4 TcTauType, TcPredType, TcThetaType, TcRhoType,
5 TcTyVar, TcTyVarSet, TcClassContext,
8 TcM, NF_TcM, TcDown, TcEnv,
11 returnTc, thenTc, thenTc_, mapTc, mapTc_, listTc,
12 foldrTc, foldlTc, mapAndUnzipTc, mapAndUnzip3Tc,
13 mapBagTc, fixTc, tryTc, tryTc_, getErrsTc,
18 returnNF_Tc, thenNF_Tc, thenNF_Tc_, mapNF_Tc,
19 fixNF_Tc, forkNF_Tc, foldrNF_Tc, foldlNF_Tc,
21 listNF_Tc, mapAndUnzipNF_Tc, mapBagNF_Tc,
23 checkTc, checkTcM, checkMaybeTc, checkMaybeTcM,
24 failTc, failWithTc, addErrTc, addErrsTc, warnTc,
25 recoverTc, checkNoErrsTc, recoverNF_Tc, discardErrsTc,
26 addErrTcM, addInstErrTcM, failWithTcM,
29 tcGetDefaultTys, tcSetDefaultTys,
30 tcGetUnique, tcGetUniques,
33 tcAddSrcLoc, tcGetSrcLoc, tcGetInstLoc,
34 tcAddErrCtxtM, tcSetErrCtxtM,
35 tcAddErrCtxt, tcSetErrCtxt,
37 tcNewMutVar, tcNewSigTyVar, tcReadMutVar, tcWriteMutVar, TcRef,
38 tcNewMutTyVar, tcReadMutTyVar, tcWriteMutTyVar,
40 InstOrigin(..), InstLoc, pprInstLoc,
42 TcError, TcWarning, TidyEnv, emptyTidyEnv,
46 #include "HsVersions.h"
48 import {-# SOURCE #-} TcEnv ( TcEnv )
50 import RnHsSyn ( RenamedPat, RenamedArithSeqInfo, RenamedHsExpr, RenamedHsOverLit )
51 import Type ( Type, Kind, PredType, ThetaType, RhoType, TauType,
53 import ErrUtils ( addShortErrLocLine, addShortWarnLocLine, ErrMsg, Message, WarnMsg )
55 import Bag ( Bag, emptyBag, isEmptyBag,
56 foldBag, unitBag, unionBags, snocBag )
57 import Class ( Class, ClassContext )
59 import Var ( Id, TyVar, newMutTyVar, newSigTyVar, readMutTyVar, writeMutTyVar )
60 import VarEnv ( TidyEnv, emptyTidyEnv )
61 import VarSet ( TyVarSet )
62 import UniqSupply ( UniqSupply, uniqFromSupply, uniqsFromSupply,
63 splitUniqSupply, mkSplitUniqSupply,
65 import SrcLoc ( SrcLoc, noSrcLoc )
66 import UniqFM ( emptyUFM )
67 import Unique ( Unique )
71 import IOExts ( IORef, newIORef, readIORef, writeIORef,
72 unsafeInterleaveIO, fixIO
76 infixr 9 `thenTc`, `thenTc_`, `thenNF_Tc`, `thenNF_Tc_`
80 %************************************************************************
84 %************************************************************************
87 type TcTyVar = TyVar -- Might be a mutable tyvar
88 type TcTyVarSet = TyVarSet
90 type TcType = Type -- A TcType can have mutable type variables
91 -- Invariant on ForAllTy in TcTypes:
93 -- a cannot occur inside a MutTyVar in T; that is,
94 -- T is "flattened" before quantifying over a
96 type TcClassContext = ClassContext
97 type TcPredType = PredType
98 type TcThetaType = ThetaType
99 type TcRhoType = RhoType
100 type TcTauType = TauType
105 %************************************************************************
107 \subsection{The main monads: TcM, NF_TcM}
109 %************************************************************************
112 type NF_TcM r = TcDown -> TcEnv -> IO r -- Can't raise UserError
113 type TcM r = TcDown -> TcEnv -> IO r -- Can raise UserError
