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Diffstat (limited to 'build_overrides/README.md')
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diff --git a/build_overrides/README.md b/build_overrides/README.md new file mode 100644 index 0000000000..cc0efbf407 --- /dev/null +++ b/build_overrides/README.md @@ -0,0 +1,28 @@ +# Build overrides in GN + +This directory is used to allow different products to customize settings +for repos which are DEPS'ed in or shared. + +For example: V8 can be built on its own (in a "standalone" configuration), +and it can be built as part of Chromium. V8 defines a top-level +target, //v8:d8 (a simple executable), which will only be built in the +standalone configuration. To indiate itis a standalone configuration, v8 can +create a file, build_overrides/v8.gni, containing a variable, +`build_standalone_d8 = true` and import it (as +import("//build_overrides/v8.gni") from its top-level BUILD.gn file. + +Chromium, on the other hand, does not need to build d8, and so it would +create its own build_overrides/v8.gni file, and in it set +`build_standalone_d8 = false`. + +The two files should define the same set of variables, but the values may +vary as appropriate to suit the the needs of the two different builds. + +The build.gni file provides a way for projects to override defaults for +variables used in //build itself (which we want to be shareable between +projects). + +TODO(crbug.com/588513): Ideally //build_overrides and, in particular, +//build_overrides/build.gni will go away completely in favor of some +mechanism that can re-use other required files like //.gn, so that we don't +have to keep requiring projects to create a bunch of different files to use GN. |