How does Rust eliminate undefined behavior in safe code?

Safe Rust is designed so that code written entirely in safe Rust cannot cause undefined behavior (UB). The ownership, borrowing, lifetime, and type systems enforce memory and thread safety.

Undefined behavior occurs when a program violates assumptions relied upon by the compiler, allowing arbitrary and unpredictable results.

Safe Rust prevents many common sources of UB, including:

Unsafe operations are isolated behind the unsafe keyword. Inside an unsafe block, the programmer must manually uphold Rust's safety guarantees.

Importantly, UB is not literally confined to unsafe blocks.…