115 type Either_TcM r = TcDown -> TcEnv -> IO r -- Either NF_TcM or TcM
116 -- Used only in this file for type signatures which
117 -- have a part that's polymorphic in whether it's NF_TcM or TcM
120 type TcRef a = IORef a
128 -> IO (Maybe r, (Bag WarnMsg, Bag ErrMsg))
130 initTc dflags tc_env do_this
132 us <- mkSplitUniqSupply 'a' ;
133 us_var <- newIORef us ;
134 errs_var <- newIORef (emptyBag,emptyBag) ;
135 tvs_var <- newIORef emptyUFM ;
138 init_down = TcDown { tc_dflags = dflags, tc_def = [],
139 tc_us = us_var, tc_loc = noSrcLoc,
140 tc_ctxt = [], tc_errs = errs_var }
143 maybe_res <- catch (do { res <- do_this init_down tc_env ;
145 (\_ -> return Nothing) ;
147 (warns,errs) <- readIORef errs_var ;
148 return (maybe_res, (warns, errs))
151 -- Monadic operations
153 returnNF_Tc :: a -> NF_TcM a
154 returnTc :: a -> TcM a
155 returnTc v down env = return v
157 thenTc :: TcM a -> (a -> TcM b) -> TcM b
158 thenNF_Tc :: NF_TcM a -> (a -> Either_TcM b) -> Either_TcM b
159 thenTc m k down env = do { r <- m down env; k r down env }
161 thenTc_ :: TcM a -> TcM b -> TcM b
162 thenNF_Tc_ :: NF_TcM a -> Either_TcM b -> Either_TcM b
163 thenTc_ m k down env = do { m down env; k down env }
165 listTc :: [TcM a] -> TcM [a]
166 listNF_Tc :: [NF_TcM a] -> NF_TcM [a]
167 listTc [] = returnTc []
168 listTc (x:xs) = x `thenTc` \ r ->
169 listTc xs `thenTc` \ rs ->
172 mapTc :: (a -> TcM b) -> [a] -> TcM [b]
173 mapTc_ :: (a -> TcM b) -> [a] -> TcM ()
174 mapNF_Tc :: (a -> NF_TcM b) -> [a] -> NF_TcM [b]
175 mapTc f [] = returnTc []
176 mapTc f (x:xs) = f x `thenTc` \ r ->
177 mapTc f xs `thenTc` \ rs ->
179 mapTc_ f xs = mapTc f xs `thenTc_` returnTc ()
182 foldrTc :: (a -> b -> TcM b) -> b -> [a] -> TcM b
183 foldrNF_Tc :: (a -> b -> NF_TcM b) -> b -> [a] -> NF_TcM b
184 foldrTc k z [] = returnTc z
185 foldrTc k z (x:xs) = foldrTc k z xs `thenTc` \r ->
188 foldlTc :: (a -> b -> TcM a) -> a -> [b] -> TcM a
189 foldlNF_Tc :: (a -> b -> NF_TcM a) -> a -> [b] -> NF_TcM a
190 foldlTc k z [] = returnTc z
191 foldlTc k z (x:xs) = k z x `thenTc` \r ->
194 mapAndUnzipTc :: (a -> TcM (b,c)) -> [a] -> TcM ([b],[c])
195 mapAndUnzipNF_Tc :: (a -> NF_TcM (b,c)) -> [a] -> NF_TcM ([b],[c])
196 mapAndUnzipTc f [] = returnTc ([],[])
197 mapAndUnzipTc f (x:xs) = f x `thenTc` \ (r1,r2) ->
198 mapAndUnzipTc f xs `thenTc` \ (rs1,rs2) ->
199 returnTc (r1:rs1, r2:rs2)
201 mapAndUnzip3Tc :: (a -> TcM (b,c,d)) -> [a] -> TcM ([b],[c],[d])
202 mapAndUnzip3Tc f [] = returnTc ([],[],[])
203 mapAndUnzip3Tc f (x:xs) = f x `thenTc` \ (r1,r2,r3) ->
204 mapAndUnzip3Tc f xs `thenTc` \ (rs1,rs2,rs3) ->
205 returnTc (r1:rs1, r2:rs2, r3:rs3)
207 mapBagTc :: (a -> TcM b) -> Bag a -> TcM (Bag b)
208 mapBagNF_Tc :: (a -> NF_TcM b) -> Bag a -> NF_TcM (Bag b)
210 = foldBag (\ b1 b2 -> b1 `thenTc` \ r1 ->
212 returnTc (unionBags r1 r2))
213 (\ a -> f a `thenTc` \ r -> returnTc (unitBag r))
217 fixTc :: (a -> TcM a) -> TcM a
