summaryrefslogtreecommitdiff
path: root/ghc/Main.hs
blob: 0dec4f6cbc13078e2e8abe397613b02779a3a57f (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
{-# LANGUAGE CPP #-}
{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE NondecreasingIndentation #-}
{-# LANGUAGE TupleSections #-}
{-# OPTIONS -fno-warn-incomplete-patterns -optc-DNON_POSIX_SOURCE #-}

-----------------------------------------------------------------------------
--
-- GHC Driver program
--
-- (c) The University of Glasgow 2005
--
-----------------------------------------------------------------------------

module Main (main) where

-- The official GHC API
import qualified GHC
import GHC              (parseTargetFiles,  Ghc, GhcMonad(..), Backend (..),
                          LoadHowMuch(..) )

import GHC.Driver.CmdLine
import GHC.Driver.Env
import GHC.Driver.Errors
import GHC.Driver.Phases
import GHC.Driver.Session
import GHC.Driver.Ppr
import GHC.Driver.Pipeline  ( oneShot, compileFile )
import GHC.Driver.MakeFile  ( doMkDependHS )
import GHC.Driver.Backpack  ( doBackpack )
import GHC.Driver.Plugins
import GHC.Driver.Config.Logger (initLogFlags)
import GHC.Driver.Config.Diagnostic

import GHC.Platform
import GHC.Platform.Ways
import GHC.Platform.Host

#if defined(HAVE_INTERNAL_INTERPRETER)
import GHCi.UI              ( interactiveUI, ghciWelcomeMsg, defaultGhciSettings )
#endif

import GHC.Runtime.Loader   ( loadFrontendPlugin )

import GHC.Unit.Module ( ModuleName, mkModuleName )
import GHC.Unit.Module.ModIface
import GHC.Unit.State  ( pprUnits, pprUnitsSimple )
import GHC.Unit.Finder ( findImportedModule, FindResult(..) )
import GHC.Unit.Types  ( IsBootInterface(..) )

import GHC.Types.Basic     ( failed )
import GHC.Types.SrcLoc
import GHC.Types.SourceError
import GHC.Types.Unique.Supply

import GHC.Utils.Error
import GHC.Utils.Misc
import GHC.Utils.Panic
import GHC.Utils.Outputable as Outputable
import GHC.Utils.Monad       ( liftIO )
import GHC.Utils.Binary        ( openBinMem, put_ )
import GHC.Utils.Logger

import GHC.Settings.Config
import GHC.Settings.Constants
import GHC.Settings.IO

import GHC.HandleEncoding
import GHC.Data.FastString
import GHC.SysTools.BaseDir

import GHC.Iface.Load
import GHC.Iface.Recomp.Binary ( fingerprintBinMem )

import GHC.Tc.Utils.Monad      ( initIfaceCheck )

-- Standard Haskell libraries
import System.IO
import System.Environment
import System.Exit
import Control.Monad
import Control.Monad.Trans.Class
import Control.Monad.Trans.Except (throwE, runExceptT)
import Data.Char
import Data.List ( isPrefixOf, partition, intercalate )
import qualified Data.Set as Set
import Data.Maybe
import Prelude

-----------------------------------------------------------------------------
-- ToDo:

-- time commands when run with -v
-- user ways
-- Win32 support: proper signal handling
-- reading the package configuration file is too slow
-- -K<size>

-----------------------------------------------------------------------------
-- GHC's command-line interface

main :: IO ()
main = do
   initGCStatistics -- See Note [-Bsymbolic and hooks]
   hSetBuffering stdout LineBuffering
   hSetBuffering stderr LineBuffering

   configureHandleEncoding
   GHC.defaultErrorHandler defaultFatalMessager defaultFlushOut $ do
    -- 1. extract the -B flag from the args
    argv0 <- getArgs

    let (minusB_args, argv1) = partition ("-B" `isPrefixOf`) argv0
        mbMinusB | null minusB_args = Nothing
                 | otherwise = Just (drop 2 (last minusB_args))

    let argv2 = map (mkGeneralLocated "on the commandline") argv1

    -- 2. Parse the "mode" flags (--make, --interactive etc.)
    (mode, argv3, flagWarnings) <- parseModeFlags argv2

    -- If all we want to do is something like showing the version number
    -- then do it now, before we start a GHC session etc. This makes
    -- getting basic information much more resilient.

