2 % (c) The GRASP Project, Glasgow University, 1992-2002
6 TcRn, TcM, RnM, -- The monad is opaque outside this module
8 -- Standard monadic operations
9 thenM, thenM_, returnM, failM,
11 -- Non-standard operations
12 runTcRn, fixM, tryM, ioToTcRn,
13 newMutVar, readMutVar, writeMutVar,
14 getEnv, setEnv, updEnv, unsafeInterleaveM,
16 -- The environment types
17 Env(..), TopEnv(..), TcGblEnv(..),
18 TcLclEnv(..), RnLclEnv(..),
21 RnMode(..), isInterfaceMode, isCmdLineMode,
22 EntityUsage, emptyUsages, ErrCtxt,
23 ImportAvails(..), emptyImportAvails, plusImportAvails,
24 plusAvail, pruneAvails,
25 AvailEnv, emptyAvailEnv, unitAvailEnv, plusAvailEnv,
26 mkAvailEnv, lookupAvailEnv, lookupAvailEnv_maybe, availEnvElts, addAvail,
33 Stage(..), topStage, topSpliceStage,
34 Level, impLevel, topLevel,
37 Inst(..), InstOrigin(..), InstLoc(..), pprInstLoc, instLocSrcLoc,
38 LIE, emptyLIE, unitLIE, plusLIE, consLIE,
39 plusLIEs, mkLIE, isEmptyLIE, lieToList, listToLIE,
45 #include "HsVersions.h"
47 import HsSyn ( PendingSplice, HsOverLit, MonoBinds, RuleDecl, ForeignDecl )
48 import RnHsSyn ( RenamedHsExpr, RenamedPat, RenamedArithSeqInfo )
49 import HscTypes ( GhciMode, ExternalPackageState, HomePackageTable, NameCache,
50 GlobalRdrEnv, LocalRdrEnv, FixityEnv, TypeEnv, TyThing,
51 Avails, GenAvailInfo(..), AvailInfo, availName,
52 IsBootInterface, Deprecations )
53 import Packages ( PackageName )
54 import TcType ( TcTyVarSet, TcType, TcTauType, TcThetaType, TcPredType, TcKind,
55 tcCmpPred, tcCmpType, tcCmpTypes )
56 import InstEnv ( DFunId, InstEnv )
59 import NameSet ( NameSet, emptyNameSet )
61 import Class ( Class )
62 import Var ( Id, TyVar )
63 import VarEnv ( TidyEnv )
65 import SrcLoc ( SrcLoc )
66 import VarSet ( IdSet )
67 import ErrUtils ( Messages, Message )
68 import CmdLineOpts ( DynFlags )
69 import UniqSupply ( UniqSupply )
70 import BasicTypes ( IPName )
71 import Util ( thenCmp )
74 import DATA_IOREF ( IORef, newIORef, readIORef, writeIORef )
75 import UNSAFE_IO ( unsafeInterleaveIO )
76 import FIX_IO ( fixIO )
77 import EXCEPTION ( Exception )
78 import Maybe ( mapMaybe )
79 import ListSetOps ( unionLists )
80 import Panic ( tryMost )
85 type TcRef a = IORef a
86 type TcId = Id -- Type may be a TcType
90 %************************************************************************
92 Standard monad definition for TcRn
93 All the combinators for the monad can be found in TcRnMonad
95 %************************************************************************
97 The monad itself has to be defined here,
98 because it is mentioned by ErrCtxt
101 newtype TcRn m a = TcRn (Env m -> IO a)
104 type TcM a = TcRn TcLclEnv a
105 type RnM a = TcRn RnLclEnv a
107 returnM :: a -> TcRn m a
108 returnM a = TcRn (\ env -> return a)
110 thenM :: TcRn m a -> (a -> TcRn m b) -> TcRn m b
111 thenM (TcRn m) f = TcRn (\ env -> do { r <- m env ;
114 thenM_ :: TcRn m a -> TcRn m b -> TcRn m b
115 thenM_ (TcRn m) f = TcRn (\ env -> do { m env ; unTcRn f env })
118 failM = TcRn (\ env -> ioError (userError "TcRn failure"))
120 instance Monad (TcRn m) where
124 fail s = failM -- Ignore the string
128 %************************************************************************
130 Fundmantal combinators specific to the monad
132 %************************************************************************
137 runTcRn :: Env m -> TcRn m a -> IO a
138 runTcRn env (TcRn m) = m env
141 The fixpoint combinator
144 {-# NOINLINE fixM #-}
145 -- Aargh! Not inlining fixTc alleviates a space leak problem.
