged" ; -- No need to update .hi file
111 do let mod_vers_unchanged = case old_iface of
112 Just iface -> pi_vers iface == pi_vers final_iface
114 when (mod_vers_unchanged && opt_D_dump_rn_trace) $
115 putStrLn "Module version unchanged, but usages differ; hence need new hi file"
117 if_hdl <- openFile filename WriteMode
118 printForIface if_hdl (pprIface final_iface)
122 full_new_iface = completeIface new_iface local_tycons local_classes
123 inst_info final_ids tidy_binds
128 %************************************************************************
130 \subsection{Checking if the new interface is up to date
132 %************************************************************************
135 checkIface :: Maybe ParsedIface -- The old interface, read from M.hi
136 -> ParsedIface -- The new interface; but with all version numbers = 1
137 -> IO (Maybe ParsedIface) -- Nothing => no change; no need to write new Iface
138 -- Just pi => Here is the new interface to write
139 -- with correct version numbers
140 -- The I/O part is just so it can print differences
142 -- NB: the fixities, declarations, rules are all assumed
143 -- to be sorted by increasing order of hsDeclName, so that
144 -- we can compare for equality
146 checkIface Nothing new_iface
147 -- No old interface, so definitely write a new one!
148 = return (Just new_iface)
150 checkIface (Just iface) new_iface
151 | no_output_change && no_usage_change
154 | otherwise -- Add updated version numbers
155 = do { dumpIfSet opt_D_dump_hi_diffs "Interface file changes" pp_diffs ;
156 return (Just new_iface )}
159 final_iface = new_iface { pi_vers = new_mod_vers,
160 pi_fixity = (new_fixity_vers, new_fixities),
161 pi_rules = (new_rules_vers, new_rules),
162 pi_decls = final_decls }
164 no_usage_change = pi_usages iface == pi_usages new_iface
166 no_output_change = no_decl_changed &&
167 new_fixity_vers == fixity_vers &&
168 new_rules_vers == rules_vers &&
171 no_export_change = pi_exports iface == pi_exports new_iface
173 new_mod_vers | no_output_change = mod_vers
174 | otherwise = bumpVersion mod_vers
176 mod_vers = pi_vers iface
178 (fixity_vers, fixities) = pi_fixity iface
179 (_, new_fixities) = pi_fixity new_iface
180 new_fixity_vers | fixities == new_fixities = fixity_vers
181 | otherwise = bumpVersion fixity_vers
183 (rules_vers, rules) = pi_rules iface
184 (_, new_rules) = pi_rules new_iface
185 new_rules_vers | rules == new_rules = rules_vers
186 | otherwise = bumpVersion rules_vers
188 (no_decl_changed, pp_diffs, final_decls) = merge_decls True empty [] (pi_decls iface) (pi_decls new_iface)
190 -- Fill in the version number on the new declarations
191 -- by looking at the old declarations.
192 -- Set the flag if anything changes.
193 -- Assumes that the decls are sorted by hsDeclName
194 merge_decls ok_so_far pp acc [] [] = (ok_so_far, pp, reverse acc)
195 merge_decls ok_so_far pp acc old [] = (False, pp, reverse acc)
196 merge_decls ok_so_far pp acc [] (nvd:nvds) = merge_decls False (pp $$ only_new nvd) (nvd:acc) [] nvds
197 merge_decls ok_so_far pp acc (vd@(v,d):vds) (nvd@(_,nd):nvds)
198 = case d_name `compare` nd_name of
199 LT -> merge_decls False (pp $$ only_old vd) acc vds (nvd:nvds)
200 GT -> merge_decls False (pp $$ only_new nvd) (nvd:acc) (vd:vds) nvds
201 EQ | d == nd -> merge_decls ok_so_far pp (vd:acc) vds nvds
202 | otherwise -> merge_decls False (pp $$ changed d nd) ((bumpVersion v, nd):acc) vds nvds
204 d_name = hsDeclName d
205 nd_name = hsDeclName nd
207 only_old (_,d) = ptext SLIT("Only in old iface:") <+> ppr d
208 only_new (_,d) = ptext SLIT("Only in new iface:") <+> ppr d
209 changed d nd = ptext SLIT("Changed in iface: ") <+> ((ptext SLIT("Old:") <+> ppr d) $$
210 (ptext SLIT("New:") <+> ppr nd))
215 %************************************************************************
217 \subsection{Printing the interface}
219 %************************************************************************
