mirrored from https://gitlab.haskell.org/ghc/ghc.git
-
Notifications
You must be signed in to change notification settings - Fork 704
/
RnExpr.lhs
1365 lines (1149 loc) · 54.7 KB
/
RnExpr.lhs
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
%
% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
%
\section[RnExpr]{Renaming of expressions}
Basically dependency analysis.
Handles @Match@, @GRHSs@, @HsExpr@, and @Qualifier@ datatypes. In
general, all of these functions return a renamed thing, and a set of
free variables.
\begin{code}
module RnExpr (
rnLExpr, rnExpr, rnStmts
) where
#include "HsVersions.h"
import {-# SOURCE #-} TcSplice( runQuasiQuoteExpr )
import RnBinds ( rnLocalBindsAndThen, rnLocalValBindsLHS, rnLocalValBindsRHS,
rnMatchGroup, rnGRHS, makeMiniFixityEnv)
import HsSyn
import TcRnMonad
import Module ( getModule )
import RnEnv
import RnSplice ( rnBracket, rnSpliceExpr, checkThLocalName )
import RnTypes
import RnPat
import DynFlags
import BasicTypes ( FixityDirection(..) )
import PrelNames
import Name
import NameSet
import RdrName
import UniqSet
import Data.List
import Util
import ListSetOps ( removeDups )
import Outputable
import SrcLoc
import FastString
import Control.Monad
import TysWiredIn ( nilDataConName )
\end{code}
\begin{code}
-- XXX
thenM :: Monad a => a b -> (b -> a c) -> a c
thenM = (>>=)
thenM_ :: Monad a => a b -> a c -> a c
thenM_ = (>>)
\end{code}
%************************************************************************
%* *
\subsubsection{Expressions}
%* *
%************************************************************************
\begin{code}
rnExprs :: [LHsExpr RdrName] -> RnM ([LHsExpr Name], FreeVars)
rnExprs ls = rnExprs' ls emptyUniqSet
where
rnExprs' [] acc = return ([], acc)
rnExprs' (expr:exprs) acc
= rnLExpr expr `thenM` \ (expr', fvExpr) ->
-- Now we do a "seq" on the free vars because typically it's small
-- or empty, especially in very long lists of constants
let
acc' = acc `plusFV` fvExpr
in
acc' `seq` rnExprs' exprs acc' `thenM` \ (exprs', fvExprs) ->
return (expr':exprs', fvExprs)
\end{code}
Variables. We look up the variable and return the resulting name.
\begin{code}
rnLExpr :: LHsExpr RdrName -> RnM (LHsExpr Name, FreeVars)
rnLExpr = wrapLocFstM rnExpr
rnExpr :: HsExpr RdrName -> RnM (HsExpr Name, FreeVars)
finishHsVar :: Name -> RnM (HsExpr Name, FreeVars)
-- Separated from rnExpr because it's also used
-- when renaming infix expressions
-- See Note [Adding the implicit parameter to 'assert']
finishHsVar name
= do { this_mod <- getModule
; when (nameIsLocalOrFrom this_mod name) $
checkThLocalName name
; ignore_asserts <- goptM Opt_IgnoreAsserts
; if ignore_asserts || not (name `hasKey` assertIdKey)
then return (HsVar name, unitFV name)
else do { e <- mkAssertErrorExpr
; return (e, unitFV name) } }
rnExpr (HsVar v)
= do { mb_name <- lookupOccRn_maybe v
; case mb_name of {
Nothing -> do { opt_TypeHoles <- woptM Opt_WarnTypedHoles
; if opt_TypeHoles && startsWithUnderscore (rdrNameOcc v)
then return (HsUnboundVar v, emptyFVs)
else do { n <- reportUnboundName v; finishHsVar n } } ;
Just name
| name == nilDataConName -- Treat [] as an ExplicitList, so that
-- OverloadedLists works correctly
-> rnExpr (ExplicitList placeHolderType Nothing [])
| otherwise
-> finishHsVar name }}
rnExpr (HsIPVar v)
= return (HsIPVar v, emptyFVs)
rnExpr (HsLit lit@(HsString s))
= do {
opt_OverloadedStrings <- xoptM Opt_OverloadedStrings
; if opt_OverloadedStrings then
rnExpr (HsOverLit (mkHsIsString s placeHolderType))
else -- Same as below
rnLit lit `thenM_`
return (HsLit lit, emptyFVs)
}
rnExpr (HsLit lit)
= rnLit lit `thenM_`
return (HsLit lit, emptyFVs)
rnExpr (HsOverLit lit)
= rnOverLit lit `thenM` \ (lit', fvs) ->
return (HsOverLit lit', fvs)
rnExpr (HsApp fun arg)
= rnLExpr fun `thenM` \ (fun',fvFun) ->
rnLExpr arg `thenM` \ (arg',fvArg) ->
return (HsApp fun' arg', fvFun `plusFV` fvArg)
rnExpr (OpApp e1 (L op_loc (HsVar op_rdr)) _ e2)
= do { (e1', fv_e1) <- rnLExpr e1
; (e2', fv_e2) <- rnLExpr e2
; op_name <- setSrcSpan op_loc (lookupOccRn op_rdr)
; (op', fv_op) <- finishHsVar op_name
-- NB: op' is usually just a variable, but might be
-- an applicatoin (assert "Foo.hs:47")
-- Deal with fixity
-- When renaming code synthesised from "deriving" declarations
-- we used to avoid fixity stuff, but we can't easily tell any
-- more, so I've removed the test. Adding HsPars in TcGenDeriv
-- should prevent bad things happening.
