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, instLocSrcLoc,
34 LIE, emptyLIE, unitLIE, plusLIE, consLIE,
35 plusLIEs, mkLIE, isEmptyLIE, lieToList, listToLIE,
41 #include "HsVersions.h"
43 import HsSyn ( PendingSplice, HsOverLit, MonoBinds, RuleDecl, ForeignDecl )
44 import RnHsSyn ( RenamedPat, RenamedArithSeqInfo )
45 import HscTypes ( FixityEnv,
46 HscEnv, TypeEnv, TyThing,
47 Avails, GenAvailInfo(..), AvailInfo,
48 availName, IsBootInterface, Deprecations )
49 import Packages ( PackageName )
50 import TcType ( TcTyVarSet, TcType, TcTauType, TcThetaType,
51 TcPredType, TcKind, tcCmpPred, tcCmpType, tcCmpTypes )
52 import InstEnv ( DFunId, InstEnv )
54 import RdrName ( GlobalRdrEnv, LocalRdrEnv )
57 import NameSet ( NameSet, emptyNameSet, DefUses )
58 import OccName ( OccEnv )
60 import Class ( Class )
61 import Var ( Id, TyVar )
62 import VarEnv ( TidyEnv )
64 import SrcLoc ( SrcLoc )
65 import VarSet ( IdSet )
66 import ErrUtils ( Messages, Message )
67 import UniqSupply ( UniqSupply )
68 import BasicTypes ( IPName )
69 import Util ( thenCmp )
72 import Maybe ( mapMaybe )
73 import ListSetOps ( unionLists )
77 %************************************************************************
79 Standard monad definition for TcRn
80 All the combinators for the monad can be found in TcRnMonad
82 %************************************************************************
84 The monad itself has to be defined here, because it is mentioned by ErrCtxt
87 type TcRef a = IORef a
88 type TcId = Id -- Type may be a TcType
91 type TcRnIf a b c = IOEnv (Env a b) c
92 type IfM lcl a = TcRnIf IfGblEnv lcl a -- Iface stuff
93 type IfG a = IfM () a -- Top level
94 type IfL a = IfM IfLclEnv a -- Nested
95 type TcRn a = TcRnIf TcGblEnv TcLclEnv a
96 type RnM a = TcRn a -- Historical
97 type TcM a = TcRn a -- Historical
101 %************************************************************************
103 The main environment types
105 %************************************************************************
108 data Env gbl lcl -- Changes as we move into an expression
110 env_top :: HscEnv, -- Top-level stuff that never changes
111 -- Includes all info about imported things
113 env_us :: TcRef UniqSupply, -- Unique supply for local varibles
115 env_gbl :: gbl, -- Info about things defined at the top level
116 -- of the module being compiled
118 env_lcl :: lcl -- Nested stuff -- changes as we go into
122 -- TcGblEnv describes the top-level of the module at the
123 -- point at which the typechecker is finished work.
124 -- It is this structure that is handed on to the desugarer
128 tcg_mod :: Module, -- Module being compiled
129 tcg_rdr_env :: GlobalRdrEnv, -- Top level envt; used during renaming
130 tcg_default :: Maybe [Type], -- Types used for defaulting
131 -- Nothing => no 'default' decl
133 tcg_fix_env :: FixityEnv, -- Just for things in this module
135 tcg_type_env :: TypeEnv, -- Global type env for the module we are compiling now
136 -- All TyCons and Classes (for this module) end up in here right away,
137 -- along with their derived constructors, selectors.
139 -- (Ids defined in this module start in the local envt,
140 -- though they move to the global envt during zonking)
142 tcg_type_env_var :: TcRef TypeEnv,
143 -- Used only to initialise the interface-file
144 -- typechecker in initIfaceTcRn, so that it can see stuff
145 -- bound in this module when dealing with hi-boot recursions
146 -- Updated at intervals (e.g. after dealing with types and classes)
148 tcg_inst_env :: InstEnv, -- Instance envt for *home-package* modules
149 -- Includes the dfuns in tcg_insts
150 tcg_inst_uses :: TcRef NameSet, -- Home-package Dfuns actually used
151 -- Used to generate version dependencies
152 -- This records usages, rather like tcg_dus, but it has to
153 -- be a mutable variable so it can be augmented
154 -- when we look up an instance. These uses of dfuns are
155 -- rather like the free variables of the program, but
156 -- are implicit instead of explicit.
