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๏ปฟ# GYP (Generate Your Projects) User Documentation
Status: Draft (as of 2009-05-19)
Mark Mentovai <mark@chromium.org>,
Steven Knight <sgk@chromium.org>
_et al._
Modified: 2009-05-19
[TOC]
## Introduction
This document is intended to provide a user-level guide to GYP. The
emphasis here is on how to use GYP to accomplish specific tasks, not on
the complete technical language specification. (For that, see the
[LanguageSpecification](LanguageSpecification).)
The document below starts with some overviews to provide context: an
overview of the structure of a `.gyp` file itself, an overview of a
typical executable-program target in a `.gyp` file, an an overview of a
typical library target in a `.gyp` file.
After the overviews, there are examples of `gyp` patterns for different
common use cases.
## Skeleton of a typical Chromium .gyp file
Here is the skeleton of a typical `.gyp` file in the Chromium tree:
```
{
'variables': {
.
.
.
},
'includes': [
'../build/common.gypi',
],
'target_defaults': {
.
.
.
},
'targets': [
{
'target_name': 'target_1',
.
.
.
},
{
'target_name': 'target_2',
.
.
.
},
],
'conditions': [
['OS=="linux"', {
'targets': [
{
'target_name': 'linux_target_3',
.
.
.
},
],
}],
['OS=="win"', {
'targets': [
{
'target_name': 'windows_target_4',
.
.
.
},
],
}, { # OS != "win"
'targets': [
{
'target_name': 'non_windows_target_5',
.
.
.
},
}],
],
}
```
The entire file just contains a Python dictionary. (It's actually JSON,
with two small Pythonic deviations: comments are introduced with `#`,
and a `,` (comma)) is legal after the last element in a list or
dictionary.)
The top-level pieces in the `.gyp` file are as follows:
`'variables'`: Definitions of variables that can be interpolated and
used in various other parts of the file.
`'includes'`: A list of of other files that will be included in this
file. By convention, included files have the suffix `.gypi` (gyp
include).
`'target_defaults'`: Settings that will apply to _all_ of the targets
defined in this `.gyp` file.
`'targets'`: The list of targets for which this `.gyp` file can
generate builds. Each target is a dictionary that contains settings
describing all the information necessary to build the target.
`'conditions'`: A list of condition specifications that can modify the
contents of the items in the global dictionary defined by this `.gyp`
file based on the values of different variablwes. As implied by the
above example, the most common use of a `conditions` section in the
top-level dictionary is to add platform-specific targets to the
`targets` list.
## Skeleton of a typical executable target in a .gyp file
The most straightforward target is probably a simple executable program.
Here is an example `executable` target that demonstrates the features
that should cover most simple uses of gyp:
```
{
'targets': [
{
'target_name': 'foo',
'type': 'executable',
'msvs_guid': '5ECEC9E5-8F23-47B6-93E0-C3B328B3BE65',
'dependencies': [
'xyzzy',
'../bar/bar.gyp:bar',
],
'defines': [
'DEFINE_FOO',
'DEFINE_A_VALUE=value',
],
'include_dirs': [
'..',
],
'sources': [
'file1.cc',
'file2.cc',
],
'conditions': [
['OS=="linux"', {
'defines': [
'LINUX_DEFINE',
],
'include_dirs': [
'include/linux',
],
}],
['OS=="win"', {
'defines': [
'WINDOWS_SPECIFIC_DEFINE',
],
}, { # OS != "win",
'defines': [
'NON_WINDOWS_DEFINE',
],
}]
],
},
],
}
```
The top-level settings in the target include:
`'target_name'`: The name by which the target should be known, which
should be unique across all `.gyp` files. This name will be used as the
project name in the generated Visual Studio solution, as the target name
in the generated XCode configuration, and as the alias for building this
target from the command line of the generated SCons configuration.
`'type'`: Set to `executable`, logically enough.
`'msvs_guid'`: THIS IS ONLY TRANSITIONAL. This is a hard-coded GUID
values that will be used in the generated Visual Studio solution
file(s). This allows us to check in a `chrome.sln` file that
interoperates with gyp-generated project files. Once everything in
Chromium is being generated by gyp, it will no longer be important that
the GUIDs stay constant across invocations, and we'll likely get rid of
these settings,
`'dependencies'`: This lists other targets that this target depends on.