222 pprIface (ParsedIface { pi_mod = mod, pi_vers = mod_vers, pi_orphan = orphan,
223 pi_usages = usages, pi_exports = exports,
224 pi_fixity = (fix_vers, fixities),
225 pi_insts = insts, pi_decls = decls,
226 pi_rules = (rule_vers, rules), pi_deprecs = deprecs })
227 = vcat [ ptext SLIT("__interface")
228 <+> doubleQuotes (ptext opt_InPackage)
229 <+> ppr mod <+> ppr mod_vers <+> pp_sub_vers
230 <+> (if orphan then char '!' else empty)
231 <+> int opt_HiVersion
232 <+> ptext SLIT("where")
233 , vcat (map pprExport exports)
234 , vcat (map pprUsage usages)
235 , pprFixities fixities
236 , vcat [ppr i <+> semi | i <- insts]
237 , vcat [ppr_vers v <+> ppr d <> semi | (v,d) <- decls]
242 ppr_vers v | v == initialVersion = empty
245 | fix_vers == initialVersion && rule_vers == initialVersion = empty
246 | otherwise = brackets (ppr fix_vers <+> ppr rule_vers)
249 When printing export lists, we print like this:
251 AvailTC C [C, x, y] C(x,y)
252 AvailTC C [x, y] C!(x,y) -- Exporting x, y but not C
255 pprExport :: ExportItem -> SDoc
256 pprExport (mod, items)
257 = hsep [ ptext SLIT("__export "), ppr mod, hsep (map upp_avail items) ] <> semi
259 upp_avail :: RdrAvailInfo -> SDoc
260 upp_avail (Avail name) = pprOccName name
261 upp_avail (AvailTC name []) = empty
262 upp_avail (AvailTC name ns) = hcat [pprOccName name, bang, upp_export ns']
264 bang | name `elem` ns = empty
265 | otherwise = char '|'
266 ns' = filter (/= name) ns
268 upp_export [] = empty
269 upp_export names = braces (hsep (map pprOccName names))
274 pprUsage :: ImportVersion OccName -> SDoc
275 pprUsage (m, has_orphans, is_boot, whats_imported)
276 = hsep [ptext SLIT("import"), pprModuleName m,
278 upp_import_versions whats_imported
281 pp_orphan | has_orphans = char '!'
283 pp_boot | is_boot = char '@'
286 -- Importing the whole module is indicated by an empty list
287 upp_import_versions NothingAtAll = empty
288 upp_import_versions (Everything v) = dcolon <+> int v
289 upp_import_versions (Specifically vm vf vr nvs)
290 = dcolon <+> int vm <+> int vf <+> int vr <+> hsep [ ppr n <+> int v | (n,v) <- nvs ]
295 pprFixities [] = empty
296 pprFixities fixes = hsep (map ppr fixes) <> semi
299 pprRules rules = hsep [ptext SLIT("{-## __R"), hsep (map ppr rules), ptext SLIT("##-}")]
301 pprDeprecs [] = empty
302 pprDeprecs deps = hsep [ ptext SLIT("{-## __D"), guts, ptext SLIT("##-}")]
304 guts = hsep [ ppr ie <+> doubleQuotes (ppr txt) <> semi
305 | Deprecation ie txt _ <- deps ]
309 %************************************************************************
311 \subsection{Completing the new interface}
313 %************************************************************************
316 completeIface new_iface local_tycons local_classes
317 inst_info final_ids tidy_binds
319 = new_iface { pi_decls = [(initialVersion,d) | d <- sortLt lt_decl all_decls],
320 pi_insts = sortLt lt_inst_decl inst_dcls,
321 pi_rules = (initialVersion, rule_dcls)
324 all_decls = cls_dcls ++ ty_dcls ++ bagToList val_dcls
325 (inst_dcls, inst_ids) = ifaceInstances inst_info
326 cls_dcls = map ifaceClass local_classes
328 ty_dcls = map ifaceTyCon (filter (not . isWiredInName . getName) local_tycons)
330 (val_dcls, emitted_ids) = ifaceBinds (inst_ids `unionVarSet` orphan_rule_ids)
333 rule_dcls | opt_OmitInterfacePragmas = []
334 | otherwise = ifaceRules tidy_orphan_rules emitted_ids
336 orphan_rule_ids = unionVarSets [ ruleSomeFreeVars interestingId rule
337 | ProtoCoreRule _ _ rule <- tidy_orphan_rules]
339 lt_decl d1 d2 = hsDeclName d1 < hsDeclName d2
340 lt_inst_decl d1 d2 = instDeclName d1 < instDeclName d2
341 -- Even instance decls have names, namely the dfun name
345 %************************************************************************
347 \subsection{Completion stuff}
349 %************************************************************************
352 ifaceRules :: [ProtoCoreRule] -> IdSet -> [RdrNameRuleDecl]
353 ifaceRules rules emitted
354 = orphan_rules ++ local_rules
