[FartyMcFarter]

> Just like with array access, the compiler can often optimize the checks away, making the safe and unsafe versions equivalent when the compiler can prove it.

Can it "often" solve the halting problem as well?

The hope that this kind of optimization will happen sounds a bit fanciful for any non-trivial part of a program.

[steveklabnik]

You would be surprised, at least with array access stuff. And, if it doesn't, you can often help it understand with a bit of work. Sometimes an assert before a loop or re-slicing something can take a check in the body of a loop and move it out to a single one.

I ported a small C function to Rust recently that involved some looping, and all of the bounds checking was completely eliminated, even once I took the line-by-line port and turned it into a slightly higher level one with slices and iterators instead of pointer + length.