2 % (c) The AQUA Project, Glasgow University, 1998
4 \section[StdIdInfo]{Standard unfoldings}
6 This module contains definitions for the IdInfo for things that
7 have a standard form, namely:
11 * method and superclass selectors
12 * primitive operations
16 mkSpecPragmaId, mkWorkerId,
18 mkDictFunId, mkDefaultMethodId,
21 mkDataConId, mkDataConWrapId,
23 mkPrimOpId, mkCCallOpId,
25 -- And some particular Ids; see below for why they are wired in
27 unsafeCoerceId, realWorldPrimId,
28 eRROR_ID, rEC_SEL_ERROR_ID, pAT_ERROR_ID, rEC_CON_ERROR_ID,
29 rEC_UPD_ERROR_ID, iRREFUT_PAT_ERROR_ID, nON_EXHAUSTIVE_GUARDS_ERROR_ID,
30 nO_METHOD_BINDING_ERROR_ID, aBSENT_ERROR_ID, pAR_ERROR_ID
33 #include "HsVersions.h"
36 import TysPrim ( openAlphaTyVars, alphaTyVar, alphaTy,
37 intPrimTy, realWorldStatePrimTy
39 import TysWiredIn ( boolTy, charTy, mkListTy )
40 import PrelNames ( pREL_ERR, pREL_GHC )
41 import PrelRules ( primOpRule )
42 import Rules ( addRule )
43 import Type ( Type, ClassContext, mkDictTy, mkDictTys, mkTyConApp, mkTyVarTys,
44 mkFunTys, mkFunTy, mkSigmaTy, classesToPreds,
45 isUnLiftedType, mkForAllTys, mkTyVarTy, tyVarsOfType, tyVarsOfTypes,
46 splitSigmaTy, splitFunTy_maybe,
47 splitFunTys, splitForAllTys, unUsgTy,
50 import Module ( Module )
51 import CoreUtils ( exprType, mkInlineMe )
52 import CoreUnfold ( mkTopUnfolding, mkCompulsoryUnfolding, mkOtherCon )
53 import Literal ( Literal(..) )
54 import Subst ( mkTopTyVarSubst, substClasses )
55 import TyCon ( TyCon, isNewTyCon, tyConTyVars, tyConDataCons, isDataTyCon,
56 tyConTheta, isProductTyCon, isUnboxedTupleTyCon )
57 import Class ( Class, classBigSig, classTyCon, classTyVars, classSelIds )
58 import Var ( Id, TyVar )
59 import VarSet ( isEmptyVarSet )
60 import Name ( mkDerivedName, mkWiredInIdName, mkLocalName,
61 mkWorkerOcc, mkSuperDictSelOcc, mkCCallName,
64 import OccName ( mkSrcVarOcc )
65 import PrimOp ( PrimOp(DataToTagOp, CCallOp),
66 primOpSig, mkPrimOpIdName,
69 import Demand ( wwStrict, wwPrim, mkStrictnessInfo )
