That would mean everything is unsafe, since every crate depends on core (or on std which depends on core), which has "unsafe" code.
The design of "unsafe" in Rust, instead, is to allow building safe abstractions on top of unsafe code (or be able to clearly mark when the abstraction itself is unsafe). That way, for instance, users of `Vec::push` do not have to worry that it uses uninitialized memory (which is unsafe).
https://doc.rust-lang.org/src/alloc/string.rs.html#1215-1230
Using unsafe doesnt necessarily mean you will have undefined behaviour, it just means you have to think really hard about the behaviour because the compiler won't have your back.
- uses unsafe - no unsafe, but dependencies may use unsafe - no unsafe, no dependencies except the standard library may use unsafe - no unsafe, not even in the standard library uses
The current situation is the second one, but many cases probably want the third, and occasionally the fourth.
The best part is, this should be fairly easily solved by crates.io upon submission (is there any use of unsafe and are all dependencies marked as strict or more strictly than yours?).
The obvious implementation is for unsafe to be infectious like const. You have unsafe code, your crate is unsafe. You depend on an unsafe crate, your crate becomes unsafe.