158 -- Now a bunch of things about this module that are simply
159 -- accumulated, but never consulted until the end.
160 -- Nevertheless, it's convenient to accumulate them along
161 -- with the rest of the info from this module.
162 tcg_exports :: Avails, -- What is exported
163 tcg_imports :: ImportAvails, -- Information about what was imported
164 -- from where, including things bound
167 tcg_dus :: DefUses, -- What is defined in this module and what is used.
168 -- The latter is used to generate
169 -- (a) version tracking; no need to recompile if these
170 -- things have not changed version stamp
171 -- (b) unused-import info
173 tcg_keep :: NameSet, -- Set of names to keep alive, and to expose in the
174 -- interface file (but not to export to the user).
175 -- These are typically extra definitions generated from
176 -- data type declarations which would otherwise be
177 -- dropped as dead code.
179 -- The next fields accumulate the payload of the module
180 -- The binds, rules and foreign-decl fiels are collected
181 -- initially in un-zonked form and are finally zonked in tcRnSrcDecls
182 tcg_binds :: MonoBinds Id, -- Value bindings in this module
183 tcg_deprecs :: Deprecations, -- ...Deprecations
184 tcg_insts :: [DFunId], -- ...Instances
185 tcg_rules :: [RuleDecl Id], -- ...Rules
186 tcg_fords :: [ForeignDecl Id] -- ...Foreign import & exports
190 %************************************************************************
192 The interface environments
193 Used when dealing with IfaceDecls
195 %************************************************************************
200 -- The type environment for the module being compiled,
201 -- in case the interface refers back to it via a reference that
202 -- was originally a hi-boot file.
203 -- We need the module name so we can test when it's appropriate
204 -- to look in this env.
205 if_rec_types :: Maybe (Module, IfG TypeEnv),
206 -- Allows a read effect, so it can be in a mutable
207 -- variable; c.f. handling the external package type env
208 -- Nothing => interactive stuff, no loops possible
210 if_is_boot :: ModuleEnv (ModuleName, IsBootInterface)
211 -- Tells what we know about boot interface files
212 -- When we're importing a module we know absolutely
213 -- nothing about, so we assume it's from
214 -- another package, where we aren't doing
215 -- dependency tracking. So it won't be a hi-boot file.
220 -- The module for the current IfaceDecl
221 -- So if we see f = \x -> x
222 -- it means M.f = \x -> x, where M is the if_mod
223 if_mod :: ModuleName,
225 if_tv_env :: OccEnv TyVar, -- Nested tyvar bindings
226 if_id_env :: OccEnv Id -- Nested id binding
231 %************************************************************************
233 The local typechecker environment
235 %************************************************************************
237 The Global-Env/Local-Env story
238 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
239 During type checking, we keep in the tcg_type_env
240 * All types and classes
241 * All Ids derived from types and classes (constructors, selectors)
243 At the end of type checking, we zonk the local bindings,
244 and as we do so we add to the tcg_type_env
245 * Locally defined top-level Ids
247 Why? Because they are now Ids not TcIds. This final GlobalEnv is
248 a) fed back (via the knot) to typechecking the
249 unfoldings of interface signatures
250 b) used in the ModDetails of this module
253 data TcLclEnv -- Changes as we move inside an expression
254 -- Discarded after typecheck/rename; not passed on to desugarer
256 tcl_loc :: SrcLoc, -- Source location
257 tcl_ctxt :: ErrCtxt, -- Error context
258 tcl_errs :: TcRef Messages, -- Place to accumulate errors
260 tcl_th_ctxt :: ThStage, -- Template Haskell context
261 tcl_arrow_ctxt :: ArrowCtxt, -- Arrow-notation context
263 tcl_rdr :: LocalRdrEnv, -- Local name envt