    -- In particular, if we wait until later before giving the version
    -- number then bootstrapping gets confused, as it tries to find out
    -- what version of GHC it's using before package.conf exists, so
    -- starting the session fails.
    case mode of
        Left preStartupMode ->
            do case preStartupMode of
                   ShowSupportedExtensions   -> showSupportedExtensions mbMinusB
                   ShowVersion               -> showVersion
                   ShowNumVersion            -> putStrLn cProjectVersion
                   ShowOptions isInteractive -> showOptions isInteractive
        Right postStartupMode ->
            -- start our GHC session
            GHC.runGhc mbMinusB $ do

            dflags <- GHC.getSessionDynFlags

            case postStartupMode of
                Left preLoadMode ->
                    liftIO $ do
                        case preLoadMode of
                            ShowInfo               -> showInfo dflags
                            ShowGhcUsage           -> showGhcUsage  dflags
                            ShowGhciUsage          -> showGhciUsage dflags
                            PrintWithDynFlags f    -> putStrLn (f dflags)
                Right postLoadMode ->
                    main' postLoadMode dflags argv3 flagWarnings

main' :: PostLoadMode -> DynFlags -> [Located String] -> [Warn]
      -> Ghc ()
main' postLoadMode dflags0 args flagWarnings = do

  -- set the default GhcMode, backend and GhcLink.  The backend
  -- can be further adjusted on a module by module basis, using only
  -- the -fllvm and -fasm flags.  If the default backend is not
  -- LLVM or NCG, -fllvm and -fasm have no effect.
  let dflt_backend = backend dflags0
      (mode, bcknd, link)
         = case postLoadMode of
               DoInteractive   -> (CompManager, Interpreter,  LinkInMemory)
               DoEval _        -> (CompManager, Interpreter,  LinkInMemory)
               DoMake          -> (CompManager, dflt_backend, LinkBinary)
               DoBackpack      -> (CompManager, dflt_backend, LinkBinary)
               DoMkDependHS    -> (MkDepend,    dflt_backend, LinkBinary)
               DoAbiHash       -> (OneShot,     dflt_backend, LinkBinary)
               _               -> (OneShot,     dflt_backend, LinkBinary)

  let dflags1 = dflags0{ ghcMode   = mode,
                         backend   = bcknd,
                         ghcLink   = link,
                         verbosity = case postLoadMode of
                                         DoEval _ -> 0
                                         _other   -> 1
                        }

      -- turn on -fimplicit-import-qualified for GHCi now, so that it
      -- can be overridden from the command-line
      -- XXX: this should really be in the interactive DynFlags, but
      -- we don't set that until later in interactiveUI
      -- We also set -fignore-optim-changes and -fignore-hpc-changes,
      -- which are program-level options. Again, this doesn't really
      -- feel like the right place to handle this, but we don't have
      -- a great story for the moment.
      dflags2  | DoInteractive <- postLoadMode = def_ghci_flags
               | DoEval _      <- postLoadMode = def_ghci_flags
               | otherwise                     = dflags1
        where def_ghci_flags = dflags1 `gopt_set` Opt_ImplicitImportQualified
                                       `gopt_set` Opt_IgnoreOptimChanges
                                       `gopt_set` Opt_IgnoreHpcChanges

  logger1 <- getLogger
  let logger2 = setLogFlags logger1 (initLogFlags dflags2)

        -- The rest of the arguments are "dynamic"
        -- Leftover ones are presumably files
  (dflags3, fileish_args, dynamicFlagWarnings) <-
      GHC.parseDynamicFlags logger2 dflags2 args

  let dflags4 = case bcknd of
                Interpreter | not (gopt Opt_ExternalInterpreter dflags3) ->
                    let platform = targetPlatform dflags3
                        dflags3a = dflags3 { targetWays_ = hostFullWays }
                        dflags3b = foldl gopt_set dflags3a
                                 $ concatMap (wayGeneralFlags platform)
                                             hostFullWays
                        dflags3c = foldl gopt_unset dflags3b
                                 $ concatMap (wayUnsetGeneralFlags platform)
                                             hostFullWays
                    in dflags3c
                _ ->
                    dflags3

  let logger4 = setLogFlags logger2 (initLogFlags dflags4)

  GHC.prettyPrintGhcErrors logger4 $ do

  let flagWarnings' = flagWarnings ++ dynamicFlagWarnings

  handleSourceError (\e -> do
       GHC.printException e
       liftIO $ exitWith (ExitFailure 1)) $ do
         liftIO $ handleFlagWarnings logger4 (initDiagOpts dflags4) flagWarnings'

  liftIO $ showBanner postLoadMode dflags4

  let (dflags5, srcs, objs) = parseTargetFiles dflags4 (map unLoc fileish_args)

  -- we've finished manipulating the DynFlags, update the session
  _ <- GHC.setSessionDynFlags dflags5
  dflags6 <- GHC.getSessionDynFlags
  hsc_env <- GHC.getSession
  logger <- getLogger

        ---------------- Display configuration -----------
  case verbosity dflags6 of
    v | v == 4 -> liftIO $ dumpUnitsSimple hsc_env
      | v >= 5 -> liftIO $ dumpUnits       hsc_env
      | otherwise -> return ()

  liftIO $ initUniqSupply (initialUnique dflags6) (uniqueIncrement dflags6)
        ---------------- Final sanity checking -----------
  liftIO $ checkOptions postLoadMode dflags6 srcs objs