; fixity <- lookupFixityRn op_name
; final_e <- mkOpAppRn e1' (L op_loc op') fixity e2'
; return (final_e, fv_e1 `plusFV` fv_op `plusFV` fv_e2) }
rnExpr (OpApp _ other_op _ _)
= failWith (vcat [ hang (ptext (sLit "Infix application with a non-variable operator:"))
2 (ppr other_op)
, ptext (sLit "(Probably resulting from a Template Haskell splice)") ])
rnExpr (NegApp e _)
= rnLExpr e `thenM` \ (e', fv_e) ->
lookupSyntaxName negateName `thenM` \ (neg_name, fv_neg) ->
mkNegAppRn e' neg_name `thenM` \ final_e ->
return (final_e, fv_e `plusFV` fv_neg)
------------------------------------------
-- Template Haskell extensions
-- Don't ifdef-GHCI them because we want to fail gracefully
-- (not with an rnExpr crash) in a stage-1 compiler.
rnExpr e@(HsBracket br_body) = rnBracket e br_body
rnExpr (HsSpliceE is_typed splice) = rnSpliceExpr is_typed splice
rnExpr (HsQuasiQuoteE qq)
= runQuasiQuoteExpr qq `thenM` \ lexpr' ->
-- Wrap the result of the quasi-quoter in parens so that we don't
-- lose the outermost location set by runQuasiQuote (#7918)
rnExpr (HsPar lexpr')
---------------------------------------------
-- Sections
-- See Note [Parsing sections] in Parser.y.pp
rnExpr (HsPar (L loc (section@(SectionL {}))))
= do { (section', fvs) <- rnSection section
; return (HsPar (L loc section'), fvs) }
rnExpr (HsPar (L loc (section@(SectionR {}))))
= do { (section', fvs) <- rnSection section
; return (HsPar (L loc section'), fvs) }
rnExpr (HsPar e)
= do { (e', fvs_e) <- rnLExpr e
; return (HsPar e', fvs_e) }
rnExpr expr@(SectionL {})
= do { addErr (sectionErr expr); rnSection expr }
rnExpr expr@(SectionR {})
= do { addErr (sectionErr expr); rnSection expr }
---------------------------------------------
rnExpr (HsCoreAnn ann expr)
= rnLExpr expr `thenM` \ (expr', fvs_expr) ->
return (HsCoreAnn ann expr', fvs_expr)
rnExpr (HsSCC lbl expr)
= rnLExpr expr `thenM` \ (expr', fvs_expr) ->
return (HsSCC lbl expr', fvs_expr)
rnExpr (HsTickPragma info expr)
= rnLExpr expr `thenM` \ (expr', fvs_expr) ->
return (HsTickPragma info expr', fvs_expr)
rnExpr (HsLam matches)
= rnMatchGroup LambdaExpr rnLExpr matches `thenM` \ (matches', fvMatch) ->
return (HsLam matches', fvMatch)
rnExpr (HsLamCase arg matches)
= rnMatchGroup CaseAlt rnLExpr matches `thenM` \ (matches', fvs_ms) ->
return (HsLamCase arg matches', fvs_ms)
rnExpr (HsCase expr matches)
= rnLExpr expr `thenM` \ (new_expr, e_fvs) ->
rnMatchGroup CaseAlt rnLExpr matches `thenM` \ (new_matches, ms_fvs) ->
return (HsCase new_expr new_matches, e_fvs `plusFV` ms_fvs)
rnExpr (HsLet binds expr)
= rnLocalBindsAndThen binds $ \ binds' ->
rnLExpr expr `thenM` \ (expr',fvExpr) ->
return (HsLet binds' expr', fvExpr)
rnExpr (HsDo do_or_lc stmts _)
= do { ((stmts', _), fvs) <- rnStmts do_or_lc rnLExpr stmts (\ _ -> return ((), emptyFVs))
; return ( HsDo do_or_lc stmts' placeHolderType, fvs ) }
rnExpr (ExplicitList _ _ exps)
= do { opt_OverloadedLists <- xoptM Opt_OverloadedLists
; (exps', fvs) <- rnExprs exps
; if opt_OverloadedLists
then do {
; (from_list_n_name, fvs') <- lookupSyntaxName fromListNName
; return (ExplicitList placeHolderType (Just from_list_n_name) exps', fvs `plusFV` fvs') }
else
return (ExplicitList placeHolderType Nothing exps', fvs) }
rnExpr (ExplicitPArr _ exps)
= rnExprs exps `thenM` \ (exps', fvs) ->
return (ExplicitPArr placeHolderType exps', fvs)
rnExpr (ExplicitTuple tup_args boxity)
= do { checkTupleSection tup_args
; checkTupSize (length tup_args)
; (tup_args', fvs) <- mapAndUnzipM rnTupArg tup_args
; return (ExplicitTuple tup_args' boxity, plusFVs fvs) }
where
rnTupArg (Present e) = do { (e',fvs) <- rnLExpr e; return (Present e', fvs) }
rnTupArg (Missing _) = return (Missing placeHolderType, emptyFVs)
rnExpr (RecordCon con_id _ rbinds)
= do { conname <- lookupLocatedOccRn con_id
; (rbinds', fvRbinds) <- rnHsRecBinds (HsRecFieldCon (unLoc conname)) rbinds
; return (RecordCon conname noPostTcExpr rbinds',
fvRbinds `addOneFV` unLoc conname) }
rnExpr (RecordUpd expr rbinds _ _ _)
= do { (expr', fvExpr) <- rnLExpr expr
; (rbinds', fvRbinds) <- rnHsRecBinds HsRecFieldUpd rbinds
; return (RecordUpd expr' rbinds' [] [] [],
fvExpr `plusFV` fvRbinds) }
rnExpr (ExprWithTySig expr pty)
= do { (pty', fvTy) <- rnLHsType ExprWithTySigCtx pty
; (expr', fvExpr) <- bindSigTyVarsFV (hsExplicitTvs pty') $
rnLExpr expr
; return (ExprWithTySig expr' pty', fvExpr `plusFV` fvTy) }
rnExpr (HsIf _ p b1 b2)
= do { (p', fvP) <- rnLExpr p
; (b1', fvB1) <- rnLExpr b1
; (b2', fvB2) <- rnLExpr b2
; (mb_ite, fvITE) <- lookupIfThenElse
; return (HsIf mb_ite p' b1' b2', plusFVs [fvITE, fvP, fvB1, fvB2]) }
rnExpr (HsMultiIf ty alts)
= do { (alts', fvs) <- mapFvRn (rnGRHS IfAlt rnLExpr) alts
; return (HsMultiIf ty alts', fvs) }
rnExpr (HsType a)
= rnLHsType HsTypeCtx a `thenM` \ (t, fvT) ->
return (HsType t, fvT)
rnExpr (ArithSeq _ _ seq)
= do { opt_OverloadedLists <- xoptM Opt_OverloadedLists
; (new_seq, fvs) <- rnArithSeq seq
; if opt_OverloadedLists
then do {
; (from_list_name, fvs') <- lookupSyntaxName fromListName
; return (ArithSeq noPostTcExpr (Just from_list_name) new_seq, fvs `plusFV` fvs') }
else
return (ArithSeq noPostTcExpr Nothing new_seq, fvs) }
rnExpr (PArrSeq _ seq)
= rnArithSeq seq `thenM` \ (new_seq, fvs) ->
return (PArrSeq noPostTcExpr new_seq, fvs)
\end{code}
These three are pattern syntax appearing in expressions.
