GHC.hs 74.6 KB
Newer Older
1
-- -----------------------------------------------------------------------------
2
--
3
-- (c) The University of Glasgow, 2005
4
5
6
--
-- The GHC API
--
7
-- -----------------------------------------------------------------------------
8
9
10

module GHC (
	-- * Initialisation
11
	Session,
12
13
14
15
16
	defaultErrorHandler,
	defaultCleanupHandler,
	newSession,

	-- * Flags and settings
17
	DynFlags(..), DynFlag(..), Severity(..), GhcMode(..), HscTarget(..), dopt,
18
	parseDynamicFlags,
19
20
	getSessionDynFlags,
	setSessionDynFlags,
21
22

	-- * Targets
23
	Target(..), TargetId(..), Phase,
24
25
26
	setTargets,
	getTargets,
	addTarget,
27
	removeTarget,
28
29
	guessTarget,
	
30
31
32
33
34
35
        -- * Extending the program scope 
        extendGlobalRdrScope,  -- :: Session -> [GlobalRdrElt] -> IO ()
        setGlobalRdrScope,     -- :: Session -> [GlobalRdrElt] -> IO ()
        extendGlobalTypeScope, -- :: Session -> [Id] -> IO ()
        setGlobalTypeScope,    -- :: Session -> [Id] -> IO ()

36
	-- * Loading\/compiling the program
37
	depanal,
38
	load, LoadHowMuch(..), SuccessFlag(..),	-- also does depanal
39
	workingDirectoryChanged,
40
	checkModule, CheckedModule(..),
41
	TypecheckedSource, ParsedSource, RenamedSource,
42
43

	-- * Inspecting the module structure of the program
Simon Marlow's avatar
Simon Marlow committed
44
	ModuleGraph, ModSummary(..), ms_mod_name, ModLocation(..),
45
	getModuleGraph,
46
	isLoaded,
47
48
	topSortModuleGraph,

49
50
51
52
	-- * Inspecting modules
	ModuleInfo,
	getModuleInfo,
	modInfoTyThings,
53
	modInfoTopLevelScope,
54
55
	modInfoPrintUnqualified,
	modInfoExports,
56
	modInfoInstances,
57
58
	modInfoIsExportedName,
	modInfoLookupName,
59
	lookupGlobalName,
60

61
62
63
	-- * Printing
	PrintUnqualified, alwaysQualify,

64
65
	-- * Interactive evaluation
	getBindings, getPrintUnqual,
Simon Marlow's avatar
Simon Marlow committed
66
        findModule,
67
68
#ifdef GHCI
	setContext, getContext,	
69
	getNamesInScope,
Simon Marlow's avatar
Simon Marlow committed
70
	getRdrNamesInScope,
71
	moduleIsInterpreted,
72
	getInfo,
73
74
	exprType,
	typeKind,
75
	parseName,
76
77
78
	RunResult(..),
	runStmt,
	showModule,
ei@vuokko.info's avatar
ei@vuokko.info committed
79
	compileExpr, HValue, dynCompileExpr,
80
	lookupName,
81
82
83
#endif

	-- * Abstract syntax elements
84

Simon Marlow's avatar
Simon Marlow committed
85
86
87
        -- ** Packages
        PackageId,

88
	-- ** Modules
Simon Marlow's avatar
Simon Marlow committed
89
90
	Module, mkModule, pprModule, moduleName, modulePackageId,
        ModuleName, mkModuleName, moduleNameString,
91

92
	-- ** Names
93
94
95
	Name, 
	nameModule, nameParent_maybe, pprParenSymName, nameSrcLoc,
	NamedThing(..),
Simon Marlow's avatar
Simon Marlow committed
96
	RdrName(Qual,Unqual),
97
98
	
	-- ** Identifiers
99
	Id, idType,
100
	isImplicitId, isDeadBinder,
101
	isExportedId, isLocalId, isGlobalId,
102
	isRecordSelector,
103
	isPrimOpId, isFCallId, isClassOpId_maybe,
104
105
	isDataConWorkId, idDataCon,
	isBottomingId, isDictonaryId,
106
	recordSelectorFieldLabel,
107
108
109

	-- ** Type constructors
	TyCon, 
110
	tyConTyVars, tyConDataCons, tyConArity,
111
	isClassTyCon, isSynTyCon, isNewTyCon, isPrimTyCon, isFunTyCon,
112
113
	isOpenTyCon,
	synTyConDefn, synTyConType, synTyConResKind,
114

115
116
117
118
	-- ** Type variables
	TyVar,
	alphaTyVars,

119
120
	-- ** Data constructors
	DataCon,
121
122
123
124
	dataConSig, dataConType, dataConTyCon, dataConFieldLabels,
	dataConIsInfix, isVanillaDataCon,
	dataConStrictMarks,  
	StrictnessMark(..), isMarkedStrict,
125
126
127

	-- ** Classes
	Class, 
128
129
	classMethods, classSCTheta, classTvsFds,
	pprFundeps,
130

131
	-- ** Instances
132
	Instance, 
133
	instanceDFunId, pprInstance, pprInstanceHdr,
134

135
	-- ** Types and Kinds
136
	Type, dropForAlls, splitForAllTys, funResultTy, pprParendType,
137
	Kind,
138
139
	PredType,
	ThetaType, pprThetaArrow,
140
141

	-- ** Entities
142
143
	TyThing(..), 

144
145
146
	-- ** Syntax
	module HsSyn, -- ToDo: remove extraneous bits

147
148
149
150
151
152
153
154
155
	-- ** Fixities
	FixityDirection(..), 
	defaultFixity, maxPrecedence, 
	negateFixity,
	compareFixity,

	-- ** Source locations
	SrcLoc, pprDefnLoc,

156
157
158
159
	-- * Exceptions
	GhcException(..), showGhcException,

	-- * Miscellaneous
160
161
	sessionHscEnv,
	cyclicModuleErr,
162
163
  ) where

164
165
166
{-
 ToDo:

167
  * inline bits of HscMain here to simplify layering: hscTcExpr, hscStmt.
168
169
170
171
172
173
174
  * what StaticFlags should we expose, if any?
-}

#include "HsVersions.h"

