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, zapEnv,
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,
50 NameCache, GlobalRdrEnv, LocalRdrEnv, FixityEnv,
51 TypeEnv, TyThing, Avails, GenAvailInfo(..), AvailInfo,
52 availName, IsBootInterface, Deprecations,
53 ExternalPackageState(..), emptyExternalPackageState )
54 import Packages ( PackageName )
55 import TcType ( TcTyVarSet, TcType, TcTauType, TcThetaType,
56 TcPredType, TcKind, tcCmpPred, tcCmpType, tcCmpTypes )
57 import InstEnv ( DFunId, InstEnv )
60 import NameSet ( NameSet, emptyNameSet )
62 import Class ( Class )
63 import Var ( Id, TyVar )
64 import VarEnv ( TidyEnv )
66 import SrcLoc ( SrcLoc )
67 import VarSet ( IdSet )
68 import ErrUtils ( Messages, Message )
69 import CmdLineOpts ( DynFlags )
70 import UniqSupply ( UniqSupply )
71 import BasicTypes ( IPName )
72 import Util ( thenCmp )
75 import DATA_IOREF ( IORef, newIORef, readIORef, writeIORef )
76 import UNSAFE_IO ( unsafeInterleaveIO )
77 import FIX_IO ( fixIO )
78 import EXCEPTION ( Exception(..) )
79 import IO ( isUserError )
80 import Maybe ( mapMaybe )
81 import ListSetOps ( unionLists )
82 import Panic ( tryJust )
87 type TcRef a = IORef a
88 type TcId = Id -- Type may be a TcType
92 %************************************************************************
94 Standard monad definition for TcRn
95 All the combinators for the monad can be found in TcRnMonad
97 %************************************************************************
99 The monad itself has to be defined here,
100 because it is mentioned by ErrCtxt
103 newtype TcRn m a = TcRn (Env m -> IO a)
106 type TcM a = TcRn TcLclEnv a
107 type RnM a = TcRn RnLclEnv a
109 returnM :: a -> TcRn m a
110 returnM a = TcRn (\ env -> return a)
112 thenM :: TcRn m a -> (a -> TcRn m b) -> TcRn m b
113 thenM (TcRn m) f = TcRn (\ env -> do { r <- m env ;
116 thenM_ :: TcRn m a -> TcRn m b -> TcRn m b
117 thenM_ (TcRn m) f = TcRn (\ env -> do { m env ; unTcRn f env })
120 failM = TcRn (\ env -> ioError (userError "TcRn failure"))
122 instance Monad (TcRn m) where
126 fail s = failM -- Ignore the string
130 %************************************************************************
132 Fundmantal combinators specific to the monad
134 %************************************************************************
139 runTcRn :: Env m -> TcRn m a -> IO a
140 runTcRn env (TcRn m) = m env
143 The fixpoint combinator
146 {-# NOINLINE fixM #-}
147 -- Aargh! Not inlining fixTc alleviates a space leak problem.
148 -- Normally fixTc is used with a lazy tuple match: if the optimiser is
149 -- shown the definition of fixTc, it occasionally transforms the code
150 -- in such a way that the code generator doesn't spot the selector
153 fixM :: (a -> TcRn m a) -> TcRn m a
154 fixM f = TcRn (\ env -> fixIO (\ r -> unTcRn (f r) env))
160 tryM :: TcRn m r -> TcRn m (Either Exception r)
161 -- Reflect exception into TcRn monad
162 tryM (TcRn thing) = TcRn (\ env -> tryJust tc_errors (thing env))
164 #if __GLASGOW_HASKELL__ > 504 || __GLASGOW_HASKELL__ < 500
165 tc_errors e@(IOException ioe) | isUserError ioe = Just e
167 tc_errors e | isUserError e = Just e
169 tc_errors _other = Nothing
170 -- type checker failures show up as UserErrors only
176 unsafeInterleaveM :: TcRn m a -> TcRn m a
177 unsafeInterleaveM (TcRn m) = TcRn (\ env -> unsafeInterleaveIO (m env))
182 Performing arbitrary I/O, plus the read/write var (for efficiency)
185 ioToTcRn :: IO a -> TcRn m a
186 ioToTcRn io = TcRn (\ env -> io)
188 newMutVar :: a -> TcRn m (TcRef a)
189 newMutVar val = TcRn (\ env -> newIORef val)
191 writeMutVar :: TcRef a -> a -> TcRn m ()
192 writeMutVar var val = TcRn (\ env -> writeIORef var val)
194 readMutVar :: TcRef a -> TcRn m a
195 readMutVar var = TcRn (\ env -> readIORef var)
198 Getting the environment
201 getEnv :: TcRn m (Env m)
202 {-# INLINE getEnv #-}
203 getEnv = TcRn (\ env -> return env)
205 setEnv :: Env n -> TcRn n a -> TcRn m a
206 {-# INLINE setEnv #-}
207 setEnv new_env (TcRn m) = TcRn (\ env -> m new_env)