  ---------------- Do the business -----------
  handleSourceError (\e -> do
       GHC.printException e
       liftIO $ exitWith (ExitFailure 1)) $ do
    case postLoadMode of
       ShowInterface f        -> liftIO $ showIface logger
                                                    (hsc_dflags hsc_env)
                                                    (hsc_units  hsc_env)
                                                    (hsc_NC     hsc_env)
                                                    f
       DoMake                 -> doMake srcs
       DoMkDependHS           -> doMkDependHS (map fst srcs)
       StopBefore p           -> liftIO (oneShot hsc_env p srcs)
       DoInteractive          -> ghciUI srcs Nothing
       DoEval exprs           -> ghciUI srcs $ Just $ reverse exprs
       DoAbiHash              -> abiHash (map fst srcs)
       ShowPackages           -> liftIO $ showUnits hsc_env
       DoFrontend f           -> doFrontend f srcs
       DoBackpack             -> doBackpack (map fst srcs)

  liftIO $ dumpFinalStats logger

ghciUI :: [(FilePath, Maybe Phase)] -> Maybe [String] -> Ghc ()
#if !defined(HAVE_INTERNAL_INTERPRETER)
ghciUI _ _ =
  throwGhcException (CmdLineError "not built for interactive use")
#else
ghciUI srcs maybe_expr = interactiveUI defaultGhciSettings srcs maybe_expr
#endif


-- -----------------------------------------------------------------------------
-- Option sanity checks

-- | Ensure sanity of options.
--
-- Throws 'UsageError' or 'CmdLineError' if not.
checkOptions :: PostLoadMode -> DynFlags -> [(String,Maybe Phase)] -> [String] -> IO ()
     -- Final sanity checking before kicking off a compilation (pipeline).
checkOptions mode dflags srcs objs = do
     -- Complain about any unknown flags
   let unknown_opts = [ f | (f@('-':_), _) <- srcs ]
   when (notNull unknown_opts) (unknownFlagsErr unknown_opts)

   when (not (Set.null (rtsWays (ways dflags)))
         && isInterpretiveMode mode) $
        hPutStrLn stderr ("Warning: -debug, -threaded and -ticky are ignored by GHCi")

        -- -prof and --interactive are not a good combination
   when ((fullWays (ways dflags) /= hostFullWays)
         && isInterpretiveMode mode
         && not (gopt Opt_ExternalInterpreter dflags)) $
      do throwGhcException (UsageError
              "-fexternal-interpreter is required when using --interactive with a non-standard way (-prof, -static, or -dynamic).")
        -- -ohi sanity check
   if (isJust (outputHi dflags) &&
      (isCompManagerMode mode || srcs `lengthExceeds` 1))
        then throwGhcException (UsageError "-ohi can only be used when compiling a single source file")
        else do

        -- -o sanity checking
   if (srcs `lengthExceeds` 1 && isJust (outputFile dflags)
         && not (isLinkMode mode))
        then throwGhcException (UsageError "can't apply -o to multiple source files")
        else do

   let not_linking = not (isLinkMode mode) || isNoLink (ghcLink dflags)

   when (not_linking && not (null objs)) $
        hPutStrLn stderr ("Warning: the following files would be used as linker inputs, but linking is not being done: " ++ unwords objs)

        -- Check that there are some input files
        -- (except in the interactive case)
   if null srcs && (null objs || not_linking) && needsInputsMode mode
        then throwGhcException (UsageError "no input files")
        else do

   case mode of
      StopBefore HCc | backend dflags /= ViaC
        -> throwGhcException $ UsageError $
           "the option -C is only available with an unregisterised GHC"
      StopBefore (As False) | ghcLink dflags == NoLink
        -> throwGhcException $ UsageError $
           "the options -S and -fno-code are incompatible. Please omit -S"

      _ -> return ()

     -- Verify that output files point somewhere sensible.
   verifyOutputFiles dflags

-- Compiler output options

-- Called to verify that the output files point somewhere valid.
--
-- The assumption is that the directory portion of these output
-- options will have to exist by the time 'verifyOutputFiles'
-- is invoked.
--
-- We create the directories for -odir, -hidir, -outputdir etc. ourselves if
-- they don't exist, so don't check for those here (#2278).
verifyOutputFiles :: DynFlags -> IO ()
verifyOutputFiles dflags = do
  let ofile = outputFile dflags
  when (isJust ofile) $ do
     let fn = fromJust ofile
     flg <- doesDirNameExist fn
     when (not flg) (nonExistentDir "-o" fn)
  let ohi = outputHi dflags
  when (isJust ohi) $ do
     let hi = fromJust ohi
     flg <- doesDirNameExist hi
     when (not flg) (nonExistentDir "-ohi" hi)
 where
   nonExistentDir flg dir =
     throwGhcException (CmdLineError ("error: directory portion of " ++
                             show dir ++ " does not exist (used with " ++
                             show flg ++ " option.)"))

