This file is indexed.

/usr/share/boost-build/src/build-system.jam is in libboost1.62-tools-dev 1.62.0+dfsg-5.

This file is owned by root:root, with mode 0o644.

The actual contents of the file can be viewed below.

  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
# Copyright 2003, 2005, 2007 Dave Abrahams
# Copyright 2006, 2007 Rene Rivera
# Copyright 2003, 2004, 2005, 2006 Vladimir Prus
# Distributed under the Boost Software License, Version 1.0.
# (See accompanying file LICENSE_1_0.txt or copy at
# http://www.boost.org/LICENSE_1_0.txt)

# This file is part of Boost Build version 2. You can think of it as forming the
# main() routine. It is invoked by the bootstrapping code in bootstrap.jam.

import build-request ;
import builtin ;
import "class" : new ;
import configure ;
import config-cache ;
import feature ;
import generators ;
import make ;
import modules ;
import os ;
import path ;
import project ;
import property ;
import property-set ;
import regex ;
import sequence ;
import targets ;
import toolset ;
import utility ;
import version ;
import virtual-target ;


################################################################################
#
# Module global data.
#
################################################################################

# Shortcut used in this module for accessing used command-line parameters.
.argv = [ modules.peek : ARGV ] ;

# Flag indicating we should display additional debugging information related to
# locating and loading Boost Build configuration files.
.debug-config = [ MATCH ^(--debug-configuration)$ : $(.argv) ] ;

# Virtual targets obtained when building main targets references on the command
# line. When running 'bjam --clean main_target' we want to clean only files
# belonging to that main target so we need to record which targets are produced
# for it.
.results-of-main-targets = ;

# Was an XML dump requested?
.out-xml = [ MATCH ^--out-xml=(.*)$ : $(.argv) ] ;

# Default toolset & version to be used in case no other toolset has been used
# explicitly by either the loaded configuration files, the loaded project build
# scripts or an explicit toolset request on the command line. If not specified,
# an arbitrary default will be used based on the current host OS. This value,
# while not strictly necessary, has been added to allow testing Boost-Build's
# default toolset usage functionality.
.default-toolset = ;
.default-toolset-version = ;


################################################################################
#
# Public rules.
#
################################################################################

# Returns the property set with the free features from the currently processed
# build request.
#
rule command-line-free-features ( )
{
    return $(.command-line-free-features) ;
}


# Returns the location of the build system. The primary use case is building
# Boost where it is sometimes needed to get the location of other components
# (e.g. BoostBook files) and it is convenient to use locations relative to the
# Boost Build path.
#
rule location ( )
{
    local r = [ modules.binding build-system ] ;
    return $(r:P) ;
}


# Sets the default toolset & version to be used in case no other toolset has
# been used explicitly by either the loaded configuration files, the loaded
# project build scripts or an explicit toolset request on the command line. For
# more detailed information see the comment related to used global variables.
#
rule set-default-toolset ( toolset : version ? )
{
    .default-toolset = $(toolset) ;
    .default-toolset-version = $(version) ;
}

rule set-pre-build-hook ( function )
{
    .pre-build-hook = $(function) ;
}

rule set-post-build-hook ( function )
{
    .post-build-hook = $(function) ;
}

################################################################################
#
# Local rules.
#
################################################################################

# Returns actual Jam targets to be used for executing a clean request.
#
local rule actual-clean-targets ( )
{
    # The cleaning is tricky. Say, if user says 'bjam --clean foo' where 'foo'
    # is a directory, then we want to clean targets which are in 'foo' as well
    # as those in any children Jamfiles under foo but not in any unrelated
    # Jamfiles. To achieve this we first mark all projects explicitly detected
    # as targets for this build system run as needing to be cleaned.
    for local t in $(targets)
    {
        if [ class.is-a $(t) : project-target ]
        {
            local project = [ $(t).project-module ] ;
            .should-clean-project.$(project) = true ;
        }
    }

