source: doc/theses/jiada_liang_MMath/test1.rs @ d287f3e

use std::mem;

#[repr(u8)] enum Fieldless {
    Tuple() = 5,
    Struct{} = 10,
    Unit = 12,
}
impl Fieldless {
    fn discriminant(&self) -> u8 {
        // SAFETY: Because `Self` is marked `repr(u8)`, its layout is a `repr(C)` `union`
        // between `repr(C)` structs, each of which has the `u8` discriminant as its first
        // field, so we can read the discriminant without offsetting the pointer.
        unsafe { *<*const _>::from(self).cast::<u8>() }
    }
}
fn main() {
        let mut fl : Fieldless;
        fl = Fieldless::Struct{};
        match fl {
                Fieldless::Struct{} => println!( "Struct" ),
                _ => (),
        }
        if mem::discriminant(&fl) == mem::discriminant(&Fieldless::Struct{}) {
                println!( "Struct" );
        }
        if fl.discriminant() == 10 {
                println!( "Struct" );
        }
}

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