|author||Michael Spang <firstname.lastname@example.org>||Mon Aug 10 00:02:33 2020 -0400|
|committer||Commit Bot <email@example.com>||Wed Aug 19 17:11:18 2020 +0000|
Identify current toolchain on error Currently errors from GN identify the source location that failed, but not the toolchain. This can be confusing, and adding a print(current_toolchain) is often helpful when debugging these errors. This patch changes GN to include the toolchain in the error message whenever there's an error in a non-default toolchain. This produces output like the following: ERROR at //subdir/BUILD.gn:3:1 (//:toolchain): Assertion failed. assert(only_true_in_default_toolchain) ^----- See //BUILD.gn:51:14: which caused the file to be included. deps = [ "subdir" ] ^------- Bug: 184 Change-Id: I8463f04cf94242c4f7c518d4840ae8f586b4e4fa Reviewed-on: https://gn-review.googlesource.com/c/gn/+/9640 Commit-Queue: Brett Wilson <firstname.lastname@example.org> Reviewed-by: 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.