-----------------------------------------------------------------------------
-- GHC modes of operation

type Mode = Either PreStartupMode PostStartupMode
type PostStartupMode = Either PreLoadMode PostLoadMode

data PreStartupMode
  = ShowVersion                          -- ghc -V/--version
  | ShowNumVersion                       -- ghc --numeric-version
  | ShowSupportedExtensions              -- ghc --supported-extensions
  | ShowOptions Bool {- isInteractive -} -- ghc --show-options

showVersionMode, showNumVersionMode, showSupportedExtensionsMode, showOptionsMode :: Mode
showVersionMode             = mkPreStartupMode ShowVersion
showNumVersionMode          = mkPreStartupMode ShowNumVersion
showSupportedExtensionsMode = mkPreStartupMode ShowSupportedExtensions
showOptionsMode             = mkPreStartupMode (ShowOptions False)

mkPreStartupMode :: PreStartupMode -> Mode
mkPreStartupMode = Left

isShowVersionMode :: Mode -> Bool
isShowVersionMode (Left ShowVersion) = True
isShowVersionMode _ = False

isShowNumVersionMode :: Mode -> Bool
isShowNumVersionMode (Left ShowNumVersion) = True
isShowNumVersionMode _ = False

data PreLoadMode
  = ShowGhcUsage                           -- ghc -?
  | ShowGhciUsage                          -- ghci -?
  | ShowInfo                               -- ghc --info
  | PrintWithDynFlags (DynFlags -> String) -- ghc --print-foo

showGhcUsageMode, showGhciUsageMode, showInfoMode :: Mode
showGhcUsageMode = mkPreLoadMode ShowGhcUsage
showGhciUsageMode = mkPreLoadMode ShowGhciUsage
showInfoMode = mkPreLoadMode ShowInfo

printSetting :: String -> Mode
printSetting k = mkPreLoadMode (PrintWithDynFlags f)
    where f dflags = fromMaybe (panic ("Setting not found: " ++ show k))
                   $ lookup k (compilerInfo dflags)

mkPreLoadMode :: PreLoadMode -> Mode
mkPreLoadMode = Right . Left

isShowGhcUsageMode :: Mode -> Bool
isShowGhcUsageMode (Right (Left ShowGhcUsage)) = True
isShowGhcUsageMode _ = False

isShowGhciUsageMode :: Mode -> Bool
isShowGhciUsageMode (Right (Left ShowGhciUsage)) = True
isShowGhciUsageMode _ = False

data PostLoadMode
  = ShowInterface FilePath  -- ghc --show-iface
  | DoMkDependHS            -- ghc -M
  | StopBefore Phase        -- ghc -E | -C | -S
                            -- StopBefore StopLn is the default
  | DoMake                  -- ghc --make
  | DoBackpack              -- ghc --backpack foo.bkp
  | DoInteractive           -- ghc --interactive
  | DoEval [String]         -- ghc -e foo -e bar => DoEval ["bar", "foo"]
  | DoAbiHash               -- ghc --abi-hash
  | ShowPackages            -- ghc --show-packages
  | DoFrontend ModuleName   -- ghc --frontend Plugin.Module

doMkDependHSMode, doMakeMode, doInteractiveMode,
  doAbiHashMode, showUnitsMode :: Mode
doMkDependHSMode = mkPostLoadMode DoMkDependHS
doMakeMode = mkPostLoadMode DoMake
doInteractiveMode = mkPostLoadMode DoInteractive
doAbiHashMode = mkPostLoadMode DoAbiHash
showUnitsMode = mkPostLoadMode ShowPackages

showInterfaceMode :: FilePath -> Mode
showInterfaceMode fp = mkPostLoadMode (ShowInterface fp)

stopBeforeMode :: Phase -> Mode
stopBeforeMode phase = mkPostLoadMode (StopBefore phase)

doEvalMode :: String -> Mode
doEvalMode str = mkPostLoadMode (DoEval [str])

doFrontendMode :: String -> Mode
doFrontendMode str = mkPostLoadMode (DoFrontend (mkModuleName str))

doBackpackMode :: Mode
doBackpackMode = mkPostLoadMode DoBackpack

mkPostLoadMode :: PostLoadMode -> Mode
mkPostLoadMode = Right . Right

isDoInteractiveMode :: Mode -> Bool
isDoInteractiveMode (Right (Right DoInteractive)) = True
isDoInteractiveMode _ = False

isStopLnMode :: Mode -> Bool
isStopLnMode (Right (Right (StopBefore StopLn))) = True
isStopLnMode _ = False

isDoMakeMode :: Mode -> Bool
isDoMakeMode (Right (Right DoMake)) = True
isDoMakeMode _ = False

isDoEvalMode :: Mode -> Bool
isDoEvalMode (Right (Right (DoEval _))) = True
isDoEvalMode _ = False

