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(..), tryJust )
79 import IO ( isUserError )
80 import Maybe ( mapMaybe )
81 import ListSetOps ( unionLists )
86 type TcRef a = IORef a
87 type TcId = Id -- Type may be a TcType
91 %************************************************************************
93 Standard monad definition for TcRn
94 All the combinators for the monad can be found in TcRnMonad
96 %************************************************************************
98 The monad itself has to be defined here,
99 because it is mentioned by ErrCtxt
102 newtype TcRn m a = TcRn (Env m -> IO a)
105 type TcM a = TcRn TcLclEnv a
106 type RnM a = TcRn RnLclEnv a
108 returnM :: a -> TcRn m a
109 returnM a = TcRn (\ env -> return a)
111 thenM :: TcRn m a -> (a -> TcRn m b) -> TcRn m b
112 thenM (TcRn m) f = TcRn (\ env -> do { r <- m env ;
115 thenM_ :: TcRn m a -> TcRn m b -> TcRn m b
116 thenM_ (TcRn m) f = TcRn (\ env -> do { m env ; unTcRn f env })
119 failM = TcRn (\ env -> ioError (userError "TcRn failure"))
121 instance Monad (TcRn m) where
125 fail s = failM -- Ignore the string
129 %************************************************************************
131 Fundmantal combinators specific to the monad
133 %************************************************************************
138 runTcRn :: Env m -> TcRn m a -> IO a
139 runTcRn env (TcRn m) = m env
142 The fixpoint combinator
145 {-# NOINLINE fixM #-}
146 -- Aargh! Not inlining fixTc alleviates a space leak problem.
147 -- Normally fixTc is used with a lazy tuple match: if the optimiser is
148 -- shown the definition of fixTc, it occasionally transforms the code
149 -- in such a way that the code generator doesn't spot the selector
152 fixM :: (a -> TcRn m a) -> TcRn m a
153 fixM f = TcRn (\ env -> fixIO (\ r -> unTcRn (f r) env))
159 tryM :: TcRn m r -> TcRn m (Either Exception r)
160 -- Reflect exception into TcRn monad
161 tryM (TcRn thing) = TcRn (\ env -> tryJust tc_errors (thing env))
163 #if __GLASGOW_HASKELL__ > 504
164 tc_errors e@(IOException ioe) | isUserError ioe = Just e
166 tc_errors e@(IOException _) | isUserError e = Just e
168 tc_errors _other = Nothing
169 -- type checker failures show up as UserErrors only
175 unsafeInterleaveM :: TcRn m a -> TcRn m a
176 unsafeInterleaveM (TcRn m) = TcRn (\ env -> unsafeInterleaveIO (m env))
181 Performing arbitrary I/O, plus the read/write var (for efficiency)
184 ioToTcRn :: IO a -> TcRn m a
185 ioToTcRn io = TcRn (\ env -> io)
187 newMutVar :: a -> TcRn m (TcRef a)
188 newMutVar val = TcRn (\ env -> newIORef val)
190 writeMutVar :: TcRef a -> a -> TcRn m ()
191 writeMutVar var val = TcRn (\ env -> writeIORef var val)
193 readMutVar :: TcRef a -> TcRn m a
194 readMutVar var = TcRn (\ env -> readIORef var)
197 Getting the environment
200 getEnv :: TcRn m (Env m)
201 {-# INLINE getEnv #-}
202 getEnv = TcRn (\ env -> return env)
204 setEnv :: Env n -> TcRn n a -> TcRn m a
205 {-# INLINE setEnv #-}
206 setEnv new_env (TcRn m) = TcRn (\ env -> m new_env)
208 updEnv :: (Env m -> Env n) -> TcRn n a -> TcRn m a
209 {-# INLINE updEnv #-}
210 updEnv upd (TcRn m) = TcRn (\ env -> m (upd env))
214 zapEnv :: TcRn m a -> TcRn m a
215 zapEnv act = TcRn $ \env@Env{ env_top=top, env_gbl=gbl, env_lcl=lcl } ->
225 eps_snap <- readIORef eps
226 ref <- newIORef $! emptyExternalPackageState{ eps_PTE = eps_PTE eps_snap }
237 type_env = tcg_type_env gbl
241 tcg_type_env = type_env
248 -- leave the rest empty
251 case act of { TcRn f -> f env' }
255 %************************************************************************