356 orphan_rules = [ toHsRule fn rule | ProtoCoreRule _ fn rule <- rules ]
357 local_rules = [ toHsRule fn rule
358 | fn <- varSetElems emitted,
359 rule <- rulesRules (idSpecialisation fn),
360 not (isBuiltinRule rule),
361 -- We can't print builtin rules in interface files
362 -- Since they are built in, an importing module
363 -- will have access to them anyway
365 -- Sept 00: I've disabled this test. It doesn't stop many, if any, rules
366 -- from coming out, and to make it work properly we need to add
367 all (`elemVarSet` emitted) (varSetElems (ruleSomeLhsFreeVars interestingId rule))
368 -- Spit out a rule only if all its lhs free vars are emitted
369 -- This is a good reason not to do it when we emit the Id itself
374 ifaceInstances :: Bag InstInfo -> ([RdrNameInstDecl], IdSet)
375 -- The IdSet is the needed dfuns
377 ifaceInstances inst_infos
378 = (decls, needed_ids)
380 decls = map to_decl togo_insts
381 togo_insts = filter is_togo_inst (bagToList inst_infos)
382 needed_ids = mkVarSet [dfun_id | InstInfo _ _ _ _ dfun_id _ _ _ <- togo_insts]
383 is_togo_inst (InstInfo _ _ _ _ dfun_id _ _ _) = isLocallyDefined dfun_id
386 to_decl (InstInfo clas tvs tys theta dfun_id _ _ _)
388 -- The deNoteType is very important. It removes all type
389 -- synonyms from the instance type in interface files.
390 -- That in turn makes sure that when reading in instance decls
391 -- from interface files that the 'gating' mechanism works properly.
392 -- Otherwise you could have
393 -- type Tibble = T Int
394 -- instance Foo Tibble where ...
395 -- and this instance decl wouldn't get imported into a module
396 -- that mentioned T but not Tibble.
397 forall_ty = mkSigmaTy tvs (classesToPreds theta)
398 (deNoteType (mkDictTy clas tys))
399 tidy_ty = tidyTopType forall_ty
401 InstDecl (toHsType tidy_ty) EmptyMonoBinds [] (Just (toRdrName dfun_id)) noSrcLoc
405 ifaceTyCon :: TyCon -> RdrNameHsDecl
408 = TyClD (TySynonym (toRdrName tycon)
409 (toHsTyVars tyvars) (toHsType ty)
412 (tyvars, ty) = getSynTyConDefn tycon
416 = TyClD (TyData new_or_data (toHsContext (tyConTheta tycon))
419 (map ifaceConDecl (tyConDataCons tycon))
420 (tyConFamilySize tycon)
421 Nothing NoDataPragmas noSrcLoc)
423 tyvars = tyConTyVars tycon
424 new_or_data | isNewTyCon tycon = NewType
425 | otherwise = DataType
427 ifaceConDecl data_con
428 = ConDecl (toRdrName data_con) (error "ifaceConDecl")
429 (toHsTyVars ex_tyvars)
430 (toHsContext ex_theta)
433 (tyvars1, _, ex_tyvars, ex_theta, arg_tys, tycon1) = dataConSig data_con
434 field_labels = dataConFieldLabels data_con
435 strict_marks = dataConStrictMarks data_con
438 = ASSERT( tycon == tycon1 && tyvars == tyvars1 )
439 VanillaCon (zipWith mk_bang_ty strict_marks arg_tys)
442 = RecCon (zipWith mk_field strict_marks field_labels)
444 mk_bang_ty NotMarkedStrict ty = Unbanged (toHsType ty)
445 mk_bang_ty (MarkedUnboxed _ _) ty = Unpacked (toHsType ty)
446 mk_bang_ty MarkedStrict ty = Banged (toHsType ty)
448 mk_field strict_mark field_label
449 = ([toRdrName field_label], mk_bang_ty strict_mark (fieldLabelType field_label))
452 = pprPanic "pprIfaceTyDecl" (ppr tycon)
455 = TyClD (ClassDecl (toHsContext sc_theta)
457 (toHsTyVars clas_tyvars)
459 (map toClassOpSig op_stuff)
460 EmptyMonoBinds NoClassPragmas
461 bogus bogus bogus [] noSrcLoc
464 bogus = error "ifaceClass"
465 (clas_tyvars, clas_fds, sc_theta, _, op_stuff) = classExtraBigSig clas
467 toClassOpSig (sel_id, dm_id, explicit_dm)
468 = ASSERT( sel_tyvars == clas_tyvars)
469 ClassOpSig (toRdrName sel_id) (Just (bogus, explicit_dm)) (toHsType op_ty) noSrcLoc
471 (sel_tyvars, _, op_ty) = splitSigmaTy (idType sel_id)
475 %************************************************************************
477 \subsection{Value bindings}
479 %************************************************************************
482 ifaceBinds :: IdSet -- These Ids are needed already
483 -> [Id] -- Ids used at code-gen time; they have better pragma info!