264 -- Does *not* include global name envt; may shadow it
265 -- Includes both ordinary variables and type variables;
266 -- they are kept distinct because tyvar have a different
267 -- occurrence contructor (Name.TvOcc)
268 -- We still need the unsullied global name env so that
269 -- we can look up record field names
271 tcl_env :: NameEnv TcTyThing, -- The local type environment: Ids and TyVars
272 -- defined in this module
274 tcl_tyvars :: TcRef TcTyVarSet, -- The "global tyvars"
275 -- Namely, the in-scope TyVars bound in tcl_lenv,
276 -- plus the tyvars mentioned in the types of Ids bound in tcl_lenv
277 -- Why mutable? see notes with tcGetGlobalTyVars
279 tcl_lie :: TcRef LIE -- Place to accumulate type constraints
282 ---------------------------
283 -- Template Haskell levels
284 ---------------------------
286 type ThLevel = Int -- Always >= 0
289 = Comp -- Ordinary compiling, at level topLevel
290 | Splice ThLevel -- Inside a splice
291 | Brack ThLevel -- Inside brackets;
292 (TcRef [PendingSplice]) -- accumulate pending splices here
293 (TcRef LIE) -- and type constraints here
294 topStage, topSpliceStage :: ThStage
296 topSpliceStage = Splice (topLevel - 1) -- Stage for the body of a top-level splice
299 impLevel, topLevel :: ThLevel
300 topLevel = 1 -- Things defined at top level of this module
301 impLevel = 0 -- Imported things; they can be used inside a top level splice
305 -- g1 = $(map ...) is OK
306 -- g2 = $(f ...) is not OK; because we havn't compiled f yet
309 ---------------------------
310 -- Arrow-notation stages
311 ---------------------------
313 -- In arrow notation, a variable bound by a proc (or enclosed let/kappa)
314 -- is not in scope to the left of an arrow tail (-<). For example
316 -- proc x -> (e1 -< e2)
318 -- Here, x is not in scope in e1, but it is in scope in e2. This can get
319 -- a bit complicated:
322 -- prox y -> (proc z -> e1) -< e2
324 -- Here, x and z are in scope in e1, but y is not. Here's how we track this:
325 -- a) Assign an "proc level" to each proc, being the number of
326 -- lexically-enclosing procs + 1.
327 -- b) Assign to each local variable the proc-level of its lexically
329 -- c) Keep a list of out-of-scope procs. When moving to the left of
330 -- an arrow-tail, add the proc-level of the immediately enclosing
332 -- d) When looking up a variable, complain if its proc-level is in
335 type ProcLevel = Int -- Always >= 0
336 topProcLevel = 0 -- Not inside any proc
338 data ArrowCtxt = ArrCtxt { proc_level :: ProcLevel, -- Current level
339 proc_banned :: [ProcLevel] } -- Out of scope proc-levels
341 topArrowCtxt = ArrCtxt { proc_level = topProcLevel, proc_banned = [] }
343 ---------------------------
345 ---------------------------
348 = AGlobal TyThing -- Used only in the return type of a lookup
349 | ATcId TcId ThLevel ProcLevel -- Ids defined in this module; may not be fully zonked
350 | ATyVar TyVar -- Type variables
351 | ARecTyCon TcKind -- Used temporarily, during kind checking, for the
352 | ARecClass TcKind -- tycons and clases in this recursive group
354 instance Outputable TcTyThing where -- Debugging only
355 ppr (AGlobal g) = text "AGlobal" <+> ppr g
356 ppr (ATcId g tl pl) = text "ATcId" <+> ppr g <+> ppr tl <+> ppr pl
357 ppr (ATyVar t) = text "ATyVar" <+> ppr t
358 ppr (ARecTyCon k) = text "ARecTyCon" <+> ppr k
359 ppr (ARecClass k) = text "ARecClass" <+> ppr k
363 type ErrCtxt = [TidyEnv -> TcM (TidyEnv, Message)]
364 -- Innermost first. Monadic so that we have a chance
365 -- to deal with bound type variables just before error
366 -- message construction
370 %************************************************************************
374 %************************************************************************
376 EntityUsage tells what things are actually need in order to compile this
377 module. It is used for generating the usage-version field of the ModIface.
