Last change
on this file since 3f37f5b was
1725989,
checked in by Peter A. Buhr <pabuhr@…>, 2 months ago
|
add enumeration test programs for different programming languages
|
-
Property mode set to
100644
|
File size:
825 bytes
|
Rev | Line | |
---|
[1725989] | 1 | use std::mem; |
---|
| 2 | |
---|
| 3 | #[repr(u8)] enum Fieldless { |
---|
| 4 | Tuple() = 5, |
---|
| 5 | Struct{} = 10, |
---|
| 6 | Unit = 12, |
---|
| 7 | } |
---|
| 8 | impl 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 | } |
---|
| 16 | fn 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.