70 import DataCon ( DataCon, StrictnessMark(..),
71 dataConFieldLabels, dataConRepArity, dataConTyCon,
72 dataConArgTys, dataConRepType, dataConRepStrictness,
73 dataConName, dataConTheta,
74 dataConSig, dataConStrictMarks, dataConId
76 import Id ( idType, mkId,
77 mkVanillaId, mkTemplateLocals,
78 mkTemplateLocal, setInlinePragma, idCprInfo
80 import IdInfo ( IdInfo, vanillaIdInfo, mkIdInfo,
81 exactArity, setUnfoldingInfo, setCafInfo, setCprInfo,
82 setArityInfo, setInlinePragInfo, setSpecInfo,
83 mkStrictnessInfo, setStrictnessInfo,
84 IdFlavour(..), InlinePragInfo(..), CafInfo(..), StrictnessInfo(..), CprInfo(..)
86 import FieldLabel ( FieldLabel, FieldLabelTag, mkFieldLabel, fieldLabelName,
87 firstFieldLabelTag, allFieldLabelTags, fieldLabelType
92 import Maybe ( isJust )
98 %************************************************************************
100 \subsection{Wired in Ids}
102 %************************************************************************
106 = [ -- These error-y things are wired in because we don't yet have
107 -- a way to express in an interface file that the result type variable
108 -- is 'open'; that is can be unified with an unboxed type
110 -- [The interface file format now carry such information, but there's
111 -- no way yet of expressing at the definition site for these error-reporting
112 -- functions that they have an 'open' result type. -- sof 1/99]
116 , iRREFUT_PAT_ERROR_ID
117 , nON_EXHAUSTIVE_GUARDS_ERROR_ID
118 , nO_METHOD_BINDING_ERROR_ID
124 -- These two can't be defined in Haskell
131 %************************************************************************
133 \subsection{Easy ones}
135 %************************************************************************
138 mkSpecPragmaId occ uniq ty loc
139 = mkId (mkLocalName uniq occ loc) ty (mkIdInfo SpecPragmaId)
140 -- Maybe a SysLocal? But then we'd lose the location
142 mkDefaultMethodId dm_name rec_c ty
143 = mkVanillaId dm_name ty
145 mkWorkerId uniq unwrkr ty
146 = mkVanillaId (mkDerivedName mkWorkerOcc (getName unwrkr) uniq) ty
149 %************************************************************************
151 \subsection{Data constructors}
153 %************************************************************************
156 mkDataConId :: Name -> DataCon -> Id
157 -- Makes the *worker* for the data constructor; that is, the function
158 -- that takes the reprsentation arguments and builds the constructor.
159 mkDataConId work_name data_con
160 = mkId work_name (dataConRepType data_con) info
162 info = mkIdInfo (DataConId data_con)
163 `setArityInfo` exactArity arity
164 `setStrictnessInfo` strict_info
165 `setCprInfo` cpr_info
167 arity = dataConRepArity data_con
169 strict_info = mkStrictnessInfo (dataConRepStrictness data_con, False)
171 cpr_info | isProductTyCon tycon &&
172 not (isUnboxedTupleTyCon tycon) &&
173 arity > 0 = ReturnsCPR
174 | otherwise = NoCPRInfo
176 tycon = dataConTyCon data_con
177 -- Newtypes don't have a worker at all
179 -- If we are a product with 0 args we must be void(like)
180 -- We can't create an unboxed tuple with 0 args for this
181 -- and since Void has only one, constant value it should
182 -- just mean returning a pointer to a pre-existing cell.
183 -- So we won't really gain from doing anything fancy
184 -- and we treat this case as Top.
187 The wrapper for a constructor is an ordinary top-level binding that evaluates
188 any strict args, unboxes any args that are going to be flattened, and calls
191 We're going to build a constructor that looks like:
193 data (Data a, C b) => T a b = T1 !a !Int b
196 \d1::Data a, d2::C b ->
197 \p q r -> case p of { p ->
199 Con T1 [a,b] [p,q,r]}}
203 * d2 is thrown away --- a context in a data decl is used to make sure
204 one *could* construct dictionaries at the site the constructor
205 is used, but the dictionary isn't actually used.
207 * We have to check that we can construct Data dictionaries for
208 the types a and Int. Once we've done that we can throw d1 away too.
210 * We use (case p of q -> ...) to evaluate p, rather than "seq" because
211 all that matters is that the arguments are evaluated. "seq" is
212 very careful to preserve evaluation order, which we don't need
215 You might think that we could simply give constructors some strictness
216 info, like PrimOps, and let CoreToStg do the let-to-case transformation.
217 But we don't do that because in the case of primops and functions strictness
218 is a *property* not a *requirement*. In the case of constructors we need to
219 do something active to evaluate the argument.
221 Making an explicit case expression allows the simplifier to eliminate
222 it in the (common) case where the constructor arg is already evaluated.
