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### What it does
Checks any kind of arithmetic operation of any type.
Operators like `+`, `-`, `*` or `<<` are usually capable of overflowing according to the [Rust
Reference](https://doc.rust-lang.org/reference/expressions/operator-expr.html#overflow),
or can panic (`/`, `%`).
Known safe built-in types like `Wrapping` or `Saturing`, floats, operations in constant
environments, allowed types and non-constant operations that won't overflow are ignored.
### Why is this bad?
For integers, overflow will trigger a panic in debug builds or wrap the result in
release mode; division by zero will cause a panic in either mode. As a result, it is
desirable to explicitly call checked, wrapping or saturating arithmetic methods.
#### Example
```
// `n` can be any number, including `i32::MAX`.
fn foo(n: i32) -> i32 {
n + 1
}
```
Third-party types can also overflow or present unwanted side-effects.
#### Example
```
use rust_decimal::Decimal;
let _n = Decimal::MAX + Decimal::MAX;
```
### Allowed types
Custom allowed types can be specified through the "arithmetic-side-effects-allowed" filter.
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