Needless bit mask when casting from a larger integer to a smaller integer

[sorairolake]

What it does

Checks for needless bit mask when casting from a larger integer to a smaller integer to extract the trailing part of the integer. When casting casting from a larger integer to a smaller integer, the excess part is truncated, so bit mask is unnecessary.¹

Advantage

Simplify code.

Drawbacks

No response

Example

fn split_half(n: u16) -> (u8, u8) {
    (((n >> 8) & 0xff) as u8, (n & 0xff) as u8)
}

Could be written as:

fn split_half(n: u16) -> (u8, u8) {
    ((n >> 8) as u8, n as u8)
}

Comparison with existing lints

No response

Additional Context

No response

Footnotes

1. https://doc.rust-lang.org/reference/expressions/operator-expr.html#r-expr.as.numeric.int-truncation ↩