    # Construct a list of targets explicitly detected on this build system run
    # as a result of building main targets.
    local targets-to-clean ;
    for local t in $(.results-of-main-targets)
    {
        # Do not include roots or sources.
        targets-to-clean += [ virtual-target.traverse $(t) ] ;
    }
    targets-to-clean = [ sequence.unique $(targets-to-clean) ] ;

    local to-clean ;
    for local t in [ virtual-target.all-targets ]
    {
        # Remove only derived targets and only those asked to be cleaned,
        # whether directly or by belonging to one of the removed projects.
        local p = [ $(t).project ] ;
        if [ $(t).action ] && ( $(t) in $(targets-to-clean) ||
            [ should-clean-project [ $(p).project-module ] ] )
        {
            to-clean += $(t) ;
        }
    }

    local to-clean-actual ;
    for local t in $(to-clean)
    {
        to-clean-actual += [ $(t).actualize ] ;
    }
    return $(to-clean-actual) ;
}


# Given a target id, try to find and return the corresponding target. This is
# only invoked when there is no Jamfile in ".". This code somewhat duplicates
# code in project-target.find but we can not reuse that code without a
# project-targets instance.
#
local rule find-target ( target-id )
{
    local split = [ MATCH (.*)//(.*) : $(target-id) ] ;

    local pm ;
    if $(split)
    {
        pm = [ project.find $(split[1]) : "." ] ;
    }
    else
    {
        pm = [ project.find $(target-id) : "." ] ;
    }

    local result ;
    if $(pm)
    {
        result = [ project.target $(pm) ] ;
    }

    if $(split)
    {
        result = [ $(result).find $(split[2]) ] ;
    }

    return $(result) ;
}


# Initializes a new configuration module.
#
local rule initialize-config-module ( module-name : location ? )
{
    project.initialize $(module-name) : $(location) ;
    if USER_MODULE in [ RULENAMES ]
    {
        USER_MODULE $(module-name) ;
    }
}


# Helper rule used to load configuration files. Loads the first configuration
# file with the given 'filename' at 'path' into module with name 'module-name'.
# Not finding the requested file may or may not be treated as an error depending
# on the must-find parameter. Returns a normalized path to the loaded
# configuration file or nothing if no file was loaded.
#
local rule load-config ( module-name : filename : path + : must-find ? )
{
    if $(.debug-config)
    {
        local path-string = $(path) ;
        if $(path-string) = "" { path-string = . ; }
        ECHO notice: Searching '$(path-string)' for $(module-name)
            configuration file '$(filename)'. ;
    }
    local where = [ GLOB $(path) : $(filename) ] ;
    if $(where)
    {
        where = [ NORMALIZE_PATH $(where[1]) ] ;
        if $(.debug-config)
        {
            local where-string = $(where:D) ;
            if $(where-string) = "" { where-string = . ; }
            where-string = '$(where-string)' ;
            ECHO notice: Loading $(module-name) configuration file '$(filename)'
                from $(where-string:J=" "). ;
        }

        # Set source location so that path-constant in config files with
        # relative paths work. This is of most importance for
        # project-config.jam, but may be used in other config files as well.
        local attributes = [ project.attributes $(module-name) ] ;
        $(attributes).set source-location : $(where:D) : exact ;
        modules.load $(module-name) : $(filename) : $(path) ;
        project.load-used-projects $(module-name) ;
    }
    else if $(must-find) || $(.debug-config)
    {
        local path-string = $(path) ;
        if $(path-string) = "" { path-string = . ; }
        path-string = '$(path-string)' ;
        path-string = $(path-string:J=" ") ;
        if $(must-find)
        {
            import errors ;
            errors.user-error Configuration file '$(filename)' not found "in"
                $(path-string). ;
        }
        ECHO notice: Configuration file '$(filename)' not found "in"
            $(path-string). ;
    }
    return $(where) ;
}