257 The main environment types
259 %************************************************************************
262 data Env a -- Changes as we move into an expression
264 env_top :: TopEnv, -- Top-level stuff that never changes
265 -- Mainly a bunch of updatable refs
266 -- Includes all info about imported things
267 env_gbl :: TcGblEnv, -- Info about things defined at the top leve
268 -- of the module being compiled
270 env_lcl :: a, -- Different for the type checker
273 env_loc :: SrcLoc -- Source location
276 data TopEnv -- Built once at top level then does not change
277 -- Concerns imported stuff
278 -- Exceptions: error recovery points, meta computation points
280 top_mode :: GhciMode,
281 top_dflags :: DynFlags,
283 -- Stuff about imports
284 top_eps :: TcRef ExternalPackageState,
285 -- PIT, ImportedModuleInfo
286 -- DeclsMap, IfaceRules, IfaceInsts, InstGates
287 -- TypeEnv, InstEnv, RuleBase
288 -- Mutable, because we demand-load declarations that extend the state
290 top_hpt :: HomePackageTable,
291 -- The home package table that we've accumulated while
292 -- compiling the home package,
293 -- *excluding* the module we are compiling right now.
294 -- (In one-shot mode the current module is the only
295 -- home-package module, so tc_hpt is empty. All other
296 -- modules count as "external-package" modules.)
297 -- tc_hpt is not mutable because we only demand-load
298 -- external packages; the home package is eagerly
299 -- loaded by the compilation manager.
301 -- The global name supply
302 top_nc :: TcRef NameCache, -- Maps original names to Names
303 top_us :: TcRef UniqSupply, -- Unique supply for this module
304 top_errs :: TcRef Messages
307 -- TcGblEnv describes the top-level of the module at the
308 -- point at which the typechecker is finished work.
309 -- It is this structure that is handed on to the desugarer
313 tcg_mod :: Module, -- Module being compiled
314 tcg_usages :: TcRef EntityUsage, -- What version of what entities
315 -- have been used from other home-pkg modules
316 tcg_rdr_env :: GlobalRdrEnv, -- Top level envt; used during renaming
317 tcg_fix_env :: FixityEnv, -- Ditto
318 tcg_default :: [Type], -- Types used for defaulting
320 tcg_type_env :: TypeEnv, -- Global type env for the module we are compiling now
321 -- All TyCons and Classes (for this module) end up in here right away,
322 -- along with their derived constructors, selectors.
324 -- (Ids defined in this module start in the local envt,
325 -- though they move to the global envt during zonking)
327 tcg_inst_env :: TcRef InstEnv, -- Global instance env: a combination of
328 -- tc_pcs, tc_hpt, *and* tc_insts
329 -- This field is mutable so that it can be updated inside a
330 -- Template Haskell splice, which might suck in some new
331 -- instance declarations. This is a slightly different strategy
332 -- than for the type envt, where we look up first in tcg_type_env
333 -- and then in the mutable EPS, because the InstEnv for this module
334 -- is constructed (in principle at least) only from the modules
335 -- 'below' this one, so it's this-module-specific
337 -- On the other hand, a declaration quote [d| ... |] may introduce
338 -- some new instance declarations that we *don't* want to persist
339 -- outside the quote, so we tiresomely need to revert the InstEnv
340 -- after finishing the quote (see TcSplice.tcBracket)
342 -- Now a bunch of things about this module that are simply
343 -- accumulated, but never consulted until the end.
344 -- Nevertheless, it's convenient to accumulate them along
345 -- with the rest of the info from this module.