#if defined(HAVE_INTERNAL_INTERPRETER)
isInteractiveMode :: PostLoadMode -> Bool
isInteractiveMode DoInteractive = True
isInteractiveMode _             = False
#endif

-- isInterpretiveMode: byte-code compiler involved
isInterpretiveMode :: PostLoadMode -> Bool
isInterpretiveMode DoInteractive = True
isInterpretiveMode (DoEval _)    = True
isInterpretiveMode _             = False

needsInputsMode :: PostLoadMode -> Bool
needsInputsMode DoMkDependHS    = True
needsInputsMode (StopBefore _)  = True
needsInputsMode DoMake          = True
needsInputsMode _               = False

-- True if we are going to attempt to link in this mode.
-- (we might not actually link, depending on the GhcLink flag)
isLinkMode :: PostLoadMode -> Bool
isLinkMode (StopBefore StopLn) = True
isLinkMode DoMake              = True
isLinkMode DoInteractive       = True
isLinkMode (DoEval _)          = True
isLinkMode _                   = False

isCompManagerMode :: PostLoadMode -> Bool
isCompManagerMode DoMake        = True
isCompManagerMode DoInteractive = True
isCompManagerMode (DoEval _)    = True
isCompManagerMode _             = False

-- -----------------------------------------------------------------------------
-- Parsing the mode flag

parseModeFlags :: [Located String]
               -> IO (Mode,
                      [Located String],
                      [Warn])
parseModeFlags args = do
  let ((leftover, errs1, warns), (mModeFlag, errs2, flags')) =
          runCmdLine (processArgs mode_flags args)
                     (Nothing, [], [])
      mode = case mModeFlag of
             Nothing     -> doMakeMode
             Just (m, _) -> m

  -- See Note [Handling errors when parsing commandline flags]
  unless (null errs1 && null errs2) $ throwGhcException $ errorsToGhcException $
      map (("on the commandline", )) $ map (unLoc . errMsg) errs1 ++ errs2

  return (mode, flags' ++ leftover, warns)

type ModeM = CmdLineP (Maybe (Mode, String), [String], [Located String])
  -- mode flags sometimes give rise to new DynFlags (eg. -C, see below)
  -- so we collect the new ones and return them.

mode_flags :: [Flag ModeM]
mode_flags =
  [  ------- help / version ----------------------------------------------
    defFlag "?"                     (PassFlag (setMode showGhcUsageMode))
  , defFlag "-help"                 (PassFlag (setMode showGhcUsageMode))
  , defFlag "V"                     (PassFlag (setMode showVersionMode))
  , defFlag "-version"              (PassFlag (setMode showVersionMode))
  , defFlag "-numeric-version"      (PassFlag (setMode showNumVersionMode))
  , defFlag "-info"                 (PassFlag (setMode showInfoMode))
  , defFlag "-show-options"         (PassFlag (setMode showOptionsMode))
  , defFlag "-supported-languages"  (PassFlag (setMode showSupportedExtensionsMode))
  , defFlag "-supported-extensions" (PassFlag (setMode showSupportedExtensionsMode))
  , defFlag "-show-packages"        (PassFlag (setMode showUnitsMode))
  ] ++
  [ defFlag k'                      (PassFlag (setMode (printSetting k)))
  | k <- ["Project version",
          "Project Git commit id",
          "Booter version",
          "Stage",
          "Build platform",
          "Host platform",
          "Target platform",
          "Have interpreter",
          "Object splitting supported",
          "Have native code generator",
          "Support SMP",
          "Unregisterised",
          "Tables next to code",
          "RTS ways",
          "Leading underscore",
          "Debug on",
          "LibDir",
          "Global Package DB",
          "C compiler flags",
          "C compiler link flags",
          "ld flags"],
    let k' = "-print-" ++ map (replaceSpace . toLower) k
        replaceSpace ' ' = '-'
        replaceSpace c   = c
  ] ++
      ------- interfaces ----------------------------------------------------
  [ defFlag "-show-iface"  (HasArg (\f -> setMode (showInterfaceMode f)
                                               "--show-iface"))