379 Note that we do not record version info for entities from
380 other (non-home) packages. If the package changes, GHC doesn't help.
383 type EntityUsage = NameSet
384 -- The Names are all the (a) home-package
385 -- (b) "big" (i.e. no data cons, class ops)
386 -- (c) non-locally-defined
388 -- names that have been slurped in so far.
389 -- This is used to generate the "usage" information for this module.
391 emptyUsages :: EntityUsage
392 emptyUsages = emptyNameSet
396 %************************************************************************
398 Operations over ImportAvails
400 %************************************************************************
402 ImportAvails summarises what was imported from where, irrespective
403 of whether the imported things are actually used or not
404 It is used * when processing the export list
405 * when constructing usage info for the inteface file
406 * to identify the list of directly imported modules
407 for initialisation purposes
408 * when figuring out what things are really unused
414 -- All the things that are available from the import
415 -- Its domain is all the "main" things;
416 -- i.e. *excluding* class ops and constructors
417 -- (which appear inside their parent AvailTC)
419 imp_qual :: ModuleEnv AvailEnv,
420 -- Used to figure out "module M" export specifiers
421 -- (see 1.4 Report Section 5.1.1). Ultimately, we want to find
422 -- everything that is unambiguously in scope as 'M.x'
423 -- and where plain 'x' is (perhaps ambiguously) in scope.
424 -- So the starting point is all things that are in scope as 'M.x',
425 -- which is what this field tells us.
427 -- Domain is the *module qualifier* for imports.
428 -- e.g. import List as Foo
429 -- would add a binding Foo |-> ...stuff from List...
431 -- We keep the stuff as an AvailEnv so that it's easy to
432 -- combine stuff coming from different (unqualified)
433 -- imports of the same module
435 imp_mods :: ModuleEnv (Module, Maybe Bool),
436 -- Domain is all directly-imported modules
437 -- Maybe value answers the question "is the import restricted?"
438 -- Nothing => unrestricted import (e.g., "import Foo")
439 -- Just True => restricted import, at least one entity (e.g., "import Foo(x)")
440 -- Just False => fully restricted import (e.g., "import Foo ()")
442 -- A distinction is made between the first and the third in order
443 -- to more precisely emit warnings about unused imports.
445 -- We need the Module in the range because we can't get
446 -- the keys of a ModuleEnv
448 -- (a) to help construct the usage information in
449 -- the interface file; if we import everything we
450 -- need to recompile if the module version changes
451 -- (b) to specify what child modules to initialise
453 imp_dep_mods :: ModuleEnv (ModuleName, IsBootInterface),
454 -- Home-package modules needed by the module being compiled
456 -- It doesn't matter whether any of these dependencies are actually
457 -- *used* when compiling the module; they are listed if they are below
458 -- it at all. For example, suppose M imports A which imports X. Then
459 -- compiling M might not need to consult X.hi, but X is still listed
460 -- in M's dependencies.
462 imp_dep_pkgs :: [PackageName],
463 -- Packages needed by the module being compiled, whether
464 -- directly, or via other modules in this package, or via
465 -- modules imported from other packages.