The gyp-generated files will guarantee that the other targets are built
before this target. Any library targets in the `dependencies` list will
be linked with this target. The various settings (`defines`,
`include_dirs`, etc.) listed in the `direct_dependent_settings` sections
of the targets in this list will be applied to how _this_ target is
built and linked. See the more complete discussion of
`direct_dependent_settings`, below.
`'defines'`: The C preprocessor definitions that will be passed in on
compilation command lines (using `-D` or `/D` options).
`'include_dirs'`: The directories in which included header files live.
These will be passed in on compilation command lines (using `-I` or `/I`
options).
`'sources'`: The source files for this target.
`'conditions'`: A block of conditions that will be evaluated to update
the different settings in the target dictionary.
## Skeleton of a typical library target in a .gyp file
The vast majority of targets are libraries. Here is an example of a
library target including the additional features that should cover most
needs of libraries:
```
{
'targets': [
{
'target_name': 'foo',
'type': '<(library)'
'msvs_guid': '5ECEC9E5-8F23-47B6-93E0-C3B328B3BE65',
'dependencies': [
'xyzzy',
'../bar/bar.gyp:bar',
],
'defines': [
'DEFINE_FOO',
'DEFINE_A_VALUE=value',
],
'include_dirs': [
'..',
],
'direct_dependent_settings': {
'defines': [
'DEFINE_FOO',
'DEFINE_ADDITIONAL',
],
'linkflags': [
],
},
'export_dependent_settings': [
'../bar/bar.gyp:bar',
],
'sources': [
'file1.cc',
'file2.cc',
],
'conditions': [
['OS=="linux"', {
'defines': [
'LINUX_DEFINE',
],
'include_dirs': [
'include/linux',
],
],
['OS=="win"', {
'defines': [
'WINDOWS_SPECIFIC_DEFINE',
],
}, { # OS != "win",
'defines': [
'NON_WINDOWS_DEFINE',
],
}]
],
],
}
```
The possible entries in a library target are largely the same as those
that can be specified for an executable target (`defines`,
`include_dirs`, etc.). The differences include:
`'type'`: This should almost always be set to '<(library)', which allows
the user to define at gyp time whether libraries are to be built static
or shared. (On Linux, at least, linking with shared libraries saves
significant link time.) If it's necessary to pin down the type of
library to be built, the `type` can be set explicitly to
`static_library` or `shared_library`.
`'direct_dependent_settings'`: This defines the settings that will be
applied to other targets that _directly depend_ on this target--that is,
that list _this_ target in their `'dependencies'` setting. This is
where you list the `defines`, `include_dirs`, `cflags` and `linkflags`
that other targets that compile or link against this target need to
build consistently.
`'export_dependent_settings'`: This lists the targets whose
`direct_dependent_settings` should be "passed on" to other targets that
use (depend on) this target. `TODO: expand on this description.`
## Use Cases
These use cases are intended to cover the most common actions performed
by developers using GYP.
Note that these examples are _not_ fully-functioning, self-contained
examples (or else they'd be way too long). Each example mostly contains
just the keywords and settings relevant to the example, with perhaps a
few extra keywords for context. The intent is to try to show the
specific pieces you need to pay attention to when doing something.
[NOTE: if practical use shows that these examples are confusing without
additional context, please add what's necessary to clarify things.]
### Add new source files
There are similar but slightly different patterns for adding a
platform-independent source file vs. adding a source file that only
builds on some of the supported platforms.
#### Add a source file that builds on all platforms
**Simplest possible case**: You are adding a file(s) that builds on all
platforms.
Just add the file(s) to the `sources` list of the appropriate dictionary
in the `targets` list:
```
{
'targets': [
{
'target_name': 'my_target',
'type': 'executable',
'sources': [
'../other/file_1.cc',
'new_file.cc',
'subdir/file3.cc',
],
},
],
},
```
File path names are relative to the directory in which the `.gyp` file lives.
Keep the list sorted alphabetically (unless there's a really, really,
_really_ good reason not to).