      ------- primary modes ------------------------------------------------
  , defFlag "c"            (PassFlag (\f -> do setMode (stopBeforeMode StopLn) f
                                               addFlag "-no-link" f))
  , defFlag "M"            (PassFlag (setMode doMkDependHSMode))
  , defFlag "E"            (PassFlag (setMode (stopBeforeMode anyHsc)))
  , defFlag "C"            (PassFlag (setMode (stopBeforeMode HCc)))
  , defFlag "S"            (PassFlag (setMode (stopBeforeMode (As False))))
  , defFlag "-make"        (PassFlag (setMode doMakeMode))
  , defFlag "-backpack"    (PassFlag (setMode doBackpackMode))
  , defFlag "-interactive" (PassFlag (setMode doInteractiveMode))
  , defFlag "-abi-hash"    (PassFlag (setMode doAbiHashMode))
  , defFlag "e"            (SepArg   (\s -> setMode (doEvalMode s) "-e"))
  , defFlag "-frontend"    (SepArg   (\s -> setMode (doFrontendMode s) "-frontend"))
  ]

setMode :: Mode -> String -> EwM ModeM ()
setMode newMode newFlag = liftEwM $ do
    (mModeFlag, errs, flags') <- getCmdLineState
    let (modeFlag', errs') =
            case mModeFlag of
            Nothing -> ((newMode, newFlag), errs)
            Just (oldMode, oldFlag) ->
                case (oldMode, newMode) of
                    -- -c/--make are allowed together, and mean --make -no-link
                    _ |  isStopLnMode oldMode && isDoMakeMode newMode
                      || isStopLnMode newMode && isDoMakeMode oldMode ->
                      ((doMakeMode, "--make"), [])

                    -- If we have both --help and --interactive then we
                    -- want showGhciUsage
                    _ | isShowGhcUsageMode oldMode &&
                        isDoInteractiveMode newMode ->
                            ((showGhciUsageMode, oldFlag), [])
                      | isShowGhcUsageMode newMode &&
                        isDoInteractiveMode oldMode ->
                            ((showGhciUsageMode, newFlag), [])

                    -- If we have both -e and --interactive then -e always wins
                    _ | isDoEvalMode oldMode &&
                        isDoInteractiveMode newMode ->
                            ((oldMode, oldFlag), [])
                      | isDoEvalMode newMode &&
                        isDoInteractiveMode oldMode ->
                            ((newMode, newFlag), [])

                    -- Otherwise, --help/--version/--numeric-version always win
                      | isDominantFlag oldMode -> ((oldMode, oldFlag), [])
                      | isDominantFlag newMode -> ((newMode, newFlag), [])
                    -- We need to accumulate eval flags like "-e foo -e bar"
                    (Right (Right (DoEval esOld)),
                     Right (Right (DoEval [eNew]))) ->
                        ((Right (Right (DoEval (eNew : esOld))), oldFlag),
                         errs)
                    -- Saying e.g. --interactive --interactive is OK
                    _ | oldFlag == newFlag -> ((oldMode, oldFlag), errs)

                    -- --interactive and --show-options are used together
                    (Right (Right DoInteractive), Left (ShowOptions _)) ->
                      ((Left (ShowOptions True),
                        "--interactive --show-options"), errs)
                    (Left (ShowOptions _), (Right (Right DoInteractive))) ->
                      ((Left (ShowOptions True),
                        "--show-options --interactive"), errs)
                    -- Otherwise, complain
                    _ -> let err = flagMismatchErr oldFlag newFlag
                         in ((oldMode, oldFlag), err : errs)
    putCmdLineState (Just modeFlag', errs', flags')
  where isDominantFlag f = isShowGhcUsageMode   f ||
                           isShowGhciUsageMode  f ||
                           isShowVersionMode    f ||
                           isShowNumVersionMode f

flagMismatchErr :: String -> String -> String
flagMismatchErr oldFlag newFlag
    = "cannot use `" ++ oldFlag ++  "' with `" ++ newFlag ++ "'"

addFlag :: String -> String -> EwM ModeM ()
addFlag s flag = liftEwM $ do
  (m, e, flags') <- getCmdLineState
  putCmdLineState (m, e, mkGeneralLocated loc s : flags')
    where loc = "addFlag by " ++ flag ++ " on the commandline"

-- ----------------------------------------------------------------------------
-- Run --make mode

doMake :: [(String,Maybe Phase)] -> Ghc ()
doMake srcs  = do
    let (hs_srcs, non_hs_srcs) = partition isHaskellishTarget srcs

    hsc_env <- GHC.getSession

    -- if we have no haskell sources from which to do a dependency
    -- analysis, then just do one-shot compilation and/or linking.
    -- This means that "ghc Foo.o Bar.o -o baz" links the program as
    -- we expect.
    if (null hs_srcs)
       then liftIO (oneShot hsc_env StopLn srcs)
       else do

    o_files <- mapM (\x -> liftIO $ compileFile hsc_env StopLn x)
                 non_hs_srcs
    dflags <- GHC.getSessionDynFlags
    let dflags' = dflags { ldInputs = map (FileOption "") o_files
                                      ++ ldInputs dflags }
    _ <- GHC.setSessionDynFlags dflags'

    targets <- mapM (\(src, phase) -> GHC.guessTarget src Nothing phase) hs_srcs
    GHC.setTargets targets
    ok_flag <- GHC.load LoadAllTargets

    when (failed ok_flag) (liftIO $ exitWith (ExitFailure 1))
    return ()


