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//@ check-pass
//! Checks that niche optimizations are encoded correctly.
#![crate_type = "lib"]
#![feature(transmutability)]
#![allow(dead_code, incomplete_features, non_camel_case_types)]
mod assert {
use std::mem::{Assume, TransmuteFrom};
pub fn is_transmutable<Src, Dst>()
where
Dst: TransmuteFrom<Src, {
Assume {
alignment: false,
lifetimes: false,
safety: true,
validity: false,
}
}>
{}
pub fn is_maybe_transmutable<Src, Dst>()
where
Dst: TransmuteFrom<Src, {
Assume {
alignment: false,
lifetimes: false,
safety: true,
validity: true,
}
}>
{}
}
#[repr(u8)] enum V0 { V = 0 }
#[repr(u8)] enum V1 { V = 1 }
#[repr(u8)] enum V2 { V = 2 }
#[repr(u8)] enum V253 { V = 253 }
#[repr(u8)] enum V254 { V = 254 }
#[repr(u8)] enum V255 { V = 255 }
fn bool() {
enum OptionLike {
A(bool),
B,
}
const _: () = {
assert!(std::mem::size_of::<OptionLike>() == 1);
};
assert::is_transmutable::<OptionLike, u8>();
assert::is_transmutable::<bool, OptionLike>();
assert::is_transmutable::<V0, OptionLike>();
assert::is_transmutable::<V1, OptionLike>();
assert::is_transmutable::<V2, OptionLike>();
}
fn one_niche() {
#[repr(u8)]
enum N1 {
S = 0,
E = 255 - 1,
}
enum OptionLike {
A(N1),
B,
}
const _: () = {
assert!(std::mem::size_of::<OptionLike>() == 1);
};
assert::is_transmutable::<OptionLike, u8>();
assert::is_transmutable::<V0, OptionLike>();
assert::is_transmutable::<V1, OptionLike>();
assert::is_transmutable::<V254, OptionLike>();
}
fn one_niche_alt() {
#[repr(u8)]
enum N1 {
S = 1,
E = 255 - 1,
}
enum OptionLike {
A(N1),
B,
C,
}
const _: () = {
assert!(std::mem::size_of::<OptionLike>() == 1);
};
assert::is_transmutable::<OptionLike, u8>();
assert::is_transmutable::<V1, OptionLike>();
assert::is_transmutable::<V2, OptionLike>();
assert::is_transmutable::<V254, OptionLike>();
}
fn two_niche() {
#[repr(u8)]
enum Niche {
S = 0,
E = 255 - 2,
}
enum OptionLike {
A(Niche),
B,
C,
}
const _: () = {
assert!(std::mem::size_of::<OptionLike>() == 1);
};
assert::is_transmutable::<OptionLike, u8>();
assert::is_transmutable::<V0, OptionLike>();
assert::is_transmutable::<V1, OptionLike>();
assert::is_transmutable::<V2, OptionLike>();
assert::is_transmutable::<V253, OptionLike>();
}
fn no_niche() {
use std::mem::MaybeUninit;
#[repr(u8)]
enum Niche {
S = 0,
E = 255 - 1,
}
enum OptionLike {
A(Niche),
B,
C,
}
const _: () = {
assert!(std::mem::size_of::<OptionLike>() == 1);
};
#[repr(C)]
struct Pair<T, U>(T, U);
assert::is_transmutable::<V0, Niche>();
assert::is_transmutable::<V254, Niche>();
assert::is_transmutable::<Pair<V0, Niche>, OptionLike>();
assert::is_transmutable::<Pair<V1, MaybeUninit<u8>>, OptionLike>();
assert::is_transmutable::<Pair<V2, MaybeUninit<u8>>, OptionLike>();
}
fn niche_fields() {
enum Kind {
A(bool, bool),
B(bool),
}
assert::is_maybe_transmutable::<u16, Kind>();
}
|