484 -> [CoreBind] -- In dependency order, later depend on earlier
485 -> (Bag RdrNameHsDecl, IdSet) -- Set of Ids actually spat out
487 ifaceBinds needed_ids final_ids binds
488 = go needed_ids (reverse binds) emptyBag emptyVarSet
489 -- Reverse so that later things will
490 -- provoke earlier ones to be emitted
492 final_id_map = listToUFM [(id,id) | id <- final_ids]
493 get_idinfo id = case lookupUFM final_id_map id of
494 Just id' -> idInfo id'
495 Nothing -> pprTrace "ifaceBinds not found:" (ppr id) $
498 -- The 'needed' set contains the Ids that are needed by earlier
499 -- interface file emissions. If the Id isn't in this set, and isn't
500 -- exported, there's no need to emit anything
501 need_id needed_set id = id `elemVarSet` needed_set || isUserExportedId id
503 go needed [] decls emitted
504 | not (isEmptyVarSet needed) = pprTrace "ifaceBinds: free vars:"
505 (sep (map ppr (varSetElems needed)))
507 | otherwise = (decls, emitted)
509 go needed (NonRec id rhs : binds) decls emitted
511 = if omitIfaceSigForId id then
512 go (needed `delVarSet` id) binds decls (emitted `extendVarSet` id)
514 go ((needed `unionVarSet` extras) `delVarSet` id)
516 (decl `consBag` decls)
517 (emitted `extendVarSet` id)
519 = go needed binds decls emitted
521 (decl, extras) = ifaceId get_idinfo False id rhs
523 -- Recursive groups are a bit more of a pain. We may only need one to
524 -- start with, but it may call out the next one, and so on. So we
525 -- have to look for a fixed point. We don't want necessarily them all,
526 -- because without -O we may only need the first one (if we don't emit
528 go needed (Rec pairs : binds) decls emitted
529 = go needed' binds decls' emitted'
531 (new_decls, new_emitted, extras) = go_rec needed pairs
532 decls' = new_decls `unionBags` decls
533 needed' = (needed `unionVarSet` extras) `minusVarSet` mkVarSet (map fst pairs)
534 emitted' = emitted `unionVarSet` new_emitted
536 go_rec :: IdSet -> [(Id,CoreExpr)] -> (Bag RdrNameHsDecl, IdSet, IdSet)
538 | null decls = (emptyBag, emptyVarSet, emptyVarSet)
539 | otherwise = (more_decls `unionBags` listToBag decls,
540 more_emitted `unionVarSet` mkVarSet (map fst needed_prs),
541 more_extras `unionVarSet` extras)
543 (needed_prs,leftover_prs) = partition is_needed pairs
544 (decls, extras_s) = unzip [ifaceId get_idinfo True id rhs
545 | (id,rhs) <- needed_prs, not (omitIfaceSigForId id)]
546 extras = unionVarSets extras_s
547 (more_decls, more_emitted, more_extras) = go_rec extras leftover_prs
548 is_needed (id,_) = need_id needed id
553 ifaceId :: (Id -> IdInfo) -- This function "knows" the extra info added
554 -- by the STG passes. Sigh
555 -> Bool -- True <=> recursive, so don't print unfolding
557 -> CoreExpr -- The Id's right hand side
558 -> (RdrNameHsDecl, IdSet) -- The emitted stuff, plus any *extra* needed Ids
560 ifaceId get_idinfo is_rec id rhs
561 = (SigD (IfaceSig (toRdrName id) (toHsType id_type) hs_idinfo noSrcLoc), new_needed_ids)
564 core_idinfo = idInfo id
565 stg_idinfo = get_idinfo id
567 hs_idinfo | opt_OmitInterfacePragmas = []
568 | otherwise = arity_hsinfo ++ caf_hsinfo ++ cpr_hsinfo ++
569 strict_hsinfo ++ wrkr_hsinfo ++ unfold_hsinfo
571 ------------ Arity --------------
572 arity_info = arityInfo stg_idinfo
573 stg_arity = arityLowerBound arity_info
574 arity_hsinfo = case arityInfo stg_idinfo of
575 a@(ArityExactly n) -> [HsArity a]