467 imp_orphs :: [ModuleName]
468 -- Orphan modules below us in the import tree
471 mkModDeps :: [(ModuleName, IsBootInterface)]
472 -> ModuleEnv (ModuleName, IsBootInterface)
473 mkModDeps deps = foldl add emptyModuleEnv deps
475 add env elt@(m,_) = extendModuleEnvByName env m elt
477 emptyImportAvails :: ImportAvails
478 emptyImportAvails = ImportAvails { imp_env = emptyAvailEnv,
479 imp_qual = emptyModuleEnv,
480 imp_mods = emptyModuleEnv,
481 imp_dep_mods = emptyModuleEnv,
485 plusImportAvails :: ImportAvails -> ImportAvails -> ImportAvails
487 (ImportAvails { imp_env = env1, imp_qual = unqual1, imp_mods = mods1,
488 imp_dep_mods = dmods1, imp_dep_pkgs = dpkgs1, imp_orphs = orphs1 })
489 (ImportAvails { imp_env = env2, imp_qual = unqual2, imp_mods = mods2,
490 imp_dep_mods = dmods2, imp_dep_pkgs = dpkgs2, imp_orphs = orphs2 })
491 = ImportAvails { imp_env = env1 `plusAvailEnv` env2,
492 imp_qual = plusModuleEnv_C plusAvailEnv unqual1 unqual2,
493 imp_mods = mods1 `plusModuleEnv` mods2,
494 imp_dep_mods = plusModuleEnv_C plus_mod_dep dmods1 dmods2,
495 imp_dep_pkgs = dpkgs1 `unionLists` dpkgs2,
496 imp_orphs = orphs1 `unionLists` orphs2 }
498 plus_mod_dep (m1, boot1) (m2, boot2)
499 = WARN( not (m1 == m2), (ppr m1 <+> ppr m2) $$ (ppr boot1 <+> ppr boot2) )
500 -- Check mod-names match
501 (m1, boot1 && boot2) -- If either side can "see" a non-hi-boot interface, use that
504 %************************************************************************
506 Avails, AvailEnv, etc
508 v%************************************************************************
511 plusAvail (Avail n1) (Avail n2) = Avail n1
512 plusAvail (AvailTC n1 ns1) (AvailTC n2 ns2) = AvailTC n2 (ns1 `unionLists` ns2)
515 plusAvail a1 a2 = pprPanic "RnEnv.plusAvail" (hsep [ppr a1,ppr a2])
518 -------------------------
519 pruneAvails :: (Name -> Bool) -- Keep if this is True
522 pruneAvails keep avails
523 = mapMaybe del avails
525 del :: AvailInfo -> Maybe AvailInfo -- Nothing => nothing left!
526 del (Avail n) | keep n = Just (Avail n)
527 | otherwise = Nothing
528 del (AvailTC n ns) | null ns' = Nothing
529 | otherwise = Just (AvailTC n ns')
534 ---------------------------------------
536 ---------------------------------------
539 type AvailEnv = NameEnv AvailInfo -- Maps a Name to the AvailInfo that contains it
541 emptyAvailEnv :: AvailEnv
542 emptyAvailEnv = emptyNameEnv
544 unitAvailEnv :: AvailInfo -> AvailEnv
545 unitAvailEnv a = unitNameEnv (availName a) a
547 plusAvailEnv :: AvailEnv -> AvailEnv -> AvailEnv
548 plusAvailEnv = plusNameEnv_C plusAvail
550 lookupAvailEnv_maybe :: AvailEnv -> Name -> Maybe AvailInfo
551 lookupAvailEnv_maybe = lookupNameEnv
553 lookupAvailEnv :: AvailEnv -> Name -> AvailInfo
554 lookupAvailEnv env n = case lookupNameEnv env n of
556 Nothing -> pprPanic "lookupAvailEnv" (ppr n)
558 availEnvElts = nameEnvElts
560 addAvail :: AvailEnv -> AvailInfo -> AvailEnv
561 addAvail avails avail = extendNameEnv_C plusAvail avails (availName avail) avail
563 mkAvailEnv :: [AvailInfo] -> AvailEnv
564 -- 'avails' may have several items with the same availName
565 -- E.g import Ix( Ix(..), index )
566 -- will give Ix(Ix,index,range) and Ix(index)
567 -- We want to combine these; addAvail does that
568 mkAvailEnv avails = foldl addAvail emptyAvailEnv avails
571 %************************************************************************
573 \subsection{Where from}
575 %************************************************************************
577 The @WhereFrom@ type controls where the renamer looks for an interface file
581 = ImportByUser IsBootInterface -- Ordinary user import (perhaps {-# SOURCE #-})
582 | ImportBySystem -- Non user import.
