Rust Unsafe Skill

When to Use Unsafe

• FFI with C libraries
• Raw pointers for performance
• Type transmutation (rare, dangerous)
• Unsafe trait implementations

Safety Documentation

/// SAFETY: The slice is guaranteed to be non-empty by the caller.
/// This is enforced by the type system via NonEmptySlice.
unsafe fn get_first_unchecked(slice: &[i32]) -> i32 {
    debug_assert!(!slice.is_empty());
    *slice.get_unchecked(0)
}