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// check-pass
//! The payloads of an enum variant should be ordered after its tag.
#![crate_type = "lib"]
#![feature(arbitrary_enum_discriminant)]
#![feature(transmutability)]
#![allow(dead_code)]
mod assert {
use std::mem::{Assume, BikeshedIntrinsicFrom};
pub struct Context;
pub fn is_transmutable<Src, Dst>()
where
Dst: BikeshedIntrinsicFrom<Src, Context, {
Assume::ALIGNMENT
.and(Assume::LIFETIMES)
.and(Assume::SAFETY)
.and(Assume::VALIDITY)
}>
{}
}
#[repr(u8)] enum V0 { V = 0 }
#[repr(u8)] enum V1 { V = 1 }
#[repr(u8)] enum V2 { V = 2 }
#[repr(u8)] enum E01 { V0(V1) = 0u8 }
#[repr(u8)] enum E012 { V0(V1, V2) = 0u8 }
fn should_order_tag_and_fields_correctly() {
// An implementation that (incorrectly) arranges E01 as [0x01, 0x00] will,
// in principle, reject this transmutation.
assert::is_transmutable::<E01, V0>();
// Again, but with one more field.
assert::is_transmutable::<E012, E01>();
}
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