File: deriving-default-enum.rs

package info (click to toggle)
rustc 1.87.0%2Bdfsg1-1
  • links: PTS, VCS
  • area: main
  • in suites: forky, sid
  • size: 925,564 kB
  • sloc: xml: 158,127; python: 36,039; javascript: 19,761; sh: 19,737; cpp: 18,981; ansic: 13,133; asm: 4,376; makefile: 710; perl: 29; lisp: 28; ruby: 19; sql: 11
file content (27 lines) | stat: -rw-r--r-- 538 bytes parent folder | download | duplicates (15)
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
//@ run-pass

// nb: does not impl Default
#[derive(Debug, PartialEq)]
struct NotDefault;

#[derive(Debug, Default, PartialEq)]
enum Foo {
    #[default]
    Alpha,
    #[allow(dead_code)]
    Beta(NotDefault),
}

// #[default] on a generic enum does not add `Default` bounds to the type params.
#[derive(Default)]
enum MyOption<T> {
    #[default]
    None,
    #[allow(dead_code)]
    Some(T),
}

fn main() {
    assert!(matches!(Foo::default(), Foo::Alpha));
    assert!(matches!(MyOption::<NotDefault>::default(), MyOption::None));
}