2 % (c) The GRASP Project, Glasgow University, 1992-2002
6 TcRnIf, TcRn, TcM, RnM, IfM, IfL, IfG, -- The monad is opaque outside this module
9 -- The environment types
11 TcGblEnv(..), TcLclEnv(..),
12 IfGblEnv(..), IfLclEnv(..),
15 EntityUsage, emptyUsages, ErrCtxt,
16 ImportAvails(..), emptyImportAvails, plusImportAvails,
17 plusAvail, pruneAvails,
18 AvailEnv, emptyAvailEnv, unitAvailEnv, plusAvailEnv,
19 mkAvailEnv, lookupAvailEnv, lookupAvailEnv_maybe, availEnvElts, addAvail,
20 WhereFrom(..), mkModDeps,
26 ThStage(..), topStage, topSpliceStage,
27 ThLevel, impLevel, topLevel,
30 ArrowCtxt(..), topArrowCtxt, ProcLevel, topProcLevel,
33 Inst(..), InstOrigin(..), InstLoc(..), pprInstLoc,
34 instLocSrcLoc, instLocSrcSpan,
35 LIE, emptyLIE, unitLIE, plusLIE, consLIE,
36 plusLIEs, mkLIE, isEmptyLIE, lieToList, listToLIE,
42 #include "HsVersions.h"
44 import HsSyn ( PendingSplice, HsOverLit, LHsBind, LRuleDecl, LForeignDecl,
46 import HscTypes ( FixityEnv,
47 HscEnv, TypeEnv, TyThing,
48 Avails, GenAvailInfo(..), AvailInfo,
49 availName, IsBootInterface, Deprecations )
50 import Packages ( PackageName )
51 import TcType ( TcTyVarSet, TcType, TcTauType, TcThetaType,
52 TcPredType, TcKind, tcCmpPred, tcCmpType, tcCmpTypes )
53 import InstEnv ( DFunId, InstEnv )
55 import RdrName ( GlobalRdrEnv, LocalRdrEnv )
58 import NameSet ( NameSet, emptyNameSet, DefUses )
59 import OccName ( OccEnv )
61 import Class ( Class )
62 import Var ( Id, TyVar )
63 import VarEnv ( TidyEnv )
65 import SrcLoc ( SrcSpan, SrcLoc, srcSpanStart )
66 import VarSet ( IdSet )
67 import ErrUtils ( Messages, Message )
68 import UniqSupply ( UniqSupply )
69 import BasicTypes ( IPName )
70 import Util ( thenCmp )
73 import Maybe ( mapMaybe )
74 import ListSetOps ( unionLists )
78 %************************************************************************
80 Standard monad definition for TcRn
81 All the combinators for the monad can be found in TcRnMonad
83 %************************************************************************
85 The monad itself has to be defined here, because it is mentioned by ErrCtxt
88 type TcRef a = IORef a
89 type TcId = Id -- Type may be a TcType
92 type TcRnIf a b c = IOEnv (Env a b) c
93 type IfM lcl a = TcRnIf IfGblEnv lcl a -- Iface stuff
94 type IfG a = IfM () a -- Top level
95 type IfL a = IfM IfLclEnv a -- Nested
96 type TcRn a = TcRnIf TcGblEnv TcLclEnv a
97 type RnM a = TcRn a -- Historical
98 type TcM a = TcRn a -- Historical
102 %************************************************************************
104 The main environment types
106 %************************************************************************
109 data Env gbl lcl -- Changes as we move into an expression
111 env_top :: HscEnv, -- Top-level stuff that never changes
112 -- Includes all info about imported things
114 env_us :: TcRef UniqSupply, -- Unique supply for local varibles
116 env_gbl :: gbl, -- Info about things defined at the top level
117 -- of the module being compiled
119 env_lcl :: lcl -- Nested stuff -- changes as we go into
123 -- TcGblEnv describes the top-level of the module at the
124 -- point at which the typechecker is finished work.
125 -- It is this structure that is handed on to the desugarer
129 tcg_mod :: Module, -- Module being compiled
130 tcg_rdr_env :: GlobalRdrEnv, -- Top level envt; used during renaming
131 tcg_default :: Maybe [Type], -- Types used for defaulting
132 -- Nothing => no 'default' decl
134 tcg_fix_env :: FixityEnv, -- Just for things in this module
136 tcg_type_env :: TypeEnv, -- Global type env for the module we are compiling now
137 -- All TyCons and Classes (for this module) end up in here right away,
138 -- along with their derived constructors, selectors.