218 fixNF_Tc :: (a -> NF_TcM a) -> NF_TcM a
219 fixTc m env down = fixIO (\ loop -> m loop env down)
221 recoverTc :: TcM r -> TcM r -> TcM r
222 recoverNF_Tc :: NF_TcM r -> TcM r -> NF_TcM r
223 recoverTc recover m down env
224 = catch (m down env) (\ _ -> recover down env)
226 returnNF_Tc = returnTc
230 recoverNF_Tc = recoverTc
235 mapAndUnzipNF_Tc = mapAndUnzipTc
236 mapBagNF_Tc = mapBagTc
239 @forkNF_Tc@ runs a sub-typecheck action *lazily* in a separate state
240 thread. Ideally, this elegantly ensures that it can't zap any type
241 variables that belong to the main thread. But alas, the environment
242 contains TyCon and Class environments that include TcKind stuff,
243 which is a Royal Pain. By the time this fork stuff is used they'll
244 have been unified down so there won't be any kind variables, but we
245 can't express that in the current typechecker framework.
247 So we compromise and use unsafeInterleaveIO.
249 We throw away any error messages!
252 forkNF_Tc :: NF_TcM r -> NF_TcM r
253 forkNF_Tc m down@(TcDown { tc_us = u_var }) env
255 -- Get a fresh unique supply
256 us <- readIORef u_var
257 let (us1, us2) = splitUniqSupply us
260 unsafeInterleaveIO (do {
261 us_var' <- newIORef us2 ;
262 err_var' <- newIORef (emptyBag,emptyBag) ;
263 let { down' = down { tc_us = us_var', tc_errs = err_var' } };
265 -- ToDo: optionally dump any error messages
270 traceTc :: SDoc -> NF_TcM ()
271 traceTc doc down env = printDump doc
273 ioToTc :: IO a -> NF_TcM a
274 ioToTc io down env = io
278 %************************************************************************
280 \subsection{Error handling}
282 %************************************************************************
285 getErrsTc :: NF_TcM (Bag WarnMsg, Bag ErrMsg)
287 = readIORef (getTcErrs down)
290 failTc down env = give_up
293 give_up = IOERROR (userError "Typecheck failed")
295 failWithTc :: Message -> TcM a -- Add an error message and fail
296 failWithTc err_msg = failWithTcM (emptyTidyEnv, err_msg)
298 addErrTc :: Message -> NF_TcM ()
299 addErrTc err_msg = addErrTcM (emptyTidyEnv, err_msg)
301 addErrsTc :: [Message] -> NF_TcM ()
302 addErrsTc [] = returnNF_Tc ()
303 addErrsTc err_msgs = listNF_Tc (map addErrTc err_msgs) `thenNF_Tc_` returnNF_Tc ()
305 -- The 'M' variants do the TidyEnv bit
306 failWithTcM :: (TidyEnv, Message) -> TcM a -- Add an error message and fail
307 failWithTcM env_and_msg
308 = addErrTcM env_and_msg `thenNF_Tc_`
311 checkTc :: Bool -> Message -> TcM () -- Check that the boolean is true
312 checkTc True err = returnTc ()
313 checkTc False err = failWithTc err
315 checkTcM :: Bool -> TcM () -> TcM () -- Check that the boolean is true
316 checkTcM True err = returnTc ()
317 checkTcM False err = err
319 checkMaybeTc :: Maybe val -> Message -> TcM val
320 checkMaybeTc (Just val) err = returnTc val
321 checkMaybeTc Nothing err = failWithTc err