146 -- Normally fixTc is used with a lazy tuple match: if the optimiser is
147 -- shown the definition of fixTc, it occasionally transforms the code
148 -- in such a way that the code generator doesn't spot the selector
151 fixM :: (a -> TcRn m a) -> TcRn m a
152 fixM f = TcRn (\ env -> fixIO (\ r -> unTcRn (f r) env))
158 tryM :: TcRn m r -> TcRn m (Either Exception r)
159 -- Reflect exception into TcRn monad
160 tryM (TcRn thing) = TcRn (\ env -> tryMost (thing env))
166 unsafeInterleaveM :: TcRn m a -> TcRn m a
167 unsafeInterleaveM (TcRn m) = TcRn (\ env -> unsafeInterleaveIO (m env))
172 Performing arbitrary I/O, plus the read/write var (for efficiency)
175 ioToTcRn :: IO a -> TcRn m a
176 ioToTcRn io = TcRn (\ env -> io)
178 newMutVar :: a -> TcRn m (TcRef a)
179 newMutVar val = TcRn (\ env -> newIORef val)
181 writeMutVar :: TcRef a -> a -> TcRn m ()
182 writeMutVar var val = TcRn (\ env -> writeIORef var val)
184 readMutVar :: TcRef a -> TcRn m a
185 readMutVar var = TcRn (\ env -> readIORef var)
188 Getting the environment
191 getEnv :: TcRn m (Env m)
192 {-# INLINE getEnv #-}
193 getEnv = TcRn (\ env -> return env)
195 setEnv :: Env n -> TcRn n a -> TcRn m a
196 {-# INLINE setEnv #-}
197 setEnv new_env (TcRn m) = TcRn (\ env -> m new_env)
199 updEnv :: (Env m -> Env n) -> TcRn n a -> TcRn m a
200 {-# INLINE updEnv #-}
201 updEnv upd (TcRn m) = TcRn (\ env -> m (upd env))
205 %************************************************************************
207 The main environment types
209 %************************************************************************
212 data Env a -- Changes as we move into an expression
214 env_top :: TopEnv, -- Top-level stuff that never changes
215 -- Mainly a bunch of updatable refs
216 -- Includes all info about imported things
217 env_gbl :: TcGblEnv, -- Info about things defined at the top leve
218 -- of the module being compiled
220 env_lcl :: a, -- Different for the type checker
223 env_loc :: SrcLoc -- Source location
226 data TopEnv -- Built once at top level then does not change
227 -- Concerns imported stuff
228 -- Exceptions: error recovery points, meta computation points
230 top_mode :: GhciMode,
231 top_dflags :: DynFlags,
233 -- Stuff about imports
234 top_eps :: TcRef ExternalPackageState,
235 -- PIT, ImportedModuleInfo
236 -- DeclsMap, IfaceRules, IfaceInsts, InstGates
237 -- TypeEnv, InstEnv, RuleBase
238 -- Mutable, because we demand-load declarations that extend the state
240 top_hpt :: HomePackageTable,
241 -- The home package table that we've accumulated while
242 -- compiling the home package,
243 -- *excluding* the module we are compiling right now.
244 -- (In one-shot mode the current module is the only
245 -- home-package module, so tc_hpt is empty. All other
246 -- modules count as "external-package" modules.)