# Loads all the configuration files used by Boost Build in the following order:
#
#   -- test-config --
#   Loaded only if specified on the command-line using the --test-config
# command-line parameter. It is ok for this file not to exist even if specified.
# If this configuration file is loaded, regular site and user configuration
# files will not be. If a relative path is specified, file is searched for in
# the current folder.
#
#   -- site-config --
#   Always named site-config.jam. Will only be found if located on the system
# root path (Windows), /etc (non-Windows), user's home folder or the Boost Build
# path, in that order. Not loaded in case the test-config configuration file is
# loaded or the --ignore-site-config command-line option is specified.
#
#   -- user-config --
#   Named user-config.jam by default or may be named explicitly using the
# --user-config command-line option or the BOOST_BUILD_USER_CONFIG environment
# variable. If named explicitly the file is looked for from the current working
# directory and if the default one is used then it is searched for in the
# user's home directory and the Boost Build path, in that order. Not loaded in
# case either the test-config configuration file is loaded or an empty file name
# is explicitly specified. If the file name has been given explicitly then the
# file must exist.
#
#   -- project-config --
#   Always named project-config.jam. Looked up in the current working folder and
# then upwards through its parents up to the root folder.
#
# Test configurations have been added primarily for use by Boost Build's
# internal unit testing system but may be used freely in other places as well.
#
local rule load-configuration-files
{
    # Flag indicating that site configuration should not be loaded.
    local ignore-site-config =
        [ MATCH ^(--ignore-site-config)$ : $(.argv) ] ;

    initialize-config-module test-config ;
    local test-config = [ MATCH ^--test-config=(.*)$ : $(.argv) ] ;
    local uq = [ MATCH \"(.*)\" : $(test-config) ] ;
    if $(uq)
    {
        test-config = $(uq) ;
    }
    if $(test-config)
    {
        local where = [ load-config test-config : $(test-config:BS) :
            $(test-config:D) ] ;
        if $(where)
        {
            if $(.debug-config)
            {
                ECHO "notice: Regular site and user configuration files will" ;
                ECHO "notice: be ignored due to the test configuration being"
                    "loaded." ;
            }
        }
        else
        {
            test-config = ;
        }
    }

    local user-path = [ os.home-directories ] [ os.environ BOOST_BUILD_PATH ] ;
    local site-path = /etc $(user-path) ;
    if [ os.name ] in NT CYGWIN
    {
        site-path = [ modules.peek : SystemRoot ] $(user-path) ;
    }

    if $(.debug-config) && ! $(test-config) && $(ignore-site-config)
    {
        ECHO "notice: Site configuration files will be ignored due to the" ;
        ECHO "notice: --ignore-site-config command-line option." ;
    }

    initialize-config-module site-config ;
    if ! $(test-config) && ! $(ignore-site-config)
    {
        load-config site-config : site-config.jam : $(site-path) ;
    }

    initialize-config-module user-config ;
    if ! $(test-config)
    {
        local user-config = [ MATCH ^--user-config=(.*)$ : $(.argv) ] ;
        user-config = $(user-config[-1]) ;
        user-config ?= [ os.environ BOOST_BUILD_USER_CONFIG ] ;
        # Special handling for the case when the OS does not strip the quotes
        # around the file name, as is the case when using Cygwin bash.
        user-config = [ utility.unquote $(user-config) ] ;
        local explicitly-requested = $(user-config) ;
        user-config ?= user-config.jam ;

        if $(user-config)
        {
            if $(explicitly-requested)
            {
                # Treat explicitly entered user paths as native OS path
                # references and, if non-absolute, root them at the current
                # working directory.
                user-config = [ path.make $(user-config) ] ;
                user-config = [ path.root $(user-config) [ path.pwd ] ] ;
                user-config = [ path.native $(user-config) ] ;

                if $(.debug-config)
                {
                    ECHO notice: Loading explicitly specified user configuration
                        file: ;
                    ECHO "    $(user-config)" ;
                }

                load-config user-config : $(user-config:BS) : $(user-config:D)
                    : must-exist ;
            }
            else
            {
                load-config user-config : $(user-config) : $(user-path) ;
            }
        }
        else if $(.debug-config)
        {
            ECHO notice: User configuration file loading explicitly disabled. ;
        }
    }