323 checkMaybeTcM :: Maybe val -> TcM val -> TcM val
324 checkMaybeTcM (Just val) err = returnTc val
325 checkMaybeTcM Nothing err = err
327 addErrTcM :: (TidyEnv, Message) -> NF_TcM () -- Add an error message but don't fail
328 addErrTcM (tidy_env, err_msg) down env
329 = add_err_tcm tidy_env err_msg ctxt loc down env
331 ctxt = getErrCtxt down
334 addInstErrTcM :: InstLoc -> (TidyEnv, Message) -> NF_TcM () -- Add an error message but don't fail
335 addInstErrTcM inst_loc@(_, loc, ctxt) (tidy_env, err_msg) down env
336 = add_err_tcm tidy_env err_msg full_ctxt loc down env
338 full_ctxt = (\env -> returnNF_Tc (env, pprInstLoc inst_loc)) : ctxt
340 add_err_tcm tidy_env err_msg ctxt loc down env
342 (warns, errs) <- readIORef errs_var
343 ctxt_msgs <- do_ctxt tidy_env ctxt down env
344 let err = addShortErrLocLine loc $
345 vcat (err_msg : ctxt_to_use ctxt_msgs)
346 writeIORef errs_var (warns, errs `snocBag` err)
348 errs_var = getTcErrs down
350 do_ctxt tidy_env [] down env
352 do_ctxt tidy_env (c:cs) down env
354 (tidy_env', m) <- c tidy_env down env
355 ms <- do_ctxt tidy_env' cs down env
358 -- warnings don't have an 'M' variant
359 warnTc :: Bool -> Message -> NF_TcM ()
360 warnTc warn_if_true warn_msg down env
363 (warns,errs) <- readIORef errs_var
364 ctxt_msgs <- do_ctxt emptyTidyEnv ctxt down env
365 let warn = addShortWarnLocLine loc $
366 vcat (warn_msg : ctxt_to_use ctxt_msgs)
367 writeIORef errs_var (warns `snocBag` warn, errs)
371 errs_var = getTcErrs down
372 ctxt = getErrCtxt down
375 -- (tryTc r m) succeeds if m succeeds and generates no errors
376 -- If m fails then r is invoked, passing the warnings and errors from m
377 -- If m succeeds, (tryTc r m) checks whether m generated any errors messages
378 -- (it might have recovered internally)
379 -- If so, then r is invoked, passing the warnings and errors from m
381 tryTc :: ((Bag WarnMsg, Bag ErrMsg) -> TcM r) -- Recovery action
382 -> TcM r -- Thing to try
384 tryTc recover main down env
386 m_errs_var <- newIORef (emptyBag,emptyBag)
387 catch (my_main m_errs_var) (\ _ -> my_recover m_errs_var)
389 my_recover m_errs_var
390 = do warns_and_errs <- readIORef m_errs_var
391 recover warns_and_errs down env
394 = do result <- main (setTcErrs down m_errs_var) env
396 -- Check that m has no errors; if it has internal recovery
397 -- mechanisms it might "succeed" but having found a bunch of
398 -- errors along the way.
399 (m_warns, m_errs) <- readIORef m_errs_var
400 if isEmptyBag m_errs then
403 give_up -- This triggers the catch
406 -- (checkNoErrsTc m) succeeds iff m succeeds and generates no errors
407 -- If m fails then (checkNoErrsTc m) fails.
408 -- If m succeeds, it checks whether m generated any errors messages
409 -- (it might have recovered internally)
410 -- If so, it fails too.
411 -- Regardless, any errors generated by m are propagated to the enclosing context.
