summaryrefslogtreecommitdiff
path: root/compiler/main/GHC.hs
blob: 4e6e0f43c21d643c686f38b1263b08c97746e70a (plain)
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
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
{-# LANGUAGE CPP, NondecreasingIndentation, ScopedTypeVariables #-}
{-# LANGUAGE TupleSections, NamedFieldPuns #-}
{-# LANGUAGE ViewPatterns #-}
{-# LANGUAGE TypeFamilies #-}

-- -----------------------------------------------------------------------------
--
-- (c) The University of Glasgow, 2005-2012
--
-- The GHC API
--
-- -----------------------------------------------------------------------------

module GHC (
        -- * Initialisation
        defaultErrorHandler,
        defaultCleanupHandler,
        prettyPrintGhcErrors,
        withSignalHandlers,
        withCleanupSession,

        -- * GHC Monad
        Ghc, GhcT, GhcMonad(..), HscEnv,
        runGhc, runGhcT, initGhcMonad,
        gcatch, gbracket, gfinally,
        printException,
        handleSourceError,
        needsTemplateHaskellOrQQ,

        -- * Flags and settings
        DynFlags(..), GeneralFlag(..), Severity(..), HscTarget(..), gopt,
        GhcMode(..), GhcLink(..), defaultObjectTarget,
        parseDynamicFlags,
        getSessionDynFlags, setSessionDynFlags,
        getProgramDynFlags, setProgramDynFlags, setLogAction,
        getInteractiveDynFlags, setInteractiveDynFlags,

        -- * Targets
        Target(..), TargetId(..), Phase,
        setTargets,
        getTargets,
        addTarget,
        removeTarget,
        guessTarget,

        -- * Loading\/compiling the program
        depanal,
        load, LoadHowMuch(..), InteractiveImport(..),
        SuccessFlag(..), succeeded, failed,
        defaultWarnErrLogger, WarnErrLogger,
        workingDirectoryChanged,
        parseModule, typecheckModule, desugarModule, loadModule,
        ParsedModule(..), TypecheckedModule(..), DesugaredModule(..),
        TypecheckedSource, ParsedSource, RenamedSource,   -- ditto
        TypecheckedMod, ParsedMod,
        moduleInfo, renamedSource, typecheckedSource,
        parsedSource, coreModule,

        -- ** Compiling to Core
        CoreModule(..),
        compileToCoreModule, compileToCoreSimplified,

        -- * Inspecting the module structure of the program
        ModuleGraph, emptyMG, mapMG, mkModuleGraph, mgModSummaries,
        mgLookupModule,
        ModSummary(..), ms_mod_name, ModLocation(..),
        getModSummary,
        getModuleGraph,
        isLoaded,
        topSortModuleGraph,

        -- * Inspecting modules
        ModuleInfo,
        getModuleInfo,
        modInfoTyThings,
        modInfoTopLevelScope,
        modInfoExports,
        modInfoExportsWithSelectors,
        modInfoInstances,
        modInfoIsExportedName,
        modInfoLookupName,
        modInfoIface,
        modInfoSafe,
        lookupGlobalName,
        findGlobalAnns,
        mkPrintUnqualifiedForModule,
        ModIface(..),
        SafeHaskellMode(..),

        -- * Querying the environment
        -- packageDbModules,

        -- * Printing
        PrintUnqualified, alwaysQualify,

        -- * Interactive evaluation

        -- ** Executing statements
        execStmt, execStmt', ExecOptions(..), execOptions, ExecResult(..),
        resumeExec,

        -- ** Adding new declarations
        runDecls, runDeclsWithLocation, runParsedDecls,

        -- ** Get/set the current context
        parseImportDecl,
        setContext, getContext,
        setGHCiMonad, getGHCiMonad,

        -- ** Inspecting the current context
        getBindings, getInsts, getPrintUnqual,
        findModule, lookupModule,
        isModuleTrusted, moduleTrustReqs,
        getNamesInScope,
        getRdrNamesInScope,
        getGRE,
        moduleIsInterpreted,
        getInfo,
        showModule,
        moduleIsBootOrNotObjectLinkable,
        getNameToInstancesIndex,

        -- ** Inspecting types and kinds
        exprType, TcRnExprMode(..),
        typeKind,

        -- ** Looking up a Name
        parseName,
        lookupName,

        -- ** Compiling expressions
        HValue, parseExpr, compileParsedExpr,
        InteractiveEval.compileExpr, dynCompileExpr,
        ForeignHValue,
        compileExprRemote, compileParsedExprRemote,

        -- ** Docs
        getDocs, GetDocsFailure(..),

        -- ** Other
        runTcInteractive,   -- Desired by some clients (#8878)
        isStmt, hasImport, isImport, isDecl,

        -- ** The debugger
        SingleStep(..),
        Resume(..),
        History(historyBreakInfo, historyEnclosingDecls),
        GHC.getHistorySpan, getHistoryModule,
        abandon, abandonAll,
        getResumeContext,
        GHC.obtainTermFromId, GHC.obtainTermFromVal, reconstructType,
        modInfoModBreaks,
        ModBreaks(..), BreakIndex,
        BreakInfo(breakInfo_number, breakInfo_module),
        InteractiveEval.back,
        InteractiveEval.forward,

        -- * Abstract syntax elements

        -- ** Packages
        UnitId,

        -- ** Modules
        Module, mkModule, pprModule, moduleName, moduleUnitId,
        ModuleName, mkModuleName, moduleNameString,

        -- ** Names
        Name,
        isExternalName, nameModule, pprParenSymName, nameSrcSpan,
        NamedThing(..),
        RdrName(Qual,Unqual),

        -- ** Identifiers
        Id, idType,
        isImplicitId, isDeadBinder,
        isExportedId, isLocalId, isGlobalId,
        isRecordSelector,
        isPrimOpId, isFCallId, isClassOpId_maybe,
        isDataConWorkId, idDataCon,
        isBottomingId, isDictonaryId,
        recordSelectorTyCon,

        -- ** Type constructors
        TyCon,
        tyConTyVars, tyConDataCons, tyConArity,
        isClassTyCon, isTypeSynonymTyCon, isTypeFamilyTyCon, isNewTyCon,
        isPrimTyCon, isFunTyCon,
        isFamilyTyCon, isOpenFamilyTyCon, isOpenTypeFamilyTyCon,
        tyConClass_maybe,
        synTyConRhs_maybe, synTyConDefn_maybe, tyConKind,

        -- ** Type variables
        TyVar,
        alphaTyVars,

        -- ** Data constructors
        DataCon,
        dataConSig, dataConType, dataConTyCon, dataConFieldLabels,
        dataConIsInfix, isVanillaDataCon, dataConUserType,
        dataConSrcBangs,
        StrictnessMark(..), isMarkedStrict,

        -- ** Classes
        Class,
        classMethods, classSCTheta, classTvsFds, classATs,
        pprFundeps,

        -- ** Instances
        ClsInst,
        instanceDFunId,
        pprInstance, pprInstanceHdr,
        pprFamInst,

        FamInst,

        -- ** Types and Kinds
        Type, splitForAllTys, funResultTy,
        pprParendType, pprTypeApp,
        Kind,
        PredType,
        ThetaType, pprForAll, pprThetaArrowTy,

        -- ** Entities
        TyThing(..),

        -- ** Syntax
        module HsSyn, -- ToDo: remove extraneous bits

        -- ** Fixities
        FixityDirection(..),
        defaultFixity, maxPrecedence,
        negateFixity,
        compareFixity,
        LexicalFixity(..),

        -- ** Source locations
        SrcLoc(..), RealSrcLoc,
        mkSrcLoc, noSrcLoc,
        srcLocFile, srcLocLine, srcLocCol,
        SrcSpan(..), RealSrcSpan,
        mkSrcSpan, srcLocSpan, isGoodSrcSpan, noSrcSpan,
        srcSpanStart, srcSpanEnd,
        srcSpanFile,
        srcSpanStartLine, srcSpanEndLine,
        srcSpanStartCol, srcSpanEndCol,