140 -- (Ids defined in this module start in the local envt,
141 -- though they move to the global envt during zonking)
143 tcg_type_env_var :: TcRef TypeEnv,
144 -- Used only to initialise the interface-file
145 -- typechecker in initIfaceTcRn, so that it can see stuff
146 -- bound in this module when dealing with hi-boot recursions
147 -- Updated at intervals (e.g. after dealing with types and classes)
149 tcg_inst_env :: InstEnv, -- Instance envt for *home-package* modules
150 -- Includes the dfuns in tcg_insts
151 tcg_inst_uses :: TcRef NameSet, -- Home-package Dfuns actually used
152 -- Used to generate version dependencies
153 -- This records usages, rather like tcg_dus, but it has to
154 -- be a mutable variable so it can be augmented
155 -- when we look up an instance. These uses of dfuns are
156 -- rather like the free variables of the program, but
157 -- are implicit instead of explicit.
159 -- Now a bunch of things about this module that are simply
160 -- accumulated, but never consulted until the end.
161 -- Nevertheless, it's convenient to accumulate them along
162 -- with the rest of the info from this module.
163 tcg_exports :: Avails, -- What is exported
164 tcg_imports :: ImportAvails, -- Information about what was imported
165 -- from where, including things bound
168 tcg_dus :: DefUses, -- What is defined in this module and what is used.
169 -- The latter is used to generate
170 -- (a) version tracking; no need to recompile if these
171 -- things have not changed version stamp
172 -- (b) unused-import info
174 tcg_keep :: NameSet, -- Set of names to keep alive, and to expose in the
175 -- interface file (but not to export to the user).
176 -- These are typically extra definitions generated from
177 -- data type declarations which would otherwise be
178 -- dropped as dead code.
180 -- The next fields accumulate the payload of the module
181 -- The binds, rules and foreign-decl fiels are collected
182 -- initially in un-zonked form and are finally zonked in tcRnSrcDecls
183 tcg_binds :: Bag (LHsBind Id), -- Value bindings in this module
184 tcg_deprecs :: Deprecations, -- ...Deprecations
185 tcg_insts :: [DFunId], -- ...Instances
186 tcg_rules :: [LRuleDecl Id], -- ...Rules
187 tcg_fords :: [LForeignDecl Id] -- ...Foreign import & exports
191 %************************************************************************
193 The interface environments
194 Used when dealing with IfaceDecls
196 %************************************************************************
201 -- The type environment for the module being compiled,
202 -- in case the interface refers back to it via a reference that
203 -- was originally a hi-boot file.
204 -- We need the module name so we can test when it's appropriate
205 -- to look in this env.
206 if_rec_types :: Maybe (Module, IfG TypeEnv),
207 -- Allows a read effect, so it can be in a mutable
208 -- variable; c.f. handling the external package type env
209 -- Nothing => interactive stuff, no loops possible
211 if_is_boot :: ModuleEnv (ModuleName, IsBootInterface)
212 -- Tells what we know about boot interface files
213 -- When we're importing a module we know absolutely
214 -- nothing about, so we assume it's from
215 -- another package, where we aren't doing
216 -- dependency tracking. So it won't be a hi-boot file.
