Bun Rust rewrite hits pervasive soundness failures

Jarred Sumner’s "move fast and break things" approach has officially collided with Rust's borrow checker, exposing the dangers of large-scale AI "vibe coding" in systems programming.

• –The rewrite relies on 13,000+ `unsafe` blocks to perform a 1:1 translation from Zig, effectively bypassing Rust's safety guarantees.
• –Concrete examples of UB include lifetime erasure in core path handling, allowing safe Rust code to produce dangling pointers.
• –Critics argue the "slopaghetti" codebase inherits C-style risks without the benefits of Rust idiomaticity, creating a massive maintenance and security debt.
• –While maintainers view this as an "incremental starting point," the sheer volume of unsound code makes manual audit and refactoring a Herculean task.
• –The incident serves as a stark warning: LLMs are currently incapable of safely automating architectural shifts in memory-sensitive languages.