        -- ** Located
        GenLocated(..), Located,

        -- *** Constructing Located
        noLoc, mkGeneralLocated,

        -- *** Deconstructing Located
        getLoc, unLoc,
        getRealSrcSpan, unRealSrcSpan,

        -- ** HasSrcSpan
        HasSrcSpan(..), SrcSpanLess, dL, cL,

        -- *** Combining and comparing Located values
        eqLocated, cmpLocated, combineLocs, addCLoc,
        leftmost_smallest, leftmost_largest, rightmost,
        spans, isSubspanOf,

        -- * Exceptions
        GhcException(..), showGhcException,

        -- * Token stream manipulations
        Token,
        getTokenStream, getRichTokenStream,
        showRichTokenStream, addSourceToTokens,

        -- * Pure interface to the parser
        parser,

        -- * API Annotations
        ApiAnns,AnnKeywordId(..),AnnotationComment(..),
        getAnnotation, getAndRemoveAnnotation,
        getAnnotationComments, getAndRemoveAnnotationComments,
        unicodeAnn,

        -- * Miscellaneous
        --sessionHscEnv,
        cyclicModuleErr,
  ) where

{-
 ToDo:

  * inline bits of HscMain here to simplify layering: hscTcExpr, hscStmt.
-}

#include "HsVersions.h"

import GhcPrelude hiding (init)

import ByteCodeTypes
import InteractiveEval
import InteractiveEvalTypes
import GHCi
import GHCi.RemoteTypes

import PprTyThing       ( pprFamInst )
import HscMain
import GhcMake
import DriverPipeline   ( compileOne' )
import GhcMonad
import TcRnMonad        ( finalSafeMode, fixSafeInstances, initIfaceTcRn )
import LoadIface        ( loadSysInterface )
import TcRnTypes
import Packages
import NameSet
import RdrName
import HsSyn
import Type     hiding( typeKind )
import TcType
import Id
import TysPrim          ( alphaTyVars )
import TyCon
import Class
import DataCon
import Name             hiding ( varName )
import Avail
import InstEnv
import FamInstEnv ( FamInst )
import SrcLoc
import CoreSyn
import TidyPgm
import DriverPhases     ( Phase(..), isHaskellSrcFilename )
import Finder
import HscTypes
import CmdLineParser
import DynFlags hiding (WarnReason(..))
import SysTools
import SysTools.BaseDir
import Annotations
import Module
import Panic
import Platform
import Bag              ( listToBag )
import ErrUtils
import MonadUtils
import Util
import StringBuffer
import Outputable
import BasicTypes
import Maybes           ( expectJust )
import FastString
import qualified Parser
import Lexer
import ApiAnnotation
import qualified GHC.LanguageExtensions as LangExt
import NameEnv
import CoreFVs          ( orphNamesOfFamInst )
import FamInstEnv       ( famInstEnvElts )
import TcRnDriver
import Inst
import FamInst
import FileCleanup

import Data.Foldable
import qualified Data.Map.Strict as Map
import Data.Set (Set)
import qualified Data.Sequence as Seq
import System.Directory ( doesFileExist )
import Data.Maybe
import Data.Time
import Data.Typeable    ( Typeable )
import Data.Word        ( Word8 )
import Control.Monad
import System.Exit      ( exitWith, ExitCode(..) )
import Exception
import Data.IORef
import System.FilePath


-- %************************************************************************
-- %*                                                                      *
--             Initialisation: exception handlers
-- %*                                                                      *
-- %************************************************************************


-- | Install some default exception handlers and run the inner computation.
-- Unless you want to handle exceptions yourself, you should wrap this around
-- the top level of your program.  The default handlers output the error
-- message(s) to stderr and exit cleanly.
defaultErrorHandler :: (ExceptionMonad m)
                    => FatalMessager -> FlushOut -> m a -> m a
defaultErrorHandler fm (FlushOut flushOut) inner =
  -- top-level exception handler: any unrecognised exception is a compiler bug.
  ghandle (\exception -> liftIO $ do
           flushOut
           case fromException exception of
                -- an IO exception probably isn't our fault, so don't panic
                Just (ioe :: IOException) ->
                  fatalErrorMsg'' fm (show ioe)
                _ -> case fromException exception of
                     Just UserInterrupt ->
                         -- Important to let this one propagate out so our
                         -- calling process knows we were interrupted by ^C
                         liftIO $ throwIO UserInterrupt
                     Just StackOverflow ->
                         fatalErrorMsg'' fm "stack overflow: use +RTS -K<size> to increase it"
                     _ -> case fromException exception of
                          Just (ex :: ExitCode) -> liftIO $ throwIO ex
                          _ ->
                              fatalErrorMsg'' fm
                                  (show (Panic (show exception)))
           exitWith (ExitFailure 1)
         ) $

  -- error messages propagated as exceptions
  handleGhcException
            (\ge -> liftIO $ do
                flushOut
                case ge of
                     Signal _ -> exitWith (ExitFailure 1)
                     _ -> do fatalErrorMsg'' fm (show ge)
                             exitWith (ExitFailure 1)
            ) $
  inner

-- | This function is no longer necessary, cleanup is now done by
-- runGhc/runGhcT.
{-# DEPRECATED defaultCleanupHandler "Cleanup is now done by runGhc/runGhcT" #-}
defaultCleanupHandler :: (ExceptionMonad m) => DynFlags -> m a -> m a
defaultCleanupHandler _ m = m
 where _warning_suppression = m `gonException` undefined


-- %************************************************************************
-- %*                                                                      *
--             The Ghc Monad
-- %*                                                                      *
-- %************************************************************************

-- | Run function for the 'Ghc' monad.
--
-- It initialises the GHC session and warnings via 'initGhcMonad'.  Each call
-- to this function will create a new session which should not be shared among
-- several threads.
--
-- Any errors not handled inside the 'Ghc' action are propagated as IO
-- exceptions.

runGhc :: Maybe FilePath  -- ^ See argument to 'initGhcMonad'.
       -> Ghc a           -- ^ The action to perform.
       -> IO a
runGhc mb_top_dir ghc = do
  ref <- newIORef (panic "empty session")
  let session = Session ref
  flip unGhc session $ withSignalHandlers $ do -- catch ^C
    initGhcMonad mb_top_dir
    withCleanupSession ghc

-- | Run function for 'GhcT' monad transformer.
--
-- It initialises the GHC session and warnings via 'initGhcMonad'.  Each call
-- to this function will create a new session which should not be shared among
-- several threads.

runGhcT :: ExceptionMonad m =>
           Maybe FilePath  -- ^ See argument to 'initGhcMonad'.
        -> GhcT m a        -- ^ The action to perform.
        -> m a
runGhcT mb_top_dir ghct = do
  ref <- liftIO $ newIORef (panic "empty session")
  let session = Session ref
  flip unGhcT session $ withSignalHandlers $ do -- catch ^C
    initGhcMonad mb_top_dir
    withCleanupSession ghct

withCleanupSession :: GhcMonad m => m a -> m a
withCleanupSession ghc = ghc `gfinally` cleanup
  where
   cleanup = do
      hsc_env <- getSession
      let dflags = hsc_dflags hsc_env
      liftIO $ do
          cleanTempFiles dflags
          cleanTempDirs dflags
          stopIServ hsc_env -- shut down the IServ
          --  exceptions will be blocked while we clean the temporary files,
          -- so there shouldn't be any difficulty if we receive further
          -- signals.

