[Rusky]

There's some good discussion of how it happened here: https://www.reddit.com/r/rust/comments/7cwpbq/fearless_concu...

One of the biggest contributors is "custom derive," which cuts out a lot of boilerplate. Another is that Gecko C++ is also pretty old and so doesn't rely on a lot of what is now standard. It's also just a ground-up rewrite, which has the advantage of hindsight.

It's not a trick of moving code around.

[zellyn]

Oh, thanks. Perfect link. It makes sense that rewrites are smaller, but the reduction factor was still surprising.