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// run-pass
#![feature(arbitrary_enum_discriminant, const_raw_ptr_deref, test)]
extern crate test;
use test::black_box;
#[allow(dead_code)]
#[repr(u8)]
enum Enum {
Unit = 3,
Tuple(u16) = 2,
Struct {
a: u8,
b: u16,
} = 1,
}
impl Enum {
const unsafe fn tag(&self) -> u8 {
*(self as *const Self as *const u8)
}
}
#[allow(dead_code)]
#[repr(u8)]
enum FieldlessEnum {
Unit = 3,
Tuple() = 2,
Struct {} = 1,
}
fn main() {
const UNIT: Enum = Enum::Unit;
const TUPLE: Enum = Enum::Tuple(5);
const STRUCT: Enum = Enum::Struct{a: 7, b: 11};
// Ensure discriminants are correct during runtime execution
assert_eq!(3, unsafe { black_box(UNIT).tag() });
assert_eq!(2, unsafe { black_box(TUPLE).tag() });
assert_eq!(1, unsafe { black_box(STRUCT).tag() });
// Ensure discriminants are correct during CTFE
const UNIT_TAG: u8 = unsafe { UNIT.tag() };
const TUPLE_TAG: u8 = unsafe { TUPLE.tag() };
const STRUCT_TAG: u8 = unsafe { STRUCT.tag() };
assert_eq!(3, UNIT_TAG);
assert_eq!(2, TUPLE_TAG);
assert_eq!(1, STRUCT_TAG);
// Ensure `as` conversions are correct
assert_eq!(3, FieldlessEnum::Unit as u8);
assert_eq!(2, FieldlessEnum::Tuple() as u8);
assert_eq!(1, FieldlessEnum::Struct{} as u8);
}
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