-- | Initialise a GHC session.
--
-- If you implement a custom 'GhcMonad' you must call this function in the
-- monad run function.  It will initialise the session variable and clear all
-- warnings.
--
-- The first argument should point to the directory where GHC's library files
-- reside.  More precisely, this should be the output of @ghc --print-libdir@
-- of the version of GHC the module using this API is compiled with.  For
-- portability, you should use the @ghc-paths@ package, available at
-- <http://hackage.haskell.org/package/ghc-paths>.

initGhcMonad :: GhcMonad m => Maybe FilePath -> m ()
initGhcMonad mb_top_dir
  = do { env <- liftIO $
                do { top_dir <- findTopDir mb_top_dir
                   ; mySettings <- initSysTools top_dir
                   ; myLlvmConfig <- initLlvmConfig top_dir
                   ; dflags <- initDynFlags (defaultDynFlags mySettings myLlvmConfig)
                   ; checkBrokenTablesNextToCode dflags
                   ; setUnsafeGlobalDynFlags dflags
                      -- c.f. DynFlags.parseDynamicFlagsFull, which
                      -- creates DynFlags and sets the UnsafeGlobalDynFlags
                   ; newHscEnv dflags }
       ; setSession env }

-- | The binutils linker on ARM emits unnecessary R_ARM_COPY relocations which
-- breaks tables-next-to-code in dynamically linked modules. This
-- check should be more selective but there is currently no released
-- version where this bug is fixed.
-- See https://sourceware.org/bugzilla/show_bug.cgi?id=16177 and
-- https://gitlab.haskell.org/ghc/ghc/issues/4210#note_78333
checkBrokenTablesNextToCode :: MonadIO m => DynFlags -> m ()
checkBrokenTablesNextToCode dflags
  = do { broken <- checkBrokenTablesNextToCode' dflags
       ; when broken
         $ do { _ <- liftIO $ throwIO $ mkApiErr dflags invalidLdErr
              ; liftIO $ fail "unsupported linker"
              }
       }
  where
    invalidLdErr = text "Tables-next-to-code not supported on ARM" <+>
                   text "when using binutils ld (please see:" <+>
                   text "https://sourceware.org/bugzilla/show_bug.cgi?id=16177)"

checkBrokenTablesNextToCode' :: MonadIO m => DynFlags -> m Bool
checkBrokenTablesNextToCode' dflags
  | not (isARM arch)              = return False
  | WayDyn `notElem` ways dflags  = return False
  | not (tablesNextToCode dflags) = return False
  | otherwise                     = do
    linkerInfo <- liftIO $ getLinkerInfo dflags
    case linkerInfo of
      GnuLD _  -> return True
      _        -> return False
  where platform = targetPlatform dflags
        arch = platformArch platform


-- %************************************************************************
-- %*                                                                      *
--             Flags & settings
-- %*                                                                      *
-- %************************************************************************

-- $DynFlags
--
-- The GHC session maintains two sets of 'DynFlags':
--
--   * The "interactive" @DynFlags@, which are used for everything
--     related to interactive evaluation, including 'runStmt',
--     'runDecls', 'exprType', 'lookupName' and so on (everything
--     under \"Interactive evaluation\" in this module).
--
--   * The "program" @DynFlags@, which are used when loading
--     whole modules with 'load'
--
-- 'setInteractiveDynFlags', 'getInteractiveDynFlags' work with the
-- interactive @DynFlags@.
--
-- 'setProgramDynFlags', 'getProgramDynFlags' work with the
-- program @DynFlags@.
--
-- 'setSessionDynFlags' sets both @DynFlags@, and 'getSessionDynFlags'
-- retrieves the program @DynFlags@ (for backwards compatibility).


-- | Updates both the interactive and program DynFlags in a Session.
-- This also reads the package database (unless it has already been
-- read), and prepares the compilers knowledge about packages.  It can
-- be called again to load new packages: just add new package flags to
-- (packageFlags dflags).
--
-- Returns a list of new packages that may need to be linked in using
-- the dynamic linker (see 'linkPackages') as a result of new package
-- flags.  If you are not doing linking or doing static linking, you
-- can ignore the list of packages returned.
--
setSessionDynFlags :: GhcMonad m => DynFlags -> m [InstalledUnitId]
setSessionDynFlags dflags = do
  dflags' <- checkNewDynFlags dflags
  (dflags'', preload) <- liftIO $ initPackages dflags'
  modifySession $ \h -> h{ hsc_dflags = dflags''
                         , hsc_IC = (hsc_IC h){ ic_dflags = dflags'' } }
  invalidateModSummaryCache
  return preload

-- | Sets the program 'DynFlags'.  Note: this invalidates the internal
-- cached module graph, causing more work to be done the next time
-- 'load' is called.
setProgramDynFlags :: GhcMonad m => DynFlags -> m [InstalledUnitId]
setProgramDynFlags dflags = setProgramDynFlags_ True dflags

-- | Set the action taken when the compiler produces a message.  This
-- can also be accomplished using 'setProgramDynFlags', but using
-- 'setLogAction' avoids invalidating the cached module graph.
setLogAction :: GhcMonad m => LogAction -> m ()
setLogAction action = do
  dflags' <- getProgramDynFlags
  void $ setProgramDynFlags_ False $
    dflags' { log_action = action }

setProgramDynFlags_ :: GhcMonad m => Bool -> DynFlags -> m [InstalledUnitId]
setProgramDynFlags_ invalidate_needed dflags = do
  dflags' <- checkNewDynFlags dflags
  dflags_prev <- getProgramDynFlags
  (dflags'', preload) <-
    if (packageFlagsChanged dflags_prev dflags')
       then liftIO $ initPackages dflags'
       else return (dflags', [])
  modifySession $ \h -> h{ hsc_dflags = dflags'' }
  when invalidate_needed $ invalidateModSummaryCache
  return preload


-- When changing the DynFlags, we want the changes to apply to future
-- loads, but without completely discarding the program.  But the
-- DynFlags are cached in each ModSummary in the hsc_mod_graph, so
-- after a change to DynFlags, the changes would apply to new modules
-- but not existing modules; this seems undesirable.
--
-- Furthermore, the GHC API client might expect that changing
-- log_action would affect future compilation messages, but for those
-- modules we have cached ModSummaries for, we'll continue to use the
-- old log_action.  This is definitely wrong (#7478).
--
-- Hence, we invalidate the ModSummary cache after changing the
-- DynFlags.  We do this by tweaking the date on each ModSummary, so
-- that the next downsweep will think that all the files have changed
-- and preprocess them again.  This won't necessarily cause everything
-- to be recompiled, because by the time we check whether we need to
-- recopmile a module, we'll have re-summarised the module and have a
-- correct ModSummary.
--
invalidateModSummaryCache :: GhcMonad m => m ()
invalidateModSummaryCache =
  modifySession $ \h -> h { hsc_mod_graph = mapMG inval (hsc_mod_graph h) }
 where
  inval ms = ms { ms_hs_date = addUTCTime (-1) (ms_hs_date ms) }

-- | Returns the program 'DynFlags'.
getProgramDynFlags :: GhcMonad m => m DynFlags
getProgramDynFlags = getSessionDynFlags

-- | Set the 'DynFlags' used to evaluate interactive expressions.
-- Note: this cannot be used for changes to packages.  Use
-- 'setSessionDynFlags', or 'setProgramDynFlags' and then copy the
-- 'pkgState' into the interactive @DynFlags@.
setInteractiveDynFlags :: GhcMonad m => DynFlags -> m ()
setInteractiveDynFlags dflags = do
  dflags' <- checkNewDynFlags dflags
  dflags'' <- checkNewInteractiveDynFlags dflags'
  modifySession $ \h -> h{ hsc_IC = (hsc_IC h) { ic_dflags = dflags'' }}

