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diff --git a/gn/docs/standalone.md b/gn/docs/standalone.md new file mode 100644 index 00000000000..29d62360f7f --- /dev/null +++ b/gn/docs/standalone.md @@ -0,0 +1,44 @@ +# Introduction + +This page is about how to design a project that can build independently +with GN but also be brought into the Chrome build. + +GN is in principle no different than GYP in that there is some core +configuration that must be the same between both the standalone build +and the Chrome build. However, GN is much more explicit in its naming +and configuration, so the similarities between the two builds are also +much more explicit and there is less flexibility in how things are +configured. + +# What you need for a minimal GN build + +Requirements: + + * A master build config file. Chrome's is `//build/config/BUILDCONFIG.gn` + * A separate build file for the toolchain definition. It's not a good idea + to put these in a BUILD.gn file shared with any target definitions for + complex reasons. Chrome's are in `//build/toolchain/<platform>/BUILD.gn`. + * A `BUILD.gn` file in the root directory. This will be loaded after the + build config file to start the build. + +You may want a `.gn` file in the root directory. When you run GN it +recursively looks up the directory tree until it finds this file, and it +treats the containing directory as the "source root". This file also +defines the location of the master build config file: + + * See Chrome's `src/.gn` file. + * Unlike Chrome, you probably don't need to define a secondary root. + * see `gn help dotfile` for more. + +Adding a `.gn` file in a repository that is pulled into Chrome means +that then running GN in your subdirectory will configure a build for +your subproject rather than for all of Chrome. This could be an +advantage or a disadvantage. + +If you are in a directory with such a file and you want to not use it +(e.g., to do the full Chrome build instead), you can use the command-line +flags `--root` and `--dotfile` to set the values you want. + +If you want a completely standalone build that has nothing to do with Chrome +and doesn't use Chrome's `//build` files, you can look at an example in +[//tools/gn/example](../example). |