#ifdef GHCI
import qualified Linker
ei@vuokko.info's avatar
ei@vuokko.info committed
175
import Data.Dynamic     ( Dynamic )
176
import Linker		( HValue, extendLinkEnv )
177
178
import TcRnDriver	( tcRnLookupRdrName, tcRnGetInfo,
			  tcRnLookupName, getModuleExports )
179
180
import RdrName		( plusGlobalRdrEnv, Provenance(..), 
			  ImportSpec(..), ImpDeclSpec(..), ImpItemSpec(..),
181
			  mkGlobalRdrEnv )
182
import HscMain		( hscParseIdentifier, hscStmt, hscTcExpr, hscKcType )
Simon Marlow's avatar
Simon Marlow committed
183
import Name		( nameOccName )
184
185
186
187
188
import Type		( tidyType )
import VarEnv		( emptyTidyEnv )
import GHC.Exts		( unsafeCoerce# )
#endif

189
import Packages		( initPackages )
190
import NameSet		( NameSet, nameSetToList, elemNameSet )
Simon Marlow's avatar
Simon Marlow committed
191
import RdrName		( GlobalRdrEnv, GlobalRdrElt(..), RdrName(..), 
192
193
			  globalRdrEnvElts, extendGlobalRdrEnv,
                          emptyGlobalRdrEnv )
194
import HsSyn
195
196
197
import Type		( Kind, Type, dropForAlls, PredType, ThetaType,
			  pprThetaArrow, pprParendType, splitForAllTys,
			  funResultTy )
198
import Id		( Id, idType, isImplicitId, isDeadBinder,
199
                          isExportedId, isLocalId, isGlobalId,
200
201
                          isRecordSelector, recordSelectorFieldLabel,
                          isPrimOpId, isFCallId, isClassOpId_maybe,
202
203
                          isDataConWorkId, idDataCon,
                          isBottomingId )
204
205
import Var		( TyVar )
import TysPrim		( alphaTyVars )
206
import TyCon		( TyCon, isClassTyCon, isSynTyCon, isNewTyCon,
207
208
209
			  isPrimTyCon, isFunTyCon, isOpenTyCon, tyConArity,
			  tyConTyVars, tyConDataCons, synTyConDefn,
			  synTyConType, synTyConResKind )
210
211
212
213
214
215
import Class		( Class, classSCTheta, classTvsFds, classMethods )
import FunDeps		( pprFundeps )
import DataCon		( DataCon, dataConWrapId, dataConSig, dataConTyCon,
			  dataConFieldLabels, dataConStrictMarks, 
			  dataConIsInfix, isVanillaDataCon )
import Name		( Name, nameModule, NamedThing(..), nameParent_maybe,
Simon Marlow's avatar
Simon Marlow committed
216
			  nameSrcLoc )
217
import OccName		( parenSymOcc )
218
import NameEnv		( nameEnvElts )
219
import InstEnv		( Instance, instanceDFunId, pprInstance, pprInstanceHdr )
220
import SrcLoc
221
222
import DriverPipeline
import DriverPhases	( Phase(..), isHaskellSrcFilename, startPhase )
223
import HeaderInfo	( getImports, getOptions )
224
import Finder
225
import HscMain		( newHscEnv, hscFileCheck, HscChecked(..) )
226
227
import HscTypes
import DynFlags
228
229
import SysTools     ( initSysTools, cleanTempFiles, cleanTempFilesExcept,
                      cleanTempDirs )
230
import Module
Simon Marlow's avatar
Simon Marlow committed
231
import UniqFM
ei@vuokko.info's avatar
ei@vuokko.info committed
232
import PackageConfig    ( PackageId, stringToPackageId )
233
234
import FiniteMap
import Panic
235
import Digraph
236
import Bag		( unitBag )
237
import ErrUtils		( Severity(..), showPass, fatalErrorMsg, debugTraceMsg,
Simon Marlow's avatar
Simon Marlow committed
238
			  mkPlainErrMsg, printBagOfErrors )
239
import qualified ErrUtils
240
import Util
241
import StringBuffer	( StringBuffer, hGetStringBuffer )
242
import Outputable
243
import BasicTypes
244
import TcType           ( tcSplitSigmaTy, isDictTy )
245
import Maybes		( expectJust, mapCatMaybes )
246
247
248

import Control.Concurrent
import System.Directory ( getModificationTime, doesFileExist )
249
import Data.Maybe	( isJust, isNothing )
250
251
252
253
254
255
256
257
import Data.List	( partition, nub )
import qualified Data.List as List
import Control.Monad	( unless, when )
import System.Exit	( exitWith, ExitCode(..) )
import System.Time	( ClockTime )
import Control.Exception as Exception hiding (handle)
import Data.IORef
import System.IO
258
import System.IO.Error	( isDoesNotExistError )
259
import Prelude hiding (init)
260

261
262
263
264
265
266
#if __GLASGOW_HASKELL__ < 600
import System.IO as System.IO.Error ( try )
#else
import System.IO.Error	( try )
#endif

267
-- -----------------------------------------------------------------------------
268
-- Exception handlers
269
270
271
272
273

-- | 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.
274
275
defaultErrorHandler :: DynFlags -> IO a -> IO a
defaultErrorHandler dflags inner = 
276
277
278
279
280
  -- top-level exception handler: any unrecognised exception is a compiler bug.
  handle (\exception -> do
  	   hFlush stdout
	   case exception of
		-- an IO exception probably isn't our fault, so don't panic
281
282
		IOException _ ->
		  fatalErrorMsg dflags (text (show exception))
283
		AsyncException StackOverflow ->
284
285
286
		  fatalErrorMsg dflags (text "stack overflow: use +RTS -K<size> to increase it")
		_other ->
		  fatalErrorMsg dflags (text (show (Panic (show exception))))
287
288
289
	   exitWith (ExitFailure 1)
         ) $

290
291
  -- program errors: messages with locations attached.  Sometimes it is
  -- convenient to just throw these as exceptions.
292
  handleDyn (\dyn -> do printBagOfErrors dflags (unitBag dyn)
293
294
295
			exitWith (ExitFailure 1)) $

  -- error messages propagated as exceptions
296
297
298
299
300
  handleDyn (\dyn -> do
  		hFlush stdout
  		case dyn of
		     PhaseFailed _ code -> exitWith code
		     Interrupted -> exitWith (ExitFailure 1)
301
		     _ -> do fatalErrorMsg dflags (text (show (dyn :: GhcException)))
302
303
304
305
306
307
308
309
			     exitWith (ExitFailure 1)
	    ) $
  inner