346 tcg_exports :: Avails, -- What is exported
347 tcg_imports :: ImportAvails, -- Information about what was imported
348 -- from where, including things bound
351 -- The next fields accumulate the payload of the module
352 -- The binds, rules and foreign-decl fiels are collected
353 -- initially in un-zonked form and are finally zonked in tcRnSrcDecls
354 tcg_binds :: MonoBinds Id, -- Value bindings in this module
355 tcg_deprecs :: Deprecations, -- ...Deprecations
356 tcg_insts :: [DFunId], -- ...Instances
357 tcg_rules :: [RuleDecl Id], -- ...Rules
358 tcg_fords :: [ForeignDecl Id] -- ...Foreign import & exports
363 %************************************************************************
365 The local typechecker environment
367 %************************************************************************
369 The Global-Env/Local-Env story
370 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
371 During type checking, we keep in the tcg_type_env
372 * All types and classes
373 * All Ids derived from types and classes (constructors, selectors)
375 At the end of type checking, we zonk the local bindings,
376 and as we do so we add to the tcg_type_env
377 * Locally defined top-level Ids
379 Why? Because they are now Ids not TcIds. This final GlobalEnv is
380 a) fed back (via the knot) to typechecking the
381 unfoldings of interface signatures
382 b) used in the ModDetails of this module
387 tcl_ctxt :: ErrCtxt, -- Error context
389 tcl_level :: Stage, -- Template Haskell context
391 tcl_env :: NameEnv TcTyThing, -- The local type environment: Ids and TyVars
392 -- defined in this module
394 tcl_tyvars :: TcRef TcTyVarSet, -- The "global tyvars"
395 -- Namely, the in-scope TyVars bound in tcl_lenv,
396 -- plus the tyvars mentioned in the types of
397 -- Ids bound in tcl_lenv
398 -- Why mutable? see notes with tcGetGlobalTyVars
400 tcl_lie :: TcRef LIE -- Place to accumulate type constraints
406 = Comp -- Ordinary compiling, at level topLevel
407 | Splice Level -- Inside a splice
408 | Brack Level -- Inside brackets;
409 (TcRef [PendingSplice]) -- accumulate pending splices here
410 (TcRef LIE) -- and type constraints here
411 topStage, topSpliceStage :: Stage
413 topSpliceStage = Splice (topLevel - 1) -- Stage for the body of a top-level splice
416 impLevel, topLevel :: Level
417 topLevel = 1 -- Things defined at top level of this module
418 impLevel = 0 -- Imported things; they can be used inside a top level splice
422 -- g1 = $(map ...) is OK
423 -- g2 = $(f ...) is not OK; because we havn't compiled f yet
426 = AGlobal TyThing -- Used only in the return type of a lookup
427 | ATcId TcId Level -- Ids defined in this module; may not be fully zonked
428 | ATyVar TyVar -- Type variables
429 | AThing TcKind -- Used temporarily, during kind checking
430 -- Here's an example of how the AThing guy is used
431 -- Suppose we are checking (forall a. T a Int):
432 -- 1. We first bind (a -> AThink kv), where kv is a kind variable.
433 -- 2. Then we kind-check the (T a Int) part.
434 -- 3. Then we zonk the kind variable.
435 -- 4. Now we know the kind for 'a', and we add (a -> ATyVar a::K) to the environment
437 instance Outputable TcTyThing where -- Debugging only
438 ppr (AGlobal g) = text "AGlobal" <+> ppr g
439 ppr (ATcId g l) = text "ATcId" <+> ppr g <+> ppr l
440 ppr (ATyVar t) = text "ATyVar" <+> ppr t
441 ppr (AThing k) = text "AThing" <+> ppr k
445 type ErrCtxt = [TidyEnv -> TcM (TidyEnv, Message)]
446 -- Innermost first. Monadic so that we have a chance
447 -- to deal with bound type variables just before error
448 -- message construction
452 %************************************************************************
454 The local renamer environment
456 %************************************************************************
462 rn_lenv :: LocalRdrEnv -- Local name envt
463 -- Does *not* include global name envt; may shadow it
464 -- Includes both ordinary variables and type variables;
465 -- they are kept distinct because tyvar have a different
466 -- occurrence contructor (Name.TvOcc)
467 -- We still need the unsullied global name env so that
468 -- we can look up record field names
471 data RnMode = SourceMode -- Renaming source code
472 | InterfaceMode Module -- Renaming interface declarations from M
473 | CmdLineMode -- Renaming a command-line expression
475 isInterfaceMode (InterfaceMode _) = True
476 isInterfaceMode _ = False
478 isCmdLineMode CmdLineMode = True
479 isCmdLineMode _ = False
483 %************************************************************************
487 %************************************************************************
489 EntityUsage tells what things are actually need in order to compile this
490 module. It is used for generating the usage-version field of the ModIface.
