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, 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 porcessing 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
476 -- All the things that are available from the import
477 -- Its domain is all the "main" things;
478 -- i.e. *excluding* class ops and constructors
479 -- (which appear inside their parent AvailTC)
481 imp_qual :: ModuleEnv AvailEnv,
482 -- Used to figure out "module M" export specifiers
483 -- (see 1.4 Report Section 5.1.1). Ultimately, we want to find
484 -- everything that is unambiguously in scope as 'M.x'
485 -- and where plain 'x' is (perhaps ambiguously) in scope.
486 -- So the starting point is all things that are in scope as 'M.x',
487 -- which is what this field tells us.
489 -- Domain is the *module qualifier* for imports.
490 -- e.g. import List as Foo
491 -- would add a binding Foo |-> ...stuff from List...
493 -- We keep the stuff as an AvailEnv so that it's easy to
494 -- combine stuff coming from different (unqualified)
495 -- imports of the same module
497 imp_mods :: ModuleEnv (Module, Bool),
498 -- Domain is all directly-imported modules
499 -- Bool is True if there was an unrestricted import
500 -- (i.e. not a selective list)
501 -- We need the Module in the range because we can't get
502 -- the keys of a ModuleEnv
504 -- (a) to help construct the usage information in
505 -- the interface file; if we import everything we
506 -- need to recompile if the module version changes
507 -- (b) to specify what child modules to initialise
509 imp_dep_mods :: ModuleEnv (ModuleName, IsBootInterface),
510 -- Home-package modules needed by the module being compiled
512 -- It doesn't matter whether any of these dependencies are actually
513 -- *used* when compiling the module; they are listed if they are below
514 -- it at all. For example, suppose M imports A which imports X. Then
515 -- compiling M might not need to consult X.hi, but X is still listed
516 -- in M's dependencies.
518 imp_dep_pkgs :: [PackageName],
519 -- Packages needed by the module being compiled, whether
520 -- directly, or via other modules in this package, or via
521 -- modules imported from other packages.
523 imp_orphs :: [ModuleName]
524 -- Orphan modules below us in the import tree
527 emptyImportAvails :: ImportAvails
528 emptyImportAvails = ImportAvails { imp_env = emptyAvailEnv,
529 imp_qual = emptyModuleEnv,
530 imp_mods = emptyModuleEnv,
531 imp_dep_mods = emptyModuleEnv,
535 plusImportAvails :: ImportAvails -> ImportAvails -> ImportAvails
537 (ImportAvails { imp_env = env1, imp_qual = unqual1, imp_mods = mods1,
538 imp_dep_mods = dmods1, imp_dep_pkgs = dpkgs1, imp_orphs = orphs1 })
539 (ImportAvails { imp_env = env2, imp_qual = unqual2, imp_mods = mods2,
540 imp_dep_mods = dmods2, imp_dep_pkgs = dpkgs2, imp_orphs = orphs2 })
541 = ImportAvails { imp_env = env1 `plusAvailEnv` env2,
542 imp_qual = plusModuleEnv_C plusAvailEnv unqual1 unqual2,
543 imp_mods = mods1 `plusModuleEnv` mods2,
544 imp_dep_mods = plusModuleEnv_C plus_mod_dep dmods1 dmods2,
545 imp_dep_pkgs = dpkgs1 `unionLists` dpkgs2,
546 imp_orphs = orphs1 `unionLists` orphs2 }
548 plus_mod_dep (m1, boot1) (m2, boot2)
549 = WARN( not (m1 == m2), (ppr m1 <+> ppr m2) $$ (ppr boot1 <+> ppr boot2) )
550 -- Check mod-names match
551 (m1, boot1 && boot2) -- If either side can "see" a non-hi-boot interface, use that
554 %************************************************************************
556 Avails, AvailEnv, etc
558 v%************************************************************************
561 plusAvail (Avail n1) (Avail n2) = Avail n1
562 plusAvail (AvailTC n1 ns1) (AvailTC n2 ns2) = AvailTC n2 (ns1 `unionLists` ns2)
565 plusAvail a1 a2 = pprPanic "RnEnv.plusAvail" (hsep [ppr a1,ppr a2])
568 -------------------------
569 pruneAvails :: (Name -> Bool) -- Keep if this is True
572 pruneAvails keep avails
573 = mapMaybe del avails
575 del :: AvailInfo -> Maybe AvailInfo -- Nothing => nothing left!
