Lifetimes would prevent the particular use-after-free example here, but the UB that miri currently flags would still exist, as it's related to pointer provenance, not lifetimes.

https://www.reddit.com/r/rust/comments/1hxjdvp/eli5_what_is_...

Unsafe code still mostly needs lifetimes. It extends the functionality, not removing them. I wonder how much nasty things they have done then.