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))]
324 where n_tys = length tys
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 field_name = fieldLabelName field_label
385 data_cons = tyConDataCons tycon
386 tyvars = tyConTyVars tycon -- These scope over the types in
387 -- the FieldLabels of constructors of this type
388 tycon_theta = tyConTheta tycon -- The context on the data decl
389 -- eg data (Eq a, Ord b) => T a b = ...
390 (field_tyvars,field_tau) = splitForAllTys field_ty
392 data_ty = mkTyConApp tycon tyvar_tys
393 tyvar_tys = mkTyVarTys tyvars
395 -- Very tiresomely, the selectors are (unnecessarily!) overloaded over
396 -- just the dictionaries in the types of the constructors that contain
397 -- the relevant field. Urgh.
398 -- NB: this code relies on the fact that DataCons are quantified over
399 -- the identical type variables as their parent TyCon
400 dict_tys = [mkDictTy cls tys | (cls, tys) <- tycon_theta, needed_dict (cls, tys)]
401 needed_dict pred = or [ pred `elem` (dataConTheta dc)
402 | (DataAlt dc, _, _) <- the_alts]
405 selector_ty = mkForAllTys tyvars $ mkForAllTys field_tyvars $
406 mkFunTys dict_tys $ mkFunTy data_ty field_tau
408 info = mkIdInfo (RecordSelId field_label)
409 `setArityInfo` exactArity (1 + length dict_tys)
410 `setUnfoldingInfo` unfolding
411 `setCafInfo` NoCafRefs
412 -- ToDo: consider adding further IdInfo
414 unfolding = mkTopUnfolding sel_rhs
417 (data_id:dict_ids) = mkTemplateLocals (data_ty:dict_tys)
418 alts = map mk_maybe_alt data_cons
419 the_alts = catMaybes alts
420 default_alt | all isJust alts = [] -- No default needed
421 | otherwise = [(DEFAULT, [], error_expr)]
423 sel_rhs | isNewTyCon tycon = new_sel_rhs
424 | otherwise = data_sel_rhs
426 data_sel_rhs = mkLams tyvars $ mkLams field_tyvars $
427 mkLams dict_ids $ Lam data_id $
428 Case (Var data_id) data_id (the_alts ++ default_alt)
430 new_sel_rhs = mkLams tyvars $ mkLams field_tyvars $ Lam data_id $
431 Note (Coerce (unUsgTy field_tau) (unUsgTy data_ty)) (Var data_id)
433 mk_maybe_alt data_con
434 = case maybe_the_arg_id of
436 Just the_arg_id -> Just (DataAlt data_con, arg_ids,
437 mkVarApps (Var the_arg_id) field_tyvars)
439 arg_ids = mkTemplateLocals (dataConArgTys data_con tyvar_tys)
440 -- The first one will shadow data_id, but who cares
441 field_lbls = dataConFieldLabels data_con
442 maybe_the_arg_id = assocMaybe (field_lbls `zip` arg_ids) field_label
444 error_expr = mkApps (Var rEC_SEL_ERROR_ID) [Type (unUsgTy field_tau), err_string]
445 -- preserves invariant that type args are *not* usage-annotated on top. KSW 1999-04.
446 err_string = App (Var unpack_id) (Lit (MachStr (_PK_ full_msg)))
447 full_msg = showSDoc (sep [text "No match in record selector", ppr sel_id])
451 %************************************************************************
453 \subsection{Dictionary selectors}
455 %************************************************************************
457 Selecting a field for a dictionary. If there is just one field, then
458 there's nothing to do.