225 mkDataConWrapId data_con
228 wrap_id = mkId (dataConName data_con) wrap_ty info
229 work_id = dataConId data_con
231 info = mkIdInfo (DataConWrapId data_con)
232 `setUnfoldingInfo` mkTopUnfolding (mkInlineMe wrap_rhs)
233 `setCprInfo` cpr_info
234 -- The Cpr info can be important inside INLINE rhss, where the
235 -- wrapper constructor isn't inlined
236 `setArityInfo` exactArity arity
237 -- It's important to specify the arity, so that partial
238 -- applications are treated as values
239 `setCafInfo` NoCafRefs
240 -- The wrapper Id ends up in STG code as an argument,
241 -- sometimes before its definition, so we want to
242 -- signal that it has no CAFs
244 wrap_ty = mkForAllTys all_tyvars $
248 cpr_info = idCprInfo work_id
250 wrap_rhs | isNewTyCon tycon
251 = ASSERT( null ex_tyvars && null ex_dict_args && length orig_arg_tys == 1 )
252 -- No existentials on a newtype, but it can have a context
253 -- e.g. newtype Eq a => T a = MkT (...)
255 mkLams tyvars $ mkLams dict_args $ Lam id_arg1 $
256 Note (Coerce result_ty (head orig_arg_tys)) (Var id_arg1)
258 {- I nuked this because map (:) xs would create a
259 new local lambda for the (:) in core-to-stg.
260 There isn't a defn for the worker!
262 | null dict_args && all not_marked_strict strict_marks
263 = Var work_id -- The common case. Not only is this efficient,
264 -- but it also ensures that the wrapper is replaced
265 -- by the worker even when there are no args.
269 -- This is really important in rule matching,
270 -- which is a bit sad. (We could match on the wrappers,
271 -- but that makes it less likely that rules will match
272 -- when we bring bits of unfoldings together
276 = mkLams all_tyvars $ mkLams dict_args $
277 mkLams ex_dict_args $ mkLams id_args $
278 foldr mk_case con_app
279 (zip (ex_dict_args++id_args) strict_marks) i3 []
281 con_app i rep_ids = mkApps (Var work_id)
282 (map varToCoreExpr (all_tyvars ++ reverse rep_ids))
284 (tyvars, theta, ex_tyvars, ex_theta, orig_arg_tys, tycon) = dataConSig data_con
285 all_tyvars = tyvars ++ ex_tyvars
287 dict_tys = mkDictTys theta
288 ex_dict_tys = mkDictTys ex_theta
289 all_arg_tys = dict_tys ++ ex_dict_tys ++ orig_arg_tys
290 result_ty = mkTyConApp tycon (mkTyVarTys tyvars)
292 mkLocals i tys = (zipWith mkTemplateLocal [i..i+n-1] tys, i+n)
296 (dict_args, i1) = mkLocals 1 dict_tys
297 (ex_dict_args,i2) = mkLocals i1 ex_dict_tys
298 (id_args,i3) = mkLocals i2 orig_arg_tys
300 (id_arg1:_) = id_args -- Used for newtype only
302 strict_marks = dataConStrictMarks data_con
303 not_marked_strict NotMarkedStrict = True
304 not_marked_strict other = False
308 :: (Id, StrictnessMark) -- arg, strictness
309 -> (Int -> [Id] -> CoreExpr) -- body
310 -> Int -- next rep arg id
311 -> [Id] -- rep args so far
313 mk_case (arg,strict) body i rep_args
315 NotMarkedStrict -> body i (arg:rep_args)
317 | isUnLiftedType (idType arg) -> body i (arg:rep_args)
319 Case (Var arg) arg [(DEFAULT,[], body i (arg:rep_args))]
321 MarkedUnboxed con tys ->
322 Case (Var arg) arg [(DataAlt con, con_args,
323 body i' (reverse con_args++rep_args))]
325 (con_args,i') = mkLocals i tys
329 %************************************************************************
331 \subsection{Record selectors}
333 %************************************************************************
335 We're going to build a record selector unfolding that looks like this:
