|author||Scott Graham <email@example.com>||Wed Nov 18 13:43:59 2020 -0800|
|committer||Commit Bot <firstname.lastname@example.org>||Fri Nov 20 20:38:13 2020 +0000|
Support `format --read-tree=json` Allows roundtripping to json and back with `gn format --dump-tree=json a.gn` and then `gn format --read-tree=json a.gn`. The preexisting .json format is not the most pleasant to work with, but this does at least allow for programmatic editing of the gn files with knowledge of structure, going beyond naive string replacement. For example, a python script to change `deps` inside `source_sets` from `=` to `+=` to support a BUILDCONFIG.gn change: https://gist.github.com/sgraham/bd9ffee312f307d5f417019a9c0f0777 The .json format was extended slightly, mostly to include location information which is necessary to faithfully roundtrip including whitespace. If the input .gn is formatted by `gn format`, then it can roundtrip to json without change. This was confirmed by running --dump-tree=json => --read-tree=json on all .gn and .gni files in both the Fuchsia and Chromium trees (https://gist.github.com/sgraham/bc561f19cd354746dd2469103e1f97d4), as well as by adding a roundtrip step to the formatter tests in-repo. Change-Id: Ie10bbbcb32b8184400ca9bb1f6ab63e5ca9c89e7 Reviewed-on: https://gn-review.googlesource.com/c/gn/+/10700 Reviewed-by: Brett Wilson <email@example.com> Commit-Queue: Scott Graham <firstname.lastname@example.org>
GN is a meta-build system that generates build files for Ninja.
Alternatively, you can build GN from source:
git clone https://gn.googlesource.com/gn cd gn python build/gen.py ninja -C out # To run tests: out/gn_unittests
On Windows, it is expected that
lib.exe can be found in
PATH, so you'll want to run from a Visual Studio command prompt, or similar.
On Linux and Mac, the default compiler is
clang++, a recent version is expected to be found in
PATH. This can be overridden by setting
There is a simple example in examples/simple_build directory that is a good place to get started with the minimal configuration.
To build and run the simple example with the default gcc compiler:
cd examples/simple_build ../../out/gn gen -C out ninja -C out ./out/hello
For a maximal configuration see the Chromium setup:
and the Fuchsia setup:
If you find a bug, you can see if it is known or report it in the bug database.
GN uses Gerrit for code review. The short version of how to patch is:
Register at https://gn-review.googlesource.com. ... edit code ... ninja -C out && out/gn_unittests
Then, to upload a change for review:
git commit git push origin HEAD:refs/for/master
The first time you do this you'll get an error from the server about a missing change-ID. Follow the directions in the error message to install the change-ID hook and run
git commit --amend to apply the hook to the current commit.
When revising a change, use:
git commit --amend git push origin HEAD:refs/for/master
which will add the new changes to the existing code review, rather than creating a new one.
We ask that all contributors sign Google's Contributor License Agreement (either individual or corporate as appropriate, select ‘any other Google project’).
You may ask questions and follow along with GN‘s development on Chromium’s gn-dev@ Google Group.