Fix problems pointed out by building with clang-cl.

After it's fairly
easy to build with clang-cl (and goma!), so I gave it a try:

set CC=c:\src\goma\goma-win64\gomacc.exe c:\src\chrome\src\third_party\llvm-build\Release+Asserts\bin\clang-cl.exe
set CXX=c:\src\goma\goma-win64\gomacc.exe c:\src\chrome\src\third_party\llvm-build\Release+Asserts\bin\clang-cl.exe
set CFLAGS=-Wno-c++11-narrowing
set LD=c:\src\chrome\src\third_party\llvm-build\Release+Asserts\bin\lld-link.exe
python build\
ninja -C out -j100

clang-cl caught a few issues, so this fixes them:
- remove a few unused private fields
- remove a few needless std::move() calls that prevent optimizations
- fix a benign -Wformat warning with char16_t
- fix some struct/class mismatches
- make a test actually test what it intended to test
- remove a const on a value type that had no effect
- fix field initialization order warnings in Value ctors

No behavior change.

Bug: none
Change-Id: I816a0382f2ef4f3a42d7945db6db5ce74fa9d5eb
Commit-Queue: Nico Weber <>
Reviewed-by: Scott Graham <>
14 files changed
tree: 4e690db98f59f01397d85c8a2f7d3e2cdec8cd72
  1. build/
  2. docs/
  3. examples/
  4. infra/
  5. misc/
  6. src/
  7. .clang-format
  8. .editorconfig
  9. .gitignore
  10. .style.yapf
  13. OWNERS


GN is a meta-build system that generates build files for Ninja.

Related resources:

Getting a binary

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.


There is a simple example in examples/simple_build directory that is a good place to get started with the minimal configuration.

For a maximal configuration see the Chromium setup:

and the Fuchsia setup:

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.

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You may ask questions and follow along with GN‘s development on Chromium’s gn-dev@ Google Group.