Group Borrowing: Zero-Cost Memory Safety with Fewer Restrictions

13 days ago

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Memory safety is a significant unsolved problem with various unexplored models.
Current memory-safe languages are limited in being either fast or flexible, but not both.
Nick Smith proposes a novel approach for zero-overhead mutable aliasing without relying on reference counting, garbage collection, or generational references.
The approach distinguishes between references to an object and its contents, allowing multiple mutable references to an object while carefully managing references to its contents.
Child groups are introduced to precisely track which references are invalidated upon mutation, improving memory safety without unnecessary restrictions.
Group annotations in function signatures help the compiler understand and enforce memory safety rules across function calls.
The model potentially offers better flexibility and performance compared to Rust's borrow checker, though it may have some trade-offs.
The approach is still evolving and could inspire hybrid memory safety models in the future.

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