#### Add a platform-specific source file
##### Your platform-specific file is named `*_linux.{ext}`, `*_mac.{ext}`, `*_posix.{ext}` or `*_win.{ext}`
The simplest way to add a platform-specific source file, assuming you're
adding a completely new file and get to name it, is to use one of the
following standard suffixes:
* `_linux` (e.g. `foo_linux.cc`)
* `_mac` (e.g. `foo_mac.cc`)
* `_posix` (e.g. `foo_posix.cc`)
* `_win` (e.g. `foo_win.cc`)
Simply add the file to the `sources` list of the appropriate dict within
the `targets` list, like you would any other source file.
```
{
'targets': [
{
'target_name': 'foo',
'type': 'executable',
'sources': [
'independent.cc',
'specific_win.cc',
],
},
],
},
```
The Chromium `.gyp` files all have appropriate `conditions` entries to
filter out the files that aren't appropriate for the current platform.
In the above example, the `specific_win.cc` file will be removed
automatically from the source-list on non-Windows builds.
##### Your platform-specific file does not use an already-defined pattern
If your platform-specific file does not contain a
`*_{linux,mac,posix,win}` substring (or some other pattern that's
already in the `conditions` for the target), and you can't change the
file name, there are two patterns that can be used.
**Prefererred**: Add the file to the `sources` list of the appropriate
dictionary within the `targets` list. Add an appropriate `conditions`
section to exclude the specific files name:
```
{
'targets': [
{
'target_name': 'foo',
'type': 'executable',
'sources': [
'linux_specific.cc',
],
'conditions': [
['OS != "linux"', {
'sources!': [
# Linux-only; exclude on other platforms.
'linux_specific.cc',
]
}[,
],
},
],
},
```
Despite the duplicate listing, the above is generally preferred because
the `sources` list contains a useful global list of all sources on all
platforms with consistent sorting on all platforms.
**Non-preferred**: In some situations, however, it might make sense to
list a platform-specific file only in a `conditions` section that
specifically _includes_ it in the `sources` list:
```
{
'targets': [
{
'target_name': 'foo',
'type': 'executable',
'sources': [],
['OS == "linux"', {
'sources': [
# Only add to sources list on Linux.
'linux_specific.cc',
]
}],
},
],
},
```
The above two examples end up generating equivalent builds, with the
small exception that the `sources` lists will list the files in
different orders. (The first example defines explicitly where
`linux_specific.cc` appears in the list--perhaps in in the
middle--whereas the second example will always tack it on to the end of
the list.)
**Including or excluding files using patterns**: There are more
complicated ways to construct a `sources` list based on patterns. See
`TODO(sgk)` below.
### Add a new executable
An executable program is probably the most straightforward type of
target, since all it typically needs is a list of source files, some
compiler/linker settings (probably varied by platform), and some library
targets on which it depends and which must be used in the final link.
#### Add an executable that builds on all platforms
Add a dictionary defining the new executable target to the `targets`
list in the appropriate `.gyp` file. Example:
```
{
'targets': [
{
'target_name': 'new_unit_tests',
'type': 'executable',
'defines': [
'FOO',
],
'include_dirs': [
'..',
],
'dependencies': [
'other_target_in_this_file',
'other_gyp2:target_in_other_gyp2',
],
'sources': [
'new_additional_source.cc',
'new_unit_tests.cc',
],
},
],
}
```
#### Add a platform-specific executable
Add a dictionary defining the new executable target to the `targets`
list within an appropriate `conditions` block for the platform. The
`conditions` block should be a sibling to the top-level `targets` list:
```
{
'targets': [
],
'conditions': [
['OS=="win"', {
'targets': [
{
'target_name': 'new_unit_tests',
'type': 'executable',
'defines': [
'FOO',
],
'include_dirs': [
'..',
],
'dependencies': [
'other_target_in_this_file',
'other_gyp2:target_in_other_gyp2',
],
'sources': [
'new_additional_source.cc',
'new_unit_tests.cc',
],
},
],
}],
],
}
```
### Add settings to a target
There are several different types of settings that can be defined for
any given target.
#### Add new preprocessor definitions (`-D` or `/D` flags)
New preprocessor definitions are added by the `defines` setting:
```
{
'targets': [
{
'target_name': 'existing_target',
'defines': [
'FOO',
'BAR=some_value',
],
},
],
},
```
These may be specified directly in a target's settings, as in the above
example, or in a `conditions` section.