221 -- The module for the current IfaceDecl
222 -- So if we see f = \x -> x
223 -- it means M.f = \x -> x, where M is the if_mod
224 if_mod :: ModuleName,
226 if_tv_env :: OccEnv TyVar, -- Nested tyvar bindings
227 if_id_env :: OccEnv Id -- Nested id binding
232 %************************************************************************
234 The local typechecker environment
236 %************************************************************************
238 The Global-Env/Local-Env story
239 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
240 During type checking, we keep in the tcg_type_env
241 * All types and classes
242 * All Ids derived from types and classes (constructors, selectors)
244 At the end of type checking, we zonk the local bindings,
245 and as we do so we add to the tcg_type_env
246 * Locally defined top-level Ids
248 Why? Because they are now Ids not TcIds. This final GlobalEnv is
249 a) fed back (via the knot) to typechecking the
250 unfoldings of interface signatures
251 b) used in the ModDetails of this module
254 data TcLclEnv -- Changes as we move inside an expression
255 -- Discarded after typecheck/rename; not passed on to desugarer
257 tcl_loc :: SrcSpan, -- Source span
258 tcl_ctxt :: ErrCtxt, -- Error context
259 tcl_errs :: TcRef Messages, -- Place to accumulate errors
261 tcl_th_ctxt :: ThStage, -- Template Haskell context
262 tcl_arrow_ctxt :: ArrowCtxt, -- Arrow-notation context
264 tcl_rdr :: LocalRdrEnv, -- Local name envt
265 -- Maintained during renaming, of course, but also during
266 -- type checking, solely so that when renaming a Template-Haskell
267 -- splice we have the right environment for the renamer.
269 -- Does *not* include global name envt; may shadow it
270 -- Includes both ordinary variables and type variables;
271 -- they are kept distinct because tyvar have a different
272 -- occurrence contructor (Name.TvOcc)
273 -- We still need the unsullied global name env so that
274 -- we can look up record field names
276 tcl_env :: NameEnv TcTyThing, -- The local type environment: Ids and TyVars
277 -- defined in this module
279 tcl_tyvars :: TcRef TcTyVarSet, -- The "global tyvars"
280 -- Namely, the in-scope TyVars bound in tcl_lenv,
281 -- plus the tyvars mentioned in the types of Ids bound in tcl_lenv
282 -- Why mutable? see notes with tcGetGlobalTyVars
284 tcl_lie :: TcRef LIE -- Place to accumulate type constraints
287 ---------------------------
288 -- Template Haskell levels
289 ---------------------------
291 type ThLevel = Int -- Always >= 0
294 = Comp -- Ordinary compiling, at level topLevel
295 | Splice ThLevel -- Inside a splice
296 | Brack ThLevel -- Inside brackets;
297 (TcRef [PendingSplice]) -- accumulate pending splices here
298 (TcRef LIE) -- and type constraints here
299 topStage, topSpliceStage :: ThStage
301 topSpliceStage = Splice (topLevel - 1) -- Stage for the body of a top-level splice
304 impLevel, topLevel :: ThLevel
305 topLevel = 1 -- Things defined at top level of this module
306 impLevel = 0 -- Imported things; they can be used inside a top level splice
310 -- g1 = $(map ...) is OK
311 -- g2 = $(f ...) is not OK; because we havn't compiled f yet
314 ---------------------------
315 -- Arrow-notation stages
316 ---------------------------
318 -- In arrow notation, a variable bound by a proc (or enclosed let/kappa)
319 -- is not in scope to the left of an arrow tail (-<). For example
321 -- proc x -> (e1 -< e2)
323 -- Here, x is not in scope in e1, but it is in scope in e2. This can get
324 -- a bit complicated:
327 -- prox y -> (proc z -> e1) -< e2
329 -- Here, x and z are in scope in e1, but y is not. Here's how we track this:
330 -- a) Assign an "proc level" to each proc, being the number of
331 -- lexically-enclosing procs + 1.
332 -- b) Assign to each local variable the proc-level of its lexically
334 -- c) Keep a list of out-of-scope procs. When moving to the left of
335 -- an arrow-tail, add the proc-level of the immediately enclosing
337 -- d) When looking up a variable, complain if its proc-level is in
340 type ProcLevel = Int -- Always >= 0
341 topProcLevel = 0 -- Not inside any proc
343 data ArrowCtxt = ArrCtxt { proc_level :: ProcLevel, -- Current level
344 proc_banned :: [ProcLevel] } -- Out of scope proc-levels
346 topArrowCtxt = ArrCtxt { proc_level = topProcLevel, proc_banned = [] }
348 ---------------------------
350 ---------------------------
353 = AGlobal TyThing -- Used only in the return type of a lookup
354 | ATcId TcId ThLevel ProcLevel -- Ids defined in this module; may not be fully zonked
355 | ATyVar TyVar -- Type variables
356 | AThing TcKind -- Used temporarily, during kind checking, for the
357 -- tycons and clases in this recursive group
359 instance Outputable TcTyThing where -- Debugging only
360 ppr (AGlobal g) = text "AGlobal" <+> ppr g
361 ppr (ATcId g tl pl) = text "ATcId" <+> ppr g <+> ppr tl <+> ppr pl
362 ppr (ATyVar t) = text "ATyVar" <+> ppr t
363 ppr (AThing k) = text "AThing" <+> ppr k
367 type ErrCtxt = [TidyEnv -> TcM (TidyEnv, Message)]
368 -- Innermost first. Monadic so that we have a chance
369 -- to deal with bound type variables just before error
370 -- message construction
374 %************************************************************************
378 %************************************************************************
380 EntityUsage tells what things are actually need in order to compile this
381 module. It is used for generating the usage-version field of the ModIface.