209 updEnv :: (Env m -> Env n) -> TcRn n a -> TcRn m a
210 {-# INLINE updEnv #-}
211 updEnv upd (TcRn m) = TcRn (\ env -> m (upd env))
215 zapEnv :: TcRn m a -> TcRn m a
216 zapEnv act = TcRn $ \env@Env{ env_top=top, env_gbl=gbl, env_lcl=lcl } ->
226 eps_snap <- readIORef eps
227 ref <- newIORef $! emptyExternalPackageState{ eps_PTE = eps_PTE eps_snap }
238 type_env = tcg_type_env gbl
242 tcg_type_env = type_env
249 -- leave the rest empty
252 case act of { TcRn f -> f env' }
256 %************************************************************************
258 The main environment types
260 %************************************************************************
263 data Env a -- Changes as we move into an expression
265 env_top :: TopEnv, -- Top-level stuff that never changes
266 -- Mainly a bunch of updatable refs
267 -- Includes all info about imported things
268 env_gbl :: TcGblEnv, -- Info about things defined at the top leve
269 -- of the module being compiled
271 env_lcl :: a, -- Different for the type checker
274 env_loc :: SrcLoc -- Source location
277 data TopEnv -- Built once at top level then does not change
278 -- Concerns imported stuff
279 -- Exceptions: error recovery points, meta computation points
281 top_mode :: GhciMode,
282 top_dflags :: DynFlags,
284 -- Stuff about imports
285 top_eps :: TcRef ExternalPackageState,
286 -- PIT, ImportedModuleInfo
287 -- DeclsMap, IfaceRules, IfaceInsts, InstGates
288 -- TypeEnv, InstEnv, RuleBase
289 -- Mutable, because we demand-load declarations that extend the state
291 top_hpt :: HomePackageTable,
292 -- The home package table that we've accumulated while
293 -- compiling the home package,
294 -- *excluding* the module we are compiling right now.
295 -- (In one-shot mode the current module is the only
296 -- home-package module, so tc_hpt is empty. All other
297 -- modules count as "external-package" modules.)
298 -- tc_hpt is not mutable because we only demand-load
299 -- external packages; the home package is eagerly
300 -- loaded by the compilation manager.
302 -- The global name supply
303 top_nc :: TcRef NameCache, -- Maps original names to Names
304 top_us :: TcRef UniqSupply, -- Unique supply for this module
305 top_errs :: TcRef Messages
308 -- TcGblEnv describes the top-level of the module at the
309 -- point at which the typechecker is finished work.
310 -- It is this structure that is handed on to the desugarer
314 tcg_mod :: Module, -- Module being compiled
315 tcg_usages :: TcRef EntityUsage, -- What version of what entities
316 -- have been used from other home-pkg modules
317 tcg_rdr_env :: GlobalRdrEnv, -- Top level envt; used during renaming
318 tcg_fix_env :: FixityEnv, -- Ditto
319 tcg_default :: [Type], -- Types used for defaulting
321 tcg_type_env :: TypeEnv, -- Global type env for the module we are compiling now
322 -- All TyCons and Classes (for this module) end up in here right away,
323 -- along with their derived constructors, selectors.
325 -- (Ids defined in this module start in the local envt,
326 -- though they move to the global envt during zonking)
328 tcg_inst_env :: TcRef InstEnv, -- Global instance env: a combination of
329 -- tc_pcs, tc_hpt, *and* tc_insts
330 -- This field is mutable so that it can be updated inside a
331 -- Template Haskell splice, which might suck in some new
332 -- instance declarations. This is a slightly different strategy
333 -- than for the type envt, where we look up first in tcg_type_env
334 -- and then in the mutable EPS, because the InstEnv for this module
335 -- is constructed (in principle at least) only from the modules
336 -- 'below' this one, so it's this-module-specific
338 -- On the other hand, a declaration quote [d| ... |] may introduce
339 -- some new instance declarations that we *don't* want to persist
340 -- outside the quote, so we tiresomely need to revert the InstEnv
341 -- after finishing the quote (see TcSplice.tcBracket)
343 -- Now a bunch of things about this module that are simply
344 -- accumulated, but never consulted until the end.