578 ------------ Caf Info --------------
579 caf_hsinfo = case cafInfo stg_idinfo of
580 NoCafRefs -> [HsNoCafRefs]
583 ------------ CPR Info --------------
584 cpr_hsinfo = case cprInfo core_idinfo of
585 ReturnsCPR -> [HsCprInfo]
588 ------------ Strictness --------------
589 strict_info = strictnessInfo core_idinfo
590 bottoming_fn = isBottomingStrictness strict_info
591 strict_hsinfo = case strict_info of
592 NoStrictnessInfo -> []
593 info -> [HsStrictness info]
596 ------------ Worker --------------
597 -- We only treat a function as having a worker if
598 -- the exported arity (which is now the number of visible lambdas)
599 -- is the same as the arity at the moment of the w/w split
600 -- If so, we can safely omit the unfolding inside the wrapper, and
601 -- instead re-generate it from the type/arity/strictness info
602 -- But if the arity has changed, we just take the simple path and
603 -- put the unfolding into the interface file, forgetting the fact
604 -- that it's a wrapper.
606 -- How can this happen? Sometimes we get
607 -- f = coerce t (\x y -> $wf x y)
608 -- at the moment of w/w split; but the eta reducer turns it into
610 -- which is perfectly fine except that the exposed arity so far as
611 -- the code generator is concerned (zero) differs from the arity
612 -- when we did the split (2).
614 -- All this arises because we use 'arity' to mean "exactly how many
615 -- top level lambdas are there" in interface files; but during the
616 -- compilation of this module it means "how many things can I apply
618 work_info = workerInfo core_idinfo
619 HasWorker work_id _ = work_info
621 has_worker = case work_info of
622 HasWorker work_id wrap_arity
623 | wrap_arity == stg_arity -> True
624 | otherwise -> pprTrace "ifaceId: arity change:" (ppr id)
629 wrkr_hsinfo | has_worker = [HsWorker (toRdrName work_id)]
632 ------------ Unfolding --------------
633 inline_pragma = inlinePragInfo core_idinfo
634 dont_inline = isNeverInlinePrag inline_pragma
636 unfold_hsinfo | show_unfold = [HsUnfold inline_pragma (toUfExpr rhs)]
639 show_unfold = not has_worker && -- Not unnecessary
640 not bottoming_fn && -- Not necessary
643 rhs_is_small && -- Small enough
644 okToUnfoldInHiFile rhs -- No casms etc
646 rhs_is_small = couldBeSmallEnoughToInline opt_UF_HiFileThreshold rhs
648 ------------ Specialisations --------------
649 spec_info = specInfo core_idinfo
651 ------------ Occ info --------------
652 loop_breaker = isLoopBreaker (occInfo core_idinfo)
654 ------------ Extra free Ids --------------
655 new_needed_ids | opt_OmitInterfacePragmas = emptyVarSet
656 | otherwise = worker_ids `unionVarSet`
657 unfold_ids `unionVarSet`
660 worker_ids | has_worker && interestingId work_id = unitVarSet work_id
661 -- Conceivably, the worker might come from
663 | otherwise = emptyVarSet
665 spec_ids = filterVarSet interestingId (rulesRhsFreeVars spec_info)
667 unfold_ids | show_unfold = find_fvs rhs
668 | otherwise = emptyVarSet
670 find_fvs expr = exprSomeFreeVars interestingId expr
672 ------------ Sanity checking --------------
673 -- The arity of a wrapper function should match its strictness,
674 -- or else an importing module will get very confused indeed.
675 arity_matches_strictness
677 HasWorker _ wrap_arity -> wrap_arity == arityLowerBound arity_info
680 interestingId id = isId id && isLocallyDefined id && not (hasNoBinding id)