383 Note that we do not record version info for entities from
384 other (non-home) packages. If the package changes, GHC doesn't help.
387 type EntityUsage = NameSet
388 -- The Names are all the (a) home-package
389 -- (b) "big" (i.e. no data cons, class ops)
390 -- (c) non-locally-defined
392 -- names that have been slurped in so far.
393 -- This is used to generate the "usage" information for this module.
395 emptyUsages :: EntityUsage
396 emptyUsages = emptyNameSet
400 %************************************************************************
402 Operations over ImportAvails
404 %************************************************************************
406 ImportAvails summarises what was imported from where, irrespective
407 of whether the imported things are actually used or not
408 It is used * when processing the export list
409 * when constructing usage info for the inteface file
410 * to identify the list of directly imported modules
411 for initialisation purposes
412 * when figuring out what things are really unused
418 -- All the things that are available from the import
419 -- Its domain is all the "main" things;
420 -- i.e. *excluding* class ops and constructors
421 -- (which appear inside their parent AvailTC)
423 imp_qual :: ModuleEnv AvailEnv,
424 -- Used to figure out "module M" export specifiers
425 -- (see 1.4 Report Section 5.1.1). Ultimately, we want to find
426 -- everything that is unambiguously in scope as 'M.x'
427 -- and where plain 'x' is (perhaps ambiguously) in scope.
428 -- So the starting point is all things that are in scope as 'M.x',
429 -- which is what this field tells us.
431 -- Domain is the *module qualifier* for imports.
432 -- e.g. import List as Foo
433 -- would add a binding Foo |-> ...stuff from List...
435 -- We keep the stuff as an AvailEnv so that it's easy to
436 -- combine stuff coming from different (unqualified)
437 -- imports of the same module
439 imp_mods :: ModuleEnv (Module, Maybe Bool),
440 -- Domain is all directly-imported modules
441 -- Maybe value answers the question "is the import restricted?"
442 -- Nothing => unrestricted import (e.g., "import Foo")
443 -- Just True => restricted import, at least one entity (e.g., "import Foo(x)")
444 -- Just False => fully restricted import (e.g., "import Foo ()")
446 -- A distinction is made between the first and the third in order
447 -- to more precisely emit warnings about unused imports.
449 -- We need the Module in the range because we can't get
450 -- the keys of a ModuleEnv
452 -- (a) to help construct the usage information in
453 -- the interface file; if we import everything we
454 -- need to recompile if the module version changes
455 -- (b) to specify what child modules to initialise
457 imp_dep_mods :: ModuleEnv (ModuleName, IsBootInterface),
458 -- Home-package modules needed by the module being compiled
460 -- It doesn't matter whether any of these dependencies are actually
461 -- *used* when compiling the module; they are listed if they are below
462 -- it at all. For example, suppose M imports A which imports X. Then
463 -- compiling M might not need to consult X.hi, but X is still listed
464 -- in M's dependencies.
466 imp_dep_pkgs :: [PackageName],
467 -- Packages needed by the module being compiled, whether
468 -- directly, or via other modules in this package, or via
469 -- modules imported from other packages.