345 -- Nevertheless, it's convenient to accumulate them along
346 -- with the rest of the info from this module.
347 tcg_exports :: Avails, -- What is exported
348 tcg_imports :: ImportAvails, -- Information about what was imported
349 -- from where, including things bound
352 -- The next fields accumulate the payload of the module
353 -- The binds, rules and foreign-decl fiels are collected
354 -- initially in un-zonked form and are finally zonked in tcRnSrcDecls
355 tcg_binds :: MonoBinds Id, -- Value bindings in this module
356 tcg_deprecs :: Deprecations, -- ...Deprecations
357 tcg_insts :: [DFunId], -- ...Instances
358 tcg_rules :: [RuleDecl Id], -- ...Rules
359 tcg_fords :: [ForeignDecl Id] -- ...Foreign import & exports
364 %************************************************************************
366 The local typechecker environment
368 %************************************************************************
370 The Global-Env/Local-Env story
371 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
372 During type checking, we keep in the tcg_type_env
373 * All types and classes
374 * All Ids derived from types and classes (constructors, selectors)
376 At the end of type checking, we zonk the local bindings,
377 and as we do so we add to the tcg_type_env
378 * Locally defined top-level Ids
380 Why? Because they are now Ids not TcIds. This final GlobalEnv is
381 a) fed back (via the knot) to typechecking the
382 unfoldings of interface signatures
383 b) used in the ModDetails of this module
388 tcl_ctxt :: ErrCtxt, -- Error context
390 tcl_level :: Stage, -- Template Haskell context
392 tcl_env :: NameEnv TcTyThing, -- The local type environment: Ids and TyVars
393 -- defined in this module
395 tcl_tyvars :: TcRef TcTyVarSet, -- The "global tyvars"
396 -- Namely, the in-scope TyVars bound in tcl_lenv,
397 -- plus the tyvars mentioned in the types of
398 -- Ids bound in tcl_lenv
399 -- Why mutable? see notes with tcGetGlobalTyVars
401 tcl_lie :: TcRef LIE -- Place to accumulate type constraints
407 = Comp -- Ordinary compiling, at level topLevel
408 | Splice Level -- Inside a splice
409 | Brack Level -- Inside brackets;
410 (TcRef [PendingSplice]) -- accumulate pending splices here
411 (TcRef LIE) -- and type constraints here
412 topStage, topSpliceStage :: Stage
414 topSpliceStage = Splice (topLevel - 1) -- Stage for the body of a top-level splice
417 impLevel, topLevel :: Level
418 topLevel = 1 -- Things defined at top level of this module
419 impLevel = 0 -- Imported things; they can be used inside a top level splice
423 -- g1 = $(map ...) is OK
424 -- g2 = $(f ...) is not OK; because we havn't compiled f yet
427 = AGlobal TyThing -- Used only in the return type of a lookup
428 | ATcId TcId Level -- Ids defined in this module; may not be fully zonked
429 | ATyVar TyVar -- Type variables
430 | AThing TcKind -- Used temporarily, during kind checking
431 -- Here's an example of how the AThing guy is used
432 -- Suppose we are checking (forall a. T a Int):
433 -- 1. We first bind (a -> AThink kv), where kv is a kind variable.
434 -- 2. Then we kind-check the (T a Int) part.
435 -- 3. Then we zonk the kind variable.
