Negative Bounds for Avoiding Conflicts in Implementing Traits in Rust
summary
Introduces negative bounds (a minus operator on trait bounds) and a detection algorithm that checks unified type params plus the overlap of positive and excluded ancestor traits to avoid impl conflicts; prototype parser/resolver is implemented (~868 lines) and demonstrated resolving conflicts that previously required duplicate impls, with a claim of only adding an S·n·log n overhead and no major compile-time impact in typical cases; authors found >900 GitHub issues and tie the idea to RFC 1210 / rustc specialization.
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chapters (10)
- 0:00Negative bounds in Rust traits
- 1:05What are Rust traits
- 2:50Trait conflicts with type parameters
- 4:38Negative bounds to resolve conflicts
- 6:49Formal definition of trait conflicts
- 7:57Prototype implementation demo
- 10:51Complexity of checking algorithm
- 11:35Future work and plans
- 12:18Summary of solution
- 12:38Question and answer session begins
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