247 -- tc_hpt is not mutable because we only demand-load
248 -- external packages; the home package is eagerly
249 -- loaded by the compilation manager.
251 -- The global name supply
252 top_nc :: TcRef NameCache, -- Maps original names to Names
253 top_us :: TcRef UniqSupply, -- Unique supply for this module
254 top_errs :: TcRef Messages
257 -- TcGblEnv describes the top-level of the module at the
258 -- point at which the typechecker is finished work.
259 -- It is this structure that is handed on to the desugarer
263 tcg_mod :: Module, -- Module being compiled
264 tcg_usages :: TcRef EntityUsage, -- What version of what entities
265 -- have been used from other home-pkg modules
266 tcg_rdr_env :: GlobalRdrEnv, -- Top level envt; used during renaming
267 tcg_fix_env :: FixityEnv, -- Ditto
268 tcg_default :: [Type], -- Types used for defaulting
270 tcg_type_env :: TypeEnv, -- Global type env for the module we are compiling now
271 -- All TyCons and Classes (for this module) end up in here right away,
272 -- along with their derived constructors, selectors.
274 -- (Ids defined in this module start in the local envt,
275 -- though they move to the global envt during zonking)
277 tcg_inst_env :: TcRef InstEnv, -- Global instance env: a combination of
278 -- tc_pcs, tc_hpt, *and* tc_insts
279 -- This field is mutable so that it can be updated inside a
280 -- Template Haskell splice, which might suck in some new
281 -- instance declarations. This is a slightly different strategy
282 -- than for the type envt, where we look up first in tcg_type_env
283 -- and then in the mutable EPS, because the InstEnv for this module
284 -- is constructed (in principle at least) only from the modules
285 -- 'below' this one, so it's this-module-specific
287 -- On the other hand, a declaration quote [d| ... |] may introduce
288 -- some new instance declarations that we *don't* want to persist
289 -- outside the quote, so we tiresomely need to revert the InstEnv
290 -- after finishing the quote (see TcSplice.tcBracket)
292 -- Now a bunch of things about this module that are simply
293 -- accumulated, but never consulted until the end.
294 -- Nevertheless, it's convenient to accumulate them along
295 -- with the rest of the info from this module.
296 tcg_exports :: Avails, -- What is exported
297 tcg_imports :: ImportAvails, -- Information about what was imported
298 -- from where, including things bound
301 -- The next fields accumulate the payload of the module
302 -- The binds, rules and foreign-decl fiels are collected
303 -- initially in un-zonked form and are finally zonked in tcRnSrcDecls
304 tcg_binds :: MonoBinds Id, -- Value bindings in this module
305 tcg_deprecs :: Deprecations, -- ...Deprecations
306 tcg_insts :: [DFunId], -- ...Instances
307 tcg_rules :: [RuleDecl Id], -- ...Rules
308 tcg_fords :: [ForeignDecl Id] -- ...Foreign import & exports
313 %************************************************************************
315 The local typechecker environment
317 %************************************************************************
319 The Global-Env/Local-Env story
320 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
321 During type checking, we keep in the tcg_type_env
322 * All types and classes
323 * All Ids derived from types and classes (constructors, selectors)
325 At the end of type checking, we zonk the local bindings,
326 and as we do so we add to the tcg_type_env
327 * Locally defined top-level Ids
329 Why? Because they are now Ids not TcIds. This final GlobalEnv is
330 a) fed back (via the knot) to typechecking the
331 unfoldings of interface signatures
332 b) used in the ModDetails of this module
337 tcl_ctxt :: ErrCtxt, -- Error context