-- ---------------------------------------------------------------------------
-- Various banners and verbosity output.

showBanner :: PostLoadMode -> DynFlags -> IO ()
showBanner _postLoadMode dflags = do
   let verb = verbosity dflags

#if defined(HAVE_INTERNAL_INTERPRETER)
   -- Show the GHCi banner
   when (isInteractiveMode _postLoadMode && verb >= 1) $ putStrLn ghciWelcomeMsg
#endif

   -- Display details of the configuration in verbose mode
   when (verb >= 2) $
    do hPutStr stderr "Glasgow Haskell Compiler, Version "
       hPutStr stderr cProjectVersion
       hPutStr stderr ", stage "
       hPutStr stderr cStage
       hPutStr stderr " booted by GHC version "
       hPutStrLn stderr cBooterVersion

-- We print out a Read-friendly string, but a prettier one than the
-- Show instance gives us
showInfo :: DynFlags -> IO ()
showInfo dflags = do
        let sq x = " [" ++ x ++ "\n ]"
        putStrLn $ sq $ intercalate "\n ," $ map show $ compilerInfo dflags

-- TODO use GHC.Utils.Error once that is disentangled from all the other GhcMonad stuff?
showSupportedExtensions :: Maybe String -> IO ()
showSupportedExtensions m_top_dir = do
  res <- runExceptT $ do
    top_dir <- lift (tryFindTopDir m_top_dir) >>= \case
      Nothing -> throwE $ SettingsError_MissingData "Could not find the top directory, missing -B flag"
      Just dir -> pure dir
    initSettings top_dir
  arch_os <- case res of
    Right s -> pure $ platformArchOS $ sTargetPlatform s
    Left (SettingsError_MissingData msg) -> do
      hPutStrLn stderr $ "WARNING: " ++ show msg
      hPutStrLn stderr $ "cannot know target platform so guessing target == host (native compiler)."
      pure hostPlatformArchOS
    Left (SettingsError_BadData msg) -> do
      hPutStrLn stderr msg
      exitWith $ ExitFailure 1
  mapM_ putStrLn $ supportedLanguagesAndExtensions arch_os

showVersion :: IO ()
showVersion = putStrLn (cProjectName ++ ", version " ++ cProjectVersion)

showOptions :: Bool -> IO ()
showOptions isInteractive = putStr (unlines availableOptions)
    where
      availableOptions = concat [
        flagsForCompletion isInteractive,
        map ('-':) (getFlagNames mode_flags)
        ]
      getFlagNames opts         = map flagName opts

showGhcUsage :: DynFlags -> IO ()
showGhcUsage = showUsage False

showGhciUsage :: DynFlags -> IO ()
showGhciUsage = showUsage True

showUsage :: Bool -> DynFlags -> IO ()
showUsage ghci dflags = do
  let usage_path = if ghci then ghciUsagePath dflags
                           else ghcUsagePath dflags
  usage <- readFile usage_path
  dump usage
  where
     dump ""          = return ()
     dump ('$':'$':s) = putStr progName >> dump s
     dump (c:s)       = putChar c >> dump s

dumpFinalStats :: Logger -> IO ()
dumpFinalStats logger = do
  when (logHasDumpFlag logger Opt_D_faststring_stats) $ dumpFastStringStats logger

  when (logHasDumpFlag logger Opt_D_dump_faststrings) $ do
    fss <- getFastStringTable
    let ppr_table         = fmap ppr_segment (fss `zip` [0..])
        ppr_segment (s,n) = hang (text "Segment" <+> int n) 2 (vcat (fmap ppr_bucket (s `zip` [0..])))
        ppr_bucket  (b,n) = hang (text "Bucket" <+> int n) 2 (vcat (fmap ftext b))
    putDumpFileMaybe logger Opt_D_dump_faststrings "FastStrings" FormatText (vcat ppr_table)

dumpFastStringStats :: Logger -> IO ()
dumpFastStringStats logger = do
  segments <- getFastStringTable
  hasZ <- getFastStringZEncCounter
  let buckets = concat segments
      bucketsPerSegment = map length segments
      entriesPerBucket = map length buckets
      entries = sum entriesPerBucket
      msg = text "FastString stats:" $$ nest 4 (vcat
        [ text "segments:         " <+> int (length segments)
        , text "buckets:          " <+> int (sum bucketsPerSegment)
        , text "entries:          " <+> int entries
        , text "largest segment:  " <+> int (maximum bucketsPerSegment)
        , text "smallest segment: " <+> int (minimum bucketsPerSegment)
        , text "longest bucket:   " <+> int (maximum entriesPerBucket)
        , text "has z-encoding:   " <+> (hasZ `pcntOf` entries)
        ])
        -- we usually get more "has z-encoding" than "z-encoded", because
        -- when we z-encode a string it might hash to the exact same string,
        -- which is not counted as "z-encoded".  Only strings whose
        -- Z-encoding is different from the original string are counted in
        -- the "z-encoded" total.
  putMsg logger msg
  where
   x `pcntOf` y = int ((x * 100) `quot` y) Outputable.<> char '%'

showUnits, dumpUnits, dumpUnitsSimple :: HscEnv -> IO ()
showUnits       hsc_env = putStrLn (showSDoc (hsc_dflags hsc_env) (pprUnits (hsc_units hsc_env)))
dumpUnits       hsc_env = putMsg (hsc_logger hsc_env) (pprUnits (hsc_units hsc_env))
dumpUnitsSimple hsc_env = putMsg (hsc_logger hsc_env) (pprUnitsSimple (hsc_units hsc_env))