471 imp_orphs :: [ModuleName]
472 -- Orphan modules below us in the import tree
475 mkModDeps :: [(ModuleName, IsBootInterface)]
476 -> ModuleEnv (ModuleName, IsBootInterface)
477 mkModDeps deps = foldl add emptyModuleEnv deps
479 add env elt@(m,_) = extendModuleEnvByName env m elt
481 emptyImportAvails :: ImportAvails
482 emptyImportAvails = ImportAvails { imp_env = emptyAvailEnv,
483 imp_qual = emptyModuleEnv,
484 imp_mods = emptyModuleEnv,
485 imp_dep_mods = emptyModuleEnv,
489 plusImportAvails :: ImportAvails -> ImportAvails -> ImportAvails
491 (ImportAvails { imp_env = env1, imp_qual = unqual1, imp_mods = mods1,
492 imp_dep_mods = dmods1, imp_dep_pkgs = dpkgs1, imp_orphs = orphs1 })
493 (ImportAvails { imp_env = env2, imp_qual = unqual2, imp_mods = mods2,
494 imp_dep_mods = dmods2, imp_dep_pkgs = dpkgs2, imp_orphs = orphs2 })
495 = ImportAvails { imp_env = env1 `plusAvailEnv` env2,
496 imp_qual = plusModuleEnv_C plusAvailEnv unqual1 unqual2,
497 imp_mods = mods1 `plusModuleEnv` mods2,
498 imp_dep_mods = plusModuleEnv_C plus_mod_dep dmods1 dmods2,
499 imp_dep_pkgs = dpkgs1 `unionLists` dpkgs2,
500 imp_orphs = orphs1 `unionLists` orphs2 }
502 plus_mod_dep (m1, boot1) (m2, boot2)
503 = WARN( not (m1 == m2), (ppr m1 <+> ppr m2) $$ (ppr boot1 <+> ppr boot2) )
504 -- Check mod-names match
505 (m1, boot1 && boot2) -- If either side can "see" a non-hi-boot interface, use that
508 %************************************************************************
510 Avails, AvailEnv, etc
512 v%************************************************************************
515 plusAvail (Avail n1) (Avail n2) = Avail n1
516 plusAvail (AvailTC n1 ns1) (AvailTC n2 ns2) = AvailTC n2 (ns1 `unionLists` ns2)
519 plusAvail a1 a2 = pprPanic "RnEnv.plusAvail" (hsep [ppr a1,ppr a2])
522 -------------------------
523 pruneAvails :: (Name -> Bool) -- Keep if this is True
526 pruneAvails keep avails
527 = mapMaybe del avails
529 del :: AvailInfo -> Maybe AvailInfo -- Nothing => nothing left!
530 del (Avail n) | keep n = Just (Avail n)
531 | otherwise = Nothing
532 del (AvailTC n ns) | null ns' = Nothing
533 | otherwise = Just (AvailTC n ns')
538 ---------------------------------------
540 ---------------------------------------
543 type AvailEnv = NameEnv AvailInfo -- Maps a Name to the AvailInfo that contains it
545 emptyAvailEnv :: AvailEnv
546 emptyAvailEnv = emptyNameEnv
548 unitAvailEnv :: AvailInfo -> AvailEnv
549 unitAvailEnv a = unitNameEnv (availName a) a
551 plusAvailEnv :: AvailEnv -> AvailEnv -> AvailEnv
552 plusAvailEnv = plusNameEnv_C plusAvail
554 lookupAvailEnv_maybe :: AvailEnv -> Name -> Maybe AvailInfo
555 lookupAvailEnv_maybe = lookupNameEnv
557 lookupAvailEnv :: AvailEnv -> Name -> AvailInfo
558 lookupAvailEnv env n = case lookupNameEnv env n of
560 Nothing -> pprPanic "lookupAvailEnv" (ppr n)
562 availEnvElts = nameEnvElts
564 addAvail :: AvailEnv -> AvailInfo -> AvailEnv
565 addAvail avails avail = extendNameEnv_C plusAvail avails (availName avail) avail
567 mkAvailEnv :: [AvailInfo] -> AvailEnv
568 -- 'avails' may have several items with the same availName
569 -- E.g import Ix( Ix(..), index )
570 -- will give Ix(Ix,index,range) and Ix(index)
571 -- We want to combine these; addAvail does that
572 mkAvailEnv avails = foldl addAvail emptyAvailEnv avails
575 %************************************************************************
577 \subsection{Where from}
579 %************************************************************************
581 The @WhereFrom@ type controls where the renamer looks for an interface file
585 = ImportByUser IsBootInterface -- Ordinary user import (perhaps {-# SOURCE #-})
586 | ImportBySystem -- Non user import.
