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.

The anti-AI policy had nothing to do with Bun's PRs being rejected. This post[0] by a core zig maintainer explains why the PRs were low quality and subsequently rejected.

[0] https://ziggit.dev/t/bun-s-zig-fork-got-4x-faster-compilatio...

Was there even a PR? The post from Bun [1] says they have no plan to upstream it, and that ziggit post says the changes are undesirable. It sounds like there never was anything to reject.

[1] https://x.com/bunjavascript/status/2048428104893542781

Also, if Zig itself doesn’t accept AI contributions, it’s probably NGMI unless somebody is willing to maintain that fork.