460 ToDo: unify with mkRecordSelId.
463 mkDictSelId :: Name -> Class -> Id
464 mkDictSelId name clas
468 sel_id = mkId name ty info
469 field_lbl = mkFieldLabel name tycon ty tag
470 tag = assoc "MkId.mkDictSelId" (classSelIds clas `zip` allFieldLabelTags) sel_id
472 info = mkIdInfo (RecordSelId field_lbl)
473 `setArityInfo` exactArity 1
474 `setUnfoldingInfo` unfolding
475 `setCafInfo` NoCafRefs
477 -- We no longer use 'must-inline' on record selectors. They'll
478 -- inline like crazy if they scrutinise a constructor
480 unfolding = mkTopUnfolding rhs
482 tyvars = classTyVars clas
484 tycon = classTyCon clas
485 [data_con] = tyConDataCons tycon
486 tyvar_tys = mkTyVarTys tyvars
487 arg_tys = dataConArgTys data_con tyvar_tys
488 the_arg_id = arg_ids !! (tag - firstFieldLabelTag)
490 dict_ty = mkDictTy clas tyvar_tys
491 (dict_id:arg_ids) = mkTemplateLocals (dict_ty : arg_tys)
493 rhs | isNewTyCon tycon = mkLams tyvars $ Lam dict_id $
494 Note (Coerce (head arg_tys) dict_ty) (Var dict_id)
495 | otherwise = mkLams tyvars $ Lam dict_id $
496 Case (Var dict_id) dict_id
497 [(DataAlt data_con, arg_ids, Var the_arg_id)]
501 %************************************************************************
503 \subsection{Primitive operations
505 %************************************************************************
508 mkPrimOpId :: PrimOp -> Id
512 (tyvars,arg_tys,res_ty, arity, strict_info) = primOpSig prim_op
513 ty = mkForAllTys tyvars (mkFunTys arg_tys res_ty)
514 name = mkPrimOpIdName prim_op id
515 id = mkId name ty info
517 info = mkIdInfo (PrimOpId prim_op)
519 `setArityInfo` exactArity arity
520 `setStrictnessInfo` strict_info
522 rules = addRule id emptyCoreRules (primOpRule prim_op)
525 -- For each ccall we manufacture a separate CCallOpId, giving it
526 -- a fresh unique, a type that is correct for this particular ccall,
527 -- and a CCall structure that gives the correct details about calling
530 -- The *name* of this Id is a local name whose OccName gives the full
531 -- details of the ccall, type and all. This means that the interface
532 -- file reader can reconstruct a suitable Id
534 mkCCallOpId :: Unique -> CCall -> Type -> Id
535 mkCCallOpId uniq ccall ty
536 = ASSERT( isEmptyVarSet (tyVarsOfType ty) )
537 -- A CCallOpId should have no free type variables;
538 -- when doing substitutions won't substitute over it
541 occ_str = showSDocIface (braces (pprCCallOp ccall <+> ppr ty))
542 -- The "occurrence name" of a ccall is the full info about the
543 -- ccall; it is encoded, but may have embedded spaces etc!
545 name = mkCCallName uniq occ_str
546 prim_op = CCallOp ccall
548 info = mkIdInfo (PrimOpId prim_op)
549 `setArityInfo` exactArity arity
550 `setStrictnessInfo` strict_info
552 (_, tau) = splitForAllTys ty
553 (arg_tys, _) = splitFunTys tau
554 arity = length arg_tys
555 strict_info = mkStrictnessInfo (take arity (repeat wwPrim), False)
559 %************************************************************************
561 \subsection{DictFuns}
563 %************************************************************************
566 mkDictFunId :: Name -- Name to use for the dict fun;
573 mkDictFunId dfun_name clas inst_tyvars inst_tys inst_decl_theta
574 = mkVanillaId dfun_name dfun_ty
576 (class_tyvars, sc_theta, _, _) = classBigSig clas
577 sc_theta' = substClasses (mkTopTyVarSubst class_tyvars inst_tys) sc_theta
579 dfun_theta = classesToPreds inst_decl_theta
581 {- 1 dec 99: disable the Mark Jones optimisation for the sake
582 of compatibility with Hugs.
583 See `types/InstEnv' for a discussion related to this.
585 dfun_theta = case inst_decl_theta of
586 [] -> [] -- If inst_decl_theta is empty, then we don't
587 -- want to have any dict arguments, so that we can
588 -- expose the constant methods.
590 other -> nub (inst_decl_theta ++ filter not_const sc_theta')
591 -- Otherwise we pass the superclass dictionaries to
592 -- the dictionary function; the Mark Jones optimisation.
594 -- NOTE the "nub". I got caught by this one:
595 -- class Monad m => MonadT t m where ...
596 -- instance Monad m => MonadT (EnvT env) m where ...
597 -- Here, the inst_decl_theta has (Monad m); but so
598 -- does the sc_theta'!
600 -- NOTE the "not_const". I got caught by this one too:
601 -- class Foo a => Baz a b where ...
602 -- instance Wob b => Baz T b where..
603 -- Now sc_theta' has Foo T
605 dfun_ty = mkSigmaTy inst_tyvars dfun_theta (mkDictTy clas inst_tys)
607 not_const (clas, tys) = not (isEmptyVarSet (tyVarsOfTypes tys))
611 %************************************************************************
613 \subsection{Un-definable}
615 %************************************************************************
617 These two can't be defined in Haskell.
619 unsafeCoerce# isn't so much a PrimOp as a phantom identifier, that
620 just gets expanded into a type coercion wherever it occurs. Hence we
621 add it as a built-in Id with an unfolding here.
623 The type variables we use here are "open" type variables: this means
624 they can unify with both unlifted and lifted types. Hence we provide
625 another gun with which to shoot yourself in the foot.
629 = pcMiscPrelId unsafeCoerceIdKey pREL_GHC SLIT("unsafeCoerce#") ty info
632 `setUnfoldingInfo` mkCompulsoryUnfolding rhs
635 ty = mkForAllTys [openAlphaTyVar,openBetaTyVar]
636 (mkFunTy openAlphaTy openBetaTy)
637 [x] = mkTemplateLocals [openAlphaTy]
638 rhs = mkLams [openAlphaTyVar,openBetaTyVar,x] $
639 Note (Coerce openBetaTy openAlphaTy) (Var x)
643 @getTag#@ is another function which can't be defined in Haskell. It needs to
644 evaluate its argument and call the dataToTag# primitive.