436 -- 4. Now we know the kind for 'a', and we add (a -> ATyVar a::K) to the environment
438 instance Outputable TcTyThing where -- Debugging only
439 ppr (AGlobal g) = text "AGlobal" <+> ppr g
440 ppr (ATcId g l) = text "ATcId" <+> ppr g <+> ppr l
441 ppr (ATyVar t) = text "ATyVar" <+> ppr t
442 ppr (AThing k) = text "AThing" <+> ppr k
446 type ErrCtxt = [TidyEnv -> TcM (TidyEnv, Message)]
447 -- Innermost first. Monadic so that we have a chance
448 -- to deal with bound type variables just before error
449 -- message construction
453 %************************************************************************
455 The local renamer environment
457 %************************************************************************
463 rn_lenv :: LocalRdrEnv -- Local name envt
464 -- Does *not* include global name envt; may shadow it
465 -- Includes both ordinary variables and type variables;
466 -- they are kept distinct because tyvar have a different
467 -- occurrence contructor (Name.TvOcc)
468 -- We still need the unsullied global name env so that
469 -- we can look up record field names
472 data RnMode = SourceMode -- Renaming source code
473 | InterfaceMode Module -- Renaming interface declarations from M
474 | CmdLineMode -- Renaming a command-line expression
476 isInterfaceMode (InterfaceMode _) = True
477 isInterfaceMode _ = False
479 isCmdLineMode CmdLineMode = True
480 isCmdLineMode _ = False
484 %************************************************************************
488 %************************************************************************
490 EntityUsage tells what things are actually need in order to compile this
491 module. It is used for generating the usage-version field of the ModIface.
493 Note that we do not record version info for entities from
494 other (non-home) packages. If the package changes, GHC doesn't help.
497 type EntityUsage = NameSet
498 -- The Names are all the (a) home-package
499 -- (b) "big" (i.e. no data cons, class ops)
500 -- (c) non-locally-defined
502 -- names that have been slurped in so far.
503 -- This is used to generate the "usage" information for this module.
505 emptyUsages :: EntityUsage
506 emptyUsages = emptyNameSet
510 %************************************************************************
512 Operations over ImportAvails
514 %************************************************************************
516 ImportAvails summarises what was imported from where, irrespective
517 of whether the imported htings are actually used or not
518 It is used * when processing the export list
519 * when constructing usage info for the inteface file
520 * to identify the list of directly imported modules
521 for initialisation purposes
522 * when figuring out what things are really unused
528 -- All the things that are available from the import
529 -- Its domain is all the "main" things;
530 -- i.e. *excluding* class ops and constructors
531 -- (which appear inside their parent AvailTC)
533 imp_qual :: ModuleEnv AvailEnv,
534 -- Used to figure out "module M" export specifiers
535 -- (see 1.4 Report Section 5.1.1). Ultimately, we want to find
536 -- everything that is unambiguously in scope as 'M.x'
537 -- and where plain 'x' is (perhaps ambiguously) in scope.
538 -- So the starting point is all things that are in scope as 'M.x',
539 -- which is what this field tells us.
541 -- Domain is the *module qualifier* for imports.
542 -- e.g. import List as Foo
543 -- would add a binding Foo |-> ...stuff from List...
545 -- We keep the stuff as an AvailEnv so that it's easy to
546 -- combine stuff coming from different (unqualified)
547 -- imports of the same module
549 imp_mods :: ModuleEnv (Module, Bool),
550 -- Domain is all directly-imported modules
551 -- Bool is True if there was an unrestricted import
552 -- (i.e. not a selective list)
553 -- We need the Module in the range because we can't get
554 -- the keys of a ModuleEnv
556 -- (a) to help construct the usage information in
557 -- the interface file; if we import everything we
558 -- need to recompile if the module version changes
559 -- (b) to specify what child modules to initialise
561 imp_dep_mods :: ModuleEnv (ModuleName, IsBootInterface),
562 -- Home-package modules needed by the module being compiled
564 -- It doesn't matter whether any of these dependencies are actually
565 -- *used* when compiling the module; they are listed if they are below
566 -- it at all. For example, suppose M imports A which imports X. Then
567 -- compiling M might not need to consult X.hi, but X is still listed
568 -- in M's dependencies.
570 imp_dep_pkgs :: [PackageName],
571 -- Packages needed by the module being compiled, whether
572 -- directly, or via other modules in this package, or via
573 -- modules imported from other packages.
