nix-ninja

Incremental compilation of Ninja build files using Nix Dynamic Derivations.

Choosing ninja as the build graph representation lets us support any build system that outputs ninja like CMake, meson, premake, gn, etc.

Key features • Getting started • Design notes • Contributing

Key features

Important

There are still major todos, and depends on experimental features from an unreleased version of Nix. Come help us get nix-ninja to be useful day-to-day and working with an official Nix release!

• Parses ninja.build files and generates a derivation per compilation unit.
• Stores build inputs & outputs in content-addressed derivations for granular and Nix-native incrementality.
• Compatible CLI for ninja, so if you set $NINJA to nix-ninja then meson just works.
• Supports running locally (which runs nix build on your behalf), or inside a Nix derivation (which creates dynamic derivations).

Getting started

First you need to use nix@d904921 and enable the following experimental features:

experimental-features = ["nix-command" "dynamic-derivations" "ca-derivations" "recursive-nix"]

Then you can try building the examples:

# Builds a basic main.cpp.
nix build github:pdtpartners/nix-ninja#example-hello

# Builds a basic main.cpp with dependency inference for its header.
nix build github:pdtpartners/nix-ninja#example-header

# Builds Nix 2.27.1.
nix build github:pdtpartners/nix-ninja#example-nix

You can also try running nix-ninja outside of Nix, but you'll need both nix-ninja and nix-ninja-task to be in your $PATH. Make sure nix-ninja-task is from the /nix/store as it is needed inside derivations nix-ninja generates.

export NIX_NINJA=$(nix build --print-out-paths)
export PATH="${NIX_NINJA}/bin:$PATH"
# Meson respects this environment variable and uses it as if its ninja.
export NINJA="${NIX_NINJA}/bin/nix-ninja"

Then you can go to an example and run it like so:

$ nix-shell
$ cd examples/hello
$ meson setup build
$ cd build
$ meson compile hello
$ ./hello
Hello Nix dynamic derivations!

Contributing

We still have major TODOs, so would appreciate any help. We've organize them under two GitHub milestones:

• 0.1.0 - The first release of nix-ninja aiming for correctness.
• 0.2.0 - Major performance features to make incremental builds productive.

Regardless, pull requests are welcome for any changes. Consider opening an issue to discuss larger changes first, especially when the design space is large.

Please read CONTRIBUTING and the design notes so you understand the big picture and prior art.

License

The source code developed for nix-ninja is licensed under MIT License.