> Rust provides the RefCell wrapper There is also `Cell` (https://doc.rust-lang.org/std/cell/struct.Cell.html https://doc.rust-lang.org/std/cell/struct.Cell.ht

> Rust provides the RefCell wrapper There is also `Cell` (https://doc.rust-lang.org/std/cell/struct.Cell.html https://doc.rust-lang.org/std/cell/struct.Cell.html), which offers a different set of tradeoffs. > which policy do you want to be the zero-overhead default The one where: - The compiler can make more optimizations - I'm less likely to shoot myself in the foot my conflicting mutations is a good default for me, so I'm in favor of Rust. > a hypothetical future scenario where it is demonstrated that the optimizers are good enough This sounds like the sufficiently smart compiler (http://wiki.c2.com/?SufficientlySmartCompiler http://wiki.c2.com/?SufficientlySmartCompiler) argument. While I'd love to live in this world, we aren't there yet. Even in such a world, there would still be reasons to choose Rust over C, such as standardized dependency management or a rich type system.