The article argues that modular proofs—where impls must establish all supertrait obligations—are the only viable approach for supporting cyclic trait impls in Rust. The author explains why the alternative, 'external' proofs (where call sites prove supertraits), is incompatible with Rust's design. This is part of an ongoing series on cyclic trait impls.
Background
This is part of a blog series by a Rust compiler contributor exploring cyclic trait implementations, a long-standing feature request in the Rust ecosystem that would allow traits to reference each other cyclically.
- Source
- Lobsters
- Published
- Oct 11, 2026 at 12:56 AM
- Score
- 6.0 / 10