339 tcl_level :: Stage, -- Template Haskell context
341 tcl_env :: NameEnv TcTyThing, -- The local type environment: Ids and TyVars
342 -- defined in this module
344 tcl_tyvars :: TcRef TcTyVarSet, -- The "global tyvars"
345 -- Namely, the in-scope TyVars bound in tcl_lenv,
346 -- plus the tyvars mentioned in the types of
347 -- Ids bound in tcl_lenv
348 -- Why mutable? see notes with tcGetGlobalTyVars
350 tcl_lie :: TcRef LIE -- Place to accumulate type constraints
356 = Comp -- Ordinary compiling, at level topLevel
357 | Splice Level -- Inside a splice
358 | Brack Level -- Inside brackets;
359 (TcRef [PendingSplice]) -- accumulate pending splices here
360 (TcRef LIE) -- and type constraints here
361 topStage, topSpliceStage :: Stage
363 topSpliceStage = Splice (topLevel - 1) -- Stage for the body of a top-level splice
366 impLevel, topLevel :: Level
367 topLevel = 1 -- Things defined at top level of this module
368 impLevel = 0 -- Imported things; they can be used inside a top level splice
372 -- g1 = $(map ...) is OK
373 -- g2 = $(f ...) is not OK; because we havn't compiled f yet
376 = AGlobal TyThing -- Used only in the return type of a lookup
377 | ATcId TcId Level -- Ids defined in this module; may not be fully zonked
378 | ATyVar TyVar -- Type variables
379 | AThing TcKind -- Used temporarily, during kind checking
380 -- Here's an example of how the AThing guy is used
381 -- Suppose we are checking (forall a. T a Int):
382 -- 1. We first bind (a -> AThink kv), where kv is a kind variable.
383 -- 2. Then we kind-check the (T a Int) part.
384 -- 3. Then we zonk the kind variable.
385 -- 4. Now we know the kind for 'a', and we add (a -> ATyVar a::K) to the environment
387 instance Outputable TcTyThing where -- Debugging only
388 ppr (AGlobal g) = text "AGlobal" <+> ppr g
389 ppr (ATcId g l) = text "ATcId" <+> ppr g <+> ppr l
390 ppr (ATyVar t) = text "ATyVar" <+> ppr t
391 ppr (AThing k) = text "AThing" <+> ppr k
395 type ErrCtxt = [TidyEnv -> TcM (TidyEnv, Message)]
396 -- Innermost first. Monadic so that we have a chance
397 -- to deal with bound type variables just before error
398 -- message construction
402 %************************************************************************
404 The local renamer environment
406 %************************************************************************
412 rn_lenv :: LocalRdrEnv -- Local name envt
413 -- Does *not* include global name envt; may shadow it
414 -- Includes both ordinary variables and type variables;
415 -- they are kept distinct because tyvar have a different
416 -- occurrence contructor (Name.TvOcc)
417 -- We still need the unsullied global name env so that
418 -- we can look up record field names
421 data RnMode = SourceMode -- Renaming source code
422 | InterfaceMode Module -- Renaming interface declarations from M
423 | CmdLineMode -- Renaming a command-line expression
425 isInterfaceMode (InterfaceMode _) = True
426 isInterfaceMode _ = False
428 isCmdLineMode CmdLineMode = True
429 isCmdLineMode _ = False
433 %************************************************************************
437 %************************************************************************
439 EntityUsage tells what things are actually need in order to compile this
440 module. It is used for generating the usage-version field of the ModIface.
442 Note that we do not record version info for entities from
443 other (non-home) packages. If the package changes, GHC doesn't help.
446 type EntityUsage = NameSet
447 -- The Names are all the (a) home-package
448 -- (b) "big" (i.e. no data cons, class ops)
449 -- (c) non-locally-defined
451 -- names that have been slurped in so far.
452 -- This is used to generate the "usage" information for this module.