575 imp_orphs :: [ModuleName]
576 -- Orphan modules below us in the import tree
579 emptyImportAvails :: ImportAvails
580 emptyImportAvails = ImportAvails { imp_env = emptyAvailEnv,
581 imp_qual = emptyModuleEnv,
582 imp_mods = emptyModuleEnv,
583 imp_dep_mods = emptyModuleEnv,
587 plusImportAvails :: ImportAvails -> ImportAvails -> ImportAvails
589 (ImportAvails { imp_env = env1, imp_qual = unqual1, imp_mods = mods1,
590 imp_dep_mods = dmods1, imp_dep_pkgs = dpkgs1, imp_orphs = orphs1 })
591 (ImportAvails { imp_env = env2, imp_qual = unqual2, imp_mods = mods2,
592 imp_dep_mods = dmods2, imp_dep_pkgs = dpkgs2, imp_orphs = orphs2 })
593 = ImportAvails { imp_env = env1 `plusAvailEnv` env2,
594 imp_qual = plusModuleEnv_C plusAvailEnv unqual1 unqual2,
595 imp_mods = mods1 `plusModuleEnv` mods2,
596 imp_dep_mods = plusModuleEnv_C plus_mod_dep dmods1 dmods2,
597 imp_dep_pkgs = dpkgs1 `unionLists` dpkgs2,
598 imp_orphs = orphs1 `unionLists` orphs2 }
600 plus_mod_dep (m1, boot1) (m2, boot2)
601 = WARN( not (m1 == m2), (ppr m1 <+> ppr m2) $$ (ppr boot1 <+> ppr boot2) )
602 -- Check mod-names match
603 (m1, boot1 && boot2) -- If either side can "see" a non-hi-boot interface, use that
606 %************************************************************************
608 Avails, AvailEnv, etc
610 v%************************************************************************
613 plusAvail (Avail n1) (Avail n2) = Avail n1
614 plusAvail (AvailTC n1 ns1) (AvailTC n2 ns2) = AvailTC n2 (ns1 `unionLists` ns2)
617 plusAvail a1 a2 = pprPanic "RnEnv.plusAvail" (hsep [ppr a1,ppr a2])
620 -------------------------
621 pruneAvails :: (Name -> Bool) -- Keep if this is True
624 pruneAvails keep avails
625 = mapMaybe del avails
627 del :: AvailInfo -> Maybe AvailInfo -- Nothing => nothing left!
628 del (Avail n) | keep n = Just (Avail n)
629 | otherwise = Nothing
630 del (AvailTC n ns) | null ns' = Nothing
631 | otherwise = Just (AvailTC n ns')
636 ---------------------------------------
638 ---------------------------------------
641 type AvailEnv = NameEnv AvailInfo -- Maps a Name to the AvailInfo that contains it
643 emptyAvailEnv :: AvailEnv
644 emptyAvailEnv = emptyNameEnv
646 unitAvailEnv :: AvailInfo -> AvailEnv
647 unitAvailEnv a = unitNameEnv (availName a) a
649 plusAvailEnv :: AvailEnv -> AvailEnv -> AvailEnv
650 plusAvailEnv = plusNameEnv_C plusAvail
652 lookupAvailEnv_maybe :: AvailEnv -> Name -> Maybe AvailInfo
653 lookupAvailEnv_maybe = lookupNameEnv
655 lookupAvailEnv :: AvailEnv -> Name -> AvailInfo
656 lookupAvailEnv env n = case lookupNameEnv env n of
658 Nothing -> pprPanic "lookupAvailEnv" (ppr n)
660 availEnvElts = nameEnvElts
662 addAvail :: AvailEnv -> AvailInfo -> AvailEnv
663 addAvail avails avail = extendNameEnv_C plusAvail avails (availName avail) avail
665 mkAvailEnv :: [AvailInfo] -> AvailEnv
666 -- 'avails' may have several items with the same availName
667 -- E.g import Ix( Ix(..), index )
668 -- will give Ix(Ix,index,range) and Ix(index)
669 -- We want to combine these; addAvail does that
670 mkAvailEnv avails = foldl addAvail emptyAvailEnv avails
673 %************************************************************************
675 \subsection{Where from}
677 %************************************************************************
679 The @WhereFrom@ type controls where the renamer looks for an interface file
683 = ImportByUser IsBootInterface -- Ordinary user import (perhaps {-# SOURCE #-})
685 | ImportForUsage IsBootInterface -- Import when chasing usage info from an interaface file
686 -- Failure in this case is not an error
688 | ImportBySystem -- Non user import.
