thurbeen/unsafe-checker

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⚠️ **Unsafe Rust Checker Loaded**

     *  ^  *
    /◉\_~^~_/◉\
 ⚡/     o     \⚡
   '_        _'
   / '-----' \

Unsafe Rust Checker

When Unsafe is Valid

| Use Case | Example | |----------|---------| | FFI | Calling C functions | | Low-level abstractions | Implementing Vec, Arc | | Performance | Measured bottleneck with safe alternative too slow |

NOT valid: Escaping borrow checker without understanding why.

Required Documentation

// SAFETY: <why this is safe>
unsafe { ... }

/// # Safety
/// <caller requirements>
pub unsafe fn dangerous() { ... }

Quick Reference

| Operation | Safety Requirements | |-----------|---------------------| | *ptr deref | Valid, aligned, initialized | | &*ptr | + No aliasing violations | | transmute | Same size, valid bit pattern | | extern "C" | Correct signature, ABI | | static mut | Synchronization guaranteed | | impl Send/Sync | Actually thread-safe |

Common Errors

| Error | Fix | |-------|-----| | Null pointer deref | Check for null before deref | | Use after free | Ensure lifetime validity | | Data race | Add proper synchronization | | Alignment violation | Use #[repr(C)], check alignment | | Invalid bit pattern | Use MaybeUninit | | Missing SAFETY comment | Add // SAFETY: |

Deprecated → Better

| Deprecated | Use Instead | |------------|-------------| | mem::uninitialized() | MaybeUninit<T> | | mem::zeroed() for refs | MaybeUninit<T> | | Raw pointer arithmetic | NonNull<T>, ptr::add | | CString::new().unwrap().as_ptr() | Store CString first | | static mut | AtomicT or Mutex | | Manual extern | bindgen |

FFI Crates

| Direction | Crate | |-----------|-------| | C → Rust | bindgen | | Rust → C | cbindgen | | Python | PyO3 | | Node.js | napi-rs |

Claude knows unsafe Rust. Focus on SAFETY comments and soundness.