492 Note that we do not record version info for entities from
493 other (non-home) packages. If the package changes, GHC doesn't help.
496 type EntityUsage = NameSet
497 -- The Names are all the (a) home-package
498 -- (b) "big" (i.e. no data cons, class ops)
499 -- (c) non-locally-defined
501 -- names that have been slurped in so far.
502 -- This is used to generate the "usage" information for this module.
504 emptyUsages :: EntityUsage
505 emptyUsages = emptyNameSet
509 %************************************************************************
511 Operations over ImportAvails
513 %************************************************************************
515 ImportAvails summarises what was imported from where, irrespective
516 of whether the imported htings are actually used or not
517 It is used * when processing the export list
518 * when constructing usage info for the inteface file
519 * to identify the list of directly imported modules
520 for initialisation purposes
521 * when figuring out what things are really unused
527 -- All the things that are available from the import
528 -- Its domain is all the "main" things;
529 -- i.e. *excluding* class ops and constructors
530 -- (which appear inside their parent AvailTC)
532 imp_qual :: ModuleEnv AvailEnv,
533 -- Used to figure out "module M" export specifiers
534 -- (see 1.4 Report Section 5.1.1). Ultimately, we want to find
535 -- everything that is unambiguously in scope as 'M.x'
536 -- and where plain 'x' is (perhaps ambiguously) in scope.
537 -- So the starting point is all things that are in scope as 'M.x',
538 -- which is what this field tells us.
540 -- Domain is the *module qualifier* for imports.
541 -- e.g. import List as Foo
542 -- would add a binding Foo |-> ...stuff from List...
544 -- We keep the stuff as an AvailEnv so that it's easy to
545 -- combine stuff coming from different (unqualified)
546 -- imports of the same module
548 imp_mods :: ModuleEnv (Module, Bool),
549 -- Domain is all directly-imported modules
550 -- Bool is True if there was an unrestricted import
551 -- (i.e. not a selective list)
552 -- We need the Module in the range because we can't get
553 -- the keys of a ModuleEnv
555 -- (a) to help construct the usage information in
556 -- the interface file; if we import everything we
557 -- need to recompile if the module version changes
558 -- (b) to specify what child modules to initialise
560 imp_dep_mods :: ModuleEnv (ModuleName, IsBootInterface),
561 -- Home-package modules needed by the module being compiled
563 -- It doesn't matter whether any of these dependencies are actually
564 -- *used* when compiling the module; they are listed if they are below
565 -- it at all. For example, suppose M imports A which imports X. Then
566 -- compiling M might not need to consult X.hi, but X is still listed
567 -- in M's dependencies.
569 imp_dep_pkgs :: [PackageName],
570 -- Packages needed by the module being compiled, whether
571 -- directly, or via other modules in this package, or via
572 -- modules imported from other packages.