-- | Get the 'DynFlags' used to evaluate interactive expressions.
getInteractiveDynFlags :: GhcMonad m => m DynFlags
getInteractiveDynFlags = withSession $ \h -> return (ic_dflags (hsc_IC h))


parseDynamicFlags :: MonadIO m =>
                     DynFlags -> [Located String]
                  -> m (DynFlags, [Located String], [Warn])
parseDynamicFlags = parseDynamicFlagsCmdLine

-- | Checks the set of new DynFlags for possibly erroneous option
-- combinations when invoking 'setSessionDynFlags' and friends, and if
-- found, returns a fixed copy (if possible).
checkNewDynFlags :: MonadIO m => DynFlags -> m DynFlags
checkNewDynFlags dflags = do
  -- See Note [DynFlags consistency]
  let (dflags', warnings) = makeDynFlagsConsistent dflags
  liftIO $ handleFlagWarnings dflags (map (Warn NoReason) warnings)
  return dflags'

checkNewInteractiveDynFlags :: MonadIO m => DynFlags -> m DynFlags
checkNewInteractiveDynFlags dflags0 = do
  -- We currently don't support use of StaticPointers in expressions entered on
  -- the REPL. See #12356.
  dflags1 <-
      if xopt LangExt.StaticPointers dflags0
      then do liftIO $ printOrThrowWarnings dflags0 $ listToBag
                [mkPlainWarnMsg dflags0 interactiveSrcSpan
                 $ text "StaticPointers is not supported in GHCi interactive expressions."]
              return $ xopt_unset dflags0 LangExt.StaticPointers
      else return dflags0
  return dflags1


-- %************************************************************************
-- %*                                                                      *
--             Setting, getting, and modifying the targets
-- %*                                                                      *
-- %************************************************************************

-- ToDo: think about relative vs. absolute file paths. And what
-- happens when the current directory changes.

-- | Sets the targets for this session.  Each target may be a module name
-- or a filename.  The targets correspond to the set of root modules for
-- the program\/library.  Unloading the current program is achieved by
-- setting the current set of targets to be empty, followed by 'load'.
setTargets :: GhcMonad m => [Target] -> m ()
setTargets targets = modifySession (\h -> h{ hsc_targets = targets })

-- | Returns the current set of targets
getTargets :: GhcMonad m => m [Target]
getTargets = withSession (return . hsc_targets)

-- | Add another target.
addTarget :: GhcMonad m => Target -> m ()
addTarget target
  = modifySession (\h -> h{ hsc_targets = target : hsc_targets h })

-- | Remove a target
removeTarget :: GhcMonad m => TargetId -> m ()
removeTarget target_id
  = modifySession (\h -> h{ hsc_targets = filter (hsc_targets h) })
  where
   filter targets = [ t | t@(Target id _ _) <- targets, id /= target_id ]

-- | Attempts to guess what Target a string refers to.  This function
-- implements the @--make@/GHCi command-line syntax for filenames:
--
--   - if the string looks like a Haskell source filename, then interpret it
--     as such
--
--   - if adding a .hs or .lhs suffix yields the name of an existing file,
--     then use that
--
--   - otherwise interpret the string as a module name
--
guessTarget :: GhcMonad m => String -> Maybe Phase -> m Target
guessTarget str (Just phase)
   = return (Target (TargetFile str (Just phase)) True Nothing)
guessTarget str Nothing
   | isHaskellSrcFilename file
   = return (target (TargetFile file Nothing))
   | otherwise
   = do exists <- liftIO $ doesFileExist hs_file
        if exists
           then return (target (TargetFile hs_file Nothing))
           else do
        exists <- liftIO $ doesFileExist lhs_file
        if exists
           then return (target (TargetFile lhs_file Nothing))
           else do
        if looksLikeModuleName file
           then return (target (TargetModule (mkModuleName file)))
           else do
        dflags <- getDynFlags
        liftIO $ throwGhcExceptionIO
                 (ProgramError (showSDoc dflags $
                 text "target" <+> quotes (text file) <+>
                 text "is not a module name or a source file"))
     where
         (file,obj_allowed)
                | '*':rest <- str = (rest, False)
                | otherwise       = (str,  True)

         hs_file  = file <.> "hs"
         lhs_file = file <.> "lhs"

         target tid = Target tid obj_allowed Nothing


-- | Inform GHC that the working directory has changed.  GHC will flush
-- its cache of module locations, since it may no longer be valid.
--
-- Note: Before changing the working directory make sure all threads running
-- in the same session have stopped.  If you change the working directory,
-- you should also unload the current program (set targets to empty,
-- followed by load).
workingDirectoryChanged :: GhcMonad m => m ()
workingDirectoryChanged = withSession $ (liftIO . flushFinderCaches)


-- %************************************************************************
-- %*                                                                      *
--             Running phases one at a time
-- %*                                                                      *
-- %************************************************************************

class ParsedMod m where
  modSummary   :: m -> ModSummary
  parsedSource :: m -> ParsedSource

class ParsedMod m => TypecheckedMod m where
  renamedSource     :: m -> Maybe RenamedSource
  typecheckedSource :: m -> TypecheckedSource
  moduleInfo        :: m -> ModuleInfo
  tm_internals      :: m -> (TcGblEnv, ModDetails)
        -- ToDo: improvements that could be made here:
        --  if the module succeeded renaming but not typechecking,
        --  we can still get back the GlobalRdrEnv and exports, so
        --  perhaps the ModuleInfo should be split up into separate
        --  fields.

class TypecheckedMod m => DesugaredMod m where
  coreModule :: m -> ModGuts

-- | The result of successful parsing.
data ParsedModule =
  ParsedModule { pm_mod_summary   :: ModSummary
               , pm_parsed_source :: ParsedSource
               , pm_extra_src_files :: [FilePath]
               , pm_annotations :: ApiAnns }
               -- See Note [Api annotations] in ApiAnnotation.hs

instance ParsedMod ParsedModule where
  modSummary m    = pm_mod_summary m
  parsedSource m = pm_parsed_source m

-- | The result of successful typechecking.  It also contains the parser
--   result.
data TypecheckedModule =
  TypecheckedModule { tm_parsed_module       :: ParsedModule
                    , tm_renamed_source      :: Maybe RenamedSource
                    , tm_typechecked_source  :: TypecheckedSource
                    , tm_checked_module_info :: ModuleInfo
                    , tm_internals_          :: (TcGblEnv, ModDetails)
                    }

instance ParsedMod TypecheckedModule where
  modSummary m   = modSummary (tm_parsed_module m)
  parsedSource m = parsedSource (tm_parsed_module m)

instance TypecheckedMod TypecheckedModule where
  renamedSource m     = tm_renamed_source m
  typecheckedSource m = tm_typechecked_source m
  moduleInfo m        = tm_checked_module_info m
  tm_internals m      = tm_internals_ m

-- | The result of successful desugaring (i.e., translation to core).  Also
--  contains all the information of a typechecked module.
data DesugaredModule =
  DesugaredModule { dm_typechecked_module :: TypecheckedModule
                  , dm_core_module        :: ModGuts
             }

instance ParsedMod DesugaredModule where
  modSummary m   = modSummary (dm_typechecked_module m)
  parsedSource m = parsedSource (dm_typechecked_module m)

instance TypecheckedMod DesugaredModule where
  renamedSource m     = renamedSource (dm_typechecked_module m)
  typecheckedSource m = typecheckedSource (dm_typechecked_module m)
  moduleInfo m        = moduleInfo (dm_typechecked_module m)
  tm_internals m      = tm_internals_ (dm_typechecked_module m)

instance DesugaredMod DesugaredModule where
  coreModule m = dm_core_module m

type ParsedSource      = Located (HsModule GhcPs)
type RenamedSource     = (HsGroup GhcRn, [LImportDecl GhcRn], Maybe [(LIE GhcRn, Avails)],
                          Maybe LHsDocString)
type TypecheckedSource = LHsBinds GhcTc