412 checkNoErrsTc :: TcM r -> TcM r
414 = tryTc my_recover main
416 my_recover (m_warns, m_errs) down env
417 = do (warns, errs) <- readIORef errs_var
418 writeIORef errs_var (warns `unionBags` m_warns,
419 errs `unionBags` m_errs)
422 errs_var = getTcErrs down
425 -- (tryTc_ r m) tries m; if it succeeds it returns it,
426 -- otherwise it returns r. Any error messages added by m are discarded,
427 -- whether or not m succeeds.
428 tryTc_ :: TcM r -> TcM r -> TcM r
430 = tryTc my_recover main
432 my_recover warns_and_errs = recover
434 -- (discardErrsTc m) runs m, but throw away all its error messages.
435 discardErrsTc :: Either_TcM r -> Either_TcM r
436 discardErrsTc main down env
437 = do new_errs_var <- newIORef (emptyBag,emptyBag)
438 main (setTcErrs down new_errs_var) env
443 %************************************************************************
445 \subsection{Mutable variables}
447 %************************************************************************
450 tcNewMutVar :: a -> NF_TcM (TcRef a)
451 tcNewMutVar val down env = newIORef val
453 tcWriteMutVar :: TcRef a -> a -> NF_TcM ()
454 tcWriteMutVar var val down env = writeIORef var val
456 tcReadMutVar :: TcRef a -> NF_TcM a
457 tcReadMutVar var down env = readIORef var
459 tcNewMutTyVar :: Name -> Kind -> NF_TcM TyVar
460 tcNewMutTyVar name kind down env = newMutTyVar name kind
462 tcNewSigTyVar :: Name -> Kind -> NF_TcM TyVar
463 tcNewSigTyVar name kind down env = newSigTyVar name kind
465 tcReadMutTyVar :: TyVar -> NF_TcM (Maybe Type)
466 tcReadMutTyVar tyvar down env = readMutTyVar tyvar
468 tcWriteMutTyVar :: TyVar -> Maybe Type -> NF_TcM ()
469 tcWriteMutTyVar tyvar val down env = writeMutTyVar tyvar val
473 %************************************************************************
475 \subsection{The environment}
477 %************************************************************************
480 tcGetEnv :: NF_TcM TcEnv
481 tcGetEnv down env = return env
483 tcSetEnv :: TcEnv -> Either_TcM a -> Either_TcM a
484 tcSetEnv new_env m down old_env = m down new_env
488 %************************************************************************
490 \subsection{Source location}
492 %************************************************************************
495 tcGetDefaultTys :: NF_TcM [Type]
496 tcGetDefaultTys down env = return (getDefaultTys down)
498 tcSetDefaultTys :: [Type] -> TcM r -> TcM r
499 tcSetDefaultTys tys m down env = m (setDefaultTys down tys) env
501 tcAddSrcLoc :: SrcLoc -> Either_TcM a -> Either_TcM a
502 tcAddSrcLoc loc m down env = m (setLoc down loc) env
504 tcGetSrcLoc :: NF_TcM SrcLoc
505 tcGetSrcLoc down env = return (getLoc down)
507 tcGetInstLoc :: InstOrigin -> NF_TcM InstLoc
508 tcGetInstLoc origin down env = return (origin, getLoc down, getErrCtxt down)
510 tcSetErrCtxtM, tcAddErrCtxtM :: (TidyEnv -> NF_TcM (TidyEnv, Message))
512 tcSetErrCtxtM msg m down env = m (setErrCtxt down msg) env
513 tcAddErrCtxtM msg m down env = m (addErrCtxt down msg) env
515 tcSetErrCtxt, tcAddErrCtxt :: Message -> Either_TcM r -> Either_TcM r
517 tcSetErrCtxt msg m down env = m (setErrCtxt down (\env -> returnNF_Tc (env, msg))) env
518 tcAddErrCtxt msg m down env = m (addErrCtxt down (\env -> returnNF_Tc (env, msg))) env
522 %************************************************************************
524 \subsection{Unique supply}
526 %************************************************************************