648 = pcMiscPrelId getTagIdKey pREL_GHC SLIT("getTag#") ty info
651 `setUnfoldingInfo` mkCompulsoryUnfolding rhs
652 -- We don't provide a defn for this; you must inline it
654 ty = mkForAllTys [alphaTyVar] (mkFunTy alphaTy intPrimTy)
655 [x,y] = mkTemplateLocals [alphaTy,alphaTy]
656 rhs = mkLams [alphaTyVar,x] $
657 Case (Var x) y [ (DEFAULT, [], mkApps (Var dataToTagId) [Type alphaTy, Var y]) ]
659 dataToTagId = mkPrimOpId DataToTagOp
662 @realWorld#@ used to be a magic literal, \tr{void#}. If things get
663 nasty as-is, change it back to a literal (@Literal@).
666 realWorldPrimId -- :: State# RealWorld
667 = pcMiscPrelId realWorldPrimIdKey pREL_GHC SLIT("realWorld#")
669 (noCafIdInfo `setUnfoldingInfo` mkOtherCon [])
670 -- The mkOtherCon makes it look that realWorld# is evaluated
671 -- which in turn makes Simplify.interestingArg return True,
672 -- which in turn makes INLINE things applied to realWorld# likely
677 %************************************************************************
679 \subsection[PrelVals-error-related]{@error@ and friends; @trace@}
681 %************************************************************************
683 GHC randomly injects these into the code.
685 @patError@ is just a version of @error@ for pattern-matching
686 failures. It knows various ``codes'' which expand to longer
687 strings---this saves space!
689 @absentErr@ is a thing we put in for ``absent'' arguments. They jolly
690 well shouldn't be yanked on, but if one is, then you will get a
691 friendly message from @absentErr@ (rather than a totally random
694 @parError@ is a special version of @error@ which the compiler does
695 not know to be a bottoming Id. It is used in the @_par_@ and @_seq_@
696 templates, but we don't ever expect to generate code for it.
700 = pc_bottoming_Id errorIdKey pREL_ERR SLIT("error") errorTy
702 = generic_ERROR_ID patErrorIdKey SLIT("patError")
704 = generic_ERROR_ID recSelErrIdKey SLIT("recSelError")
706 = generic_ERROR_ID recConErrorIdKey SLIT("recConError")
708 = generic_ERROR_ID recUpdErrorIdKey SLIT("recUpdError")
710 = generic_ERROR_ID irrefutPatErrorIdKey SLIT("irrefutPatError")
711 nON_EXHAUSTIVE_GUARDS_ERROR_ID
712 = generic_ERROR_ID nonExhaustiveGuardsErrorIdKey SLIT("nonExhaustiveGuardsError")
713 nO_METHOD_BINDING_ERROR_ID
714 = generic_ERROR_ID noMethodBindingErrorIdKey SLIT("noMethodBindingError")
717 = pc_bottoming_Id absentErrorIdKey pREL_ERR SLIT("absentErr")
718 (mkSigmaTy [openAlphaTyVar] [] openAlphaTy)
721 = pcMiscPrelId parErrorIdKey pREL_ERR SLIT("parError")
722 (mkSigmaTy [openAlphaTyVar] [] openAlphaTy) noCafIdInfo
727 %************************************************************************
729 \subsection{Utilities}
731 %************************************************************************
734 pcMiscPrelId :: Unique{-IdKey-} -> Module -> FAST_STRING -> Type -> IdInfo -> Id
735 pcMiscPrelId key mod str ty info
737 name = mkWiredInIdName key mod (mkSrcVarOcc str) imp
738 imp = mkId name ty info -- the usual case...
741 -- We lie and say the thing is imported; otherwise, we get into
742 -- a mess with dependency analysis; e.g., core2stg may heave in
743 -- random calls to GHCbase.unpackPS__. If GHCbase is the module
744 -- being compiled, then it's just a matter of luck if the definition
745 -- will be in "the right place" to be in scope.
747 pc_bottoming_Id key mod name ty
748 = pcMiscPrelId key mod name ty bottoming_info
750 bottoming_info = noCafIdInfo
751 `setStrictnessInfo` mkStrictnessInfo ([wwStrict], True)
753 -- these "bottom" out, no matter what their arguments
755 generic_ERROR_ID u n = pc_bottoming_Id u pREL_ERR n errorTy
758 noCafIdInfo = vanillaIdInfo `setCafInfo` NoCafRefs
760 (openAlphaTyVar:openBetaTyVar:_) = openAlphaTyVars
761 openAlphaTy = mkTyVarTy openAlphaTyVar
762 openBetaTy = mkTyVarTy openBetaTyVar
765 errorTy = mkUsgTy UsMany $
766 mkSigmaTy [openAlphaTyVar] [] (mkFunTys [mkUsgTy UsOnce (mkListTy charTy)]
767 (mkUsgTy UsMany openAlphaTy))
768 -- Notice the openAlphaTyVar. It says that "error" can be applied
769 -- to unboxed as well as boxed types. This is OK because it never
770 -- returns, so the return type is irrelevant.