Add lints IMPLICIT_SATURATING_MUL and IMPLICIT_SATURATING_DIV

[alex-semenyuk]

What it does

Add lint similar to IMPLICIT_SATURATING_SUB and IMPLICIT_SATURATING_ADD, but for MUL and DIV.

Lint Name

IMPLICIT_SATURATING_MUL and IMPLICIT_SATURATING_DIV

Category

pedantic

Advantage

As mentioned at clippy::implicit_saturating_sub and clippy::implicit_saturating_add, the built-in function is more readable and may be faster.

Drawbacks

No response

Example

 let mut i: u32 = 3;
 i *= 2;

let mut i: u32 = 6;
i /= 2;

Could be written as:

let mut i: u32 = 3;
i = i.saturating_mul(2);

let mut i: u32 = 6;
i = i.saturating_div(2);

[llogiq]

I don't see anything saturating in your "bad" examples. Why should we lint assigning ops that multiply or divide?

[alex-semenyuk]

Thanks, fill the section about Advantage

[llogiq]

I might misunderstand something, but not all multiplication and division should saturate by default.

Implementing saturating multiplication manually is quite complex. Division is far easier (one only needs to consider the divide by zero case, but even then the sign needs to be applied), but still non-trivial.

So what pattern should the lint check for?