    # We look for project-config.jam from "." upward. I am not sure this is 100%
    # right decision, we might as well check for it only alongside the Jamroot
    # file. However:
    # - We need to load project-config.jam before Jamroot
    # - We probably need to load project-config.jam even if there is no Jamroot
    #   - e.g. to implement automake-style out-of-tree builds.
    local file = [ path.glob "." : project-config.jam ] ;
    if ! $(file)
    {
        file = [ path.glob-in-parents "." : project-config.jam ] ;
    }
    if $(file)
    {
        initialize-config-module project-config : $(file:D) ;
        load-config project-config : project-config.jam : $(file:D) ;
    }

    project.end-load ;
}


# Autoconfigure toolsets based on any instances of --toolset=xx,yy,...zz or
# toolset=xx,yy,...zz in the command line. May return additional properties to
# be processed as if they had been specified by the user.
#
local rule process-explicit-toolset-requests
{
    local extra-properties ;

    local option-toolsets  = [ regex.split-list [ MATCH ^--toolset=(.*)$ : $(.argv) ] : "," ] ;
    local feature-toolsets = [ regex.split-list [ MATCH   ^toolset=(.*)$ : $(.argv) ] : "," ] ;

    for local t in $(option-toolsets) $(feature-toolsets)
    {
        # Parse toolset-version/properties.
        local toolset = [ MATCH ([^/]+)/?.* : $(t) ] ;
        local properties = [ feature.expand-subfeatures <toolset>$(toolset) : true ] ;
        local toolset-property = [ property.select <toolset> : $(properties) ] ;
        local known ;
        if $(toolset-property:G=) in [ feature.values <toolset> ]
        {
            known = true ;
        }

        # If the toolset is not known, configure it now.

        # TODO: we should do 'using $(toolset)' in case no version has been
        # specified and there are no versions defined for the given toolset to
        # allow the toolset to configure its default version. For this we need
        # to know how to detect whether a given toolset has any versions
        # defined. An alternative would be to do this whenever version is not
        # specified but that would require that toolsets correctly handle the
        # case when their default version is configured multiple times which
        # should be checked for all existing toolsets first.

        if ! $(known)
        {
            if $(.debug-config)
            {
                ECHO "notice: [cmdline-cfg] toolset $(toolset) not"
                    "previously configured; attempting to auto-configure now" ;
            }
            local t,v = [ MATCH ([^-]+)-?(.+)? : $(toolset) ] ;
            toolset.using $(t,v[1]) : $(t,v[2]) ;
        }

        # Make sure we get an appropriate property into the build request in
        # case toolset has been specified using the "--toolset=..." command-line
        # option form.
        if ! $(t) in $(.argv) $(feature-toolsets)
        {
            if $(.debug-config)
            {
                ECHO notice: [cmdline-cfg] adding toolset=$(t) to the build
                    request. ;
            }
            extra-properties += toolset=$(t) ;
        }
    }

    return $(extra-properties) ;
}


# Returns whether the given project (identifed by its project module) should be
# cleaned because it or any of its parent projects have already been marked as
# needing to be cleaned in this build. As an optimization, will explicitly mark
# all encountered project needing to be cleaned in case thay have not already
# been marked so.
#
local rule should-clean-project ( project )
{
    if ! $(.should-clean-project.$(project))-is-defined
    {
        local r = "" ;
        if ! [ project.is-jamroot-module $(project) ]
        {
            local parent = [ project.attribute $(project) parent-module ] ;
            if $(parent)
            {
                r = [ should-clean-project $(parent) ] ;
            }
        }
        .should-clean-project.$(project) = $(r) ;
    }

    return $(.should-clean-project.$(project)) ;
}


################################################################################
#
# main()
# ------
#
################################################################################