-- | Install a default cleanup handler to remove temporary files
-- deposited by a GHC run.  This is seperate from
-- 'defaultErrorHandler', because you might want to override the error
-- handling, but still get the ordinary cleanup behaviour.
310
311
defaultCleanupHandler :: DynFlags -> IO a -> IO a
defaultCleanupHandler dflags inner = 
312
313
314
315
316
317
318
319
320
    -- make sure we clean up after ourselves
    later (unless (dopt Opt_KeepTmpFiles dflags) $
               do cleanTempFiles dflags
                  cleanTempDirs dflags
          )
          -- exceptions will be blocked while we clean the temporary files,
          -- so there shouldn't be any difficulty if we receive further
          -- signals.
    inner
321
322
323
324


-- | Starts a new session.  A session consists of a set of loaded
-- modules, a set of options (DynFlags), and an interactive context.
325
-- ToDo: GhcMode should say "keep typechecked code" and\/or "keep renamed
326
-- code".
327
328
329
330
331
332
333
334
335
newSession :: GhcMode -> Maybe FilePath -> IO Session
newSession mode mb_top_dir = do
  -- catch ^C
  main_thread <- myThreadId
  putMVar interruptTargetThread [main_thread]
  installSignalHandlers

  dflags0 <- initSysTools mb_top_dir defaultDynFlags
  dflags  <- initDynFlags dflags0
336
  env <- newHscEnv dflags{ ghcMode=mode }
337
  ref <- newIORef env
338
339
340
341
342
343
344
345
346
347
348
349
  return (Session ref)

-- tmp: this breaks the abstraction, but required because DriverMkDepend
-- needs to call the Finder.  ToDo: untangle this.
sessionHscEnv :: Session -> IO HscEnv
sessionHscEnv (Session ref) = readIORef ref

withSession :: Session -> (HscEnv -> IO a) -> IO a
withSession (Session ref) f = do h <- readIORef ref; f h

modifySession :: Session -> (HscEnv -> HscEnv) -> IO ()
modifySession (Session ref) f = do h <- readIORef ref; writeIORef ref $! f h
350
351
352
353
354
355

-- -----------------------------------------------------------------------------
-- Flags & settings

-- | Grabs the DynFlags from the Session
getSessionDynFlags :: Session -> IO DynFlags
356
getSessionDynFlags s = withSession s (return . hsc_dflags)
357

358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
-- | Updates the 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 :: Session -> DynFlags -> IO [PackageId]
setSessionDynFlags (Session ref) dflags = do
  hsc_env <- readIORef ref
  (dflags', preload) <- initPackages dflags
  writeIORef ref $! hsc_env{ hsc_dflags = dflags' }
  return preload
375

376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
-- | If there is no -o option, guess the name of target executable
-- by using top-level source file name as a base.
guessOutputFile :: Session -> IO ()
guessOutputFile s = modifySession s $ \env ->
    let dflags = hsc_dflags env
        mod_graph = hsc_mod_graph env
        mainModuleSrcPath, guessedName :: Maybe String
        mainModuleSrcPath = do
            let isMain = (== mainModIs dflags) . ms_mod
            [ms] <- return (filter isMain mod_graph)
            ml_hs_file (ms_location ms)
        guessedName = fmap basenameOf mainModuleSrcPath
    in
    case outputFile dflags of
        Just _ -> env
        Nothing -> env { hsc_dflags = dflags { outputFile = guessedName } }

393
-- -----------------------------------------------------------------------------
394
-- Targets
395
396
397
398
399
400

-- 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
401
-- the program\/library.  Unloading the current program is achieved by
402
-- setting the current set of targets to be empty, followed by load.
403
setTargets :: Session -> [Target] -> IO ()
404
setTargets s targets = modifySession s (\h -> h{ hsc_targets = targets })
405
406

-- | returns the current set of targets
407
408
getTargets :: Session -> IO [Target]
getTargets s = withSession s (return . hsc_targets)
409

410
-- | Add another target
411
412
413
addTarget :: Session -> Target -> IO ()
addTarget s target
  = modifySession s (\h -> h{ hsc_targets = target : hsc_targets h })
414

415
416
417
418
419
420
-- | Remove a target
removeTarget :: Session -> TargetId -> IO ()
removeTarget s target_id
  = modifySession s (\h -> h{ hsc_targets = filter (hsc_targets h) })
  where
   filter targets = [ t | t@(Target id _) <- targets, id /= target_id ]
421

422
423
424
425
426
427
428
429
430
-- 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
--
431
432
433
434
guessTarget :: String -> Maybe Phase -> IO Target
guessTarget file (Just phase)
   = return (Target (TargetFile file (Just phase)) Nothing)
guessTarget file Nothing
435
   | isHaskellSrcFilename file
436
   = return (Target (TargetFile file Nothing) Nothing)
437
438
   | otherwise
   = do exists <- doesFileExist hs_file
439
440
441
	if exists
	   then return (Target (TargetFile hs_file Nothing) Nothing)
	   else do
442
	exists <- doesFileExist lhs_file
443
444
445
	if exists
	   then return (Target (TargetFile lhs_file Nothing) Nothing)
	   else do
Simon Marlow's avatar
Simon Marlow committed
446
	return (Target (TargetModule (mkModuleName file)) Nothing)
447
     where 
448
449
	 hs_file  = file `joinFileExt` "hs"
	 lhs_file = file `joinFileExt` "lhs"
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
-- -----------------------------------------------------------------------------
-- Extending the program scope

extendGlobalRdrScope :: Session -> [GlobalRdrElt] -> IO ()
extendGlobalRdrScope session rdrElts
    = modifySession session $ \hscEnv ->
      let global_rdr = hsc_global_rdr_env hscEnv
      in hscEnv{ hsc_global_rdr_env = foldl extendGlobalRdrEnv global_rdr rdrElts }

setGlobalRdrScope :: Session -> [GlobalRdrElt] -> IO ()
setGlobalRdrScope session rdrElts
    = modifySession session $ \hscEnv ->
      hscEnv{ hsc_global_rdr_env = foldl extendGlobalRdrEnv emptyGlobalRdrEnv rdrElts }

extendGlobalTypeScope :: Session -> [Id] -> IO ()
extendGlobalTypeScope session ids
    = modifySession session $ \hscEnv ->
      let global_type = hsc_global_type_env hscEnv
      in hscEnv{ hsc_global_type_env = extendTypeEnvWithIds global_type ids }

setGlobalTypeScope :: Session -> [Id] -> IO ()
setGlobalTypeScope session ids
    = modifySession session $ \hscEnv ->
      hscEnv{ hsc_global_type_env = extendTypeEnvWithIds emptyTypeEnv ids }

