n2, an alternative ninja implementation

n2 (pronounced "into") implements enough of ninja to successfully build some projects that build with ninja.

I wrote it to explore some alternative ideas I had around how to structure a build system.

Here's a small demo of n2 building some of Clang.

More reading

• Design notes.
• Development tips.

Differences from Ninja

n2 is missing many Ninja features.

n2 does some things Ninja doesn't:

• Builds start tasks as soon as an out of date one is found, rather than gathering all the out of date tasks before executing.
• Fancier status output, modeled after Bazel.
• -d trace generates a performance trace as used by Chrome's about:tracing or alternatives (speedscope, perfetto).