| commit | d0a6f072070988e7b038496c4e7d6c562b649732 | [log] [tgz] |
|---|---|---|
| author | Robert Sesek <rsesek@chromium.org> | Fri May 15 11:21:22 2020 -0400 |
| committer | Commit Bot <commit-bot@chromium.org> | Tue May 19 16:44:35 2020 +0000 |
| tree | 30b0c28e7a18989dc99aacef8398a711cdfaba7d | |
| parent | 3cbdb62872734f3ca71c9571fe6876a15ca55984 [diff] |
Add weak_frameworks linking option The -weak_framework linker flag adds a dynamic library dependency to the output, but it instructs the loader to skip loading the library if it is not present and leave the external symbols unresolved. This is typically used when a framework is present in a new version of an SDK that is not present on an older OS. See https://developer.apple.com/library/archive/documentation/MacOSX/Conceptual/BPFrameworks/Concepts/WeakLinking.html for details. Currently users of gn implement this using a config, but due to the way configs propagate, the -weak_link ldflags get lost at static_library boundaries. Having first-class support for weakly linked frameworks simplifies that. Bug: chromium:1082896 Change-Id: Ia93bf1b67e5b9205073b8f2bf3ed9b96e3af79e4 Reviewed-on: https://gn-review.googlesource.com/c/gn/+/8464 Commit-Queue: Brett Wilson <brettw@chromium.org> Reviewed-by: Sylvain Defresne <sdefresne@chromium.org> Reviewed-by: Brett Wilson <brettw@chromium.org>
GN is a meta-build system that generates build files for Ninja.
Related resources:
You can download the latest version of GN binary for Linux, macOS and Windows.
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 cl.exe, link.exe, and 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 CC, CXX, and AR.
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.