Toward safe transmutation in Rust

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2024-10-26 03:30:06

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Currently in Rust, there is no efficient and safe way to turn an array of bytes into a structure that corresponds to the array. Changing that was the topic of Jack Wrenn's talk this year at RustConf: "Safety Goggles for Alchemists". The goal is to be able to "transmute" — Rust's name for this kind of conversion — values into arbitrary user-defined types in a safer way. Wrenn justified the approach that the project has taken to accomplish this, and spoke about the future work required to stabilize it.

The basic plan is to take the existing unsafe std::mem::transmute() function, which instructs the compiler to reinterpret part of memory as a different type (but requires the programmer to ensure that this is reasonable), and make a safe version that can check the necessary invariants itself. The first part of Wrenn's talk focused on what those invariants are, and how to check them.