Add command_launcher field to tools

This is a field to specify the command launcher for a given tool's
command. It appends the launcher to the command in the Ninja rule, but
keeps the two separate inside of GN. This allows the IDE writer tools
(e.g. the compilation command database) to be written without the
launcher prefix.

The presence of the launcher in the command has been breaking a number
of developer workflows in VSCode, CLion, and clangd. This should resolve
all of those workflows.

Change-Id: Idec6f530ddc48da01ac0c79b64032c7cc88856a4
Commit-Queue: Julie Hockett <>
Reviewed-by: Petr Hosek <>
Reviewed-by: Brett Wilson <>
8 files changed
tree: eff3bed57dccffa7facab4376e8b4d1def8c0d80
  1. .clang-format
  2. .editorconfig
  3. .gitignore
  4. .style.yapf
  9. base/
  10. build/
  11. docs/
  12. infra/
  13. tools/
  14. util/


GN is a meta-build system that generates build files for Ninja. There is documentation in docs/ and a presentation on it.

Getting started

You can download the latest version of GN binary for Linux, macOS and Windows.

Alternatively, you can build GN from source:

git clone
cd gn
python build/
ninja -C out
# To run tests:

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.

Reporting bugs

If you find a bug, you can see if it is known or report it in the bug database.

Sending patches

GN uses Gerrit for code review. The short version of how to patch is:

Register at

... edit code ...
ninja -C out && out/gn_unittests

Then, to upload a change for review:

git commit
git cl upload --gerrit

When revising a change, use:

git commit --amend
git cl upload --gerrit

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 w/ GN‘s development on Chromium’s gn-dev@ Google Group.