{
    if --version in $(.argv)
    {
        version.print ;
        EXIT ;
    }

    version.verify-engine-version ;

    load-configuration-files ;

    # Load explicitly specified toolset modules.
    local extra-properties = [ process-explicit-toolset-requests ] ;

    # Load the actual project build script modules. We always load the project
    # in the current folder so 'use-project' directives have any chance of being
    # seen. Otherwise, we would not be able to refer to subprojects using target
    # ids.
    local current-project ;
    {
        local current-module = [ project.find "." : "." ] ;
        if $(current-module)
        {
            current-project = [ project.target $(current-module) ] ;
        }
    }

    # Load the default toolset module if no other has already been specified.
    if ! [ feature.values <toolset> ]
    {
        local default-toolset = $(.default-toolset) ;
        local default-toolset-version = ;
        if $(default-toolset)
        {
            default-toolset-version = $(.default-toolset-version) ;
        }
        else
        {
            default-toolset = gcc ;
            if [ os.name ] = NT
            {
                default-toolset = msvc ;
            }
            else if [ os.name ] = VMS
            {
                default-toolset = vmsdecc ;
            }
            else if [ os.name ] = MACOSX
            {
                default-toolset = darwin ;
            }
        }

        ECHO "warning: No toolsets are configured." ;
        ECHO "warning: Configuring default toolset" \"$(default-toolset)\". ;
        ECHO "warning: If the default is wrong, your build may not work correctly." ;
        ECHO "warning: Use the \"toolset=xxxxx\" option to override our guess." ;
        ECHO "warning: For more configuration options, please consult" ;
        ECHO "warning: http://boost.org/boost-build2/doc/html/bbv2/advanced/configuration.html" ;

        toolset.using $(default-toolset) : $(default-toolset-version) ;
    }


    # Parse command line for targets and properties. Note that this requires
    # that all project files already be loaded.
    # FIXME: This is not entirely true. Additional project files may be loaded
    # only later via the project.find() rule when dereferencing encountered
    # target ids containing explicit project references. See what to do about
    # those as such 'lazy loading' may cause problems that are then extremely
    # difficult to debug.
    local build-request = [ build-request.from-command-line $(.argv)
        $(extra-properties) ] ;
    local target-ids = [ $(build-request).get-at 1 ] ;
    local properties = [ $(build-request).get-at 2 ] ;


    # Check that we actually found something to build.
    if ! $(current-project) && ! $(target-ids)
    {
        import errors ;
        errors.user-error no Jamfile "in" current directory found, and no target
            references specified. ;
    }


    # Flags indicating that this build system run has been started in order to
    # clean existing instead of create new targets. Note that these are not the
    # final flag values as they may get changed later on due to some special
    # targets being specified on the command line.
    local clean    ; if "--clean"     in $(.argv) { clean    = true ; }
    local cleanall ; if "--clean-all" in $(.argv) { cleanall = true ; }


    # List of explicitly requested files to build. Any target references read
    # from the command line parameter not recognized as one of the targets
    # defined in the loaded Jamfiles will be interpreted as an explicitly
    # requested file to build. If any such files are explicitly requested then
    # only those files and the targets they depend on will be built and they
    # will be searched for among targets that would have been built had there
    # been no explicitly requested files.
    local explicitly-requested-files


    # List of Boost Build meta-targets, virtual-targets and actual Jam targets
    # constructed in this build system run.
    local targets ;
    local virtual-targets ;
    local actual-targets ;


