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1 # Build overrides in GN | 1 # Build overrides in GN |
2 | 2 |
3 This directory is used to allow different products to customize settings | 3 This directory is used to allow different products to customize settings |
4 for repos that are DEPS'ed in or shared. | 4 for repos that are DEPS'ed in or shared. |
5 | 5 |
6 For example: V8 could be built on its own (in a "standalone" configuration), | 6 For example: V8 could be built on its own (in a "standalone" configuration), |
7 and it could be built as part of Chromium. V8 might define a top-level | 7 and it could be built as part of Chromium. V8 might define a top-level |
8 target, //v8:d8 (a simple executable), that should only be built in the | 8 target, //v8:d8 (a simple executable), that should only be built in the |
9 standalone configuration. To figure out whether or not it should be | 9 standalone configuration. To figure out whether or not it should be |
10 in a standalone configuration, v8 can create a file, build_overrides/v8.gni, | 10 in a standalone configuration, v8 can create a file, build_overrides/v8.gni, |
11 that contains a variable, `build_standalone_d8 = true`. | 11 that contains a variable, `build_standalone_d8 = true`. |
12 and import it (as import("//build_overrides/v8.gni") from its top-level | 12 and import it (as import("//build_overrides/v8.gni") from its top-level |
13 BUILD.gn file. | 13 BUILD.gn file. |
14 | 14 |
15 Chromium, on the other hand, might not need to build d8, and so it would | 15 Chromium, on the other hand, might not need to build d8, and so it would |
16 create its own build_overrides/v8.gni file, and in it set | 16 create its own build_overrides/v8.gni file, and in it set |
17 `build_standalone_d8 = false`. | 17 `build_standalone_d8 = false`. |
18 | 18 |
19 The two files should define the same set of variables, but the values can | 19 The two files should define the same set of variables, but the values can |
20 vary as appropriate to the needs of the two different builds. | 20 vary as appropriate to the needs of the two different builds. |
21 | |
22 The build.gni file provides a way for projects to override defaults for | |
23 variables used in //build itself (which we want to be shareable between | |
24 projects). | |
25 | |
26 TODO(crbug.com/588513): Ideally //build_overrides and, in particular, | |
27 //build_overrides.gni should go away completely in favor of some mechanism | |
kjellander_chromium
2016/02/22 04:18:40
I guess you mean //build_overrides/build.gni here?
Dirk Pranke
2016/02/22 04:25:04
Good catch, I meant //build_overrides/build.gni o
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28 that can re-use other required files like //.gn, so that we don't have | |
29 to keep requiring projects to create a bunch of different files to use GN. | |
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