tomevault-io 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)
}
Avoid Unsafe When Possible
// 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
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