Fil-C aborts your program if it detects unsafe memory operations. You very much can write code that is not memory safe, it will just crash. Also it has significant runtime cost.

Rust tries to prevent you from writing memory-unsafe code. But it has official ways of overcoming these barriers ("unsafe" keyword, which tells compiler - "trust me bro, I know what I'm doing) and some soundness holes. But beause safety is proven statically by compiler, it is mostly zero-cost. ("Mostly" because some things compiler can't prove and people resort to "unsafe" + runtime checks)

Two orthogonal approaches to safety. You could have Fil-C style runtime checks in Rust, in principle.