584 instance Outputable WhereFrom where
585 ppr (ImportByUser is_boot) | is_boot = ptext SLIT("{- SOURCE -}")
587 ppr ImportBySystem = ptext SLIT("{- SYSTEM -}")
591 %************************************************************************
593 \subsection[Inst-types]{@Inst@ types}
595 v%************************************************************************
597 An @Inst@ is either a dictionary, an instance of an overloaded
598 literal, or an instance of an overloaded value. We call the latter a
599 ``method'' even though it may not correspond to a class operation.
600 For example, we might have an instance of the @double@ function at
601 type Int, represented by
603 Method 34 doubleId [Int] origin
615 TcId -- The overloaded function
616 -- This function will be a global, local, or ClassOpId;
617 -- inside instance decls (only) it can also be an InstId!
618 -- The id needn't be completely polymorphic.
619 -- You'll probably find its name (for documentation purposes)
620 -- inside the InstOrigin
622 [TcType] -- The types to which its polymorphic tyvars
623 -- should be instantiated.
624 -- These types must saturate the Id's foralls.
626 TcThetaType -- The (types of the) dictionaries to which the function
627 -- must be applied to get the method
629 TcTauType -- The tau-type of the method
633 -- INVARIANT 1: in (Method u f tys theta tau loc)
634 -- type of (f tys dicts(from theta)) = tau
636 -- INVARIANT 2: tau must not be of form (Pred -> Tau)
637 -- Reason: two methods are considerd equal if the
638 -- base Id matches, and the instantiating types
639 -- match. The TcThetaType should then match too.
640 -- This only bites in the call to tcInstClassOp in TcClassDcl.mkMethodBind
644 HsOverLit -- The literal from the occurrence site
645 -- INVARIANT: never a rebindable-syntax literal
646 -- Reason: tcSyntaxName does unification, and we
647 -- don't want to deal with that during tcSimplify
648 TcType -- The type at which the literal is used
652 @Insts@ are ordered by their class/type info, rather than by their
653 unique. This allows the context-reduction mechanism to use standard finite
654 maps to do their stuff.
657 instance Ord Inst where
660 instance Eq Inst where
661 (==) i1 i2 = case i1 `cmpInst` i2 of
665 cmpInst (Dict _ pred1 _) (Dict _ pred2 _) = pred1 `tcCmpPred` pred2
666 cmpInst (Dict _ _ _) other = LT
668 cmpInst (Method _ _ _ _ _ _) (Dict _ _ _) = GT
669 cmpInst (Method _ id1 tys1 _ _ _) (Method _ id2 tys2 _ _ _) = (id1 `compare` id2) `thenCmp` (tys1 `tcCmpTypes` tys2)
670 cmpInst (Method _ _ _ _ _ _) other = LT
672 cmpInst (LitInst _ _ _ _) (Dict _ _ _) = GT
673 cmpInst (LitInst _ _ _ _) (Method _ _ _ _ _ _) = GT
674 cmpInst (LitInst _ lit1 ty1 _) (LitInst _ lit2 ty2 _) = (lit1 `compare` lit2) `thenCmp` (ty1 `tcCmpType` ty2)
678 %************************************************************************
680 \subsection[Inst-collections]{LIE: a collection of Insts}
682 %************************************************************************
687 isEmptyLIE = isEmptyBag
689 unitLIE inst = unitBag inst
690 mkLIE insts = listToBag insts
691 plusLIE lie1 lie2 = lie1 `unionBags` lie2
692 consLIE inst lie = inst `consBag` lie
693 plusLIEs lies = unionManyBags lies
694 lieToList = bagToList
695 listToLIE = listToBag
699 %************************************************************************
701 \subsection[Inst-origin]{The @InstOrigin@ type}
703 %************************************************************************
705 The @InstOrigin@ type gives information about where a dictionary came from.
706 This is important for decent error message reporting because dictionaries
707 don't appear in the original source code. Doubtless this type will evolve...
709 It appears in TcMonad because there are a couple of error-message-generation
710 functions that deal with it.