-- NOTE:
--   - things that aren't in the output of the typechecker right now:
--     - the export list
--     - the imports
--     - type signatures
--     - type/data/newtype declarations
--     - class declarations
--     - instances
--   - extra things in the typechecker's output:
--     - default methods are turned into top-level decls.
--     - dictionary bindings

-- | Return the 'ModSummary' of a module with the given name.
--
-- The module must be part of the module graph (see 'hsc_mod_graph' and
-- 'ModuleGraph').  If this is not the case, this function will throw a
-- 'GhcApiError'.
--
-- This function ignores boot modules and requires that there is only one
-- non-boot module with the given name.
getModSummary :: GhcMonad m => ModuleName -> m ModSummary
getModSummary mod = do
   mg <- liftM hsc_mod_graph getSession
   let mods_by_name = [ ms | ms <- mgModSummaries mg
                      , ms_mod_name ms == mod
                      , not (isBootSummary ms) ]
   case mods_by_name of
     [] -> do dflags <- getDynFlags
              liftIO $ throwIO $ mkApiErr dflags (text "Module not part of module graph")
     [ms] -> return ms
     multiple -> do dflags <- getDynFlags
                    liftIO $ throwIO $ mkApiErr dflags (text "getModSummary is ambiguous: " <+> ppr multiple)

-- | Parse a module.
--
-- Throws a 'SourceError' on parse error.
parseModule :: GhcMonad m => ModSummary -> m ParsedModule
parseModule ms = do
   hsc_env <- getSession
   let hsc_env_tmp = hsc_env { hsc_dflags = ms_hspp_opts ms }
   hpm <- liftIO $ hscParse hsc_env_tmp ms
   return (ParsedModule ms (hpm_module hpm) (hpm_src_files hpm)
                           (hpm_annotations hpm))
               -- See Note [Api annotations] in ApiAnnotation.hs

-- | Typecheck and rename a parsed module.
--
-- Throws a 'SourceError' if either fails.
typecheckModule :: GhcMonad m => ParsedModule -> m TypecheckedModule
typecheckModule pmod = do
 let ms = modSummary pmod
 hsc_env <- getSession
 let hsc_env_tmp = hsc_env { hsc_dflags = ms_hspp_opts ms }
 (tc_gbl_env, rn_info)
       <- liftIO $ hscTypecheckRename hsc_env_tmp ms $
                      HsParsedModule { hpm_module = parsedSource pmod,
                                       hpm_src_files = pm_extra_src_files pmod,
                                       hpm_annotations = pm_annotations pmod }
 details <- liftIO $ makeSimpleDetails hsc_env_tmp tc_gbl_env
 safe    <- liftIO $ finalSafeMode (ms_hspp_opts ms) tc_gbl_env

 return $
     TypecheckedModule {
       tm_internals_          = (tc_gbl_env, details),
       tm_parsed_module       = pmod,
       tm_renamed_source      = rn_info,
       tm_typechecked_source  = tcg_binds tc_gbl_env,
       tm_checked_module_info =
         ModuleInfo {
           minf_type_env  = md_types details,
           minf_exports   = md_exports details,
           minf_rdr_env   = Just (tcg_rdr_env tc_gbl_env),
           minf_instances = fixSafeInstances safe $ md_insts details,
           minf_iface     = Nothing,
           minf_safe      = safe,
           minf_modBreaks = emptyModBreaks
         }}

-- | Desugar a typechecked module.
desugarModule :: GhcMonad m => TypecheckedModule -> m DesugaredModule
desugarModule tcm = do
 let ms = modSummary tcm
 let (tcg, _) = tm_internals tcm
 hsc_env <- getSession
 let hsc_env_tmp = hsc_env { hsc_dflags = ms_hspp_opts ms }
 guts <- liftIO $ hscDesugar hsc_env_tmp ms tcg
 return $
     DesugaredModule {
       dm_typechecked_module = tcm,
       dm_core_module        = guts
     }

-- | Load a module.  Input doesn't need to be desugared.
--
-- A module must be loaded before dependent modules can be typechecked.  This
-- always includes generating a 'ModIface' and, depending on the
-- 'DynFlags.hscTarget', may also include code generation.
--
-- This function will always cause recompilation and will always overwrite
-- previous compilation results (potentially files on disk).
--
loadModule :: (TypecheckedMod mod, GhcMonad m) => mod -> m mod
loadModule tcm = do
   let ms = modSummary tcm
   let mod = ms_mod_name ms
   let loc = ms_location ms
   let (tcg, _details) = tm_internals tcm

   mb_linkable <- case ms_obj_date ms of
                     Just t | t > ms_hs_date ms  -> do
                         l <- liftIO $ findObjectLinkable (ms_mod ms)
                                                  (ml_obj_file loc) t
                         return (Just l)
                     _otherwise -> return Nothing

   let source_modified | isNothing mb_linkable = SourceModified
                       | otherwise             = SourceUnmodified
                       -- we can't determine stability here

   -- compile doesn't change the session
   hsc_env <- getSession
   mod_info <- liftIO $ compileOne' (Just tcg) Nothing
                                    hsc_env ms 1 1 Nothing mb_linkable
                                    source_modified

   modifySession $ \e -> e{ hsc_HPT = addToHpt (hsc_HPT e) mod mod_info }
   return tcm


-- %************************************************************************
-- %*                                                                      *
--             Dealing with Core
-- %*                                                                      *
-- %************************************************************************

-- | A CoreModule consists of just the fields of a 'ModGuts' that are needed for
-- the 'GHC.compileToCoreModule' interface.
data CoreModule
  = CoreModule {
      -- | Module name
      cm_module   :: !Module,
      -- | Type environment for types declared in this module
      cm_types    :: !TypeEnv,
      -- | Declarations
      cm_binds    :: CoreProgram,
      -- | Safe Haskell mode
      cm_safe     :: SafeHaskellMode
    }

instance Outputable CoreModule where
   ppr (CoreModule {cm_module = mn, cm_types = te, cm_binds = cb,
                    cm_safe = sf})
    = text "%module" <+> ppr mn <+> parens (ppr sf) <+> ppr te
      $$ vcat (map ppr cb)

-- | This is the way to get access to the Core bindings corresponding
-- to a module. 'compileToCore' parses, typechecks, and
-- desugars the module, then returns the resulting Core module (consisting of
-- the module name, type declarations, and function declarations) if
-- successful.
compileToCoreModule :: GhcMonad m => FilePath -> m CoreModule
compileToCoreModule = compileCore False

-- | Like compileToCoreModule, but invokes the simplifier, so
-- as to return simplified and tidied Core.
compileToCoreSimplified :: GhcMonad m => FilePath -> m CoreModule
compileToCoreSimplified = compileCore True

compileCore :: GhcMonad m => Bool -> FilePath -> m CoreModule
compileCore simplify fn = do
   -- First, set the target to the desired filename
   target <- guessTarget fn Nothing
   addTarget target
   _ <- load LoadAllTargets
   -- Then find dependencies
   modGraph <- depanal [] True
   case find ((== fn) . msHsFilePath) (mgModSummaries modGraph) of
     Just modSummary -> do
       -- Now we have the module name;
       -- parse, typecheck and desugar the module
       (tcg, mod_guts) <- -- TODO: space leaky: call hsc* directly?
         do tm <- typecheckModule =<< parseModule modSummary
            let tcg = fst (tm_internals tm)
            (,) tcg . coreModule <$> desugarModule tm
       liftM (gutsToCoreModule (mg_safe_haskell mod_guts)) $
         if simplify
          then do
             -- If simplify is true: simplify (hscSimplify), then tidy
             -- (tidyProgram).
             hsc_env <- getSession
             simpl_guts <- liftIO $ do
               plugins <- readIORef (tcg_th_coreplugins tcg)
               hscSimplify hsc_env plugins mod_guts
             tidy_guts <- liftIO $ tidyProgram hsc_env simpl_guts
             return $ Left tidy_guts
          else
             return $ Right mod_guts