529 tcGetUnique :: NF_TcM Unique
531 = do uniq_supply <- readIORef u_var
532 let (new_uniq_supply, uniq_s) = splitUniqSupply uniq_supply
533 uniq = uniqFromSupply uniq_s
534 writeIORef u_var new_uniq_supply
537 u_var = getUniqSupplyVar down
539 tcGetUniques :: Int -> NF_TcM [Unique]
540 tcGetUniques n down env
541 = do uniq_supply <- readIORef u_var
542 let (new_uniq_supply, uniq_s) = splitUniqSupply uniq_supply
543 uniqs = uniqsFromSupply n uniq_s
544 writeIORef u_var new_uniq_supply
547 u_var = getUniqSupplyVar down
549 uniqSMToTcM :: UniqSM a -> NF_TcM a
550 uniqSMToTcM m down env
551 = do uniq_supply <- readIORef u_var
552 let (new_uniq_supply, uniq_s) = splitUniqSupply uniq_supply
553 writeIORef u_var new_uniq_supply
554 return (initUs_ uniq_s m)
556 u_var = getUniqSupplyVar down
561 %************************************************************************
565 %************************************************************************
570 tc_dflags :: DynFlags,
571 tc_def :: [Type], -- Types used for defaulting
572 tc_us :: (TcRef UniqSupply), -- Unique supply
573 tc_loc :: SrcLoc, -- Source location
574 tc_ctxt :: ErrCtxt, -- Error context
575 tc_errs :: (TcRef (Bag WarnMsg, Bag ErrMsg))
578 type ErrCtxt = [TidyEnv -> NF_TcM (TidyEnv, Message)]
579 -- Innermost first. Monadic so that we have a chance
580 -- to deal with bound type variables just before error
581 -- message construction
584 -- These selectors are *local* to TcMonad.lhs
587 getTcErrs (TcDown{tc_errs=errs}) = errs
588 setTcErrs down errs = down{tc_errs=errs}
590 getDefaultTys (TcDown{tc_def=def}) = def
591 setDefaultTys down def = down{tc_def=def}
593 getLoc (TcDown{tc_loc=loc}) = loc
594 setLoc down loc = down{tc_loc=loc}
596 getUniqSupplyVar (TcDown{tc_us=us}) = us
598 getErrCtxt (TcDown{tc_ctxt=ctxt}) = ctxt
599 setErrCtxt down msg = down{tc_ctxt=[msg]}
600 addErrCtxt down msg = down{tc_ctxt = msg : tc_ctxt down}
602 doptsTc :: DynFlag -> TcM Bool
603 doptsTc dflag (TcDown{tc_dflags=dflags}) env_down
604 = return (dopt dflag dflags)
606 getDOptsTc :: TcM DynFlags
607 getDOptsTc (TcDown{tc_dflags=dflags}) env_down
614 %************************************************************************
616 \subsection{TypeChecking Errors}
618 %************************************************************************
621 type TcError = Message
622 type TcWarning = Message
624 ctxt_to_use ctxt | opt_PprStyle_Debug = ctxt
625 | otherwise = takeAtMost 3 ctxt
627 takeAtMost :: Int -> [a] -> [a]
630 takeAtMost n (x:xs) = x:takeAtMost (n-1) xs
632 arityErr kind name n m
633 = hsep [ text kind, quotes (ppr name), ptext SLIT("should have"),
634 n_arguments <> comma, text "but has been given", int m]
636 n_arguments | n == 0 = ptext SLIT("no arguments")
637 | n == 1 = ptext SLIT("1 argument")
638 | True = hsep [int n, ptext SLIT("arguments")]
643 %************************************************************************
645 \subsection[Inst-origin]{The @InstOrigin@ type}
647 %************************************************************************
649 The @InstOrigin@ type gives information about where a dictionary came from.
650 This is important for decent error message reporting because dictionaries
651 don't appear in the original source code. Doubtless this type will evolve...
653 It appears in TcMonad because there are a couple of error-message-generation
654 functions that deal with it.