576 del (Avail n) | keep n = Just (Avail n)
577 | otherwise = Nothing
578 del (AvailTC n ns) | null ns' = Nothing
579 | otherwise = Just (AvailTC n ns')
584 ---------------------------------------
586 ---------------------------------------
589 type AvailEnv = NameEnv AvailInfo -- Maps a Name to the AvailInfo that contains it
591 emptyAvailEnv :: AvailEnv
592 emptyAvailEnv = emptyNameEnv
594 unitAvailEnv :: AvailInfo -> AvailEnv
595 unitAvailEnv a = unitNameEnv (availName a) a
597 plusAvailEnv :: AvailEnv -> AvailEnv -> AvailEnv
598 plusAvailEnv = plusNameEnv_C plusAvail
600 lookupAvailEnv = lookupNameEnv
602 availEnvElts = nameEnvElts
604 addAvail :: AvailEnv -> AvailInfo -> AvailEnv
605 addAvail avails avail = extendNameEnv_C plusAvail avails (availName avail) avail
607 mkAvailEnv :: [AvailInfo] -> AvailEnv
608 -- 'avails' may have several items with the same availName
609 -- E.g import Ix( Ix(..), index )
610 -- will give Ix(Ix,index,range) and Ix(index)
611 -- We want to combine these; addAvail does that
612 mkAvailEnv avails = foldl addAvail emptyAvailEnv avails
615 %************************************************************************
617 \subsection{Where from}
619 %************************************************************************
621 The @WhereFrom@ type controls where the renamer looks for an interface file
625 = ImportByUser IsBootInterface -- Ordinary user import (perhaps {-# SOURCE #-})
627 | ImportForUsage IsBootInterface -- Import when chasing usage info from an interaface file
628 -- Failure in this case is not an error
630 | ImportBySystem -- Non user import.
632 instance Outputable WhereFrom where
633 ppr (ImportByUser is_boot) | is_boot = ptext SLIT("{- SOURCE -}")
635 ppr (ImportForUsage is_boot) | is_boot = ptext SLIT("{- USAGE SOURCE -}")
636 | otherwise = ptext SLIT("{- USAGE -}")
637 ppr ImportBySystem = ptext SLIT("{- SYSTEM -}")
641 %************************************************************************
643 \subsection[Inst-types]{@Inst@ types}
645 v%************************************************************************
647 An @Inst@ is either a dictionary, an instance of an overloaded
648 literal, or an instance of an overloaded value. We call the latter a
649 ``method'' even though it may not correspond to a class operation.
650 For example, we might have an instance of the @double@ function at
651 type Int, represented by
653 Method 34 doubleId [Int] origin
665 TcId -- The overloaded function
666 -- This function will be a global, local, or ClassOpId;
667 -- inside instance decls (only) it can also be an InstId!
668 -- The id needn't be completely polymorphic.
669 -- You'll probably find its name (for documentation purposes)
670 -- inside the InstOrigin
672 [TcType] -- The types to which its polymorphic tyvars
673 -- should be instantiated.
674 -- These types must saturate the Id's foralls.
676 TcThetaType -- The (types of the) dictionaries to which the function
677 -- must be applied to get the method
679 TcTauType -- The tau-type of the method
683 -- INVARIANT 1: in (Method u f tys theta tau loc)
684 -- type of (f tys dicts(from theta)) = tau
686 -- INVARIANT 2: tau must not be of form (Pred -> Tau)
687 -- Reason: two methods are considerd equal if the
688 -- base Id matches, and the instantiating types
689 -- match. The TcThetaType should then match too.
690 -- This only bites in the call to tcInstClassOp in TcClassDcl.mkMethodBind
694 HsOverLit -- The literal from the occurrence site
695 -- INVARIANT: never a rebindable-syntax literal
696 -- Reason: tcSyntaxName does unification, and we
697 -- don't want to deal with that during tcSimplify
698 TcType -- The type at which the literal is used
702 @Insts@ are ordered by their class/type info, rather than by their
703 unique. This allows the context-reduction mechanism to use standard finite
704 maps to do their stuff.
707 instance Ord Inst where
710 instance Eq Inst where
711 (==) i1 i2 = case i1 `cmpInst` i2 of
715 cmpInst (Dict _ pred1 _) (Dict _ pred2 _) = pred1 `tcCmpPred` pred2
716 cmpInst (Dict _ _ _) other = LT
718 cmpInst (Method _ _ _ _ _ _) (Dict _ _ _) = GT
719 cmpInst (Method _ id1 tys1 _ _ _) (Method _ id2 tys2 _ _ _) = (id1 `compare` id2) `thenCmp` (tys1 `tcCmpTypes` tys2)
720 cmpInst (Method _ _ _ _ _ _) other = LT
722 cmpInst (LitInst _ _ _ _) (Dict _ _ _) = GT
723 cmpInst (LitInst _ _ _ _) (Method _ _ _ _ _ _) = GT
724 cmpInst (LitInst _ lit1 ty1 _) (LitInst _ lit2 ty2 _) = (lit1 `compare` lit2) `thenCmp` (ty1 `tcCmpType` ty2)
728 %************************************************************************
730 \subsection[Inst-collections]{LIE: a collection of Insts}
732 %************************************************************************
737 isEmptyLIE = isEmptyBag
739 unitLIE inst = unitBag inst
740 mkLIE insts = listToBag insts
741 plusLIE lie1 lie2 = lie1 `unionBags` lie2
742 consLIE inst lie = inst `consBag` lie
743 plusLIEs lies = unionManyBags lies
744 lieToList = bagToList
745 listToLIE = listToBag
749 %************************************************************************
751 \subsection[Inst-origin]{The @InstOrigin@ type}
753 %************************************************************************
755 The @InstOrigin@ type gives information about where a dictionary came from.
756 This is important for decent error message reporting because dictionaries
757 don't appear in the original source code. Doubtless this type will evolve...