    # Process each target specified on the command-line and convert it into
    # internal Boost Build target objects. Detect special clean target. If no
    # main Boost Build targets were explictly requested use the current project
    # as the target.
    for local id in $(target-ids)
    {
        if $(id) = clean
        {
            clean = true ;
        }
        else
        {
            local t ;
            if $(current-project)
            {
                t = [ $(current-project).find $(id) : no-error ] ;
            }
            else
            {
                t = [ find-target $(id) ] ;
            }

            if ! $(t)
            {
                ECHO "notice: could not find main target" $(id) ;
                ECHO "notice: assuming it is a name of file to create." ;
                explicitly-requested-files += $(id) ;
            }
            else
            {
                targets += $(t) ;
            }
        }
    }
    if ! $(targets)
    {
        targets += [ project.target [ project.module-name "." ] ] ;
    }

    if [ option.get dump-generators : : true ]
    {
        generators.dump ;
    }

    # We wish to put config.log in the build directory corresponding to Jamroot,
    # so that the location does not differ depending on the directory we run the
    # build from. The amount of indirection necessary here is scary.
    local first-project = [ $(targets[0]).project ] ;
    local first-project-root-location = [ $(first-project).get project-root ] ;
    local first-project-root-module = [ project.load
        $(first-project-root-location) ] ;
    local first-project-root = [ project.target $(first-project-root-module) ] ;
    local first-build-build-dir = [ $(first-project-root).build-dir ] ;
    configure.set-log-file $(first-build-build-dir)/config.log ;
    config-cache.load $(first-build-build-dir)/project-cache.jam ;

    # Expand properties specified on the command line into multiple property
    # sets consisting of all legal property combinations. Each expanded property
    # set will be used for a single build run. E.g. if multiple toolsets are
    # specified then requested targets will be built with each of them.
    # The expansion is being performed as late as possible so that the feature
    # validation is performed after all necessary modules (including project targets
    # on the command line) have been loaded.
    if $(properties)
    {
        expanded += [ build-request.convert-command-line-elements $(properties) ] ;
        expanded = [ build-request.expand-no-defaults $(expanded) ] ;
        local xexpanded ;
        for local e in $(expanded)
        {
            xexpanded += [ property-set.create [ feature.split $(e) ] ] ;
        }
        expanded = $(xexpanded) ;
    }
    else
    {
        expanded = [ property-set.empty ] ;
    }

    # Now that we have a set of targets to build and a set of property sets to
    # build the targets with, we can start the main build process by using each
    # property set to generate virtual targets from all of our listed targets
    # and any of their dependants.
    for local p in $(expanded)
    {
        .command-line-free-features = [ property-set.create [ $(p).free ] ] ;
        for local t in $(targets)
        {
            local g = [ $(t).generate $(p) ] ;
            if ! [ class.is-a $(t) : project-target ]
            {
                .results-of-main-targets += $(g[2-]) ;
            }
            virtual-targets += $(g[2-]) ;
        }
    }


    # Convert collected virtual targets into actual raw Jam targets.
    for t in $(virtual-targets)
    {
        actual-targets += [ $(t).actualize ] ;
    }

    config-cache.save ;


    # If XML data output has been requested prepare additional rules and targets
    # so we can hook into Jam to collect build data while its building and have
    # it trigger the final XML report generation after all the planned targets
    # have been built.
    if $(.out-xml)
    {
        # Get a qualified virtual target name.
        rule full-target-name ( target )
        {
            local name = [ $(target).name ] ;
            local project = [ $(target).project ] ;
            local project-path = [ $(project).get location ] ;
            return $(project-path)//$(name) ;
        }

        # Generate an XML file containing build statistics for each constituent.
        #
        rule out-xml ( xml-file : constituents * )
        {
            # Prepare valid XML header and footer with some basic info.
            local nl = "
" ;
            local os        = [ modules.peek : OS OSPLAT JAMUNAME ] "" ;
            local timestamp = [ modules.peek : JAMDATE ] ;
            local cwd       = [ PWD ] ;
            local command   = $(.argv) ;
            local bb-version = [ version.boost-build ] ;
            .header on $(xml-file) =
                "<?xml version=\"1.0\" encoding=\"utf-8\"?>"
                "$(nl)<build format=\"1.0\" version=\"$(bb-version)\">"
                "$(nl)  <os name=\"$(os[1])\" platform=\"$(os[2])\"><![CDATA[$(os[3-]:J= )]]></os>"
                "$(nl)  <timestamp><![CDATA[$(timestamp)]]></timestamp>"
                "$(nl)  <directory><![CDATA[$(cwd)]]></directory>"
                "$(nl)  <command><![CDATA[\"$(command:J=\" \")\"]]></command>"
                ;
            .footer on $(xml-file) =
                "$(nl)</build>" ;