454 emptyUsages :: EntityUsage
455 emptyUsages = emptyNameSet
459 %************************************************************************
461 Operations over ImportAvails
463 %************************************************************************
465 ImportAvails summarises what was imported from where, irrespective
466 of whether the imported htings are actually used or not
467 It is used * when processing the export list
468 * when constructing usage info for the inteface file
469 * to identify the list of directly imported modules
470 for initialisation purposes
471 * when figuring out what things are really unused
477 -- All the things that are available from the import
478 -- Its domain is all the "main" things;
479 -- i.e. *excluding* class ops and constructors
480 -- (which appear inside their parent AvailTC)
482 imp_qual :: ModuleEnv AvailEnv,
483 -- Used to figure out "module M" export specifiers
484 -- (see 1.4 Report Section 5.1.1). Ultimately, we want to find
485 -- everything that is unambiguously in scope as 'M.x'
486 -- and where plain 'x' is (perhaps ambiguously) in scope.
487 -- So the starting point is all things that are in scope as 'M.x',
488 -- which is what this field tells us.
490 -- Domain is the *module qualifier* for imports.
491 -- e.g. import List as Foo
492 -- would add a binding Foo |-> ...stuff from List...
494 -- We keep the stuff as an AvailEnv so that it's easy to
495 -- combine stuff coming from different (unqualified)
496 -- imports of the same module
498 imp_mods :: ModuleEnv (Module, Bool),
499 -- Domain is all directly-imported modules
500 -- Bool is True if there was an unrestricted import
501 -- (i.e. not a selective list)
502 -- We need the Module in the range because we can't get
503 -- the keys of a ModuleEnv
505 -- (a) to help construct the usage information in
506 -- the interface file; if we import everything we
507 -- need to recompile if the module version changes
508 -- (b) to specify what child modules to initialise
510 imp_dep_mods :: ModuleEnv (ModuleName, IsBootInterface),
511 -- Home-package modules needed by the module being compiled
513 -- It doesn't matter whether any of these dependencies are actually
514 -- *used* when compiling the module; they are listed if they are below
515 -- it at all. For example, suppose M imports A which imports X. Then
516 -- compiling M might not need to consult X.hi, but X is still listed
517 -- in M's dependencies.
519 imp_dep_pkgs :: [PackageName],
520 -- Packages needed by the module being compiled, whether
521 -- directly, or via other modules in this package, or via
522 -- modules imported from other packages.
524 imp_orphs :: [ModuleName]
525 -- Orphan modules below us in the import tree
528 emptyImportAvails :: ImportAvails
529 emptyImportAvails = ImportAvails { imp_env = emptyAvailEnv,
530 imp_qual = emptyModuleEnv,
531 imp_mods = emptyModuleEnv,
532 imp_dep_mods = emptyModuleEnv,
536 plusImportAvails :: ImportAvails -> ImportAvails -> ImportAvails
538 (ImportAvails { imp_env = env1, imp_qual = unqual1, imp_mods = mods1,
539 imp_dep_mods = dmods1, imp_dep_pkgs = dpkgs1, imp_orphs = orphs1 })
540 (ImportAvails { imp_env = env2, imp_qual = unqual2, imp_mods = mods2,
541 imp_dep_mods = dmods2, imp_dep_pkgs = dpkgs2, imp_orphs = orphs2 })
542 = ImportAvails { imp_env = env1 `plusAvailEnv` env2,
543 imp_qual = plusModuleEnv_C plusAvailEnv unqual1 unqual2,
544 imp_mods = mods1 `plusModuleEnv` mods2,
545 imp_dep_mods = plusModuleEnv_C plus_mod_dep dmods1 dmods2,
546 imp_dep_pkgs = dpkgs1 `unionLists` dpkgs2,
547 imp_orphs = orphs1 `unionLists` orphs2 }
549 plus_mod_dep (m1, boot1) (m2, boot2)
550 = WARN( not (m1 == m2), (ppr m1 <+> ppr m2) $$ (ppr boot1 <+> ppr boot2) )
551 -- Check mod-names match
552 (m1, boot1 && boot2) -- If either side can "see" a non-hi-boot interface, use that
555 %************************************************************************
557 Avails, AvailEnv, etc
559 v%************************************************************************
562 plusAvail (Avail n1) (Avail n2) = Avail n1
563 plusAvail (AvailTC n1 ns1) (AvailTC n2 ns2) = AvailTC n2 (ns1 `unionLists` ns2)
566 plusAvail a1 a2 = pprPanic "RnEnv.plusAvail" (hsep [ppr a1,ppr a2])
569 -------------------------
570 pruneAvails :: (Name -> Bool) -- Keep if this is True
573 pruneAvails keep avails
574 = mapMaybe del avails
576 del :: AvailInfo -> Maybe AvailInfo -- Nothing => nothing left!