759 It appears in TcMonad because there are a couple of error-message-generation
760 functions that deal with it.
763 data InstLoc = InstLoc InstOrigin SrcLoc ErrCtxt
765 instLocSrcLoc :: InstLoc -> SrcLoc
766 instLocSrcLoc (InstLoc _ src_loc _) = src_loc
769 = OccurrenceOf Name -- Occurrence of an overloaded identifier
771 | IPOcc (IPName Name) -- Occurrence of an implicit parameter
772 | IPBind (IPName Name) -- Binding site of an implicit parameter
776 | DataDeclOrigin -- Typechecking a data declaration
778 | InstanceDeclOrigin -- Typechecking an instance decl
780 | LiteralOrigin HsOverLit -- Occurrence of a literal
782 | PatOrigin RenamedPat
784 | ArithSeqOrigin RenamedArithSeqInfo -- [x..], [x..y] etc
785 | PArrSeqOrigin RenamedArithSeqInfo -- [:x..y:] and [:x,y..z:]
787 | SignatureOrigin -- A dict created from a type signature
788 | Rank2Origin -- A dict created when typechecking the argument
789 -- of a rank-2 typed function
791 | DoOrigin -- The monad for a do expression
793 | ClassDeclOrigin -- Manufactured during a class decl
795 | InstanceSpecOrigin Class -- in a SPECIALIZE instance pragma
798 -- When specialising instances the instance info attached to
799 -- each class is not yet ready, so we record it inside the
800 -- origin information. This is a bit of a hack, but it works
801 -- fine. (Patrick is to blame [WDP].)
803 | ValSpecOrigin Name -- in a SPECIALIZE pragma for a value
805 -- Argument or result of a ccall
806 -- Dictionaries with this origin aren't actually mentioned in the
807 -- translated term, and so need not be bound. Nor should they
808 -- be abstracted over.
810 | CCallOrigin String -- CCall label
811 (Maybe RenamedHsExpr) -- Nothing if it's the result
812 -- Just arg, for an argument
814 | LitLitOrigin String -- the litlit
816 | UnknownOrigin -- Help! I give up...
820 pprInstLoc :: InstLoc -> SDoc
821 pprInstLoc (InstLoc orig locn ctxt)
822 = hsep [text "arising from", pp_orig orig, text "at", ppr locn]
824 pp_orig (OccurrenceOf name)
825 = hsep [ptext SLIT("use of"), quotes (ppr name)]
827 = hsep [ptext SLIT("use of implicit parameter"), quotes (ppr name)]
828 pp_orig (IPBind name)
829 = hsep [ptext SLIT("binding for implicit parameter"), quotes (ppr name)]
830 pp_orig RecordUpdOrigin
831 = ptext SLIT("a record update")
832 pp_orig DataDeclOrigin
833 = ptext SLIT("the data type declaration")
834 pp_orig InstanceDeclOrigin
835 = ptext SLIT("the instance declaration")
836 pp_orig (LiteralOrigin lit)
837 = hsep [ptext SLIT("the literal"), quotes (ppr lit)]
838 pp_orig (PatOrigin pat)
839 = hsep [ptext SLIT("the pattern"), quotes (ppr pat)]
840 pp_orig (ArithSeqOrigin seq)
841 = hsep [ptext SLIT("the arithmetic sequence"), quotes (ppr seq)]
842 pp_orig (PArrSeqOrigin seq)
843 = hsep [ptext SLIT("the parallel array sequence"), quotes (ppr seq)]
844 pp_orig (SignatureOrigin)
845 = ptext SLIT("a type signature")
846 pp_orig (Rank2Origin)
847 = ptext SLIT("a function with an overloaded argument type")
849 = ptext SLIT("a do statement")
850 pp_orig (ClassDeclOrigin)
851 = ptext SLIT("a class declaration")
852 pp_orig (InstanceSpecOrigin clas ty)
853 = hsep [text "a SPECIALIZE instance pragma; class",
854 quotes (ppr clas), text "type:", ppr ty]
855 pp_orig (ValSpecOrigin name)
856 = hsep [ptext SLIT("a SPECIALIZE user-pragma for"), quotes (ppr name)]
857 pp_orig (CCallOrigin clabel Nothing{-ccall result-})
858 = hsep [ptext SLIT("the result of the _ccall_ to"), quotes (text clabel)]
859 pp_orig (CCallOrigin clabel (Just arg_expr))
860 = hsep [ptext SLIT("an argument in the _ccall_ to"), quotes (text clabel) <> comma,
861 text "namely", quotes (ppr arg_expr)]
862 pp_orig (LitLitOrigin s)
863 = hsep [ptext SLIT("the ``literal-literal''"), quotes (text s)]
864 pp_orig (UnknownOrigin)
865 = ptext SLIT("...oops -- I don't know where the overloading came from!")