713 data InstLoc = InstLoc InstOrigin SrcLoc ErrCtxt
715 instLocSrcLoc :: InstLoc -> SrcLoc
716 instLocSrcLoc (InstLoc _ src_loc _) = src_loc
719 = OccurrenceOf Name -- Occurrence of an overloaded identifier
721 | IPOcc (IPName Name) -- Occurrence of an implicit parameter
722 | IPBind (IPName Name) -- Binding site of an implicit parameter
726 | DataDeclOrigin -- Typechecking a data declaration
728 | InstanceDeclOrigin -- Typechecking an instance decl
730 | LiteralOrigin HsOverLit -- Occurrence of a literal
732 | PatOrigin RenamedPat
734 | ArithSeqOrigin RenamedArithSeqInfo -- [x..], [x..y] etc
735 | PArrSeqOrigin RenamedArithSeqInfo -- [:x..y:] and [:x,y..z:]
737 | SignatureOrigin -- A dict created from a type signature
738 | Rank2Origin -- A dict created when typechecking the argument
739 -- of a rank-2 typed function
741 | DoOrigin -- The monad for a do expression
742 | ProcOrigin -- A proc expression
744 | ClassDeclOrigin -- Manufactured during a class decl
746 | InstanceSpecOrigin Class -- in a SPECIALIZE instance pragma
749 -- When specialising instances the instance info attached to
750 -- each class is not yet ready, so we record it inside the
751 -- origin information. This is a bit of a hack, but it works
752 -- fine. (Patrick is to blame [WDP].)
754 | ValSpecOrigin Name -- in a SPECIALIZE pragma for a value
756 -- Argument or result of a ccall
757 -- Dictionaries with this origin aren't actually mentioned in the
758 -- translated term, and so need not be bound. Nor should they
759 -- be abstracted over.
761 | UnknownOrigin -- Help! I give up...
765 pprInstLoc :: InstLoc -> SDoc
766 pprInstLoc (InstLoc orig locn ctxt)
767 = hsep [text "arising from", pp_orig orig, text "at", ppr locn]
769 pp_orig (OccurrenceOf name)
770 = hsep [ptext SLIT("use of"), quotes (ppr name)]
772 = hsep [ptext SLIT("use of implicit parameter"), quotes (ppr name)]
773 pp_orig (IPBind name)
774 = hsep [ptext SLIT("binding for implicit parameter"), quotes (ppr name)]
775 pp_orig RecordUpdOrigin
776 = ptext SLIT("a record update")
777 pp_orig DataDeclOrigin
778 = ptext SLIT("the data type declaration")
779 pp_orig InstanceDeclOrigin
780 = ptext SLIT("the instance declaration")
781 pp_orig (LiteralOrigin lit)
782 = hsep [ptext SLIT("the literal"), quotes (ppr lit)]
783 pp_orig (PatOrigin pat)
784 = hsep [ptext SLIT("the pattern"), quotes (ppr pat)]
785 pp_orig (ArithSeqOrigin seq)
786 = hsep [ptext SLIT("the arithmetic sequence"), quotes (ppr seq)]
787 pp_orig (PArrSeqOrigin seq)
788 = hsep [ptext SLIT("the parallel array sequence"), quotes (ppr seq)]
789 pp_orig (SignatureOrigin)
790 = ptext SLIT("a type signature")
791 pp_orig (Rank2Origin)
792 = ptext SLIT("a function with an overloaded argument type")
794 = ptext SLIT("a do statement")
796 = ptext SLIT("a proc expression")
797 pp_orig (ClassDeclOrigin)
798 = ptext SLIT("a class declaration")
799 pp_orig (InstanceSpecOrigin clas ty)
800 = hsep [text "a SPECIALIZE instance pragma; class",
801 quotes (ppr clas), text "type:", ppr ty]
802 pp_orig (ValSpecOrigin name)
803 = hsep [ptext SLIT("a SPECIALIZE user-pragma for"), quotes (ppr name)]
804 pp_orig (UnknownOrigin)
805 = ptext SLIT("...oops -- I don't know where the overloading came from!")