337 data T a b c = T1 { ..., op :: a, ...}
338 | T2 { ..., op :: a, ...}
341 sel = /\ a b c -> \ d -> case d of
346 Similarly for newtypes
348 newtype N a = MkN { unN :: a->a }
351 unN n = coerce (a->a) n
353 We need to take a little care if the field has a polymorphic type:
355 data R = R { f :: forall a. a->a }
359 f :: forall a. R -> a -> a
360 f = /\ a \ r = case r of
363 (not f :: R -> forall a. a->a, which gives the type inference mechanism
364 problems at call sites)
366 Similarly for newtypes
368 newtype N = MkN { unN :: forall a. a->a }
370 unN :: forall a. N -> a -> a
371 unN = /\a -> \n:N -> coerce (a->a) n
374 mkRecordSelId tycon field_label unpack_id
375 -- Assumes that all fields with the same field label have the same type
377 -- Annoyingly, we have to pass in the unpackCString# Id, because
378 -- we can't conjure it up out of thin air
381 sel_id = mkId (fieldLabelName field_label) selector_ty info
383 field_ty = fieldLabelType field_label
384 data_cons = tyConDataCons tycon
385 tyvars = tyConTyVars tycon -- These scope over the types in
386 -- the FieldLabels of constructors of this type
387 tycon_theta = tyConTheta tycon -- The context on the data decl
388 -- eg data (Eq a, Ord b) => T a b = ...
389 (field_tyvars,field_tau) = splitForAllTys field_ty
391 data_ty = mkTyConApp tycon tyvar_tys
392 tyvar_tys = mkTyVarTys tyvars
394 -- Very tiresomely, the selectors are (unnecessarily!) overloaded over
395 -- just the dictionaries in the types of the constructors that contain
396 -- the relevant field. Urgh.
397 -- NB: this code relies on the fact that DataCons are quantified over
398 -- the identical type variables as their parent TyCon
399 dict_tys = [mkDictTy cls tys | (cls, tys) <- tycon_theta, needed_dict (cls, tys)]
400 needed_dict pred = or [ pred `elem` (dataConTheta dc)
401 | (DataAlt dc, _, _) <- the_alts]
404 selector_ty = mkForAllTys tyvars $ mkForAllTys field_tyvars $
405 mkFunTys dict_tys $ mkFunTy data_ty field_tau
407 info = mkIdInfo (RecordSelId field_label)
408 `setArityInfo` exactArity (1 + length dict_tys)
409 `setUnfoldingInfo` unfolding
410 `setCafInfo` NoCafRefs
411 -- ToDo: consider adding further IdInfo
413 unfolding = mkTopUnfolding sel_rhs
416 (data_id:dict_ids) = mkTemplateLocals (data_ty:dict_tys)
417 alts = map mk_maybe_alt data_cons
418 the_alts = catMaybes alts
419 default_alt | all isJust alts = [] -- No default needed
420 | otherwise = [(DEFAULT, [], error_expr)]
422 sel_rhs | isNewTyCon tycon = new_sel_rhs
423 | otherwise = data_sel_rhs
425 data_sel_rhs = mkLams tyvars $ mkLams field_tyvars $
426 mkLams dict_ids $ Lam data_id $
427 Case (Var data_id) data_id (the_alts ++ default_alt)
429 new_sel_rhs = mkLams tyvars $ mkLams field_tyvars $ Lam data_id $
430 Note (Coerce (unUsgTy field_tau) (unUsgTy data_ty)) (Var data_id)
432 mk_maybe_alt data_con
433 = case maybe_the_arg_id of
435 Just the_arg_id -> Just (DataAlt data_con, arg_ids,
436 mkVarApps (Var the_arg_id) field_tyvars)
438 arg_ids = mkTemplateLocals (dataConArgTys data_con tyvar_tys)
439 -- The first one will shadow data_id, but who cares
440 field_lbls = dataConFieldLabels data_con
441 maybe_the_arg_id = assocMaybe (field_lbls `zip` arg_ids) field_label
443 error_expr = mkApps (Var rEC_SEL_ERROR_ID) [Type (unUsgTy field_tau), err_string]
444 -- preserves invariant that type args are *not* usage-annotated on top. KSW 1999-04.