657 type InstLoc = (InstOrigin, SrcLoc, ErrCtxt)
660 = OccurrenceOf Id -- Occurrence of an overloaded identifier
662 | IPOcc Name -- Occurrence of an implicit parameter
663 | IPBind Name -- Binding site of an implicit parameter
667 | DataDeclOrigin -- Typechecking a data declaration
669 | InstanceDeclOrigin -- Typechecking an instance decl
671 | LiteralOrigin RenamedHsOverLit -- Occurrence of a literal
673 | PatOrigin RenamedPat
675 | ArithSeqOrigin RenamedArithSeqInfo -- [x..], [x..y] etc
677 | SignatureOrigin -- A dict created from a type signature
678 | Rank2Origin -- A dict created when typechecking the argument
679 -- of a rank-2 typed function
681 | DoOrigin -- The monad for a do expression
683 | ClassDeclOrigin -- Manufactured during a class decl
685 | InstanceSpecOrigin Class -- in a SPECIALIZE instance pragma
688 -- When specialising instances the instance info attached to
689 -- each class is not yet ready, so we record it inside the
690 -- origin information. This is a bit of a hack, but it works
691 -- fine. (Patrick is to blame [WDP].)
693 | ValSpecOrigin Name -- in a SPECIALIZE pragma for a value
695 -- Argument or result of a ccall
696 -- Dictionaries with this origin aren't actually mentioned in the
697 -- translated term, and so need not be bound. Nor should they
698 -- be abstracted over.
700 | CCallOrigin String -- CCall label
701 (Maybe RenamedHsExpr) -- Nothing if it's the result
702 -- Just arg, for an argument
704 | LitLitOrigin String -- the litlit
706 | UnknownOrigin -- Help! I give up...
710 pprInstLoc :: InstLoc -> SDoc
711 pprInstLoc (orig, locn, ctxt)
712 = hsep [text "arising from", pp_orig orig, text "at", ppr locn]
714 pp_orig (OccurrenceOf id)
715 = hsep [ptext SLIT("use of"), quotes (ppr id)]
717 = hsep [ptext SLIT("use of implicit parameter"), quotes (char '?' <> ppr name)]
718 pp_orig (IPBind name)
719 = hsep [ptext SLIT("binding for implicit parameter"), quotes (char '?' <> ppr name)]
720 pp_orig (LiteralOrigin lit)
721 = hsep [ptext SLIT("the literal"), quotes (ppr lit)]
722 pp_orig (PatOrigin pat)
723 = hsep [ptext SLIT("the pattern"), quotes (ppr pat)]
724 pp_orig (InstanceDeclOrigin)
725 = ptext SLIT("an instance declaration")
726 pp_orig (ArithSeqOrigin seq)
727 = hsep [ptext SLIT("the arithmetic sequence"), quotes (ppr seq)]
728 pp_orig (SignatureOrigin)
729 = ptext SLIT("a type signature")
730 pp_orig (Rank2Origin)
731 = ptext SLIT("a function with an overloaded argument type")
733 = ptext SLIT("a do statement")
734 pp_orig (ClassDeclOrigin)
735 = ptext SLIT("a class declaration")
736 pp_orig (InstanceSpecOrigin clas ty)
737 = hsep [text "a SPECIALIZE instance pragma; class",
738 quotes (ppr clas), text "type:", ppr ty]
739 pp_orig (ValSpecOrigin name)
740 = hsep [ptext SLIT("a SPECIALIZE user-pragma for"), quotes (ppr name)]
741 pp_orig (CCallOrigin clabel Nothing{-ccall result-})
742 = hsep [ptext SLIT("the result of the _ccall_ to"), quotes (text clabel)]
743 pp_orig (CCallOrigin clabel (Just arg_expr))
744 = hsep [ptext SLIT("an argument in the _ccall_ to"), quotes (text clabel) <> comma,
745 text "namely", quotes (ppr arg_expr)]
746 pp_orig (LitLitOrigin s)
747 = hsep [ptext SLIT("the ``literal-literal''"), quotes (text s)]
748 pp_orig (UnknownOrigin)
749 = ptext SLIT("...oops -- I don't know where the overloading came from!")