Since all the symbols are reservedops we can simply reject them.
We return a (bogus) EWildPat in each case.
\begin{code}
rnExpr e@EWildPat = do { holes <- woptM Opt_WarnTypedHoles
; if holes
then return (hsHoleExpr, emptyFVs)
else patSynErr e
}
rnExpr e@(EAsPat {}) = patSynErr e
rnExpr e@(EViewPat {}) = patSynErr e
rnExpr e@(ELazyPat {}) = patSynErr e
\end{code}
%************************************************************************
%* *
Arrow notation
%* *
%************************************************************************
\begin{code}
rnExpr (HsProc pat body)
= newArrowScope $
rnPat ProcExpr pat $ \ pat' ->
rnCmdTop body `thenM` \ (body',fvBody) ->
return (HsProc pat' body', fvBody)
-- Ideally, these would be done in parsing, but to keep parsing simple, we do it here.
rnExpr e@(HsArrApp {}) = arrowFail e
rnExpr e@(HsArrForm {}) = arrowFail e
rnExpr other = pprPanic "rnExpr: unexpected expression" (ppr other)
-- HsWrap
hsHoleExpr :: HsExpr Name
hsHoleExpr = HsUnboundVar (mkRdrUnqual (mkVarOcc "_"))
arrowFail :: HsExpr RdrName -> RnM (HsExpr Name, FreeVars)
arrowFail e
= do { addErr (vcat [ ptext (sLit "Arrow command found where an expression was expected:")
, nest 2 (ppr e) ])
-- Return a place-holder hole, so that we can carry on
-- to report other errors
; return (hsHoleExpr, emptyFVs) }
----------------------
-- See Note [Parsing sections] in Parser.y.pp
rnSection :: HsExpr RdrName -> RnM (HsExpr Name, FreeVars)
rnSection section@(SectionR op expr)
= do { (op', fvs_op) <- rnLExpr op
; (expr', fvs_expr) <- rnLExpr expr
; checkSectionPrec InfixR section op' expr'
; return (SectionR op' expr', fvs_op `plusFV` fvs_expr) }
rnSection section@(SectionL expr op)
= do { (expr', fvs_expr) <- rnLExpr expr
; (op', fvs_op) <- rnLExpr op
; checkSectionPrec InfixL section op' expr'
; return (SectionL expr' op', fvs_op `plusFV` fvs_expr) }
rnSection other = pprPanic "rnSection" (ppr other)
\end{code}
%************************************************************************
%* *
Records
%* *
%************************************************************************
\begin{code}
rnHsRecBinds :: HsRecFieldContext -> HsRecordBinds RdrName
-> RnM (HsRecordBinds Name, FreeVars)
rnHsRecBinds ctxt rec_binds@(HsRecFields { rec_dotdot = dd })
= do { (flds, fvs) <- rnHsRecFields1 ctxt HsVar rec_binds
; (flds', fvss) <- mapAndUnzipM rn_field flds
; return (HsRecFields { rec_flds = flds', rec_dotdot = dd },
fvs `plusFV` plusFVs fvss) }
where
rn_field fld = do { (arg', fvs) <- rnLExpr (hsRecFieldArg fld)
; return (fld { hsRecFieldArg = arg' }, fvs) }
\end{code}
%************************************************************************
%* *
Arrow commands
%* *
%************************************************************************
\begin{code}
rnCmdArgs :: [LHsCmdTop RdrName] -> RnM ([LHsCmdTop Name], FreeVars)
rnCmdArgs [] = return ([], emptyFVs)
rnCmdArgs (arg:args)
= rnCmdTop arg `thenM` \ (arg',fvArg) ->
rnCmdArgs args `thenM` \ (args',fvArgs) ->
return (arg':args', fvArg `plusFV` fvArgs)
rnCmdTop :: LHsCmdTop RdrName -> RnM (LHsCmdTop Name, FreeVars)
rnCmdTop = wrapLocFstM rnCmdTop'
where
rnCmdTop' (HsCmdTop cmd _ _ _)
= do { (cmd', fvCmd) <- rnLCmd cmd
; let cmd_names = [arrAName, composeAName, firstAName] ++
nameSetToList (methodNamesCmd (unLoc cmd'))
-- Generate the rebindable syntax for the monad
; (cmd_names', cmd_fvs) <- lookupSyntaxNames cmd_names
; return (HsCmdTop cmd' placeHolderType placeHolderType (cmd_names `zip` cmd_names'),
fvCmd `plusFV` cmd_fvs) }
rnLCmd :: LHsCmd RdrName -> RnM (LHsCmd Name, FreeVars)
rnLCmd = wrapLocFstM rnCmd
rnCmd :: HsCmd RdrName -> RnM (HsCmd Name, FreeVars)
rnCmd (HsCmdArrApp arrow arg _ ho rtl)
= select_arrow_scope (rnLExpr arrow) `thenM` \ (arrow',fvArrow) ->
rnLExpr arg `thenM` \ (arg',fvArg) ->
return (HsCmdArrApp arrow' arg' placeHolderType ho rtl,
fvArrow `plusFV` fvArg)
where
select_arrow_scope tc = case ho of
HsHigherOrderApp -> tc
HsFirstOrderApp -> escapeArrowScope tc
-- See Note [Escaping the arrow scope] in TcRnTypes
-- Before renaming 'arrow', use the environment of the enclosing
-- proc for the (-<) case.