445 err_string = App (Var unpack_id) (Lit (MachStr (_PK_ full_msg)))
446 full_msg = showSDoc (sep [text "No match in record selector", ppr sel_id])
450 %************************************************************************
452 \subsection{Dictionary selectors}
454 %************************************************************************
456 Selecting a field for a dictionary. If there is just one field, then
457 there's nothing to do.
459 ToDo: unify with mkRecordSelId.
462 mkDictSelId :: Name -> Class -> Id
463 mkDictSelId name clas
467 sel_id = mkId name ty info
468 field_lbl = mkFieldLabel name tycon ty tag
469 tag = assoc "MkId.mkDictSelId" (classSelIds clas `zip` allFieldLabelTags) sel_id
471 info = mkIdInfo (RecordSelId field_lbl)
472 `setArityInfo` exactArity 1
473 `setUnfoldingInfo` unfolding
474 `setCafInfo` NoCafRefs
476 -- We no longer use 'must-inline' on record selectors. They'll
477 -- inline like crazy if they scrutinise a constructor
479 unfolding = mkTopUnfolding rhs
481 tyvars = classTyVars clas
483 tycon = classTyCon clas
484 [data_con] = tyConDataCons tycon
485 tyvar_tys = mkTyVarTys tyvars
486 arg_tys = dataConArgTys data_con tyvar_tys
487 the_arg_id = arg_ids !! (tag - firstFieldLabelTag)
489 dict_ty = mkDictTy clas tyvar_tys
490 (dict_id:arg_ids) = mkTemplateLocals (dict_ty : arg_tys)
492 rhs | isNewTyCon tycon = mkLams tyvars $ Lam dict_id $
493 Note (Coerce (head arg_tys) dict_ty) (Var dict_id)
494 | otherwise = mkLams tyvars $ Lam dict_id $
495 Case (Var dict_id) dict_id
496 [(DataAlt data_con, arg_ids, Var the_arg_id)]
500 %************************************************************************
502 \subsection{Primitive operations
504 %************************************************************************
507 mkPrimOpId :: PrimOp -> Id
511 (tyvars,arg_tys,res_ty, arity, strict_info) = primOpSig prim_op
512 ty = mkForAllTys tyvars (mkFunTys arg_tys res_ty)
513 name = mkPrimOpIdName prim_op id
514 id = mkId name ty info
516 info = mkIdInfo (PrimOpId prim_op)
518 `setArityInfo` exactArity arity
519 `setStrictnessInfo` strict_info
521 rules = addRule id emptyCoreRules (primOpRule prim_op)
524 -- For each ccall we manufacture a separate CCallOpId, giving it
525 -- a fresh unique, a type that is correct for this particular ccall,
526 -- and a CCall structure that gives the correct details about calling
529 -- The *name* of this Id is a local name whose OccName gives the full
530 -- details of the ccall, type and all. This means that the interface
531 -- file reader can reconstruct a suitable Id
533 mkCCallOpId :: Unique -> CCall -> Type -> Id
534 mkCCallOpId uniq ccall ty
535 = ASSERT( isEmptyVarSet (tyVarsOfType ty) )
536 -- A CCallOpId should have no free type variables;
537 -- when doing substitutions won't substitute over it
540 occ_str = showSDocIface (braces (pprCCallOp ccall <+> ppr ty))
541 -- The "occurrence name" of a ccall is the full info about the
542 -- ccall; it is encoded, but may have embedded spaces etc!
544 name = mkCCallName uniq occ_str
545 prim_op = CCallOp ccall
547 info = mkIdInfo (PrimOpId prim_op)
548 `setArityInfo` exactArity arity
549 `setStrictnessInfo` strict_info
551 (_, tau) = splitForAllTys ty
552 (arg_tys, _) = splitFunTys tau
553 arity = length arg_tys
554 strict_info = mkStrictnessInfo (take arity (repeat wwPrim), False)
558 %************************************************************************
560 \subsection{DictFuns}
562 %************************************************************************
565 mkDictFunId :: Name -- Name to use for the dict fun;
572 mkDictFunId dfun_name clas inst_tyvars inst_tys inst_decl_theta
573 = mkVanillaId dfun_name dfun_ty
575 dfun_theta = classesToPreds inst_decl_theta
577 {- 1 dec 99: disable the Mark Jones optimisation for the sake
578 of compatibility with Hugs.