588 instance Outputable WhereFrom where
589 ppr (ImportByUser is_boot) | is_boot = ptext SLIT("{- SOURCE -}")
591 ppr ImportBySystem = ptext SLIT("{- SYSTEM -}")
595 %************************************************************************
597 \subsection[Inst-types]{@Inst@ types}
599 v%************************************************************************
601 An @Inst@ is either a dictionary, an instance of an overloaded
602 literal, or an instance of an overloaded value. We call the latter a
603 ``method'' even though it may not correspond to a class operation.
604 For example, we might have an instance of the @double@ function at
605 type Int, represented by
607 Method 34 doubleId [Int] origin
619 TcId -- The overloaded function
620 -- This function will be a global, local, or ClassOpId;
621 -- inside instance decls (only) it can also be an InstId!
622 -- The id needn't be completely polymorphic.
623 -- You'll probably find its name (for documentation purposes)
624 -- inside the InstOrigin
626 [TcType] -- The types to which its polymorphic tyvars
627 -- should be instantiated.
628 -- These types must saturate the Id's foralls.
630 TcThetaType -- The (types of the) dictionaries to which the function
631 -- must be applied to get the method
633 TcTauType -- The tau-type of the method
637 -- INVARIANT 1: in (Method u f tys theta tau loc)
638 -- type of (f tys dicts(from theta)) = tau
640 -- INVARIANT 2: tau must not be of form (Pred -> Tau)
641 -- Reason: two methods are considerd equal if the
642 -- base Id matches, and the instantiating types
643 -- match. The TcThetaType should then match too.
644 -- This only bites in the call to tcInstClassOp in TcClassDcl.mkMethodBind
648 HsOverLit -- The literal from the occurrence site
649 -- INVARIANT: never a rebindable-syntax literal
650 -- Reason: tcSyntaxName does unification, and we
651 -- don't want to deal with that during tcSimplify
652 TcType -- The type at which the literal is used
656 @Insts@ are ordered by their class/type info, rather than by their
657 unique. This allows the context-reduction mechanism to use standard finite
658 maps to do their stuff.
661 instance Ord Inst where
664 instance Eq Inst where
665 (==) i1 i2 = case i1 `cmpInst` i2 of
669 cmpInst (Dict _ pred1 _) (Dict _ pred2 _) = pred1 `tcCmpPred` pred2
670 cmpInst (Dict _ _ _) other = LT
672 cmpInst (Method _ _ _ _ _ _) (Dict _ _ _) = GT
673 cmpInst (Method _ id1 tys1 _ _ _) (Method _ id2 tys2 _ _ _) = (id1 `compare` id2) `thenCmp` (tys1 `tcCmpTypes` tys2)
674 cmpInst (Method _ _ _ _ _ _) other = LT
676 cmpInst (LitInst _ _ _ _) (Dict _ _ _) = GT
677 cmpInst (LitInst _ _ _ _) (Method _ _ _ _ _ _) = GT
678 cmpInst (LitInst _ lit1 ty1 _) (LitInst _ lit2 ty2 _) = (lit1 `compare` lit2) `thenCmp` (ty1 `tcCmpType` ty2)
682 %************************************************************************
684 \subsection[Inst-collections]{LIE: a collection of Insts}
686 %************************************************************************
691 isEmptyLIE = isEmptyBag
693 unitLIE inst = unitBag inst
694 mkLIE insts = listToBag insts
695 plusLIE lie1 lie2 = lie1 `unionBags` lie2
696 consLIE inst lie = inst `consBag` lie
697 plusLIEs lies = unionManyBags lies
698 lieToList = bagToList
699 listToLIE = listToBag
703 %************************************************************************
705 \subsection[Inst-origin]{The @InstOrigin@ type}
707 %************************************************************************
709 The @InstOrigin@ type gives information about where a dictionary came from.
710 This is important for decent error message reporting because dictionaries
711 don't appear in the original source code. Doubtless this type will evolve...
713 It appears in TcMonad because there are a couple of error-message-generation
714 functions that deal with it.