-- Local bindings, inside the enclosing proc, are not in scope
-- inside 'arrow'. In the higher-order case (-<<), they are.
-- infix form
rnCmd (HsCmdArrForm op (Just _) [arg1, arg2])
= escapeArrowScope (rnLExpr op)
`thenM` \ (op',fv_op) ->
let L _ (HsVar op_name) = op' in
rnCmdTop arg1 `thenM` \ (arg1',fv_arg1) ->
rnCmdTop arg2 `thenM` \ (arg2',fv_arg2) ->
-- Deal with fixity
lookupFixityRn op_name `thenM` \ fixity ->
mkOpFormRn arg1' op' fixity arg2' `thenM` \ final_e ->
return (final_e,
fv_arg1 `plusFV` fv_op `plusFV` fv_arg2)
rnCmd (HsCmdArrForm op fixity cmds)
= escapeArrowScope (rnLExpr op) `thenM` \ (op',fvOp) ->
rnCmdArgs cmds `thenM` \ (cmds',fvCmds) ->
return (HsCmdArrForm op' fixity cmds', fvOp `plusFV` fvCmds)
rnCmd (HsCmdApp fun arg)
= rnLCmd fun `thenM` \ (fun',fvFun) ->
rnLExpr arg `thenM` \ (arg',fvArg) ->
return (HsCmdApp fun' arg', fvFun `plusFV` fvArg)
rnCmd (HsCmdLam matches)
= rnMatchGroup LambdaExpr rnLCmd matches `thenM` \ (matches', fvMatch) ->
return (HsCmdLam matches', fvMatch)
rnCmd (HsCmdPar e)
= do { (e', fvs_e) <- rnLCmd e
; return (HsCmdPar e', fvs_e) }
rnCmd (HsCmdCase expr matches)
= rnLExpr expr `thenM` \ (new_expr, e_fvs) ->
rnMatchGroup CaseAlt rnLCmd matches `thenM` \ (new_matches, ms_fvs) ->
return (HsCmdCase new_expr new_matches, e_fvs `plusFV` ms_fvs)
rnCmd (HsCmdIf _ p b1 b2)
= do { (p', fvP) <- rnLExpr p
; (b1', fvB1) <- rnLCmd b1
; (b2', fvB2) <- rnLCmd b2
; (mb_ite, fvITE) <- lookupIfThenElse
; return (HsCmdIf mb_ite p' b1' b2', plusFVs [fvITE, fvP, fvB1, fvB2]) }
rnCmd (HsCmdLet binds cmd)
= rnLocalBindsAndThen binds $ \ binds' ->
rnLCmd cmd `thenM` \ (cmd',fvExpr) ->
return (HsCmdLet binds' cmd', fvExpr)
rnCmd (HsCmdDo stmts _)
= do { ((stmts', _), fvs) <- rnStmts ArrowExpr rnLCmd stmts (\ _ -> return ((), emptyFVs))
; return ( HsCmdDo stmts' placeHolderType, fvs ) }
rnCmd cmd@(HsCmdCast {}) = pprPanic "rnCmd" (ppr cmd)
---------------------------------------------------
type CmdNeeds = FreeVars -- Only inhabitants are
-- appAName, choiceAName, loopAName
-- find what methods the Cmd needs (loop, choice, apply)
methodNamesLCmd :: LHsCmd Name -> CmdNeeds
methodNamesLCmd = methodNamesCmd . unLoc
methodNamesCmd :: HsCmd Name -> CmdNeeds
methodNamesCmd (HsCmdArrApp _arrow _arg _ HsFirstOrderApp _rtl)
= emptyFVs
methodNamesCmd (HsCmdArrApp _arrow _arg _ HsHigherOrderApp _rtl)
= unitFV appAName
methodNamesCmd (HsCmdArrForm {}) = emptyFVs
methodNamesCmd (HsCmdCast _ cmd) = methodNamesCmd cmd
methodNamesCmd (HsCmdPar c) = methodNamesLCmd c
methodNamesCmd (HsCmdIf _ _ c1 c2)
= methodNamesLCmd c1 `plusFV` methodNamesLCmd c2 `addOneFV` choiceAName
methodNamesCmd (HsCmdLet _ c) = methodNamesLCmd c
methodNamesCmd (HsCmdDo stmts _) = methodNamesStmts stmts
methodNamesCmd (HsCmdApp c _) = methodNamesLCmd c
methodNamesCmd (HsCmdLam match) = methodNamesMatch match
methodNamesCmd (HsCmdCase _ matches)
= methodNamesMatch matches `addOneFV` choiceAName
--methodNamesCmd _ = emptyFVs
-- Other forms can't occur in commands, but it's not convenient
-- to error here so we just do what's convenient.