            # Generate the target dependency graph.
            .contents on $(xml-file) +=
                "$(nl)  <targets>" ;
            for local t in [ virtual-target.all-targets ]
            {
                local action = [ $(t).action ] ;
                if $(action)
                    # If a target has no action, it has no dependencies.
                {
                    local name = [ full-target-name $(t) ] ;
                    local sources = [ $(action).sources ] ;
                    local dependencies ;
                    for local s in $(sources)
                    {
                        dependencies += [ full-target-name $(s) ] ;
                    }

                    local path = [ $(t).path ] ;
                    local jam-target = [ $(t).actual-name ] ;

                    .contents on $(xml-file) +=
                        "$(nl)    <target>"
                        "$(nl)      <name><![CDATA[$(name)]]></name>"
                        "$(nl)      <dependencies>"
                        "$(nl)        <dependency><![CDATA[$(dependencies)]]></dependency>"
                        "$(nl)      </dependencies>"
                        "$(nl)      <path><![CDATA[$(path)]]></path>"
                        "$(nl)      <jam-target><![CDATA[$(jam-target)]]></jam-target>"
                        "$(nl)    </target>"
                        ;
                }
            }
            .contents on $(xml-file) +=
                "$(nl)  </targets>" ;

            # Build $(xml-file) after $(constituents). Do so even if a
            # constituent action fails and regenerate the xml on every bjam run.
            INCLUDES $(xml-file) : $(constituents) ;
            ALWAYS $(xml-file) ;
            __ACTION_RULE__ on $(xml-file) =
                build-system.out-xml.generate-action ;
            out-xml.generate $(xml-file) ;
        }

        # The actual build actions are here; if we did this work in the actions
        # clause we would have to form a valid command line containing the
        # result of @(...) below (the name of the XML file).
        #
        rule out-xml.generate-action ( args * : xml-file
            : command status start end user system : output ? )
        {
            local contents =
                [ on $(xml-file) return $(.header) $(.contents) $(.footer) ] ;
            local f = @($(xml-file):E=$(contents)) ;
        }

        # Nothing to do here; the *real* actions happen in
        # out-xml.generate-action.
        actions quietly out-xml.generate { }

        # Define the out-xml file target, which depends on all the targets so
        # that it runs the collection after the targets have run.
        out-xml $(.out-xml) : $(actual-targets) ;

        # Set up a global __ACTION_RULE__ that records all the available
        # statistics about each actual target in a variable "on" the --out-xml
        # target.
        #
        rule out-xml.collect ( xml-file : target : command status start end user
            system : output ? )
        {
            local nl = "
" ;
            # Open the action with some basic info.
            .contents on $(xml-file) +=
                "$(nl)  <action status=\"$(status)\" start=\"$(start)\" end=\"$(end)\" user=\"$(user)\" system=\"$(system)\">" ;

            # If we have an action object we can print out more detailed info.
            local action = [ on $(target) return $(.action) ] ;
            if $(action)
            {
                local action-name    = [ $(action).action-name ] ;
                local action-sources = [ $(action).sources     ] ;
                local action-props   = [ $(action).properties  ] ;

                # The qualified name of the action which we created the target.
                .contents on $(xml-file) +=
                    "$(nl)    <name><![CDATA[$(action-name)]]></name>" ;