574 imp_orphs :: [ModuleName]
575 -- Orphan modules below us in the import tree
578 emptyImportAvails :: ImportAvails
579 emptyImportAvails = ImportAvails { imp_env = emptyAvailEnv,
580 imp_qual = emptyModuleEnv,
581 imp_mods = emptyModuleEnv,
582 imp_dep_mods = emptyModuleEnv,
586 plusImportAvails :: ImportAvails -> ImportAvails -> ImportAvails
588 (ImportAvails { imp_env = env1, imp_qual = unqual1, imp_mods = mods1,
589 imp_dep_mods = dmods1, imp_dep_pkgs = dpkgs1, imp_orphs = orphs1 })
590 (ImportAvails { imp_env = env2, imp_qual = unqual2, imp_mods = mods2,
591 imp_dep_mods = dmods2, imp_dep_pkgs = dpkgs2, imp_orphs = orphs2 })
592 = ImportAvails { imp_env = env1 `plusAvailEnv` env2,
593 imp_qual = plusModuleEnv_C plusAvailEnv unqual1 unqual2,
594 imp_mods = mods1 `plusModuleEnv` mods2,
595 imp_dep_mods = plusModuleEnv_C plus_mod_dep dmods1 dmods2,
596 imp_dep_pkgs = dpkgs1 `unionLists` dpkgs2,
597 imp_orphs = orphs1 `unionLists` orphs2 }
599 plus_mod_dep (m1, boot1) (m2, boot2)
600 = WARN( not (m1 == m2), (ppr m1 <+> ppr m2) $$ (ppr boot1 <+> ppr boot2) )
601 -- Check mod-names match
602 (m1, boot1 && boot2) -- If either side can "see" a non-hi-boot interface, use that
605 %************************************************************************
607 Avails, AvailEnv, etc
609 v%************************************************************************
612 plusAvail (Avail n1) (Avail n2) = Avail n1
613 plusAvail (AvailTC n1 ns1) (AvailTC n2 ns2) = AvailTC n2 (ns1 `unionLists` ns2)
616 plusAvail a1 a2 = pprPanic "RnEnv.plusAvail" (hsep [ppr a1,ppr a2])
619 -------------------------
620 pruneAvails :: (Name -> Bool) -- Keep if this is True
623 pruneAvails keep avails
624 = mapMaybe del avails
626 del :: AvailInfo -> Maybe AvailInfo -- Nothing => nothing left!
627 del (Avail n) | keep n = Just (Avail n)
628 | otherwise = Nothing
629 del (AvailTC n ns) | null ns' = Nothing
630 | otherwise = Just (AvailTC n ns')
635 ---------------------------------------
637 ---------------------------------------
640 type AvailEnv = NameEnv AvailInfo -- Maps a Name to the AvailInfo that contains it
642 emptyAvailEnv :: AvailEnv
643 emptyAvailEnv = emptyNameEnv
645 unitAvailEnv :: AvailInfo -> AvailEnv
646 unitAvailEnv a = unitNameEnv (availName a) a
648 plusAvailEnv :: AvailEnv -> AvailEnv -> AvailEnv
649 plusAvailEnv = plusNameEnv_C plusAvail
651 lookupAvailEnv_maybe :: AvailEnv -> Name -> Maybe AvailInfo
652 lookupAvailEnv_maybe = lookupNameEnv
654 lookupAvailEnv :: AvailEnv -> Name -> AvailInfo
655 lookupAvailEnv env n = case lookupNameEnv env n of
657 Nothing -> pprPanic "lookupAvailEnv" (ppr n)
659 availEnvElts = nameEnvElts
661 addAvail :: AvailEnv -> AvailInfo -> AvailEnv
662 addAvail avails avail = extendNameEnv_C plusAvail avails (availName avail) avail
664 mkAvailEnv :: [AvailInfo] -> AvailEnv
665 -- 'avails' may have several items with the same availName
666 -- E.g import Ix( Ix(..), index )
667 -- will give Ix(Ix,index,range) and Ix(index)
668 -- We want to combine these; addAvail does that
669 mkAvailEnv avails = foldl addAvail emptyAvailEnv avails
672 %************************************************************************
674 \subsection{Where from}
676 %************************************************************************
678 The @WhereFrom@ type controls where the renamer looks for an interface file
682 = ImportByUser IsBootInterface -- Ordinary user import (perhaps {-# SOURCE #-})
684 | ImportForUsage IsBootInterface -- Import when chasing usage info from an interaface file
685 -- Failure in this case is not an error
687 | ImportBySystem -- Non user import.
689 instance Outputable WhereFrom where
690 ppr (ImportByUser is_boot) | is_boot = ptext SLIT("{- SOURCE -}")
692 ppr (ImportForUsage is_boot) | is_boot = ptext SLIT("{- USAGE SOURCE -}")
693 | otherwise = ptext SLIT("{- USAGE -}")
694 ppr ImportBySystem = ptext SLIT("{- SYSTEM -}")
698 %************************************************************************
700 \subsection[Inst-types]{@Inst@ types}
702 v%************************************************************************
704 An @Inst@ is either a dictionary, an instance of an overloaded
705 literal, or an instance of an overloaded value. We call the latter a
706 ``method'' even though it may not correspond to a class operation.