#### Add a new include directory (`-I` or `/I` flags)
New include directories are added by the `include_dirs` setting:
```
{
'targets': [
{
'target_name': 'existing_target',
'include_dirs': [
'..',
'include',
],
},
],
},
```
These may be specified directly in a target's settings, as in the above
example, or in a `conditions` section.
#### Add new compiler flags
Specific compiler flags can be added with the `cflags` setting:
```
{
'targets': [
{
'target_name': 'existing_target',
'conditions': [
['OS=="win"', {
'cflags': [
'/WX',
],
}, { # OS != "win"
'cflags': [
'-Werror',
],
}],
],
},
],
},
```
Because these flags will be specific to the actual compiler involved,
they will almost always be only set within a `conditions` section.
#### Add new linker flags
Setting linker flags is OS-specific. On linux and most non-mac posix
systems, they can be added with the `ldflags` setting:
```
{
'targets': [
{
'target_name': 'existing_target',
'conditions': [
['OS=="linux"', {
'ldflags': [
'-pthread',
],
}],
],
},
],
},
```
Because these flags will be specific to the actual linker involved,
they will almost always be only set within a `conditions` section.
On OS X, linker settings are set via `xcode_settings`, on Windows via
`msvs_settings`.
#### Exclude settings on a platform
Any given settings keyword (`defines`, `include_dirs`, etc.) has a
corresponding form with a trailing `!` (exclamation point) to remove
values from a setting. One useful example of this is to remove the
Linux `-Werror` flag from the global settings defined in
`build/common.gypi`:
```
{
'targets': [
{
'target_name': 'third_party_target',
'conditions': [
['OS=="linux"', {
'cflags!': [
'-Werror',
],
}],
],
},
],
},
```
### Cross-compiling
GYP has some (relatively limited) support for cross-compiling.
If the variable `GYP_CROSSCOMPILE` or one of the toolchain-related
variables (like `CC_host` or `CC_target`) is set, GYP will think that
you wish to do a cross-compile.
When cross-compiling, each target can be part of a "host" build, a
"target" build, or both. By default, the target is assumed to be (only)
part of the "target" build. The 'toolsets' property can be set on a
target to change the default.
A target's dependencies are assumed to match the build type (so, if A
depends on B, by default that means that a target build of A depends on
a target build of B). You can explicitly depend on targets across
toolchains by specifying "#host" or "#target" in the dependencies list.
If GYP is not doing a cross-compile, the "#host" and "#target" will be
stripped as needed, so nothing breaks.
### Add a new library
TODO: write intro
#### Add a library that builds on all platforms
Add the a dictionary defining the new library target to the `targets`
list in the appropriate `.gyp` file. Example:
```
{
'targets': [
{
'target_name': 'new_library',
'type': '<(library)',
'defines': [
'FOO',
'BAR=some_value',
],
'include_dirs': [
'..',
],
'dependencies': [
'other_target_in_this_file',
'other_gyp2:target_in_other_gyp2',
],
'direct_dependent_settings': {
'include_dirs': '.',
},
'export_dependent_settings': [
'other_target_in_this_file',
],
'sources': [
'new_additional_source.cc',
'new_library.cc',
],
},
],
}
```
The use of the `<(library)` variable above should be the default `type`
setting for most library targets, as it allows the developer to choose,
at `gyp` time, whether to build with static or shared libraries.
(Building with shared libraries saves a _lot_ of link time on Linux.)
It may be necessary to build a specific library as a fixed type. Is so,
the `type` field can be hard-wired appropriately. For a static library:
```
'type': 'static_library',
```
For a shared library:
```
'type': 'shared_library',
```
#### Add a platform-specific library
Add a dictionary defining the new library target to the `targets` list
within a `conditions` block that's a sibling to the top-level `targets`
list:
```
{
'targets': [
],
'conditions': [
['OS=="win"', {
'targets': [
{
'target_name': 'new_library',
'type': '<(library)',
'defines': [
'FOO',
'BAR=some_value',
],
'include_dirs': [
'..',
],
'dependencies': [
'other_target_in_this_file',
'other_gyp2:target_in_other_gyp2',
],
'direct_dependent_settings': {
'include_dirs': '.',
},
'export_dependent_settings': [
'other_target_in_this_file',
],
'sources': [
'new_additional_source.cc',
'new_library.cc',
],
},
],
}],
],
}
```
### Dependencies between targets
GYP provides useful primitives for establishing dependencies between
targets, which need to be configured in the following situations.