476
477
-- -----------------------------------------------------------------------------
-- Loading the program
478

479
480
-- Perform a dependency analysis starting from the current targets
-- and update the session with the new module graph.
Simon Marlow's avatar
Simon Marlow committed
481
depanal :: Session -> [ModuleName] -> Bool -> IO (Maybe ModuleGraph)
482
depanal (Session ref) excluded_mods allow_dup_roots = do
483
484
485
486
487
488
489
490
  hsc_env <- readIORef ref
  let
	 dflags  = hsc_dflags hsc_env
	 gmode   = ghcMode (hsc_dflags hsc_env)
	 targets = hsc_targets hsc_env
	 old_graph = hsc_mod_graph hsc_env
	
  showPass dflags "Chasing dependencies"
491
  when (gmode == BatchCompile) $
492
	debugTraceMsg dflags 2 (hcat [
493
		     text "Chasing modules from: ",
494
	     		hcat (punctuate comma (map pprTarget targets))])
495

496
  r <- downsweep hsc_env old_graph excluded_mods allow_dup_roots
497
  case r of
498
    Just mod_graph -> writeIORef ref hsc_env{ hsc_mod_graph = mod_graph }
499
500
    _ -> return ()
  return r
501

502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
{-
-- | The result of load.
data LoadResult
  = LoadOk	Errors	-- ^ all specified targets were loaded successfully.
  | LoadFailed  Errors	-- ^ not all modules were loaded.

type Errors = [String]

data ErrMsg = ErrMsg { 
	errMsgSeverity  :: Severity,  -- warning, error, etc.
	errMsgSpans     :: [SrcSpan],
	errMsgShortDoc  :: Doc,
	errMsgExtraInfo :: Doc
	}
-}

data LoadHowMuch
   = LoadAllTargets
Simon Marlow's avatar
Simon Marlow committed
520
521
   | LoadUpTo ModuleName
   | LoadDependenciesOf ModuleName
522
523
524
525

-- | Try to load the program.  If a Module is supplied, then just
-- attempt to load up to this target.  If no Module is supplied,
-- then try to load all targets.
526
load :: Session -> LoadHowMuch -> IO SuccessFlag
527
load s@(Session ref) how_much
528
   = do 
529
530
531
532
	-- Dependency analysis first.  Note that this fixes the module graph:
	-- even if we don't get a fully successful upsweep, the full module
	-- graph is still retained in the Session.  We can tell which modules
	-- were successfully loaded by inspecting the Session's HPT.
533
	mb_graph <- depanal s [] False
534
535
536
	case mb_graph of	   
	   Just mod_graph -> load2 s how_much mod_graph 
	   Nothing        -> return Failed
537

538
load2 s@(Session ref) how_much mod_graph = do
539
        guessOutputFile s
540
541
542
543
	hsc_env <- readIORef ref

        let hpt1      = hsc_HPT hsc_env
        let dflags    = hsc_dflags hsc_env
544
        let ghci_mode = ghcMode dflags -- this never changes
545
546
547
548
549

	-- The "bad" boot modules are the ones for which we have
	-- B.hs-boot in the module graph, but no B.hs
	-- The downsweep should have ensured this does not happen
	-- (see msDeps)
Simon Marlow's avatar
Simon Marlow committed
550
551
        let all_home_mods = [ms_mod_name s 
			    | s <- mod_graph, not (isBootSummary s)]
552
#ifdef DEBUG
553
	    bad_boot_mods = [s 	      | s <- mod_graph, isBootSummary s,
Simon Marlow's avatar
Simon Marlow committed
554
					not (ms_mod_name s `elem` all_home_mods)]
555
#endif
556
557
558
559
560
561
562
563
	ASSERT( null bad_boot_mods ) return ()

        -- mg2_with_srcimps drops the hi-boot nodes, returning a 
	-- graph with cycles.  Among other things, it is used for
        -- backing out partially complete cycles following a failed
        -- upsweep, and for removing from hpt all the modules
        -- not in strict downwards closure, during calls to compile.
        let mg2_with_srcimps :: [SCC ModSummary]
564
	    mg2_with_srcimps = topSortModuleGraph True mod_graph Nothing
565

566
567
568
569
570
571
572
573
574
575
576
577
578
	    -- check the stability property for each module.
	    stable_mods@(stable_obj,stable_bco)
		| BatchCompile <- ghci_mode = ([],[])
	        | otherwise = checkStability hpt1 mg2_with_srcimps all_home_mods

	    -- prune bits of the HPT which are definitely redundant now,
	    -- to save space.
	    pruned_hpt = pruneHomePackageTable hpt1 
				(flattenSCCs mg2_with_srcimps)
				stable_mods

	evaluate pruned_hpt

579
580
	debugTraceMsg dflags 2 (text "Stable obj:" <+> ppr stable_obj $$
				text "Stable BCO:" <+> ppr stable_bco)
581
582

	-- Unload any modules which are going to be re-linked this time around.
583
584
	let stable_linkables = [ linkable
			       | m <- stable_obj++stable_bco,
Simon Marlow's avatar
Simon Marlow committed
585
				 Just hmi <- [lookupUFM pruned_hpt m],
586
				 Just linkable <- [hm_linkable hmi] ]
587
588
589
590
591
592
593
594
595
596
597
598
	unload hsc_env stable_linkables

        -- We could at this point detect cycles which aren't broken by
        -- a source-import, and complain immediately, but it seems better
        -- to let upsweep_mods do this, so at least some useful work gets
        -- done before the upsweep is abandoned.
        --hPutStrLn stderr "after tsort:\n"
        --hPutStrLn stderr (showSDoc (vcat (map ppr mg2)))

        -- Now do the upsweep, calling compile for each module in
        -- turn.  Final result is version 3 of everything.