690 instance Outputable WhereFrom where
691 ppr (ImportByUser is_boot) | is_boot = ptext SLIT("{- SOURCE -}")
693 ppr (ImportForUsage is_boot) | is_boot = ptext SLIT("{- USAGE SOURCE -}")
694 | otherwise = ptext SLIT("{- USAGE -}")
695 ppr ImportBySystem = ptext SLIT("{- SYSTEM -}")
699 %************************************************************************
701 \subsection[Inst-types]{@Inst@ types}
703 v%************************************************************************
705 An @Inst@ is either a dictionary, an instance of an overloaded
706 literal, or an instance of an overloaded value. We call the latter a
707 ``method'' even though it may not correspond to a class operation.
708 For example, we might have an instance of the @double@ function at
709 type Int, represented by
711 Method 34 doubleId [Int] origin
723 TcId -- The overloaded function
724 -- This function will be a global, local, or ClassOpId;
725 -- inside instance decls (only) it can also be an InstId!
726 -- The id needn't be completely polymorphic.
727 -- You'll probably find its name (for documentation purposes)
728 -- inside the InstOrigin
730 [TcType] -- The types to which its polymorphic tyvars
731 -- should be instantiated.
732 -- These types must saturate the Id's foralls.
734 TcThetaType -- The (types of the) dictionaries to which the function
735 -- must be applied to get the method
737 TcTauType -- The tau-type of the method
741 -- INVARIANT 1: in (Method u f tys theta tau loc)
742 -- type of (f tys dicts(from theta)) = tau
744 -- INVARIANT 2: tau must not be of form (Pred -> Tau)
745 -- Reason: two methods are considerd equal if the
746 -- base Id matches, and the instantiating types
747 -- match. The TcThetaType should then match too.
748 -- This only bites in the call to tcInstClassOp in TcClassDcl.mkMethodBind
752 HsOverLit -- The literal from the occurrence site
753 -- INVARIANT: never a rebindable-syntax literal
754 -- Reason: tcSyntaxName does unification, and we
755 -- don't want to deal with that during tcSimplify
756 TcType -- The type at which the literal is used
760 @Insts@ are ordered by their class/type info, rather than by their
761 unique. This allows the context-reduction mechanism to use standard finite
762 maps to do their stuff.
765 instance Ord Inst where
768 instance Eq Inst where
769 (==) i1 i2 = case i1 `cmpInst` i2 of
773 cmpInst (Dict _ pred1 _) (Dict _ pred2 _) = pred1 `tcCmpPred` pred2
774 cmpInst (Dict _ _ _) other = LT
776 cmpInst (Method _ _ _ _ _ _) (Dict _ _ _) = GT
777 cmpInst (Method _ id1 tys1 _ _ _) (Method _ id2 tys2 _ _ _) = (id1 `compare` id2) `thenCmp` (tys1 `tcCmpTypes` tys2)
778 cmpInst (Method _ _ _ _ _ _) other = LT
780 cmpInst (LitInst _ _ _ _) (Dict _ _ _) = GT
781 cmpInst (LitInst _ _ _ _) (Method _ _ _ _ _ _) = GT
782 cmpInst (LitInst _ lit1 ty1 _) (LitInst _ lit2 ty2 _) = (lit1 `compare` lit2) `thenCmp` (ty1 `tcCmpType` ty2)
786 %************************************************************************
788 \subsection[Inst-collections]{LIE: a collection of Insts}
790 %************************************************************************
795 isEmptyLIE = isEmptyBag
797 unitLIE inst = unitBag inst
798 mkLIE insts = listToBag insts
799 plusLIE lie1 lie2 = lie1 `unionBags` lie2
800 consLIE inst lie = inst `consBag` lie
801 plusLIEs lies = unionManyBags lies
802 lieToList = bagToList
803 listToLIE = listToBag
807 %************************************************************************
809 \subsection[Inst-origin]{The @InstOrigin@ type}
811 %************************************************************************
813 The @InstOrigin@ type gives information about where a dictionary came from.
814 This is important for decent error message reporting because dictionaries
815 don't appear in the original source code. Doubtless this type will evolve...
817 It appears in TcMonad because there are a couple of error-message-generation
818 functions that deal with it.
