Search code examples
rustenumsreferencecloneprimitive-types

How one can cast ref to enum value as u16 (base enum type) in Rust?

Given:

#[repr(u16)]
#[derive(PartialEq, Debug, Eq, Hash, Clone)]
pub enum SomeEnum {
    SomeValue1 = 1,
    SomeValue2 = 1 << 2 | Self::SomeValue1 as u16, // some bitmasks
    // ...
}

pub fn some_check(actual_value_ref: &SomeEnum, base_value: SomeEnum) -> bool {
    let actual_value_u16 = actual_value_ref.clone() as u16; // how to cast without cloning?
    let base_value_u16 = base_value as u16;
    actual_value_u16 & base_value_u16 == base_value_u16 // bitmask operation
}

How one can get value by reference for a primitive without explicit cloning? Cloning of u16 does not look like a tragedy but what's the right way to do it? Since enum is explicitly marked as #[repr(u16)] why compiler doesn't do it out-of-box?

Solution

  • To avoid explicit cloneing, I think it should suffice to derive(Copy) for SomeEnum.