599
600
601
602
603
604
        -- Topologically sort the module graph, this time including hi-boot
	-- nodes, and possibly just including the portion of the graph
	-- reachable from the module specified in the 2nd argument to load.
	-- This graph should be cycle-free.
	-- If we're restricting the upsweep to a portion of the graph, we
	-- also want to retain everything that is still stable.
605
        let full_mg :: [SCC ModSummary]
606
	    full_mg    = topSortModuleGraph False mod_graph Nothing
607
608
609

	    maybe_top_mod = case how_much of
				LoadUpTo m           -> Just m
610
			  	LoadDependenciesOf m -> Just m
611
612
			  	_		     -> Nothing

613
614
615
616
617
618
619
620
621
	    partial_mg0 :: [SCC ModSummary]
	    partial_mg0 = topSortModuleGraph False mod_graph maybe_top_mod

	    -- LoadDependenciesOf m: we want the upsweep to stop just
	    -- short of the specified module (unless the specified module
	    -- is stable).
	    partial_mg
		| LoadDependenciesOf mod <- how_much
		= ASSERT( case last partial_mg0 of 
Simon Marlow's avatar
Simon Marlow committed
622
			    AcyclicSCC ms -> ms_mod_name ms == mod; _ -> False )
623
624
625
626
		  List.init partial_mg0
		| otherwise
		= partial_mg0
  
627
628
629
	    stable_mg = 
		[ AcyclicSCC ms
	        | AcyclicSCC ms <- full_mg,
Simon Marlow's avatar
Simon Marlow committed
630
631
632
		  ms_mod_name ms `elem` stable_obj++stable_bco,
		  ms_mod_name ms `notElem` [ ms_mod_name ms' | 
						AcyclicSCC ms' <- partial_mg ] ]
633
634
635

	    mg = stable_mg ++ partial_mg

636
637
	-- clean up between compilations
	let cleanup = cleanTempFilesExcept dflags
638
			  (ppFilesFromSummaries (flattenSCCs mg2_with_srcimps))
639

640
641
        (upsweep_ok, hsc_env1, modsUpswept)
           <- upsweep (hsc_env { hsc_HPT = emptyHomePackageTable })
642
			   pruned_hpt stable_mods cleanup mg
643
644
645
646
647

	-- Make modsDone be the summaries for each home module now
	-- available; this should equal the domain of hpt3.
        -- Get in in a roughly top .. bottom order (hence reverse).

648
        let modsDone = reverse modsUpswept
649
650
651
652
653
654
655
656

        -- Try and do linking in some form, depending on whether the
        -- upsweep was completely or only partially successful.

        if succeeded upsweep_ok

         then 
           -- Easy; just relink it all.
657
           do debugTraceMsg dflags 2 (text "Upsweep completely successful.")
658
659
660
661
662
663
664
665
666
667
668
669
670

	      -- Clean up after ourselves
	      cleanTempFilesExcept dflags (ppFilesFromSummaries modsDone)

	      -- Issue a warning for the confusing case where the user
	      -- said '-o foo' but we're not going to do any linking.
	      -- We attempt linking if either (a) one of the modules is
	      -- called Main, or (b) the user said -no-hs-main, indicating
	      -- that main() is going to come from somewhere else.
	      --
	      let ofile = outputFile dflags
	      let no_hs_main = dopt Opt_NoHsMain dflags
	      let 
671
672
	 	main_mod = mainModIs dflags
		a_root_is_Main = any ((==main_mod).ms_mod) mod_graph
673
674
		do_linking = a_root_is_Main || no_hs_main

675
	      when (ghci_mode == BatchCompile && isJust ofile && not do_linking) $
676
677
	        debugTraceMsg dflags 1 (text ("Warning: output was redirected with -o, " ++
				              "but no output will be generated\n" ++
Simon Marlow's avatar
Simon Marlow committed
678
				              "because there is no " ++ moduleNameString (moduleName main_mod) ++ " module."))
679
680

	      -- link everything together
681
              linkresult <- link ghci_mode dflags do_linking (hsc_HPT hsc_env1)
682

683
	      loadFinish Succeeded linkresult ref hsc_env1
684
685
686
687
688

         else 
           -- Tricky.  We need to back out the effects of compiling any
           -- half-done cycles, both so as to clean up the top level envs
           -- and to avoid telling the interactive linker to link them.
689
           do debugTraceMsg dflags 2 (text "Upsweep partially successful.")
690
691
692
693
694
695
696
697
698
699

              let modsDone_names
                     = map ms_mod modsDone
              let mods_to_zap_names 
                     = findPartiallyCompletedCycles modsDone_names 
			  mg2_with_srcimps
              let mods_to_keep
                     = filter ((`notElem` mods_to_zap_names).ms_mod) 
			  modsDone

Simon Marlow's avatar
Simon Marlow committed
700
              let hpt4 = retainInTopLevelEnvs (map ms_mod_name mods_to_keep) 
701
					      (hsc_HPT hsc_env1)
702
703
704
705

	      -- Clean up after ourselves
	      cleanTempFilesExcept dflags (ppFilesFromSummaries mods_to_keep)

706
707
	      -- there should be no Nothings where linkables should be, now
	      ASSERT(all (isJust.hm_linkable) 
Simon Marlow's avatar
Simon Marlow committed
708
			(eltsUFM (hsc_HPT hsc_env))) do
709
	
710
711
712
	      -- Link everything together
              linkresult <- link ghci_mode dflags False hpt4

713
	      let hsc_env4 = hsc_env1{ hsc_HPT = hpt4 }
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
	      loadFinish Failed linkresult ref hsc_env4

-- Finish up after a load.

-- If the link failed, unload everything and return.
loadFinish all_ok Failed ref hsc_env
  = do unload hsc_env []
       writeIORef ref $! discardProg hsc_env
       return Failed

-- Empty the interactive context and set the module context to the topmost
-- newly loaded module, or the Prelude if none were loaded.
loadFinish all_ok Succeeded ref hsc_env
  = do writeIORef ref $! hsc_env{ hsc_IC = emptyInteractiveContext }
       return all_ok

730

731
732
733
734
735
736
737
738
739
740
-- Forget the current program, but retain the persistent info in HscEnv
discardProg :: HscEnv -> HscEnv
discardProg hsc_env
  = hsc_env { hsc_mod_graph = emptyMG, 
	      hsc_IC = emptyInteractiveContext,
	      hsc_HPT = emptyHomePackageTable }

-- used to fish out the preprocess output files for the purposes of
-- cleaning up.  The preprocessed file *might* be the same as the
-- source file, but that doesn't do any harm.
741
ppFilesFromSummaries summaries = map ms_hspp_file summaries
742