821 data InstLoc = InstLoc InstOrigin SrcLoc ErrCtxt
823 instLocSrcLoc :: InstLoc -> SrcLoc
824 instLocSrcLoc (InstLoc _ src_loc _) = src_loc
827 = OccurrenceOf Name -- Occurrence of an overloaded identifier
829 | IPOcc (IPName Name) -- Occurrence of an implicit parameter
830 | IPBind (IPName Name) -- Binding site of an implicit parameter
834 | DataDeclOrigin -- Typechecking a data declaration
836 | InstanceDeclOrigin -- Typechecking an instance decl
838 | LiteralOrigin HsOverLit -- Occurrence of a literal
840 | PatOrigin RenamedPat
842 | ArithSeqOrigin RenamedArithSeqInfo -- [x..], [x..y] etc
843 | PArrSeqOrigin RenamedArithSeqInfo -- [:x..y:] and [:x,y..z:]
845 | SignatureOrigin -- A dict created from a type signature
846 | Rank2Origin -- A dict created when typechecking the argument
847 -- of a rank-2 typed function
849 | DoOrigin -- The monad for a do expression
851 | ClassDeclOrigin -- Manufactured during a class decl
853 | InstanceSpecOrigin Class -- in a SPECIALIZE instance pragma
856 -- When specialising instances the instance info attached to
857 -- each class is not yet ready, so we record it inside the
858 -- origin information. This is a bit of a hack, but it works
859 -- fine. (Patrick is to blame [WDP].)
861 | ValSpecOrigin Name -- in a SPECIALIZE pragma for a value
863 -- Argument or result of a ccall
864 -- Dictionaries with this origin aren't actually mentioned in the
865 -- translated term, and so need not be bound. Nor should they
866 -- be abstracted over.
868 | CCallOrigin String -- CCall label
869 (Maybe RenamedHsExpr) -- Nothing if it's the result
870 -- Just arg, for an argument
872 | LitLitOrigin String -- the litlit
874 | UnknownOrigin -- Help! I give up...
878 pprInstLoc :: InstLoc -> SDoc
879 pprInstLoc (InstLoc orig locn ctxt)
880 = hsep [text "arising from", pp_orig orig, text "at", ppr locn]
882 pp_orig (OccurrenceOf name)
883 = hsep [ptext SLIT("use of"), quotes (ppr name)]
885 = hsep [ptext SLIT("use of implicit parameter"), quotes (ppr name)]
886 pp_orig (IPBind name)
887 = hsep [ptext SLIT("binding for implicit parameter"), quotes (ppr name)]
888 pp_orig RecordUpdOrigin
889 = ptext SLIT("a record update")
890 pp_orig DataDeclOrigin
891 = ptext SLIT("the data type declaration")
892 pp_orig InstanceDeclOrigin
893 = ptext SLIT("the instance declaration")
894 pp_orig (LiteralOrigin lit)
895 = hsep [ptext SLIT("the literal"), quotes (ppr lit)]
896 pp_orig (PatOrigin pat)
897 = hsep [ptext SLIT("the pattern"), quotes (ppr pat)]
898 pp_orig (ArithSeqOrigin seq)
899 = hsep [ptext SLIT("the arithmetic sequence"), quotes (ppr seq)]
900 pp_orig (PArrSeqOrigin seq)
901 = hsep [ptext SLIT("the parallel array sequence"), quotes (ppr seq)]
902 pp_orig (SignatureOrigin)
903 = ptext SLIT("a type signature")
904 pp_orig (Rank2Origin)
905 = ptext SLIT("a function with an overloaded argument type")
907 = ptext SLIT("a do statement")
908 pp_orig (ClassDeclOrigin)
909 = ptext SLIT("a class declaration")
910 pp_orig (InstanceSpecOrigin clas ty)
911 = hsep [text "a SPECIALIZE instance pragma; class",
912 quotes (ppr clas), text "type:", ppr ty]
913 pp_orig (ValSpecOrigin name)
914 = hsep [ptext SLIT("a SPECIALIZE user-pragma for"), quotes (ppr name)]
915 pp_orig (CCallOrigin clabel Nothing{-ccall result-})
916 = hsep [ptext SLIT("the result of the _ccall_ to"), quotes (text clabel)]
917 pp_orig (CCallOrigin clabel (Just arg_expr))
918 = hsep [ptext SLIT("an argument in the _ccall_ to"), quotes (text clabel) <> comma,
919 text "namely", quotes (ppr arg_expr)]
920 pp_orig (LitLitOrigin s)
921 = hsep [ptext SLIT("the ``literal-literal''"), quotes (text s)]
922 pp_orig (UnknownOrigin)
923 = ptext SLIT("...oops -- I don't know where the overloading came from!")