blob: e0bb782270e22821f416ac44a45d91236e985ffd (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
|
# `arbitrary_enum_discriminant`
The tracking issue for this feature is: [#60553]
[#60553]: https://github.com/rust-lang/rust/issues/60553
------------------------
The `arbitrary_enum_discriminant` feature permits tuple-like and
struct-like enum variants with `#[repr(<int-type>)]` to have explicit discriminants.
## Examples
```rust
#![feature(arbitrary_enum_discriminant)]
#[allow(dead_code)]
#[repr(u8)]
enum Enum {
Unit = 3,
Tuple(u16) = 2,
Struct {
a: u8,
b: u16,
} = 1,
}
impl Enum {
fn tag(&self) -> u8 {
unsafe { *(self as *const Self as *const u8) }
}
}
assert_eq!(3, Enum::Unit.tag());
assert_eq!(2, Enum::Tuple(5).tag());
assert_eq!(1, Enum::Struct{a: 7, b: 11}.tag());
```
|