707 For example, we might have an instance of the @double@ function at
708 type Int, represented by
710 Method 34 doubleId [Int] origin
722 TcId -- The overloaded function
723 -- This function will be a global, local, or ClassOpId;
724 -- inside instance decls (only) it can also be an InstId!
725 -- The id needn't be completely polymorphic.
726 -- You'll probably find its name (for documentation purposes)
727 -- inside the InstOrigin
729 [TcType] -- The types to which its polymorphic tyvars
730 -- should be instantiated.
731 -- These types must saturate the Id's foralls.
733 TcThetaType -- The (types of the) dictionaries to which the function
734 -- must be applied to get the method
736 TcTauType -- The tau-type of the method
740 -- INVARIANT 1: in (Method u f tys theta tau loc)
741 -- type of (f tys dicts(from theta)) = tau
743 -- INVARIANT 2: tau must not be of form (Pred -> Tau)
744 -- Reason: two methods are considerd equal if the
745 -- base Id matches, and the instantiating types
746 -- match. The TcThetaType should then match too.
747 -- This only bites in the call to tcInstClassOp in TcClassDcl.mkMethodBind
751 HsOverLit -- The literal from the occurrence site
752 -- INVARIANT: never a rebindable-syntax literal
753 -- Reason: tcSyntaxName does unification, and we
754 -- don't want to deal with that during tcSimplify
755 TcType -- The type at which the literal is used
759 @Insts@ are ordered by their class/type info, rather than by their
760 unique. This allows the context-reduction mechanism to use standard finite
761 maps to do their stuff.
764 instance Ord Inst where
767 instance Eq Inst where
768 (==) i1 i2 = case i1 `cmpInst` i2 of
772 cmpInst (Dict _ pred1 _) (Dict _ pred2 _) = pred1 `tcCmpPred` pred2
773 cmpInst (Dict _ _ _) other = LT
775 cmpInst (Method _ _ _ _ _ _) (Dict _ _ _) = GT
776 cmpInst (Method _ id1 tys1 _ _ _) (Method _ id2 tys2 _ _ _) = (id1 `compare` id2) `thenCmp` (tys1 `tcCmpTypes` tys2)
777 cmpInst (Method _ _ _ _ _ _) other = LT
779 cmpInst (LitInst _ _ _ _) (Dict _ _ _) = GT
780 cmpInst (LitInst _ _ _ _) (Method _ _ _ _ _ _) = GT
781 cmpInst (LitInst _ lit1 ty1 _) (LitInst _ lit2 ty2 _) = (lit1 `compare` lit2) `thenCmp` (ty1 `tcCmpType` ty2)
785 %************************************************************************
787 \subsection[Inst-collections]{LIE: a collection of Insts}
789 %************************************************************************
794 isEmptyLIE = isEmptyBag
796 unitLIE inst = unitBag inst
797 mkLIE insts = listToBag insts
798 plusLIE lie1 lie2 = lie1 `unionBags` lie2
799 consLIE inst lie = inst `consBag` lie
800 plusLIEs lies = unionManyBags lies
801 lieToList = bagToList
802 listToLIE = listToBag
806 %************************************************************************
808 \subsection[Inst-origin]{The @InstOrigin@ type}
810 %************************************************************************
812 The @InstOrigin@ type gives information about where a dictionary came from.
813 This is important for decent error message reporting because dictionaries
814 don't appear in the original source code. Doubtless this type will evolve...
816 It appears in TcMonad because there are a couple of error-message-generation
817 functions that deal with it.