     Nothing -> panic "compileToCoreModule: target FilePath not found in\
                           module dependency graph"
  where -- two versions, based on whether we simplify (thus run tidyProgram,
        -- which returns a (CgGuts, ModDetails) pair, or not (in which case
        -- we just have a ModGuts.
        gutsToCoreModule :: SafeHaskellMode
                         -> Either (CgGuts, ModDetails) ModGuts
                         -> CoreModule
        gutsToCoreModule safe_mode (Left (cg, md)) = CoreModule {
          cm_module = cg_module cg,
          cm_types  = md_types md,
          cm_binds  = cg_binds cg,
          cm_safe   = safe_mode
        }
        gutsToCoreModule safe_mode (Right mg) = CoreModule {
          cm_module  = mg_module mg,
          cm_types   = typeEnvFromEntities (bindersOfBinds (mg_binds mg))
                                           (mg_tcs mg)
                                           (mg_fam_insts mg),
          cm_binds   = mg_binds mg,
          cm_safe    = safe_mode
         }

-- %************************************************************************
-- %*                                                                      *
--             Inspecting the session
-- %*                                                                      *
-- %************************************************************************

-- | Get the module dependency graph.
getModuleGraph :: GhcMonad m => m ModuleGraph -- ToDo: DiGraph ModSummary
getModuleGraph = liftM hsc_mod_graph getSession

-- | Return @True@ <==> module is loaded.
isLoaded :: GhcMonad m => ModuleName -> m Bool
isLoaded m = withSession $ \hsc_env ->
  return $! isJust (lookupHpt (hsc_HPT hsc_env) m)

-- | Return the bindings for the current interactive session.
getBindings :: GhcMonad m => m [TyThing]
getBindings = withSession $ \hsc_env ->
    return $ icInScopeTTs $ hsc_IC hsc_env

-- | Return the instances for the current interactive session.
getInsts :: GhcMonad m => m ([ClsInst], [FamInst])
getInsts = withSession $ \hsc_env ->
    return $ ic_instances (hsc_IC hsc_env)

getPrintUnqual :: GhcMonad m => m PrintUnqualified
getPrintUnqual = withSession $ \hsc_env ->
  return (icPrintUnqual (hsc_dflags hsc_env) (hsc_IC hsc_env))

-- | Container for information about a 'Module'.
data ModuleInfo = ModuleInfo {
        minf_type_env  :: TypeEnv,
        minf_exports   :: [AvailInfo],
        minf_rdr_env   :: Maybe GlobalRdrEnv,   -- Nothing for a compiled/package mod
        minf_instances :: [ClsInst],
        minf_iface     :: Maybe ModIface,
        minf_safe      :: SafeHaskellMode,
        minf_modBreaks :: ModBreaks
  }
        -- We don't want HomeModInfo here, because a ModuleInfo applies
        -- to package modules too.

-- | Request information about a loaded 'Module'
getModuleInfo :: GhcMonad m => Module -> m (Maybe ModuleInfo)  -- XXX: Maybe X
getModuleInfo mdl = withSession $ \hsc_env -> do
  let mg = hsc_mod_graph hsc_env
  if mgElemModule mg mdl
        then liftIO $ getHomeModuleInfo hsc_env mdl
        else do
  {- if isHomeModule (hsc_dflags hsc_env) mdl
        then return Nothing
        else -} liftIO $ getPackageModuleInfo hsc_env mdl
   -- ToDo: we don't understand what the following comment means.
   --    (SDM, 19/7/2011)
   -- getPackageModuleInfo will attempt to find the interface, so
   -- we don't want to call it for a home module, just in case there
   -- was a problem loading the module and the interface doesn't
   -- exist... hence the isHomeModule test here.  (ToDo: reinstate)

getPackageModuleInfo :: HscEnv -> Module -> IO (Maybe ModuleInfo)
getPackageModuleInfo hsc_env mdl
  = do  eps <- hscEPS hsc_env
        iface <- hscGetModuleInterface hsc_env mdl
        let
            avails = mi_exports iface
            pte    = eps_PTE eps
            tys    = [ ty | name <- concatMap availNames avails,
                            Just ty <- [lookupTypeEnv pte name] ]
        --
        return (Just (ModuleInfo {
                        minf_type_env  = mkTypeEnv tys,
                        minf_exports   = avails,
                        minf_rdr_env   = Just $! availsToGlobalRdrEnv (moduleName mdl) avails,
                        minf_instances = error "getModuleInfo: instances for package module unimplemented",
                        minf_iface     = Just iface,
                        minf_safe      = getSafeMode $ mi_trust iface,
                        minf_modBreaks = emptyModBreaks
                }))

getHomeModuleInfo :: HscEnv -> Module -> IO (Maybe ModuleInfo)
getHomeModuleInfo hsc_env mdl =
  case lookupHpt (hsc_HPT hsc_env) (moduleName mdl) of
    Nothing  -> return Nothing
    Just hmi -> do
      let details = hm_details hmi
          iface   = hm_iface hmi
      return (Just (ModuleInfo {
                        minf_type_env  = md_types details,
                        minf_exports   = md_exports details,
                        minf_rdr_env   = mi_globals $! hm_iface hmi,
                        minf_instances = md_insts details,
                        minf_iface     = Just iface,
                        minf_safe      = getSafeMode $ mi_trust iface
                       ,minf_modBreaks = getModBreaks hmi
                        }))

-- | The list of top-level entities defined in a module
modInfoTyThings :: ModuleInfo -> [TyThing]
modInfoTyThings minf = typeEnvElts (minf_type_env minf)

modInfoTopLevelScope :: ModuleInfo -> Maybe [Name]
modInfoTopLevelScope minf
  = fmap (map gre_name . globalRdrEnvElts) (minf_rdr_env minf)

modInfoExports :: ModuleInfo -> [Name]
modInfoExports minf = concatMap availNames $! minf_exports minf

modInfoExportsWithSelectors :: ModuleInfo -> [Name]
modInfoExportsWithSelectors minf = concatMap availNamesWithSelectors $! minf_exports minf

-- | Returns the instances defined by the specified module.
-- Warning: currently unimplemented for package modules.
modInfoInstances :: ModuleInfo -> [ClsInst]
modInfoInstances = minf_instances

modInfoIsExportedName :: ModuleInfo -> Name -> Bool
modInfoIsExportedName minf name = elemNameSet name (availsToNameSet (minf_exports minf))

mkPrintUnqualifiedForModule :: GhcMonad m =>
                               ModuleInfo
                            -> m (Maybe PrintUnqualified) -- XXX: returns a Maybe X
mkPrintUnqualifiedForModule minf = withSession $ \hsc_env -> do
  return (fmap (mkPrintUnqualified (hsc_dflags hsc_env)) (minf_rdr_env minf))

modInfoLookupName :: GhcMonad m =>
                     ModuleInfo -> Name
                  -> m (Maybe TyThing) -- XXX: returns a Maybe X
modInfoLookupName minf name = withSession $ \hsc_env -> do
   case lookupTypeEnv (minf_type_env minf) name of
     Just tyThing -> return (Just tyThing)
     Nothing      -> do
       eps <- liftIO $ readIORef (hsc_EPS hsc_env)
       return $! lookupType (hsc_dflags hsc_env)
                            (hsc_HPT hsc_env) (eps_PTE eps) name

modInfoIface :: ModuleInfo -> Maybe ModIface
modInfoIface = minf_iface

-- | Retrieve module safe haskell mode
modInfoSafe :: ModuleInfo -> SafeHaskellMode
modInfoSafe = minf_safe

modInfoModBreaks :: ModuleInfo -> ModBreaks
modInfoModBreaks = minf_modBreaks

isDictonaryId :: Id -> Bool
isDictonaryId id
  = case tcSplitSigmaTy (idType id) of {
      (_tvs, _theta, tau) -> isDictTy tau }