743
744
745
746
747
-- -----------------------------------------------------------------------------
-- Check module

data CheckedModule = 
  CheckedModule { parsedSource      :: ParsedSource,
748
		  renamedSource     :: Maybe RenamedSource,
749
750
751
		  typecheckedSource :: Maybe TypecheckedSource,
		  checkedModuleInfo :: Maybe ModuleInfo
	        }
752
753
754
755
756
	-- 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 within CheckedModule.
757

758
type ParsedSource      = Located (HsModule RdrName)
759
type RenamedSource     = (HsGroup Name, [LImportDecl Name], Maybe [LIE Name])
760
761
type TypecheckedSource = LHsBinds Id

762
763
764
765
766
767
768
769
770
771
772
773
774
-- 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


775
776
777
778
-- | This is the way to get access to parsed and typechecked source code
-- for a module.  'checkModule' loads all the dependencies of the specified
-- module in the Session, and then attempts to typecheck the module.  If
-- successful, it returns the abstract syntax for the module.
Simon Marlow's avatar
Simon Marlow committed
779
checkModule :: Session -> ModuleName -> IO (Maybe CheckedModule)
780
checkModule session@(Session ref) mod = do
781
	-- load up the dependencies first
782
   r <- load session (LoadDependenciesOf mod)
783
784
785
786
787
   if (failed r) then return Nothing else do

	-- now parse & typecheck the module
   hsc_env <- readIORef ref   
   let mg  = hsc_mod_graph hsc_env
Simon Marlow's avatar
Simon Marlow committed
788
   case [ ms | ms <- mg, ms_mod_name ms == mod ] of
789
790
	[] -> return Nothing
	(ms:_) -> do 
791
	   mbChecked <- hscFileCheck hsc_env{hsc_dflags=ms_hspp_opts ms} ms
792
793
794
	   case mbChecked of
             Nothing -> return Nothing
             Just (HscChecked parsed renamed Nothing) ->
795
796
797
798
799
		   return (Just (CheckedModule {
					parsedSource = parsed,
					renamedSource = renamed,
					typecheckedSource = Nothing,
					checkedModuleInfo = Nothing }))
800
801
             Just (HscChecked parsed renamed
			   (Just (tc_binds, rdr_env, details))) -> do
802
		   let minf = ModuleInfo {
803
804
805
806
				minf_type_env  = md_types details,
				minf_exports   = md_exports details,
				minf_rdr_env   = Just rdr_env,
				minf_instances = md_insts details
807
808
809
			      }
		   return (Just (CheckedModule {
					parsedSource = parsed,
810
					renamedSource = renamed,
811
812
813
814
					typecheckedSource = Just tc_binds,
					checkedModuleInfo = Just minf }))

-- ---------------------------------------------------------------------------
815
816
817
818
819
-- Unloading

unload :: HscEnv -> [Linkable] -> IO ()
unload hsc_env stable_linkables	-- Unload everthing *except* 'stable_linkables'
  = case ghcMode (hsc_dflags hsc_env) of
820
821
	BatchCompile  -> return ()
	JustTypecheck -> return ()
822
823
824
825
826
827
828
#ifdef GHCI
	Interactive -> Linker.unload (hsc_dflags hsc_env) stable_linkables
#else
	Interactive -> panic "unload: no interpreter"
#endif
	other -> panic "unload: strange mode"

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
-- -----------------------------------------------------------------------------
-- checkStability

{-
  Stability tells us which modules definitely do not need to be recompiled.
  There are two main reasons for having stability:
  
   - avoid doing a complete upsweep of the module graph in GHCi when
     modules near the bottom of the tree have not changed.

   - to tell GHCi when it can load object code: we can only load object code
     for a module when we also load object code fo  all of the imports of the
     module.  So we need to know that we will definitely not be recompiling
     any of these modules, and we can use the object code.

  NB. stability is of no importance to BatchCompile at all, only Interactive.
  (ToDo: what about JustTypecheck?)

  The stability check is as follows.  Both stableObject and
  stableBCO are used during the upsweep phase later.

  -------------------
  stable m = stableObject m || stableBCO m

  stableObject m = 
	all stableObject (imports m)
	&& old linkable does not exist, or is == on-disk .o
	&& date(on-disk .o) > date(.hs)

  stableBCO m =
	all stable (imports m)
	&& date(BCO) > date(.hs)
  -------------------    

  These properties embody the following ideas:

    - if a module is stable:
	- if it has been compiled in a previous pass (present in HPT)
	  then it does not need to be compiled or re-linked.
        - if it has not been compiled in a previous pass,
	  then we only need to read its .hi file from disk and
	  link it to produce a ModDetails.

    - if a modules is not stable, we will definitely be at least
      re-linking, and possibly re-compiling it during the upsweep.
      All non-stable modules can (and should) therefore be unlinked
      before the upsweep.

    - Note that objects are only considered stable if they only depend
      on other objects.  We can't link object code against byte code.
-}

checkStability
	:: HomePackageTable		-- HPT from last compilation
	-> [SCC ModSummary]		-- current module graph (cyclic)
Simon Marlow's avatar
Simon Marlow committed
884
885
886
	-> [ModuleName]			-- all home modules
	-> ([ModuleName],		-- stableObject
	    [ModuleName])		-- stableBCO
887
888
889
890
891
892
893
894
895

checkStability hpt sccs all_home_mods = foldl checkSCC ([],[]) sccs
  where
   checkSCC (stable_obj, stable_bco) scc0
     | stableObjects = (scc_mods ++ stable_obj, stable_bco)
     | stableBCOs    = (stable_obj, scc_mods ++ stable_bco)
     | otherwise     = (stable_obj, stable_bco)
     where
	scc = flattenSCC scc0
Simon Marlow's avatar
Simon Marlow committed
896
	scc_mods = map ms_mod_name scc
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
	home_module m   = m `elem` all_home_mods && m `notElem` scc_mods

        scc_allimps = nub (filter home_module (concatMap ms_allimps scc))
	    -- all imports outside the current SCC, but in the home pkg
	
	stable_obj_imps = map (`elem` stable_obj) scc_allimps
	stable_bco_imps = map (`elem` stable_bco) scc_allimps

	stableObjects = 
	   and stable_obj_imps
	   && all object_ok scc

	stableBCOs = 
	   and (zipWith (||) stable_obj_imps stable_bco_imps)
	   && all bco_ok scc

	object_ok ms
	  | Just t <- ms_obj_date ms  =  t >= ms_hs_date ms 
					 && same_as_prev t
	  | otherwise = False
	  where
Simon Marlow's avatar
Simon Marlow committed
918
	     same_as_prev t = case lookupUFM hpt (ms_mod_name ms) of
919
920
				Just hmi  | Just l <- hm_linkable hmi
				 -> isObjectLinkable l && t == linkableTime l
921
				_other  -> True
922
		-- why '>=' rather than '>' above?  If the filesystem stores
923
924
925
926
927
928
		-- times to the nearset second, we may occasionally find that
		-- the object & source have the same modification time, 
		-- especially if the source was automatically generated
		-- and compiled.  Using >= is slightly unsafe, but it matches
		-- make's behaviour.