-- -----------------------------------------------------------------------------
-- Frontend plugin support

doFrontend :: ModuleName -> [(String, Maybe Phase)] -> Ghc ()
doFrontend modname srcs = do
    hsc_env <- getSession
    frontend_plugin <- liftIO $ loadFrontendPlugin hsc_env modname
    frontend frontend_plugin
      (reverse $ frontendPluginOpts (hsc_dflags hsc_env)) srcs

-- -----------------------------------------------------------------------------
-- ABI hash support

{-
        ghc --abi-hash Data.Foo System.Bar

Generates a combined hash of the ABI for modules Data.Foo and
System.Bar.  The modules must already be compiled, and appropriate -i
options may be necessary in order to find the .hi files.

This is used by Cabal for generating the ComponentId for a
package.  The ComponentId must change when the visible ABI of
the package changes, so during registration Cabal calls ghc --abi-hash
to get a hash of the package's ABI.
-}

-- | Print ABI hash of input modules.
--
-- The resulting hash is the MD5 of the GHC version used (#5328,
-- see 'hiVersion') and of the existing ABI hash from each module (see
-- 'mi_mod_hash').
abiHash :: [String] -- ^ List of module names
        -> Ghc ()
abiHash strs = do
  hsc_env <- getSession
  let fc        = hsc_FC hsc_env
  let home_unit = hsc_home_unit hsc_env
  let units     = hsc_units hsc_env
  let dflags    = hsc_dflags hsc_env

  liftIO $ do

  let find_it str = do
         let modname = mkModuleName str
         r <- findImportedModule fc units home_unit dflags modname Nothing
         case r of
           Found _ m -> return m
           _error    -> throwGhcException $ CmdLineError $ showSDoc dflags $
                          cannotFindModule hsc_env modname r

  mods <- mapM find_it strs

  let get_iface modl = loadUserInterface NotBoot (text "abiHash") modl
  ifaces <- initIfaceCheck (text "abiHash") hsc_env $ mapM get_iface mods

  bh <- openBinMem (3*1024) -- just less than a block
  put_ bh hiVersion
    -- package hashes change when the compiler version changes (for now)
    -- see #5328
  mapM_ (put_ bh . mi_mod_hash . mi_final_exts) ifaces
  f <- fingerprintBinMem bh

  putStrLn (showPpr dflags f)

-- -----------------------------------------------------------------------------
-- Util

unknownFlagsErr :: [String] -> a
unknownFlagsErr fs = throwGhcException $ UsageError $ concatMap oneError fs
  where
    oneError f =
        "unrecognised flag: " ++ f ++ "\n" ++
        (case match f (nubSort allNonDeprecatedFlags) of
            [] -> ""
            suggs -> "did you mean one of:\n" ++ unlines (map ("  " ++) suggs))
    -- fixes #11789
    -- If the flag contains '=',
    -- this uses both the whole and the left side of '=' for comparing.
    match f allFlags
        | elem '=' f =
              let (flagsWithEq, flagsWithoutEq) = partition (elem '=') allFlags
                  fName = takeWhile (/= '=') f
              in (fuzzyMatch f flagsWithEq) ++ (fuzzyMatch fName flagsWithoutEq)
        | otherwise = fuzzyMatch f allFlags

{- Note [-Bsymbolic and hooks]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-Bsymbolic is a flag that prevents the binding of references to global
symbols to symbols outside the shared library being compiled (see `man
ld`). When dynamically linking, we don't use -Bsymbolic on the RTS
package: that is because we want hooks to be overridden by the user,
we don't want to constrain them to the RTS package.

Unfortunately this seems to have broken somehow on OS X: as a result,
defaultHooks (in hschooks.c) is not called, which does not initialize
the GC stats. As a result, this breaks things like `:set +s` in GHCi
(#8754). As a hacky workaround, we instead call 'defaultHooks'
directly to initialize the flags in the RTS.

A byproduct of this, I believe, is that hooks are likely broken on OS
X when dynamically linking. But this probably doesn't affect most
people since we're linking GHC dynamically, but most things themselves
link statically.
-}

foreign import ccall safe "initGCStatistics"
  initGCStatistics :: IO ()