                # The sources that made up the target.
                .contents on $(xml-file) +=
                    "$(nl)    <sources>" ;
                for local source in $(action-sources)
                {
                    local source-actual = [ $(source).actual-name ] ;
                    .contents on $(xml-file) +=
                        "$(nl)      <source><![CDATA[$(source-actual)]]></source>" ;
                }
                .contents on $(xml-file) +=
                    "$(nl)    </sources>" ;

                # The properties that define the conditions under which the
                # target was built.
                .contents on $(xml-file) +=
                    "$(nl)    <properties>" ;
                for local prop in [ $(action-props).raw ]
                {
                    local prop-name = [ MATCH ^<(.*)>$ : $(prop:G) ] ;
                    .contents on $(xml-file) +=
                        "$(nl)      <property name=\"$(prop-name)\"><![CDATA[$(prop:G=)]]></property>" ;
                }
                .contents on $(xml-file) +=
                    "$(nl)    </properties>" ;
            }

            local locate = [ on $(target) return $(LOCATE) ] ;
            locate ?= "" ;
            .contents on $(xml-file) +=
                "$(nl)    <jam-target><![CDATA[$(target)]]></jam-target>"
                "$(nl)    <path><![CDATA[$(target:G=:R=$(locate))]]></path>"
                "$(nl)    <command><![CDATA[$(command)]]></command>"
                "$(nl)    <output><![CDATA[$(output)]]></output>" ;
            .contents on $(xml-file) +=
                "$(nl)  </action>" ;
        }

        # When no __ACTION_RULE__ is set "on" a target, the search falls back to
        # the global module.
        module
        {
            __ACTION_RULE__ = build-system.out-xml.collect
                [ modules.peek build-system : .out-xml ] ;
        }

        IMPORT
            build-system :
            out-xml.collect
            out-xml.generate-action
            : :
            build-system.out-xml.collect
            build-system.out-xml.generate-action
            ;
    }

    local j = [ option.get jobs ] ;
    if $(j)
    {
        modules.poke : PARALLELISM : $(j) ;
    }

    local k = [ option.get keep-going : true : true ] ;
    if $(k) in "on" "yes" "true"
    {
        modules.poke : KEEP_GOING : 1 ;
    }
    else if $(k) in "off" "no" "false"
    {
        modules.poke : KEEP_GOING : 0 ;
    }
    else
    {
        EXIT "error: Invalid value for the --keep-going option" ;
    }

    # The 'all' pseudo target is not strictly needed expect in the case when we
    # use it below but people often assume they always have this target
    # available and do not declare it themselves before use which may cause
    # build failures with an error message about not being able to build the
    # 'all' target.
    NOTFILE all ;

    # And now that all the actual raw Jam targets and all the dependencies
    # between them have been prepared all that is left is to tell Jam to update
    # those targets.
    if $(explicitly-requested-files)
    {
        # Note that this case can not be joined with the regular one when only
        # exact Boost Build targets are requested as here we do not build those
        # requested targets but only use them to construct the dependency tree
        # needed to build the explicitly requested files.
        UPDATE $(explicitly-requested-files:G=e) $(.out-xml) ;
    }
    else if $(cleanall)
    {
        UPDATE clean-all ;
    }
    else if $(clean)
    {
        common.Clean clean : [ actual-clean-targets ] ;
        UPDATE clean ;
    }
    else
    {
        configure.print-configure-checks-summary ;

        if $(.pre-build-hook)
        {
            $(.pre-build-hook) ;
        }

        DEPENDS all : $(actual-targets) ;
        if UPDATE_NOW in [ RULENAMES ]
        {
            local ok = [ UPDATE_NOW all $(.out-xml) ] ;
            if $(.post-build-hook)
            {
                $(.post-build-hook) $(ok) ;
            }
            # Prevent automatic update of the 'all' target, now that we have
            # explicitly updated what we wanted.
            UPDATE ;
        }
        else
        {
            UPDATE all $(.out-xml) ;
        }
    }
}