577 del (Avail n) | keep n = Just (Avail n)
578 | otherwise = Nothing
579 del (AvailTC n ns) | null ns' = Nothing
580 | otherwise = Just (AvailTC n ns')
585 ---------------------------------------
587 ---------------------------------------
590 type AvailEnv = NameEnv AvailInfo -- Maps a Name to the AvailInfo that contains it
592 emptyAvailEnv :: AvailEnv
593 emptyAvailEnv = emptyNameEnv
595 unitAvailEnv :: AvailInfo -> AvailEnv
596 unitAvailEnv a = unitNameEnv (availName a) a
598 plusAvailEnv :: AvailEnv -> AvailEnv -> AvailEnv
599 plusAvailEnv = plusNameEnv_C plusAvail
601 lookupAvailEnv_maybe :: AvailEnv -> Name -> Maybe AvailInfo
602 lookupAvailEnv_maybe = lookupNameEnv
604 lookupAvailEnv :: AvailEnv -> Name -> AvailInfo
605 lookupAvailEnv env n = case lookupNameEnv env n of
607 Nothing -> pprPanic "lookupAvailEnv" (ppr n)
609 availEnvElts = nameEnvElts
611 addAvail :: AvailEnv -> AvailInfo -> AvailEnv
612 addAvail avails avail = extendNameEnv_C plusAvail avails (availName avail) avail
614 mkAvailEnv :: [AvailInfo] -> AvailEnv
615 -- 'avails' may have several items with the same availName
616 -- E.g import Ix( Ix(..), index )
617 -- will give Ix(Ix,index,range) and Ix(index)
618 -- We want to combine these; addAvail does that
619 mkAvailEnv avails = foldl addAvail emptyAvailEnv avails
622 %************************************************************************
624 \subsection{Where from}
626 %************************************************************************
628 The @WhereFrom@ type controls where the renamer looks for an interface file
632 = ImportByUser IsBootInterface -- Ordinary user import (perhaps {-# SOURCE #-})
634 | ImportForUsage IsBootInterface -- Import when chasing usage info from an interaface file
635 -- Failure in this case is not an error
637 | ImportBySystem -- Non user import.
639 instance Outputable WhereFrom where
640 ppr (ImportByUser is_boot) | is_boot = ptext SLIT("{- SOURCE -}")
642 ppr (ImportForUsage is_boot) | is_boot = ptext SLIT("{- USAGE SOURCE -}")
643 | otherwise = ptext SLIT("{- USAGE -}")
644 ppr ImportBySystem = ptext SLIT("{- SYSTEM -}")
648 %************************************************************************
650 \subsection[Inst-types]{@Inst@ types}
652 v%************************************************************************
654 An @Inst@ is either a dictionary, an instance of an overloaded
655 literal, or an instance of an overloaded value. We call the latter a
656 ``method'' even though it may not correspond to a class operation.
657 For example, we might have an instance of the @double@ function at
658 type Int, represented by
660 Method 34 doubleId [Int] origin
672 TcId -- The overloaded function
673 -- This function will be a global, local, or ClassOpId;
674 -- inside instance decls (only) it can also be an InstId!
675 -- The id needn't be completely polymorphic.
676 -- You'll probably find its name (for documentation purposes)
677 -- inside the InstOrigin
679 [TcType] -- The types to which its polymorphic tyvars
680 -- should be instantiated.
