|author||Brett Wilson <firstname.lastname@example.org>||Fri Mar 20 19:19:24 2020 -0700|
|committer||Commit Bot <email@example.com>||Mon Mar 23 16:57:34 2020 +0000|
Match all toolchains by default. GN was originally designed expecting that most users would only want to interact with the default toolchain. As a result, most introspection commands match only targets in the default toolchain by default. But some builds have made greater use of the toolchain feature. For example, in Fuchsia, allshared libraries and all of their dependencies are compiled in a special "shared" toolchain with "position independent code" enabled. Most users are not aware of this. So in such builds, having introspection commands only match targets in the default toolchain can be surprising and look broken. This changes the default to match all toolchains for introspection commands that can take labels. A new --default-toolchain flag is added for the default behavior, and the previous --all-toolchains flag is removed. Change-Id: Ifa0dfa5b8c792c115443776f3b992d2d6b03bf02 Reviewed-on: https://gn-review.googlesource.com/c/gn/+/7840 Reviewed-by: Scott Graham <firstname.lastname@example.org> Commit-Queue: Brett Wilson <email@example.com>
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.