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Use when writing Rust arithmetic on amounts or other quantities derived from external/user input — guard against silent overflow.
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Enforce type-signature conventions for public Miden Assembly (.masm) procedures. Use when adding, editing, or reviewing a `pub proc` signature — parameter and return types, semantic type aliases, struct/array/tuple types, and how the signature maps onto the operand stack and the doc-comment Inputs/Outputs.
Enforce inline commenting conventions for Miden Assembly (.masm) files. Use when editing, reviewing, or creating .masm files.
Enforce doc comment conventions for Miden Assembly (.masm) procedures. Use when editing, reviewing, or creating .masm procedures, especially when documenting inputs, outputs, panic conditions, or invocation types.
Use when writing kernel, account, or note MASM code that reads from or writes to the advice provider (advice stack / advice map) — validate advice data.
Use when writing a Rust test that exercises a failure path or a MASM test that expects a `panic` / `assert` — assert on the specific expected error variant or error code.
Use when writing or reviewing MASM hot paths — prefer the cheaper equivalent instruction: `neq.0` over `gt.0` for non-zero checks, `cdrop` over an `if/else` selecting between two values, `dup.N` over `loc_load` for a value still on the stack, `eqw` over element-wise word comparison, `u32gt`/`u32lt` over generic `gt`/`lt` on known-u32 operands.
| name | checked-arithmetic |
| description | Use when writing Rust arithmetic on amounts or other quantities derived from external/user input — guard against silent overflow. |
Any arithmetic where one or more operands originates from external input (transaction body, advice provider, user RPC, deserialized payload) must use checked or overflowing arithmetic and surface the overflow:
checked_add / checked_sub / checked_mul and return an error on None.overflowing_add / widening_mul when you need the wrapping value and the overflow flag; then assert!(!overflow) (or branch) before using the result.+, -, * operators on untrusted values in release builds — debug-only overflow checks are not enough.The default +, -, * operators wrap silently in release builds, so an overflow on a balance or amount yields a wrong value with no error. Checked and overflowing operations surface the overflow so it can be rejected.
// Good: checked
let total = balance.checked_add(amount).ok_or(Error::Overflow)?;
// Good: overflowing with explicit flag check
let (product, overflow) = a.widening_mul(b);
if overflow { return Err(Error::Overflow); }
// Bad: wraps on overflow in release
let total = balance + amount;