#### Linking with another library target
```
{
'targets': [
{
'target_name': 'foo',
'dependencies': [
'libbar',
],
},
{
'target_name': 'libbar',
'type': '<(library)',
'sources': [
],
},
],
}
```
Note that if the library target is in a different `.gyp` file, you have
to specify the path to other `.gyp` file, relative to this `.gyp` file's
directory:
```
{
'targets': [
{
'target_name': 'foo',
'dependencies': [
'../bar/bar.gyp:libbar',
],
},
],
}
```
Adding a library often involves updating multiple `.gyp` files, adding
the target to the approprate `.gyp` file (possibly a newly-added `.gyp`
file), and updating targets in the other `.gyp` files that depend on
(link with) the new library.
#### Compiling with necessary flags for a library target dependency
We need to build a library (often a third-party library) with specific
preprocessor definitions or command-line flags, and need to ensure that
targets that depend on the library build with the same settings. This
situation is handled by a `direct_dependent_settings` block:
```
{
'targets': [
{
'target_name': 'foo',
'type': 'executable',
'dependencies': [
'libbar',
],
},
{
'target_name': 'libbar',
'type': '<(library)',
'defines': [
'LOCAL_DEFINE_FOR_LIBBAR',
'DEFINE_TO_USE_LIBBAR',
],
'include_dirs': [
'..',
'include/libbar',
],
'direct_dependent_settings': {
'defines': [
'DEFINE_TO_USE_LIBBAR',
],
'include_dirs': [
'include/libbar',
],
},
},
],
}
```
In the above example, the sources of the `foo` executable will be
compiled with the options `-DDEFINE_TO_USE_LIBBAR -Iinclude/libbar`,
because of those settings' being listed in the
`direct_dependent_settings` block.
Note that these settings will likely need to be replicated in the
settings for the library target itsef, so that the library will build
with the same options. This does not prevent the target from defining
additional options for its "internal" use when compiling its own source
files. (In the above example, these are the `LOCAL_DEFINE_FOR_LIBBAR`
define, and the `..` entry in the `include_dirs` list.)
#### When a library depends on an additional library at final link time
```
{
'targets': [
{
'target_name': 'foo',
'type': 'executable',
'dependencies': [
'libbar',
],
},
{
'target_name': 'libbar',
'type': '<(library)',
'dependencies': [
'libother'
],
'export_dependent_settings': [
'libother'
],
},
{
'target_name': 'libother',
'type': '<(library)',
'direct_dependent_settings': {
'defines': [
'DEFINE_FOR_LIBOTHER',
],
'include_dirs': [
'include/libother',
],
},
},
],
}
```
### Support for Mac OS X bundles
gyp supports building bundles on OS X (.app, .framework, .bundle, etc).
Here is an example of this:
```
{
'target_name': 'test_app',
'product_name': 'Test App Gyp',
'type': 'executable',
'mac_bundle': 1,
'sources': [
'main.m',
'TestAppAppDelegate.h',
'TestAppAppDelegate.m',
],
'mac_bundle_resources': [
'TestApp/English.lproj/InfoPlist.strings',
'TestApp/English.lproj/MainMenu.xib',
],
'link_settings': {
'libraries': [
'$(SDKROOT)/System/Library/Frameworks/Cocoa.framework',
],
},
'xcode_settings': {
'INFOPLIST_FILE': 'TestApp/TestApp-Info.plist',
},
},
```
The `mac_bundle` key tells gyp that this target should be a bundle.
`executable` targets get extension `.app` by default, `shared_library`
targets get `.framework` โ but you can change the bundle extensions by
setting `product_extension` if you want. Files listed in
`mac_bundle_resources` will be copied to the bundle's `Resource` folder
of the bundle. You can also set
`process_outputs_as_mac_bundle_resources` to 1 in actions and rules to
let the output of actions and rules be added to that folder (similar to
`process_outputs_as_sources`). If `product_name` is not set, the bundle
will be named after `target_name`as usual.
### Move files (refactoring)
TODO(sgk)
### Custom build steps
TODO(sgk)
#### Adding an explicit build step to generate specific files
TODO(sgk)
#### Adding a rule to handle files with a new suffix
TODO(sgk)
### Build flavors
TODO(sgk)