Move SourceFileTypeSet to Target

Have the target track which types of source files it contains, and check
that only one type exists. Prevents recompution in a few places, but
also allows for checking what language a target should be compiled

Note that it will error out if complilation-incompatible source types
are used (e.g. having C and C++ in the same target is fine, but having C
and Rust in the same target isn't).

Change-Id: I5afb038e4cfa7da79c9f264cee79a8c652797dc3
Commit-Queue: Julie Hockett <>
Reviewed-by: Brett Wilson <>
12 files changed
tree: f3afaa9e4b497fba13adf1b2027d1f9509a83d95
  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.