820 data InstLoc = InstLoc InstOrigin SrcLoc ErrCtxt
822 instLocSrcLoc :: InstLoc -> SrcLoc
823 instLocSrcLoc (InstLoc _ src_loc _) = src_loc
826 = OccurrenceOf Name -- Occurrence of an overloaded identifier
828 | IPOcc (IPName Name) -- Occurrence of an implicit parameter
829 | IPBind (IPName Name) -- Binding site of an implicit parameter
833 | DataDeclOrigin -- Typechecking a data declaration
835 | InstanceDeclOrigin -- Typechecking an instance decl
837 | LiteralOrigin HsOverLit -- Occurrence of a literal
839 | PatOrigin RenamedPat
841 | ArithSeqOrigin RenamedArithSeqInfo -- [x..], [x..y] etc
842 | PArrSeqOrigin RenamedArithSeqInfo -- [:x..y:] and [:x,y..z:]
844 | SignatureOrigin -- A dict created from a type signature
845 | Rank2Origin -- A dict created when typechecking the argument
846 -- of a rank-2 typed function
848 | DoOrigin -- The monad for a do expression
850 | ClassDeclOrigin -- Manufactured during a class decl
852 | InstanceSpecOrigin Class -- in a SPECIALIZE instance pragma
855 -- When specialising instances the instance info attached to
856 -- each class is not yet ready, so we record it inside the
857 -- origin information. This is a bit of a hack, but it works
858 -- fine. (Patrick is to blame [WDP].)
860 | ValSpecOrigin Name -- in a SPECIALIZE pragma for a value
862 -- Argument or result of a ccall
863 -- Dictionaries with this origin aren't actually mentioned in the
864 -- translated term, and so need not be bound. Nor should they
865 -- be abstracted over.
867 | CCallOrigin String -- CCall label
868 (Maybe RenamedHsExpr) -- Nothing if it's the result
869 -- Just arg, for an argument
871 | LitLitOrigin String -- the litlit
873 | UnknownOrigin -- Help! I give up...
877 pprInstLoc :: InstLoc -> SDoc
878 pprInstLoc (InstLoc orig locn ctxt)
879 = hsep [text "arising from", pp_orig orig, text "at", ppr locn]
881 pp_orig (OccurrenceOf name)
882 = hsep [ptext SLIT("use of"), quotes (ppr name)]
884 = hsep [ptext SLIT("use of implicit parameter"), quotes (ppr name)]
885 pp_orig (IPBind name)
886 = hsep [ptext SLIT("binding for implicit parameter"), quotes (ppr name)]
887 pp_orig RecordUpdOrigin
888 = ptext SLIT("a record update")
889 pp_orig DataDeclOrigin
890 = ptext SLIT("the data type declaration")
891 pp_orig InstanceDeclOrigin
892 = ptext SLIT("the instance declaration")
893 pp_orig (LiteralOrigin lit)
894 = hsep [ptext SLIT("the literal"), quotes (ppr lit)]
895 pp_orig (PatOrigin pat)
896 = hsep [ptext SLIT("the pattern"), quotes (ppr pat)]
897 pp_orig (ArithSeqOrigin seq)
898 = hsep [ptext SLIT("the arithmetic sequence"), quotes (ppr seq)]
899 pp_orig (PArrSeqOrigin seq)
900 = hsep [ptext SLIT("the parallel array sequence"), quotes (ppr seq)]
901 pp_orig (SignatureOrigin)
902 = ptext SLIT("a type signature")
903 pp_orig (Rank2Origin)
904 = ptext SLIT("a function with an overloaded argument type")
906 = ptext SLIT("a do statement")
907 pp_orig (ClassDeclOrigin)
908 = ptext SLIT("a class declaration")
909 pp_orig (InstanceSpecOrigin clas ty)
910 = hsep [text "a SPECIALIZE instance pragma; class",
911 quotes (ppr clas), text "type:", ppr ty]
912 pp_orig (ValSpecOrigin name)
913 = hsep [ptext SLIT("a SPECIALIZE user-pragma for"), quotes (ppr name)]
914 pp_orig (CCallOrigin clabel Nothing{-ccall result-})
915 = hsep [ptext SLIT("the result of the _ccall_ to"), quotes (text clabel)]
916 pp_orig (CCallOrigin clabel (Just arg_expr))
917 = hsep [ptext SLIT("an argument in the _ccall_ to"), quotes (text clabel) <> comma,
918 text "namely", quotes (ppr arg_expr)]
919 pp_orig (LitLitOrigin s)
920 = hsep [ptext SLIT("the ``literal-literal''"), quotes (text s)]
921 pp_orig (UnknownOrigin)
922 = ptext SLIT("...oops -- I don't know where the overloading came from!")