717 data InstLoc = InstLoc InstOrigin SrcSpan ErrCtxt
719 instLocSrcLoc :: InstLoc -> SrcLoc
720 instLocSrcLoc (InstLoc _ src_span _) = srcSpanStart src_span
722 instLocSrcSpan :: InstLoc -> SrcSpan
723 instLocSrcSpan (InstLoc _ src_span _) = src_span
726 = OccurrenceOf Name -- Occurrence of an overloaded identifier
728 | IPOccOrigin (IPName Name) -- Occurrence of an implicit parameter
729 | IPBindOrigin (IPName Name) -- Binding site of an implicit parameter
733 | DataDeclOrigin -- Typechecking a data declaration
735 | InstanceDeclOrigin -- Typechecking an instance decl
737 | LiteralOrigin HsOverLit -- Occurrence of a literal
739 | PatOrigin (Pat Name)
741 | ArithSeqOrigin (ArithSeqInfo Name) -- [x..], [x..y] etc
742 | PArrSeqOrigin (ArithSeqInfo Name) -- [:x..y:] and [:x,y..z:]
744 | SignatureOrigin -- A dict created from a type signature
745 | Rank2Origin -- A dict created when typechecking the argument
746 -- of a rank-2 typed function
748 | DoOrigin -- The monad for a do expression
749 | ProcOrigin -- A proc expression
751 | ClassDeclOrigin -- Manufactured during a class decl
753 | InstanceSpecOrigin Class -- in a SPECIALIZE instance pragma
756 -- When specialising instances the instance info attached to
757 -- each class is not yet ready, so we record it inside the
758 -- origin information. This is a bit of a hack, but it works
759 -- fine. (Patrick is to blame [WDP].)
761 | ValSpecOrigin Name -- in a SPECIALIZE pragma for a value
763 -- Argument or result of a ccall
764 -- Dictionaries with this origin aren't actually mentioned in the
765 -- translated term, and so need not be bound. Nor should they
766 -- be abstracted over.
768 | UnknownOrigin -- Help! I give up...
772 pprInstLoc :: InstLoc -> SDoc
773 pprInstLoc (InstLoc orig locn ctxt)
774 = hsep [text "arising from", pp_orig orig, text "at", ppr locn]
776 pp_orig (OccurrenceOf name)
777 = hsep [ptext SLIT("use of"), quotes (ppr name)]
778 pp_orig (IPOccOrigin name)
779 = hsep [ptext SLIT("use of implicit parameter"), quotes (ppr name)]
780 pp_orig (IPBindOrigin name)
781 = hsep [ptext SLIT("binding for implicit parameter"), quotes (ppr name)]
782 pp_orig RecordUpdOrigin
783 = ptext SLIT("a record update")
784 pp_orig DataDeclOrigin
785 = ptext SLIT("the data type declaration")
786 pp_orig InstanceDeclOrigin
787 = ptext SLIT("the instance declaration")
788 pp_orig (LiteralOrigin lit)
789 = hsep [ptext SLIT("the literal"), quotes (ppr lit)]
790 pp_orig (PatOrigin pat)
791 = hsep [ptext SLIT("the pattern"), quotes (ppr pat)]
792 pp_orig (ArithSeqOrigin seq)
793 = hsep [ptext SLIT("the arithmetic sequence"), quotes (ppr seq)]
794 pp_orig (PArrSeqOrigin seq)
795 = hsep [ptext SLIT("the parallel array sequence"), quotes (ppr seq)]
796 pp_orig (SignatureOrigin)
797 = ptext SLIT("a type signature")
798 pp_orig (Rank2Origin)
799 = ptext SLIT("a function with an overloaded argument type")
801 = ptext SLIT("a do statement")
803 = ptext SLIT("a proc expression")
804 pp_orig (ClassDeclOrigin)
805 = ptext SLIT("a class declaration")
806 pp_orig (InstanceSpecOrigin clas ty)
807 = hsep [text "a SPECIALIZE instance pragma; class",
808 quotes (ppr clas), text "type:", ppr ty]
809 pp_orig (ValSpecOrigin name)
810 = hsep [ptext SLIT("a SPECIALIZE user-pragma for"), quotes (ppr name)]
811 pp_orig (UnknownOrigin)
812 = ptext SLIT("...oops -- I don't know where the overloading came from!")