579 See `types/InstEnv' for a discussion related to this.
581 (class_tyvars, sc_theta, _, _) = classBigSig clas
582 not_const (clas, tys) = not (isEmptyVarSet (tyVarsOfTypes tys))
583 sc_theta' = substClasses (mkTopTyVarSubst class_tyvars inst_tys) sc_theta
584 dfun_theta = case inst_decl_theta of
585 [] -> [] -- If inst_decl_theta is empty, then we don't
586 -- want to have any dict arguments, so that we can
587 -- expose the constant methods.
589 other -> nub (inst_decl_theta ++ filter not_const sc_theta')
590 -- Otherwise we pass the superclass dictionaries to
591 -- the dictionary function; the Mark Jones optimisation.
593 -- NOTE the "nub". I got caught by this one:
594 -- class Monad m => MonadT t m where ...
595 -- instance Monad m => MonadT (EnvT env) m where ...
596 -- Here, the inst_decl_theta has (Monad m); but so
597 -- does the sc_theta'!
599 -- NOTE the "not_const". I got caught by this one too:
600 -- class Foo a => Baz a b where ...
601 -- instance Wob b => Baz T b where..
602 -- Now sc_theta' has Foo T
604 dfun_ty = mkSigmaTy inst_tyvars dfun_theta (mkDictTy clas inst_tys)
608 %************************************************************************
610 \subsection{Un-definable}
612 %************************************************************************
614 These two can't be defined in Haskell.
616 unsafeCoerce# isn't so much a PrimOp as a phantom identifier, that
617 just gets expanded into a type coercion wherever it occurs. Hence we
618 add it as a built-in Id with an unfolding here.
620 The type variables we use here are "open" type variables: this means
621 they can unify with both unlifted and lifted types. Hence we provide
622 another gun with which to shoot yourself in the foot.
626 = pcMiscPrelId unsafeCoerceIdKey pREL_GHC SLIT("unsafeCoerce#") ty info
629 `setUnfoldingInfo` mkCompulsoryUnfolding rhs
632 ty = mkForAllTys [openAlphaTyVar,openBetaTyVar]
633 (mkFunTy openAlphaTy openBetaTy)
634 [x] = mkTemplateLocals [openAlphaTy]
635 rhs = mkLams [openAlphaTyVar,openBetaTyVar,x] $
636 Note (Coerce openBetaTy openAlphaTy) (Var x)
640 @getTag#@ is another function which can't be defined in Haskell. It needs to
641 evaluate its argument and call the dataToTag# primitive.
645 = pcMiscPrelId getTagIdKey pREL_GHC SLIT("getTag#") ty info
648 `setUnfoldingInfo` mkCompulsoryUnfolding rhs
649 -- We don't provide a defn for this; you must inline it
651 ty = mkForAllTys [alphaTyVar] (mkFunTy alphaTy intPrimTy)
652 [x,y] = mkTemplateLocals [alphaTy,alphaTy]
653 rhs = mkLams [alphaTyVar,x] $
654 Case (Var x) y [ (DEFAULT, [], mkApps (Var dataToTagId) [Type alphaTy, Var y]) ]
656 dataToTagId = mkPrimOpId DataToTagOp
659 @realWorld#@ used to be a magic literal, \tr{void#}. If things get
660 nasty as-is, change it back to a literal (@Literal@).
