Possibly related to https://simonwillison.net/2026/Apr/30/zig-anti-ai/ where the Bun team wanted to upstream work to Zig that was rejected by a blanket anti-LLM contribution policy.

Zig is a moving target that has breaking changes in every release (which is fine as they are sub-1.0). But that means that AI tools have been trained on outdated syntax/etc. Zig isn't that common, so there is even less training data to begin with.

Rust on the other hand is pretty established by now and has less breaking changes. It also has more compile-time safety-guarantees that makes vibe-coding a bit more confident.

In top of that, Zig has rejected their upstream contributions. So they'd have to maintain their own compiler in the long run, which is probably just technical debt to maintain.

Probably an experiment due to Bun's PRs to Zig being rejected (Zig does not allow AI use). If Rust works well enough, and the alternative is maintaining a fork of Zig, I'd guess they'd go with Rust.

If the computer can do it for them, then why not?

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