-- | Looks up a global name: that is, any top-level name in any
-- visible module.  Unlike 'lookupName', lookupGlobalName does not use
-- the interactive context, and therefore does not require a preceding
-- 'setContext'.
lookupGlobalName :: GhcMonad m => Name -> m (Maybe TyThing)
lookupGlobalName name = withSession $ \hsc_env -> do
   liftIO $ lookupTypeHscEnv hsc_env name

findGlobalAnns :: (GhcMonad m, Typeable a) => ([Word8] -> a) -> AnnTarget Name -> m [a]
findGlobalAnns deserialize target = withSession $ \hsc_env -> do
    ann_env <- liftIO $ prepareAnnotations hsc_env Nothing
    return (findAnns deserialize ann_env target)

-- | get the GlobalRdrEnv for a session
getGRE :: GhcMonad m => m GlobalRdrEnv
getGRE = withSession $ \hsc_env-> return $ ic_rn_gbl_env (hsc_IC hsc_env)

-- | Retrieve all type and family instances in the environment, indexed
-- by 'Name'. Each name's lists will contain every instance in which that name
-- is mentioned in the instance head.
getNameToInstancesIndex :: GhcMonad m
  => [Module]        -- ^ visible modules. An orphan instance will be returned
                     -- if it is visible from at least one module in the list.
  -> Maybe [Module]  -- ^ modules to load. If this is not specified, we load
                     -- modules for everything that is in scope unqualified.
  -> m (Messages, Maybe (NameEnv ([ClsInst], [FamInst])))
getNameToInstancesIndex visible_mods mods_to_load = do
  hsc_env <- getSession
  liftIO $ runTcInteractive hsc_env $
    do { case mods_to_load of
           Nothing -> loadUnqualIfaces hsc_env (hsc_IC hsc_env)
           Just mods ->
             let doc = text "Need interface for reporting instances in scope"
             in initIfaceTcRn $ mapM_ (loadSysInterface doc) mods

       ; InstEnvs {ie_global, ie_local} <- tcGetInstEnvs
       ; let visible_mods' = mkModuleSet visible_mods
       ; (pkg_fie, home_fie) <- tcGetFamInstEnvs
       -- We use Data.Sequence.Seq because we are creating left associated
       -- mappends.
       -- cls_index and fam_index below are adapted from TcRnDriver.lookupInsts
       ; let cls_index = Map.fromListWith mappend
                 [ (n, Seq.singleton ispec)
                 | ispec <- instEnvElts ie_local ++ instEnvElts ie_global
                 , instIsVisible visible_mods' ispec
                 , n <- nameSetElemsStable $ orphNamesOfClsInst ispec
                 ]
       ; let fam_index = Map.fromListWith mappend
                 [ (n, Seq.singleton fispec)
                 | fispec <- famInstEnvElts home_fie ++ famInstEnvElts pkg_fie
                 , n <- nameSetElemsStable $ orphNamesOfFamInst fispec
                 ]
       ; return $ mkNameEnv $
           [ (nm, (toList clss, toList fams))
           | (nm, (clss, fams)) <- Map.toList $ Map.unionWith mappend
               (fmap (,Seq.empty) cls_index)
               (fmap (Seq.empty,) fam_index)
           ] }

-- -----------------------------------------------------------------------------

{- ToDo: Move the primary logic here to compiler/main/Packages.hs
-- | Return all /external/ modules available in the package database.
-- Modules from the current session (i.e., from the 'HomePackageTable') are
-- not included.  This includes module names which are reexported by packages.
packageDbModules :: GhcMonad m =>
                    Bool  -- ^ Only consider exposed packages.
                 -> m [Module]
packageDbModules only_exposed = do
   dflags <- getSessionDynFlags
   let pkgs = eltsUFM (pkgIdMap (pkgState dflags))
   return $
     [ mkModule pid modname
     | p <- pkgs
     , not only_exposed || exposed p
     , let pid = packageConfigId p
     , modname <- exposedModules p
               ++ map exportName (reexportedModules p) ]
               -}

-- -----------------------------------------------------------------------------
-- Misc exported utils

dataConType :: DataCon -> Type
dataConType dc = idType (dataConWrapId dc)

-- | print a 'NamedThing', adding parentheses if the name is an operator.
pprParenSymName :: NamedThing a => a -> SDoc
pprParenSymName a = parenSymOcc (getOccName a) (ppr (getName a))

-- ----------------------------------------------------------------------------


-- ToDo:
--   - Data and Typeable instances for HsSyn.

-- ToDo: check for small transformations that happen to the syntax in
-- the typechecker (eg. -e ==> negate e, perhaps for fromIntegral)

-- ToDo: maybe use TH syntax instead of IfaceSyn?  There's already a way
-- to get from TyCons, Ids etc. to TH syntax (reify).

-- :browse will use either lm_toplev or inspect lm_interface, depending
-- on whether the module is interpreted or not.


-- Extract the filename, stringbuffer content and dynflags associed to a module
--
-- XXX: Explain pre-conditions
getModuleSourceAndFlags :: GhcMonad m => Module -> m (String, StringBuffer, DynFlags)
getModuleSourceAndFlags mod = do
  m <- getModSummary (moduleName mod)
  case ml_hs_file $ ms_location m of
    Nothing -> do dflags <- getDynFlags
                  liftIO $ throwIO $ mkApiErr dflags (text "No source available for module " <+> ppr mod)
    Just sourceFile -> do
        source <- liftIO $ hGetStringBuffer sourceFile
        return (sourceFile, source, ms_hspp_opts m)


-- | Return module source as token stream, including comments.
--
-- The module must be in the module graph and its source must be available.
-- Throws a 'HscTypes.SourceError' on parse error.
getTokenStream :: GhcMonad m => Module -> m [Located Token]
getTokenStream mod = do
  (sourceFile, source, flags) <- getModuleSourceAndFlags mod
  let startLoc = mkRealSrcLoc (mkFastString sourceFile) 1 1
  case lexTokenStream source startLoc flags of
    POk _ ts  -> return ts
    PFailed pst ->
        do dflags <- getDynFlags
           throwErrors (getErrorMessages pst dflags)

-- | Give even more information on the source than 'getTokenStream'
-- This function allows reconstructing the source completely with
-- 'showRichTokenStream'.
getRichTokenStream :: GhcMonad m => Module -> m [(Located Token, String)]
getRichTokenStream mod = do
  (sourceFile, source, flags) <- getModuleSourceAndFlags mod
  let startLoc = mkRealSrcLoc (mkFastString sourceFile) 1 1
  case lexTokenStream source startLoc flags of
    POk _ ts -> return $ addSourceToTokens startLoc source ts
    PFailed pst ->
        do dflags <- getDynFlags
           throwErrors (getErrorMessages pst dflags)

-- | Given a source location and a StringBuffer corresponding to this
-- location, return a rich token stream with the source associated to the
-- tokens.
addSourceToTokens :: RealSrcLoc -> StringBuffer -> [Located Token]
                  -> [(Located Token, String)]
addSourceToTokens _ _ [] = []
addSourceToTokens loc buf (t@(dL->L span _) : ts)
    = case span of
      UnhelpfulSpan _ -> (t,"") : addSourceToTokens loc buf ts
      RealSrcSpan s   -> (t,str) : addSourceToTokens newLoc newBuf ts
        where
          (newLoc, newBuf, str) = go "" loc buf
          start = realSrcSpanStart s
          end = realSrcSpanEnd s
          go acc loc buf | loc < start = go acc nLoc nBuf
                         | start <= loc && loc < end = go (ch:acc) nLoc nBuf
                         | otherwise = (loc, buf, reverse acc)
              where (ch, nBuf) = nextChar buf
                    nLoc = advanceSrcLoc loc ch


