> This comment suggests you don't have much domain knowledge about how `unsafe` in Rust works, so I'm surprised you speak with such confidence.
I hate being tone police, but jeez, we're having a discussion about Rust here and talking about my personal competency is inappropriate and unwelcome.
The problem I'm talking about happens when you write libraries that contain "unsafe" blocks. You want to prove (or at least assure yourself) that no unsafe behavior is observable by clients of the library. However, the way to do this is not entirely clear, although there is research being done in this area. One known trap is that it is not sufficient to demonstrate that Rust code without "unsafe" blocks cannot observe unsafe behavior in your library.
I hate being tone police, but jeez, we're having a discussion about Rust here and talking about my personal competency is inappropriate and unwelcome.
The problem I'm talking about happens when you write libraries that contain "unsafe" blocks. You want to prove (or at least assure yourself) that no unsafe behavior is observable by clients of the library. However, the way to do this is not entirely clear, although there is research being done in this area. One known trap is that it is not sufficient to demonstrate that Rust code without "unsafe" blocks cannot observe unsafe behavior in your library.
See: https://plv.mpi-sws.org/rustbelt/popl18/paper.pdf
These concerns are not hypothetical, there have been soundness problems in the Rust standard library before and I expect it to happen again.