929
	bco_ok ms
Simon Marlow's avatar
Simon Marlow committed
930
	  = case lookupUFM hpt (ms_mod_name ms) of
931
932
933
		Just hmi  | Just l <- hm_linkable hmi ->
			not (isObjectLinkable l) && 
			linkableTime l >= ms_hs_date ms
934
		_other  -> False
935

Simon Marlow's avatar
Simon Marlow committed
936
ms_allimps :: ModSummary -> [ModuleName]
937
ms_allimps ms = map unLoc (ms_srcimps ms ++ ms_imps ms)
938

939
940
-- -----------------------------------------------------------------------------
-- Prune the HomePackageTable
941

942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
-- Before doing an upsweep, we can throw away:
--
--   - For non-stable modules:
--	- all ModDetails, all linked code
--   - all unlinked code that is out of date with respect to
--     the source file
--
-- This is VERY IMPORTANT otherwise we'll end up requiring 2x the
-- space at the end of the upsweep, because the topmost ModDetails of the
-- old HPT holds on to the entire type environment from the previous
-- compilation.

pruneHomePackageTable
   :: HomePackageTable
   -> [ModSummary]
Simon Marlow's avatar
Simon Marlow committed
957
   -> ([ModuleName],[ModuleName])
958
959
960
   -> HomePackageTable

pruneHomePackageTable hpt summ (stable_obj, stable_bco)
Simon Marlow's avatar
Simon Marlow committed
961
  = mapUFM prune hpt
962
963
964
965
  where prune hmi
	  | is_stable modl = hmi'
	  | otherwise      = hmi'{ hm_details = emptyModDetails }
	  where
Simon Marlow's avatar
Simon Marlow committed
966
	   modl = moduleName (mi_module (hm_iface hmi))
967
968
969
970
	   hmi' | Just l <- hm_linkable hmi, linkableTime l < ms_hs_date ms
		= hmi{ hm_linkable = Nothing }
		| otherwise
		= hmi
Simon Marlow's avatar
Simon Marlow committed
971
		where ms = expectJust "prune" (lookupUFM ms_map modl)
972

Simon Marlow's avatar
Simon Marlow committed
973
        ms_map = listToUFM [(ms_mod_name ms, ms) | ms <- summ]
974

975
976
977
	is_stable m = m `elem` stable_obj || m `elem` stable_bco

-- -----------------------------------------------------------------------------
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998

-- Return (names of) all those in modsDone who are part of a cycle
-- as defined by theGraph.
findPartiallyCompletedCycles :: [Module] -> [SCC ModSummary] -> [Module]
findPartiallyCompletedCycles modsDone theGraph
   = chew theGraph
     where
        chew [] = []
        chew ((AcyclicSCC v):rest) = chew rest    -- acyclic?  not interesting.
        chew ((CyclicSCC vs):rest)
           = let names_in_this_cycle = nub (map ms_mod vs)
                 mods_in_this_cycle  
                    = nub ([done | done <- modsDone, 
                                   done `elem` names_in_this_cycle])
                 chewed_rest = chew rest
             in 
             if   notNull mods_in_this_cycle
                  && length mods_in_this_cycle < length names_in_this_cycle
             then mods_in_this_cycle ++ chewed_rest
             else chewed_rest

999
1000
1001
1002
1003
-- -----------------------------------------------------------------------------
-- The upsweep

-- This is where we compile each module in the module graph, in a pass
-- from the bottom to the top of the graph.
1004
1005

-- There better had not be any cyclic groups here -- we check for them.
1006
1007
1008
1009

upsweep
    :: HscEnv			-- Includes initially-empty HPT
    -> HomePackageTable		-- HPT from last time round (pruned)
Simon Marlow's avatar
Simon Marlow committed
1010
    -> ([ModuleName],[ModuleName]) -- stable modules (see checkStability)
1011
1012
1013
1014
1015
1016
    -> IO ()			-- How to clean up unwanted tmp files
    -> [SCC ModSummary]		-- Mods to do (the worklist)
    -> IO (SuccessFlag,
           HscEnv,		-- With an updated HPT
           [ModSummary])	-- Mods which succeeded

1017
1018
upsweep hsc_env old_hpt stable_mods cleanup mods
   = upsweep' hsc_env old_hpt stable_mods cleanup mods 1 (length mods)
1019

1020
upsweep' hsc_env old_hpt stable_mods cleanup
1021
     [] _ _
1022
1023
   = return (Succeeded, hsc_env, [])

1024
upsweep' hsc_env old_hpt stable_mods cleanup
1025
     (CyclicSCC ms:_) _ _
1026
   = do fatalErrorMsg (hsc_dflags hsc_env) (cyclicModuleErr ms)
1027
1028
        return (Failed, hsc_env, [])

1029
upsweep' hsc_env old_hpt stable_mods cleanup
1030
     (AcyclicSCC mod:mods) mod_index nmods
1031
1032
1033
1034
   = do -- putStrLn ("UPSWEEP_MOD: hpt = " ++ 
	--	     show (map (moduleUserString.moduleName.mi_module.hm_iface) 
	--		       (moduleEnvElts (hsc_HPT hsc_env)))

1035
        mb_mod_info <- upsweep_mod hsc_env old_hpt stable_mods mod 
1036
                       mod_index nmods
1037
1038
1039
1040
1041
1042

	cleanup		-- Remove unwanted tmp files between compilations

        case mb_mod_info of
	    Nothing -> return (Failed, hsc_env, [])
	    Just mod_info -> do 
Simon Marlow's avatar
Simon Marlow committed
1043
		{ let this_mod = ms_mod_name mod
1044
1045