-- The type checker will complain later
---------------------------------------------------
methodNamesMatch :: MatchGroup Name (LHsCmd Name) -> FreeVars
methodNamesMatch (MG { mg_alts = ms })
= plusFVs (map do_one ms)
where
do_one (L _ (Match _ _ grhss)) = methodNamesGRHSs grhss
-------------------------------------------------
-- gaw 2004
methodNamesGRHSs :: GRHSs Name (LHsCmd Name) -> FreeVars
methodNamesGRHSs (GRHSs grhss _) = plusFVs (map methodNamesGRHS grhss)
-------------------------------------------------
methodNamesGRHS :: Located (GRHS Name (LHsCmd Name)) -> CmdNeeds
methodNamesGRHS (L _ (GRHS _ rhs)) = methodNamesLCmd rhs
---------------------------------------------------
methodNamesStmts :: [Located (StmtLR Name Name (LHsCmd Name))] -> FreeVars
methodNamesStmts stmts = plusFVs (map methodNamesLStmt stmts)
---------------------------------------------------
methodNamesLStmt :: Located (StmtLR Name Name (LHsCmd Name)) -> FreeVars
methodNamesLStmt = methodNamesStmt . unLoc
methodNamesStmt :: StmtLR Name Name (LHsCmd Name) -> FreeVars
methodNamesStmt (LastStmt cmd _) = methodNamesLCmd cmd
methodNamesStmt (BodyStmt cmd _ _ _) = methodNamesLCmd cmd
methodNamesStmt (BindStmt _ cmd _ _) = methodNamesLCmd cmd
methodNamesStmt (RecStmt { recS_stmts = stmts }) = methodNamesStmts stmts `addOneFV` loopAName
methodNamesStmt (LetStmt {}) = emptyFVs
methodNamesStmt (ParStmt {}) = emptyFVs
methodNamesStmt (TransStmt {}) = emptyFVs
-- ParStmt and TransStmt can't occur in commands, but it's not convenient to error
-- here so we just do what's convenient
\end{code}
%************************************************************************
%* *
Arithmetic sequences
%* *
%************************************************************************
\begin{code}
rnArithSeq :: ArithSeqInfo RdrName -> RnM (ArithSeqInfo Name, FreeVars)
rnArithSeq (From expr)
= rnLExpr expr `thenM` \ (expr', fvExpr) ->
return (From expr', fvExpr)
rnArithSeq (FromThen expr1 expr2)
= rnLExpr expr1 `thenM` \ (expr1', fvExpr1) ->
rnLExpr expr2 `thenM` \ (expr2', fvExpr2) ->
return (FromThen expr1' expr2', fvExpr1 `plusFV` fvExpr2)
rnArithSeq (FromTo expr1 expr2)
= rnLExpr expr1 `thenM` \ (expr1', fvExpr1) ->
rnLExpr expr2 `thenM` \ (expr2', fvExpr2) ->
return (FromTo expr1' expr2', fvExpr1 `plusFV` fvExpr2)
rnArithSeq (FromThenTo expr1 expr2 expr3)
= rnLExpr expr1 `thenM` \ (expr1', fvExpr1) ->
rnLExpr expr2 `thenM` \ (expr2', fvExpr2) ->
rnLExpr expr3 `thenM` \ (expr3', fvExpr3) ->
return (FromThenTo expr1' expr2' expr3',
plusFVs [fvExpr1, fvExpr2, fvExpr3])
\end{code}
%************************************************************************
%* *
\subsubsection{@Stmt@s: in @do@ expressions}
%* *
%************************************************************************
\begin{code}
rnStmts :: Outputable (body RdrName) => HsStmtContext Name
-> (Located (body RdrName) -> RnM (Located (body Name), FreeVars))
-> [LStmt RdrName (Located (body RdrName))]
-> ([Name] -> RnM (thing, FreeVars))
-> RnM (([LStmt Name (Located (body Name))], thing), FreeVars)
-- Variables bound by the Stmts, and mentioned in thing_inside,
-- do not appear in the result FreeVars
rnStmts ctxt _ [] thing_inside
= do { checkEmptyStmts ctxt
; (thing, fvs) <- thing_inside []
; return (([], thing), fvs) }
rnStmts MDoExpr rnBody stmts thing_inside -- Deal with mdo
= -- Behave like do { rec { ...all but last... }; last }
do { ((stmts1, (stmts2, thing)), fvs)
<- rnStmt MDoExpr rnBody (noLoc $ mkRecStmt all_but_last) $ \ _ ->
do { last_stmt' <- checkLastStmt MDoExpr last_stmt
; rnStmt MDoExpr rnBody last_stmt' thing_inside }
; return (((stmts1 ++ stmts2), thing), fvs) }
where
Just (all_but_last, last_stmt) = snocView stmts
rnStmts ctxt rnBody (lstmt@(L loc _) : lstmts) thing_inside
| null lstmts
= setSrcSpan loc $
do { lstmt' <- checkLastStmt ctxt lstmt
; rnStmt ctxt rnBody lstmt' thing_inside }
| otherwise
= do { ((stmts1, (stmts2, thing)), fvs)
<- setSrcSpan loc $
do { checkStmt ctxt lstmt
; rnStmt ctxt rnBody lstmt $ \ bndrs1 ->
rnStmts ctxt rnBody lstmts $ \ bndrs2 ->
thing_inside (bndrs1 ++ bndrs2) }
; return (((stmts1 ++ stmts2), thing), fvs) }
----------------------
rnStmt :: Outputable (body RdrName) => HsStmtContext Name
-> (Located (body RdrName) -> RnM (Located (body Name), FreeVars))
-> LStmt RdrName (Located (body RdrName))
-> ([Name] -> RnM (thing, FreeVars))
-> RnM (([LStmt Name (Located (body Name))], thing), FreeVars)
-- Variables bound by the Stmt, and mentioned in thing_inside,
-- do not appear in the result FreeVars
rnStmt ctxt rnBody (L loc (LastStmt body _)) thing_inside
= do { (body', fv_expr) <- rnBody body
; (ret_op, fvs1) <- lookupStmtName ctxt returnMName
; (thing, fvs3) <- thing_inside []
; return (([L loc (LastStmt body' ret_op)], thing),
fv_expr `plusFV` fvs1 `plusFV` fvs3) }
