An ISSTA 2026 study finds most rustc soundness bugs persisted since feature introduction

Sources: preprint, publisher record, discussion
Summary: The study, titled "Rust's Type Checker Implementation Is Unsound", examines 30 soundness bugs collected from the rustc GitHub issue tracker between 2022-01-01 and 2025-09-01. It reports that most of the bugs persist from the initial introduction of the relevant features and require significant time to be discovered, and that the bugs compromising memory safety cluster on implied bounds and trait objects. The authors report that AddressSanitizer and Miri catch the memory-safety subset, while a-mir-formality and Chalk are not yet mature enough to serve as oracles for the rest.
Why it matters: No existing tool acts as an oracle for the non-memory-safety soundness bugs, so those are found by report rather than by testing.