			-- Add new info to hsc_env
Simon Marlow's avatar
Simon Marlow committed
1046
		      hpt1     = addToUFM (hsc_HPT hsc_env) this_mod mod_info
1047
		      hsc_env1 = hsc_env { hsc_HPT = hpt1 }
1048
1049
1050
1051

			-- Space-saving: delete the old HPT entry
			-- for mod BUT if mod is a hs-boot
			-- node, don't delete it.  For the
1052
1053
1054
			-- interface, the HPT entry is probaby for the
			-- main Haskell source file.  Deleting it
			-- would force .. (what?? --SDM)
1055
		      old_hpt1 | isBootSummary mod = old_hpt
Simon Marlow's avatar
Simon Marlow committed
1056
			       | otherwise = delFromUFM old_hpt this_mod
1057

1058
		; (restOK, hsc_env2, modOKs) 
1059
			<- upsweep' hsc_env1 old_hpt1 stable_mods cleanup 
1060
				mods (mod_index+1) nmods
1061
1062
		; return (restOK, hsc_env2, mod:modOKs)
		}
1063
1064
1065
1066
1067


-- Compile a single module.  Always produce a Linkable for it if 
-- successful.  If no compilation happened, return the old Linkable.
upsweep_mod :: HscEnv
1068
            -> HomePackageTable
Simon Marlow's avatar
Simon Marlow committed
1069
	    -> ([ModuleName],[ModuleName])
1070
            -> ModSummary
1071
1072
            -> Int  -- index of module
            -> Int  -- total number of modules
1073
1074
            -> IO (Maybe HomeModInfo)	-- Nothing => Failed

1075
upsweep_mod hsc_env old_hpt (stable_obj, stable_bco) summary mod_index nmods
1076
   = do 
1077
        let 
Simon Marlow's avatar
Simon Marlow committed
1078
	    this_mod_name = ms_mod_name summary
1079
1080
1081
1082
1083
1084
	    this_mod    = ms_mod summary
	    mb_obj_date = ms_obj_date summary
	    obj_fn	= ml_obj_file (ms_location summary)
	    hs_date     = ms_hs_date summary

	    compile_it :: Maybe Linkable -> IO (Maybe HomeModInfo)
Simon Marlow's avatar
Simon Marlow committed
1085
	    compile_it  = upsweep_compile hsc_env old_hpt this_mod_name 
1086
				summary mod_index nmods
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

	case ghcMode (hsc_dflags hsc_env) of
	    BatchCompile ->
		case () of
		   -- Batch-compilating is easy: just check whether we have
		   -- an up-to-date object file.  If we do, then the compiler
		   -- needs to do a recompilation check.
		   _ | Just obj_date <- mb_obj_date, obj_date >= hs_date -> do
		           linkable <- 
				findObjectLinkable this_mod obj_fn obj_date
			   compile_it (Just linkable)

		     | otherwise ->
		           compile_it Nothing

	    interactive ->
		case () of
		    _ | is_stable_obj, isJust old_hmi ->
			   return old_hmi
			-- object is stable, and we have an entry in the
			-- old HPT: nothing to do

		      | is_stable_obj, isNothing old_hmi -> do
		           linkable <-
				findObjectLinkable this_mod obj_fn 
					(expectJust "upseep1" mb_obj_date)
			   compile_it (Just linkable)
			-- object is stable, but we need to load the interface
			-- off disk to make a HMI.

		      | is_stable_bco -> 
			   ASSERT(isJust old_hmi) -- must be in the old_hpt
			   return old_hmi
			-- BCO is stable: nothing to do

		      | Just hmi <- old_hmi,
			Just l <- hm_linkable hmi, not (isObjectLinkable l),
			linkableTime l >= ms_hs_date summary ->
			   compile_it (Just l)
			-- we have an old BCO that is up to date with respect
			-- to the source: do a recompilation check as normal.

		      | otherwise ->
			  compile_it Nothing
			-- no existing code at all: we must recompile.
		   where
Simon Marlow's avatar
Simon Marlow committed
1133
1134
		    is_stable_obj = this_mod_name `elem` stable_obj
		    is_stable_bco = this_mod_name `elem` stable_bco
1135

Simon Marlow's avatar
Simon Marlow committed
1136
		    old_hmi = lookupUFM old_hpt this_mod_name
1137
1138

-- Run hsc to compile a module
1139
upsweep_compile hsc_env old_hpt this_mod summary
1140
1141
                mod_index nmods
                mb_old_linkable = do
1142
  let
1143
1144
	-- The old interface is ok if it's in the old HPT 
	--	a) we're compiling a source file, and the old HPT
1145
	--	   entry is for a source file
1146
1147
1148
1149
1150
1151
	--	b) we're compiling a hs-boot file
	-- Case (b) allows an hs-boot file to get the interface of its
	-- real source file on the second iteration of the compilation
	-- manager, but that does no harm.  Otherwise the hs-boot file
	-- will always be recompiled

1152
        mb_old_iface 
Simon Marlow's avatar
Simon Marlow committed
1153
		= case lookupUFM old_hpt this_mod of
1154
1155
1156
1157
1158
1159
1160
		     Nothing	 			  -> Nothing
		     Just hm_info | isBootSummary summary -> Just iface
				  | not (mi_boot iface)   -> Just iface
				  | otherwise		  -> Nothing
				   where 
				     iface = hm_iface hm_info

1161
  compresult <- compile hsc_env summary mb_old_linkable mb_old_iface
1162
                        mod_index nmods
1163

1164
1165
1166
  case compresult of
        -- Compilation failed.  Compile may still have updated the PCS, tho.
        CompErrs -> return Nothing
1167

1168
1169
1170
1171
1172
	-- Compilation "succeeded", and may or may not have returned a new
	-- linkable (depending on whether compilation was actually performed
	-- or not).
	CompOK new_details new_iface new_linkable
              -> do let new_info = HomeModInfo { hm_iface = new_iface,
1173
1174
1175
1176
1177
1178
						 hm_details = new_details,
						 hm_linkable = new_linkable }
                    return (Just new_info)


-- Filter modules in the HPT
Simon Marlow's avatar
Simon Marlow committed
1179
retainInTopLevelEnvs :: [ModuleName] -> HomePackageTable -> HomePackageTable
1180
retainInTopLevelEnvs keep_these hpt
Simon Marlow's avatar
Simon Marlow committed
1181
   = listToUFM   [ (mod, expectJust "retain" mb_mod_info)
1182
		 | mod <- keep_these