663 realWorldPrimId -- :: State# RealWorld
664 = pcMiscPrelId realWorldPrimIdKey pREL_GHC SLIT("realWorld#")
666 (noCafIdInfo `setUnfoldingInfo` mkOtherCon [])
667 -- The mkOtherCon makes it look that realWorld# is evaluated
668 -- which in turn makes Simplify.interestingArg return True,
669 -- which in turn makes INLINE things applied to realWorld# likely
674 %************************************************************************
676 \subsection[PrelVals-error-related]{@error@ and friends; @trace@}
678 %************************************************************************
680 GHC randomly injects these into the code.
682 @patError@ is just a version of @error@ for pattern-matching
683 failures. It knows various ``codes'' which expand to longer
684 strings---this saves space!
686 @absentErr@ is a thing we put in for ``absent'' arguments. They jolly
687 well shouldn't be yanked on, but if one is, then you will get a
688 friendly message from @absentErr@ (rather than a totally random
691 @parError@ is a special version of @error@ which the compiler does
692 not know to be a bottoming Id. It is used in the @_par_@ and @_seq_@
693 templates, but we don't ever expect to generate code for it.
697 = pc_bottoming_Id errorIdKey pREL_ERR SLIT("error") errorTy
699 = generic_ERROR_ID patErrorIdKey SLIT("patError")
701 = generic_ERROR_ID recSelErrIdKey SLIT("recSelError")
703 = generic_ERROR_ID recConErrorIdKey SLIT("recConError")
705 = generic_ERROR_ID recUpdErrorIdKey SLIT("recUpdError")
707 = generic_ERROR_ID irrefutPatErrorIdKey SLIT("irrefutPatError")
708 nON_EXHAUSTIVE_GUARDS_ERROR_ID
709 = generic_ERROR_ID nonExhaustiveGuardsErrorIdKey SLIT("nonExhaustiveGuardsError")
710 nO_METHOD_BINDING_ERROR_ID
711 = generic_ERROR_ID noMethodBindingErrorIdKey SLIT("noMethodBindingError")
714 = pc_bottoming_Id absentErrorIdKey pREL_ERR SLIT("absentErr")
715 (mkSigmaTy [openAlphaTyVar] [] openAlphaTy)
718 = pcMiscPrelId parErrorIdKey pREL_ERR SLIT("parError")
719 (mkSigmaTy [openAlphaTyVar] [] openAlphaTy) noCafIdInfo
724 %************************************************************************
726 \subsection{Utilities}
728 %************************************************************************
731 pcMiscPrelId :: Unique{-IdKey-} -> Module -> FAST_STRING -> Type -> IdInfo -> Id
732 pcMiscPrelId key mod str ty info
734 name = mkWiredInIdName key mod (mkSrcVarOcc str) imp
735 imp = mkId name ty info -- the usual case...
738 -- We lie and say the thing is imported; otherwise, we get into
739 -- a mess with dependency analysis; e.g., core2stg may heave in
740 -- random calls to GHCbase.unpackPS__. If GHCbase is the module
741 -- being compiled, then it's just a matter of luck if the definition
742 -- will be in "the right place" to be in scope.
744 pc_bottoming_Id key mod name ty
745 = pcMiscPrelId key mod name ty bottoming_info
747 bottoming_info = noCafIdInfo
748 `setStrictnessInfo` mkStrictnessInfo ([wwStrict], True)
750 -- these "bottom" out, no matter what their arguments
752 generic_ERROR_ID u n = pc_bottoming_Id u pREL_ERR n errorTy
755 noCafIdInfo = vanillaIdInfo `setCafInfo` NoCafRefs
757 (openAlphaTyVar:openBetaTyVar:_) = openAlphaTyVars
758 openAlphaTy = mkTyVarTy openAlphaTyVar
759 openBetaTy = mkTyVarTy openBetaTyVar
762 errorTy = mkUsgTy UsMany $
763 mkSigmaTy [openAlphaTyVar] [] (mkFunTys [mkUsgTy UsOnce (mkListTy charTy)]
764 (mkUsgTy UsMany openAlphaTy))
765 -- Notice the openAlphaTyVar. It says that "error" can be applied
766 -- to unboxed as well as boxed types. This is OK because it never
767 -- returns, so the return type is irrelevant.