rnStmt ctxt rnBody (L loc (BodyStmt body _ _ _)) thing_inside
= do { (body', fv_expr) <- rnBody body
; (then_op, fvs1) <- lookupStmtName ctxt thenMName
; (guard_op, fvs2) <- if isListCompExpr ctxt
then lookupStmtName ctxt guardMName
else return (noSyntaxExpr, emptyFVs)
-- Only list/parr/monad comprehensions use 'guard'
-- Also for sub-stmts of same eg [ e | x<-xs, gd | blah ]
-- Here "gd" is a guard
; (thing, fvs3) <- thing_inside []
; return (([L loc (BodyStmt body' then_op guard_op placeHolderType)], thing),
fv_expr `plusFV` fvs1 `plusFV` fvs2 `plusFV` fvs3) }
rnStmt ctxt rnBody (L loc (BindStmt pat body _ _)) thing_inside
= do { (body', fv_expr) <- rnBody body
-- The binders do not scope over the expression
; (bind_op, fvs1) <- lookupStmtName ctxt bindMName
; (fail_op, fvs2) <- lookupStmtName ctxt failMName
; rnPat (StmtCtxt ctxt) pat $ \ pat' -> do
{ (thing, fvs3) <- thing_inside (collectPatBinders pat')
; return (([L loc (BindStmt pat' body' bind_op fail_op)], thing),
fv_expr `plusFV` fvs1 `plusFV` fvs2 `plusFV` fvs3) }}
-- fv_expr shouldn't really be filtered by the rnPatsAndThen
-- but it does not matter because the names are unique
rnStmt _ _ (L loc (LetStmt binds)) thing_inside
= do { rnLocalBindsAndThen binds $ \binds' -> do
{ (thing, fvs) <- thing_inside (collectLocalBinders binds')
; return (([L loc (LetStmt binds')], thing), fvs) } }
rnStmt ctxt rnBody (L _ (RecStmt { recS_stmts = rec_stmts })) thing_inside
= do { (return_op, fvs1) <- lookupStmtName ctxt returnMName
; (mfix_op, fvs2) <- lookupStmtName ctxt mfixName
; (bind_op, fvs3) <- lookupStmtName ctxt bindMName
; let empty_rec_stmt = emptyRecStmt { recS_ret_fn = return_op
, recS_mfix_fn = mfix_op
, recS_bind_fn = bind_op }
-- Step1: Bring all the binders of the mdo into scope
-- (Remember that this also removes the binders from the
-- finally-returned free-vars.)
-- And rename each individual stmt, making a
-- singleton segment. At this stage the FwdRefs field
-- isn't finished: it's empty for all except a BindStmt
-- for which it's the fwd refs within the bind itself
-- (This set may not be empty, because we're in a recursive
-- context.)
; rnRecStmtsAndThen rnBody rec_stmts $ \ segs -> do
{ let bndrs = nameSetToList $ foldr (unionNameSets . (\(ds,_,_,_) -> ds))
emptyNameSet segs
; (thing, fvs_later) <- thing_inside bndrs
; let (rec_stmts', fvs) = segmentRecStmts ctxt empty_rec_stmt segs fvs_later
; return ((rec_stmts', thing), fvs `plusFV` fvs1 `plusFV` fvs2 `plusFV` fvs3) } }
rnStmt ctxt _ (L loc (ParStmt segs _ _)) thing_inside
= do { (mzip_op, fvs1) <- lookupStmtName ctxt mzipName
; (bind_op, fvs2) <- lookupStmtName ctxt bindMName
; (return_op, fvs3) <- lookupStmtName ctxt returnMName
; ((segs', thing), fvs4) <- rnParallelStmts (ParStmtCtxt ctxt) return_op segs thing_inside
; return ( ([L loc (ParStmt segs' mzip_op bind_op)], thing)
, fvs1 `plusFV` fvs2 `plusFV` fvs3 `plusFV` fvs4) }
rnStmt ctxt _ (L loc (TransStmt { trS_stmts = stmts, trS_by = by, trS_form = form
, trS_using = using })) thing_inside
= do { -- Rename the 'using' expression in the context before the transform is begun
(using', fvs1) <- rnLExpr using
-- Rename the stmts and the 'by' expression
-- Keep track of the variables mentioned in the 'by' expression
; ((stmts', (by', used_bndrs, thing)), fvs2)
<- rnStmts (TransStmtCtxt ctxt) rnLExpr stmts $ \ bndrs ->
do { (by', fvs_by) <- mapMaybeFvRn rnLExpr by
; (thing, fvs_thing) <- thing_inside bndrs
; let fvs = fvs_by `plusFV` fvs_thing
used_bndrs = filter (`elemNameSet` fvs) bndrs
-- The paper (Fig 5) has a bug here; we must treat any free varaible
-- of the "thing inside", **or of the by-expression**, as used
; return ((by', used_bndrs, thing), fvs) }
-- Lookup `return`, `(>>=)` and `liftM` for monad comprehensions
; (return_op, fvs3) <- lookupStmtName ctxt returnMName
; (bind_op, fvs4) <- lookupStmtName ctxt bindMName
; (fmap_op, fvs5) <- case form of
ThenForm -> return (noSyntaxExpr, emptyFVs)
_ -> lookupStmtName ctxt fmapName
; let all_fvs = fvs1 `plusFV` fvs2 `plusFV` fvs3
`plusFV` fvs4 `plusFV` fvs5
bndr_map = used_bndrs `zip` used_bndrs
-- See Note [TransStmt binder map] in HsExpr
; traceRn (text "rnStmt: implicitly rebound these used binders:" <+> ppr bndr_map)
; return (([L loc (TransStmt { trS_stmts = stmts', trS_bndrs = bndr_map
, trS_by = by', trS_using = using', trS_form = form
, trS_ret = return_op, trS_bind = bind_op
, trS_fmap = fmap_op })], thing), all_fvs) }
rnParallelStmts :: forall thing. HsStmtContext Name
-> SyntaxExpr Name
-> [ParStmtBlock RdrName RdrName]
-> ([Name] -> RnM (thing, FreeVars))
-> RnM (([ParStmtBlock Name Name], thing), FreeVars)
-- Note [Renaming parallel Stmts]
rnParallelStmts ctxt return_op segs thing_inside
= do { orig_lcl_env <- getLocalRdrEnv
; rn_segs orig_lcl_env [] segs }
where