-- | Take a rich token stream such as produced from 'getRichTokenStream' and
-- return source code almost identical to the original code (except for
-- insignificant whitespace.)
showRichTokenStream :: [(Located Token, String)] -> String
showRichTokenStream ts = go startLoc ts ""
    where sourceFile = getFile $ map (getLoc . fst) ts
          getFile [] = panic "showRichTokenStream: No source file found"
          getFile (UnhelpfulSpan _ : xs) = getFile xs
          getFile (RealSrcSpan s : _) = srcSpanFile s
          startLoc = mkRealSrcLoc sourceFile 1 1
          go _ [] = id
          go loc ((dL->L span _, str):ts)
              = case span of
                UnhelpfulSpan _ -> go loc ts
                RealSrcSpan s
                 | locLine == tokLine -> ((replicate (tokCol - locCol) ' ') ++)
                                       . (str ++)
                                       . go tokEnd ts
                 | otherwise -> ((replicate (tokLine - locLine) '\n') ++)
                               . ((replicate (tokCol - 1) ' ') ++)
                              . (str ++)
                              . go tokEnd ts
                  where (locLine, locCol) = (srcLocLine loc, srcLocCol loc)
                        (tokLine, tokCol) = (srcSpanStartLine s, srcSpanStartCol s)
                        tokEnd = realSrcSpanEnd s

-- -----------------------------------------------------------------------------
-- Interactive evaluation

-- | Takes a 'ModuleName' and possibly a 'UnitId', and consults the
-- filesystem and package database to find the corresponding 'Module',
-- using the algorithm that is used for an @import@ declaration.
findModule :: GhcMonad m => ModuleName -> Maybe FastString -> m Module
findModule mod_name maybe_pkg = withSession $ \hsc_env -> do
  let
    dflags   = hsc_dflags hsc_env
    this_pkg = thisPackage dflags
  --
  case maybe_pkg of
    Just pkg | fsToUnitId pkg /= this_pkg && pkg /= fsLit "this" -> liftIO $ do
      res <- findImportedModule hsc_env mod_name maybe_pkg
      case res of
        Found _ m -> return m
        err       -> throwOneError $ noModError dflags noSrcSpan mod_name err
    _otherwise -> do
      home <- lookupLoadedHomeModule mod_name
      case home of
        Just m  -> return m
        Nothing -> liftIO $ do
           res <- findImportedModule hsc_env mod_name maybe_pkg
           case res of
             Found loc m | moduleUnitId m /= this_pkg -> return m
                         | otherwise -> modNotLoadedError dflags m loc
             err -> throwOneError $ noModError dflags noSrcSpan mod_name err

modNotLoadedError :: DynFlags -> Module -> ModLocation -> IO a
modNotLoadedError dflags m loc = throwGhcExceptionIO $ CmdLineError $ showSDoc dflags $
   text "module is not loaded:" <+>
   quotes (ppr (moduleName m)) <+>
   parens (text (expectJust "modNotLoadedError" (ml_hs_file loc)))

-- | Like 'findModule', but differs slightly when the module refers to
-- a source file, and the file has not been loaded via 'load'.  In
-- this case, 'findModule' will throw an error (module not loaded),
-- but 'lookupModule' will check to see whether the module can also be
-- found in a package, and if so, that package 'Module' will be
-- returned.  If not, the usual module-not-found error will be thrown.
--
lookupModule :: GhcMonad m => ModuleName -> Maybe FastString -> m Module
lookupModule mod_name (Just pkg) = findModule mod_name (Just pkg)
lookupModule mod_name Nothing = withSession $ \hsc_env -> do
  home <- lookupLoadedHomeModule mod_name
  case home of
    Just m  -> return m
    Nothing -> liftIO $ do
      res <- findExposedPackageModule hsc_env mod_name Nothing
      case res of
        Found _ m -> return m
        err       -> throwOneError $ noModError (hsc_dflags hsc_env) noSrcSpan mod_name err

lookupLoadedHomeModule :: GhcMonad m => ModuleName -> m (Maybe Module)
lookupLoadedHomeModule mod_name = withSession $ \hsc_env ->
  case lookupHpt (hsc_HPT hsc_env) mod_name of
    Just mod_info      -> return (Just (mi_module (hm_iface mod_info)))
    _not_a_home_module -> return Nothing

-- | Check that a module is safe to import (according to Safe Haskell).
--
-- We return True to indicate the import is safe and False otherwise
-- although in the False case an error may be thrown first.
isModuleTrusted :: GhcMonad m => Module -> m Bool
isModuleTrusted m = withSession $ \hsc_env ->
    liftIO $ hscCheckSafe hsc_env m noSrcSpan

-- | Return if a module is trusted and the pkgs it depends on to be trusted.
moduleTrustReqs :: GhcMonad m => Module -> m (Bool, Set InstalledUnitId)
moduleTrustReqs m = withSession $ \hsc_env ->
    liftIO $ hscGetSafe hsc_env m noSrcSpan

-- | Set the monad GHCi lifts user statements into.
--
-- Checks that a type (in string form) is an instance of the
-- @GHC.GHCi.GHCiSandboxIO@ type class. Sets it to be the GHCi monad if it is,
-- throws an error otherwise.
setGHCiMonad :: GhcMonad m => String -> m ()
setGHCiMonad name = withSession $ \hsc_env -> do
    ty <- liftIO $ hscIsGHCiMonad hsc_env name
    modifySession $ \s ->
        let ic = (hsc_IC s) { ic_monad = ty }
        in s { hsc_IC = ic }

-- | Get the monad GHCi lifts user statements into.
getGHCiMonad :: GhcMonad m => m Name
getGHCiMonad = fmap (ic_monad . hsc_IC) getSession

getHistorySpan :: GhcMonad m => History -> m SrcSpan
getHistorySpan h = withSession $ \hsc_env ->
    return $ InteractiveEval.getHistorySpan hsc_env h

obtainTermFromVal :: GhcMonad m => Int ->  Bool -> Type -> a -> m Term
obtainTermFromVal bound force ty a = withSession $ \hsc_env ->
    liftIO $ InteractiveEval.obtainTermFromVal hsc_env bound force ty a

obtainTermFromId :: GhcMonad m => Int -> Bool -> Id -> m Term
obtainTermFromId bound force id = withSession $ \hsc_env ->
    liftIO $ InteractiveEval.obtainTermFromId hsc_env bound force id


-- | Returns the 'TyThing' for a 'Name'.  The 'Name' may refer to any
-- entity known to GHC, including 'Name's defined using 'runStmt'.
lookupName :: GhcMonad m => Name -> m (Maybe TyThing)
lookupName name =
     withSession $ \hsc_env ->
       liftIO $ hscTcRcLookupName hsc_env name

-- -----------------------------------------------------------------------------
-- Pure API

-- | A pure interface to the module parser.
--
parser :: String         -- ^ Haskell module source text (full Unicode is supported)
       -> DynFlags       -- ^ the flags
       -> FilePath       -- ^ the filename (for source locations)
       -> (WarningMessages, Either ErrorMessages (Located (HsModule GhcPs)))

parser str dflags filename =
   let
       loc  = mkRealSrcLoc (mkFastString filename) 1 1
       buf  = stringToStringBuffer str
   in
   case unP Parser.parseModule (mkPState dflags buf loc) of

     PFailed pst ->
         let (warns,errs) = getMessages pst dflags in
         (warns, Left errs)

     POk pst rdr_module ->
         let (warns,_) = getMessages pst dflags in
         (warns, Right rdr_module)