681 -- These types must saturate the Id's foralls.
683 TcThetaType -- The (types of the) dictionaries to which the function
684 -- must be applied to get the method
686 TcTauType -- The tau-type of the method
690 -- INVARIANT 1: in (Method u f tys theta tau loc)
691 -- type of (f tys dicts(from theta)) = tau
693 -- INVARIANT 2: tau must not be of form (Pred -> Tau)
694 -- Reason: two methods are considerd equal if the
695 -- base Id matches, and the instantiating types
696 -- match. The TcThetaType should then match too.
697 -- This only bites in the call to tcInstClassOp in TcClassDcl.mkMethodBind
701 HsOverLit -- The literal from the occurrence site
702 -- INVARIANT: never a rebindable-syntax literal
703 -- Reason: tcSyntaxName does unification, and we
704 -- don't want to deal with that during tcSimplify
705 TcType -- The type at which the literal is used
709 @Insts@ are ordered by their class/type info, rather than by their
710 unique. This allows the context-reduction mechanism to use standard finite
711 maps to do their stuff.
714 instance Ord Inst where
717 instance Eq Inst where
718 (==) i1 i2 = case i1 `cmpInst` i2 of
722 cmpInst (Dict _ pred1 _) (Dict _ pred2 _) = pred1 `tcCmpPred` pred2
723 cmpInst (Dict _ _ _) other = LT
725 cmpInst (Method _ _ _ _ _ _) (Dict _ _ _) = GT
726 cmpInst (Method _ id1 tys1 _ _ _) (Method _ id2 tys2 _ _ _) = (id1 `compare` id2) `thenCmp` (tys1 `tcCmpTypes` tys2)
727 cmpInst (Method _ _ _ _ _ _) other = LT
729 cmpInst (LitInst _ _ _ _) (Dict _ _ _) = GT
730 cmpInst (LitInst _ _ _ _) (Method _ _ _ _ _ _) = GT
731 cmpInst (LitInst _ lit1 ty1 _) (LitInst _ lit2 ty2 _) = (lit1 `compare` lit2) `thenCmp` (ty1 `tcCmpType` ty2)
735 %************************************************************************
737 \subsection[Inst-collections]{LIE: a collection of Insts}
739 %************************************************************************
744 isEmptyLIE = isEmptyBag
746 unitLIE inst = unitBag inst
747 mkLIE insts = listToBag insts
748 plusLIE lie1 lie2 = lie1 `unionBags` lie2
749 consLIE inst lie = inst `consBag` lie
750 plusLIEs lies = unionManyBags lies
751 lieToList = bagToList
752 listToLIE = listToBag
756 %************************************************************************
758 \subsection[Inst-origin]{The @InstOrigin@ type}
760 %************************************************************************
762 The @InstOrigin@ type gives information about where a dictionary came from.
763 This is important for decent error message reporting because dictionaries
764 don't appear in the original source code. Doubtless this type will evolve...
766 It appears in TcMonad because there are a couple of error-message-generation
767 functions that deal with it.
770 data InstLoc = InstLoc InstOrigin SrcLoc ErrCtxt
772 instLocSrcLoc :: InstLoc -> SrcLoc
773 instLocSrcLoc (InstLoc _ src_loc _) = src_loc
776 = OccurrenceOf Name -- Occurrence of an overloaded identifier
778 | IPOcc (IPName Name) -- Occurrence of an implicit parameter
779 | IPBind (IPName Name) -- Binding site of an implicit parameter
783 | DataDeclOrigin -- Typechecking a data declaration
785 | InstanceDeclOrigin -- Typechecking an instance decl
787 | LiteralOrigin HsOverLit -- Occurrence of a literal
789 | PatOrigin RenamedPat
791 | ArithSeqOrigin RenamedArithSeqInfo -- [x..], [x..y] etc
792 | PArrSeqOrigin RenamedArithSeqInfo -- [:x..y:] and [:x,y..z:]
794 | SignatureOrigin -- A dict created from a type signature
795 | Rank2Origin -- A dict created when typechecking the argument
796 -- of a rank-2 typed function
798 | DoOrigin -- The monad for a do expression
800 | ClassDeclOrigin -- Manufactured during a class decl
802 | InstanceSpecOrigin Class -- in a SPECIALIZE instance pragma
805 -- When specialising instances the instance info attached to
806 -- each class is not yet ready, so we record it inside the
807 -- origin information. This is a bit of a hack, but it works
808 -- fine. (Patrick is to blame [WDP].)
