---

name: maverick-rust-unsafe description: Rust unsafe code, FFI, and safety invariants version: 1.0.0 triggers:

• unsafe
• "unsafe {"
• "unsafe fn"
• raw pointer
• "*const"
• "*mut"
• transmute
• FFI
• extern

---

Rust Unsafe Skill

When to Use Unsafe

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

Safety Documentation

Copy/// 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)
}

Avoid Unsafe When Possible

Copy// BAD - unjustified unsafe
unsafe fn get_first(slice: &[i32]) -> i32 {
    *slice.get_unchecked(0)
}

// GOOD - safe alternative
fn get_first(slice: &[i32]) -> Option<&i32> {
    slice.first()
}

Review Severity

• CRITICAL: Unsafe without justification, potential undefined behavior
• MAJOR: Missing safety documentation, unsafe could be safe
• MINOR: Debug assertions missing in unsafe code