source: doc/theses/jiada_liang_MMath/test1.rs @ 1842167

Last change on this file since 1842167 was 1725989, checked in by Peter A. Buhr <pabuhr@…>, 5 months ago

add enumeration test programs for different programming languages

  • Property mode set to 100644
File size: 825 bytes
RevLine 
[1725989]1use std::mem;
2
3#[repr(u8)] enum Fieldless {
4    Tuple() = 5,
5    Struct{} = 10,
6    Unit = 12,
7}
8impl Fieldless {
9    fn discriminant(&self) -> u8 {
10        // SAFETY: Because `Self` is marked `repr(u8)`, its layout is a `repr(C)` `union`
11        // between `repr(C)` structs, each of which has the `u8` discriminant as its first
12        // field, so we can read the discriminant without offsetting the pointer.
13        unsafe { *<*const _>::from(self).cast::<u8>() }
14    }
15}
16fn main() {
17        let mut fl : Fieldless;
18        fl = Fieldless::Struct{};
19        match fl {
20                Fieldless::Struct{} => println!( "Struct" ),
21                _ => (),
22        }
23        if mem::discriminant(&fl) == mem::discriminant(&Fieldless::Struct{}) {
24                println!( "Struct" );
25        }
26        if fl.discriminant() == 10 {
27                println!( "Struct" );
28        }
29}
30
31// Local Variables: //
32// tab-width: 4 //
33// End: //
Note: See TracBrowser for help on using the repository browser.