810 | ValSpecOrigin Name -- in a SPECIALIZE pragma for a value
812 -- Argument or result of a ccall
813 -- Dictionaries with this origin aren't actually mentioned in the
814 -- translated term, and so need not be bound. Nor should they
815 -- be abstracted over.
817 | CCallOrigin String -- CCall label
818 (Maybe RenamedHsExpr) -- Nothing if it's the result
819 -- Just arg, for an argument
821 | LitLitOrigin String -- the litlit
823 | UnknownOrigin -- Help! I give up...
827 pprInstLoc :: InstLoc -> SDoc
828 pprInstLoc (InstLoc orig locn ctxt)
829 = hsep [text "arising from", pp_orig orig, text "at", ppr locn]
831 pp_orig (OccurrenceOf name)
832 = hsep [ptext SLIT("use of"), quotes (ppr name)]
834 = hsep [ptext SLIT("use of implicit parameter"), quotes (ppr name)]
835 pp_orig (IPBind name)
836 = hsep [ptext SLIT("binding for implicit parameter"), quotes (ppr name)]
837 pp_orig RecordUpdOrigin
838 = ptext SLIT("a record update")
839 pp_orig DataDeclOrigin
840 = ptext SLIT("the data type declaration")
841 pp_orig InstanceDeclOrigin
842 = ptext SLIT("the instance declaration")
843 pp_orig (LiteralOrigin lit)
844 = hsep [ptext SLIT("the literal"), quotes (ppr lit)]
845 pp_orig (PatOrigin pat)
846 = hsep [ptext SLIT("the pattern"), quotes (ppr pat)]
847 pp_orig (ArithSeqOrigin seq)
848 = hsep [ptext SLIT("the arithmetic sequence"), quotes (ppr seq)]
849 pp_orig (PArrSeqOrigin seq)
850 = hsep [ptext SLIT("the parallel array sequence"), quotes (ppr seq)]
851 pp_orig (SignatureOrigin)
852 = ptext SLIT("a type signature")
853 pp_orig (Rank2Origin)
854 = ptext SLIT("a function with an overloaded argument type")
856 = ptext SLIT("a do statement")
857 pp_orig (ClassDeclOrigin)
858 = ptext SLIT("a class declaration")
859 pp_orig (InstanceSpecOrigin clas ty)
860 = hsep [text "a SPECIALIZE instance pragma; class",
861 quotes (ppr clas), text "type:", ppr ty]
862 pp_orig (ValSpecOrigin name)
863 = hsep [ptext SLIT("a SPECIALIZE user-pragma for"), quotes (ppr name)]
864 pp_orig (CCallOrigin clabel Nothing{-ccall result-})
865 = hsep [ptext SLIT("the result of the _ccall_ to"), quotes (text clabel)]
866 pp_orig (CCallOrigin clabel (Just arg_expr))
867 = hsep [ptext SLIT("an argument in the _ccall_ to"), quotes (text clabel) <> comma,
868 text "namely", quotes (ppr arg_expr)]
869 pp_orig (LitLitOrigin s)
870 = hsep [ptext SLIT("the ``literal-literal''"), quotes (text s)]
871 pp_orig (UnknownOrigin)
872 = ptext SLIT("...oops -- I don't know where the overloading came from!")