rn_segs :: LocalRdrEnv
-> [Name] -> [ParStmtBlock RdrName RdrName]
-> RnM (([ParStmtBlock Name Name], thing), FreeVars)
rn_segs _ bndrs_so_far []
= do { let (bndrs', dups) = removeDups cmpByOcc bndrs_so_far
; mapM_ dupErr dups
; (thing, fvs) <- bindLocalNames bndrs' (thing_inside bndrs')
; return (([], thing), fvs) }
rn_segs env bndrs_so_far (ParStmtBlock stmts _ _ : segs)
= do { ((stmts', (used_bndrs, segs', thing)), fvs)
<- rnStmts ctxt rnLExpr stmts $ \ bndrs ->
setLocalRdrEnv env $ do
{ ((segs', thing), fvs) <- rn_segs env (bndrs ++ bndrs_so_far) segs
; let used_bndrs = filter (`elemNameSet` fvs) bndrs
; return ((used_bndrs, segs', thing), fvs) }
; let seg' = ParStmtBlock stmts' used_bndrs return_op
; return ((seg':segs', thing), fvs) }
cmpByOcc n1 n2 = nameOccName n1 `compare` nameOccName n2
dupErr vs = addErr (ptext (sLit "Duplicate binding in parallel list comprehension for:")
<+> quotes (ppr (head vs)))
lookupStmtName :: HsStmtContext Name -> Name -> RnM (HsExpr Name, FreeVars)
-- Like lookupSyntaxName, but ListComp/PArrComp are never rebindable
-- Neither is ArrowExpr, which has its own desugarer in DsArrows
lookupStmtName ctxt n
= case ctxt of
ListComp -> not_rebindable
PArrComp -> not_rebindable
ArrowExpr -> not_rebindable
PatGuard {} -> not_rebindable
DoExpr -> rebindable
MDoExpr -> rebindable
MonadComp -> rebindable
GhciStmtCtxt -> rebindable -- I suppose?
ParStmtCtxt c -> lookupStmtName c n -- Look inside to
TransStmtCtxt c -> lookupStmtName c n -- the parent context
where
rebindable = lookupSyntaxName n
not_rebindable = return (HsVar n, emptyFVs)
\end{code}
Note [Renaming parallel Stmts]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Renaming parallel statements is painful. Given, say
[ a+c | a <- as, bs <- bss
| c <- bs, a <- ds ]
Note that
(a) In order to report "Defined by not used" about 'bs', we must rename
each group of Stmts with a thing_inside whose FreeVars include at least {a,c}
(b) We want to report that 'a' is illegally bound in both branches
(c) The 'bs' in the second group must obviously not be captured by
the binding in the first group
To satisfy (a) we nest the segements.
To satisfy (b) we check for duplicates just before thing_inside.
To satisfy (c) we reset the LocalRdrEnv each time.
%************************************************************************
%* *
\subsubsection{mdo expressions}
%* *
%************************************************************************
\begin{code}
type FwdRefs = NameSet
type Segment stmts = (Defs,
Uses, -- May include defs
FwdRefs, -- A subset of uses that are
-- (a) used before they are bound in this segment, or
-- (b) used here, and bound in subsequent segments
stmts) -- Either Stmt or [Stmt]
-- wrapper that does both the left- and right-hand sides
rnRecStmtsAndThen :: Outputable (body RdrName) =>
(Located (body RdrName) -> RnM (Located (body Name), FreeVars))
-> [LStmt RdrName (Located (body RdrName))]
-- assumes that the FreeVars returned includes
-- the FreeVars of the Segments
-> ([Segment (LStmt Name (Located (body Name)))] -> RnM (a, FreeVars))
-> RnM (a, FreeVars)
rnRecStmtsAndThen rnBody s cont
= do { -- (A) Make the mini fixity env for all of the stmts
fix_env <- makeMiniFixityEnv (collectRecStmtsFixities s)
-- (B) Do the LHSes
; new_lhs_and_fv <- rn_rec_stmts_lhs fix_env s
-- ...bring them and their fixities into scope
; let bound_names = collectLStmtsBinders (map fst new_lhs_and_fv)
-- Fake uses of variables introduced implicitly (warning suppression, see #4404)
implicit_uses = lStmtsImplicits (map fst new_lhs_and_fv)
; bindLocalNamesFV bound_names $
addLocalFixities fix_env bound_names $ do
-- (C) do the right-hand-sides and thing-inside
{ segs <- rn_rec_stmts rnBody bound_names new_lhs_and_fv
; (res, fvs) <- cont segs
; warnUnusedLocalBinds bound_names (fvs `unionNameSets` implicit_uses)
; return (res, fvs) }}
-- get all the fixity decls in any Let stmt
collectRecStmtsFixities :: [LStmtLR RdrName RdrName body] -> [LFixitySig RdrName]
collectRecStmtsFixities l =
foldr (\ s -> \acc -> case s of
(L _ (LetStmt (HsValBinds (ValBindsIn _ sigs)))) ->
foldr (\ sig -> \ acc -> case sig of
(L loc (FixSig s)) -> (L loc s) : acc
_ -> acc) acc sigs
_ -> acc) [] l
-- left-hand sides
rn_rec_stmt_lhs :: Outputable body => MiniFixityEnv
-> LStmt RdrName body
-- rename LHS, and return its FVs
-- Warning: we will only need the FreeVars below in the case of a BindStmt,
-- so we don't bother to compute it accurately in the other cases
-> RnM [(LStmtLR Name RdrName body, FreeVars)]
rn_rec_stmt_lhs _ (L loc (BodyStmt body a b c))
= return [(L loc (BodyStmt body a b c), emptyFVs)]
rn_rec_stmt_lhs _ (L loc (LastStmt body a))
= return [(L loc (LastStmt body a), emptyFVs)]
rn_rec_stmt_lhs fix_env (L loc (BindStmt pat body a b))
= do
-- should the ctxt be MDo instead?
(pat', fv_pat) <- rnBindPat (localRecNameMaker fix_env) pat
return [(L loc (BindStmt pat' body a b),
fv_pat)]
rn_rec_stmt_lhs _ (L _ (LetStmt binds@(HsIPBinds _)))
= failWith (badIpBinds (ptext (sLit "an mdo expression")) binds)
rn_rec_stmt_lhs fix_env (L loc (LetStmt (HsValBinds binds)))
= do (_bound_names, binds') <- rnLocalValBindsLHS fix_env binds
return [(L loc (LetStmt (HsValBinds binds')),
-- Warning: this is bogus; see function invariant
emptyFVs
)]
-- XXX Do we need to do something with the return and mfix names?
rn_rec_stmt_lhs fix_env (L _ (RecStmt { recS_stmts = stmts })) -- Flatten Rec inside Rec
= rn_rec_stmts_lhs fix_env stmts
rn_rec_stmt_lhs _ stmt@(L _ (ParStmt {})) -- Syntactically illegal in mdo
= pprPanic "rn_rec_stmt" (ppr stmt)
rn_rec_stmt_lhs _ stmt@(L _ (TransStmt {})) -- Syntactically illegal in mdo
= pprPanic "rn_rec_stmt" (ppr stmt)
rn_rec_stmt_lhs _ (L _ (LetStmt EmptyLocalBinds))
= panic "rn_rec_stmt LetStmt EmptyLocalBinds"
rn_rec_stmts_lhs :: Outputable body => MiniFixityEnv
-> [LStmt RdrName body]
-> RnM [(LStmtLR Name RdrName body, FreeVars)]
rn_rec_stmts_lhs fix_env stmts
= do { ls <- concatMapM (rn_rec_stmt_lhs fix_env) stmts
; let boundNames = collectLStmtsBinders (map fst ls)
-- First do error checking: we need to check for dups here because we
-- don't bind all of the variables from the Stmt at once
-- with bindLocatedLocals.
; checkDupNames boundNames
; return ls }
-- right-hand-sides
rn_rec_stmt :: (Outputable (body RdrName)) =>
(Located (body RdrName) -> RnM (Located (body Name), FreeVars))
-> [Name] -> LStmtLR Name RdrName (Located (body RdrName))
-> FreeVars -> RnM [Segment (LStmt Name (Located (body Name)))]
-- Rename a Stmt that is inside a RecStmt (or mdo)
-- Assumes all binders are already in scope
-- Turns each stmt into a singleton Stmt
rn_rec_stmt rnBody _ (L loc (LastStmt body _)) _
= do { (body', fv_expr) <- rnBody body
; (ret_op, fvs1) <- lookupSyntaxName returnMName
; return [(emptyNameSet, fv_expr `plusFV` fvs1, emptyNameSet,
L loc (LastStmt body' ret_op))] }
rn_rec_stmt rnBody _ (L loc (BodyStmt body _ _ _)) _
= rnBody body `thenM` \ (body', fvs) ->
lookupSyntaxName thenMName `thenM` \ (then_op, fvs1) ->
return [(emptyNameSet, fvs `plusFV` fvs1, emptyNameSet,
L loc (BodyStmt body' then_op noSyntaxExpr placeHolderType))]
rn_rec_stmt rnBody _ (L loc (BindStmt pat' body _ _)) fv_pat
= rnBody body `thenM` \ (body', fv_expr) ->
lookupSyntaxName bindMName `thenM` \ (bind_op, fvs1) ->
lookupSyntaxName failMName `thenM` \ (fail_op, fvs2) ->
let
bndrs = mkNameSet (collectPatBinders pat')
fvs = fv_expr `plusFV` fv_pat `plusFV` fvs1 `plusFV` fvs2
in
return [(bndrs, fvs, bndrs `intersectNameSet` fvs,
L loc (BindStmt pat' body' bind_op fail_op))]
rn_rec_stmt _ _ (L _ (LetStmt binds@(HsIPBinds _))) _
= failWith (badIpBinds (ptext (sLit "an mdo expression")) binds)
rn_rec_stmt _ all_bndrs (L loc (LetStmt (HsValBinds binds'))) _ = do
(binds', du_binds) <-
-- fixities and unused are handled above in rnRecStmtsAndThen
rnLocalValBindsRHS (mkNameSet all_bndrs) binds'
return [(duDefs du_binds, allUses du_binds,
emptyNameSet, L loc (LetStmt (HsValBinds binds')))]
-- no RecStmt case because they get flattened above when doing the LHSes
rn_rec_stmt _ _ stmt@(L _ (RecStmt {})) _
= pprPanic "rn_rec_stmt: RecStmt" (ppr stmt)
rn_rec_stmt _ _ stmt@(L _ (ParStmt {})) _ -- Syntactically illegal in mdo
= pprPanic "rn_rec_stmt: ParStmt" (ppr stmt)
rn_rec_stmt _ _ stmt@(L _ (TransStmt {})) _ -- Syntactically illegal in mdo
= pprPanic "rn_rec_stmt: TransStmt" (ppr stmt)
rn_rec_stmt _ _ (L _ (LetStmt EmptyLocalBinds)) _
= panic "rn_rec_stmt: LetStmt EmptyLocalBinds"