61 lines
1.0 KiB
Rust
61 lines
1.0 KiB
Rust
|
// Copyright 2019 The Fuchsia Authors. All rights reserved.
|
||
|
|
// Use of this source code is governed by a BSD-style license that can be
|
||
|
|
// found in the LICENSE file.
|
||
|
|
|
||
|
|
#![allow(warnings)]
|
||
|
|
|
||
|
|
use std::{marker::PhantomData, option::IntoIter};
|
||
|
|
|
||
|
|
use zerocopy::FromBytes;
|
||
|
|
|
||
|
|
struct IsFromBytes<T: FromBytes>(T);
|
||
|
|
|
||
|
|
// Fail compilation if `$ty: !FromBytes`.
|
||
|
|
macro_rules! is_from_bytes {
|
||
|
|
($ty:ty) => {
|
||
|
|
const _: () = {
|
||
|
|
let _: IsFromBytes<$ty>;
|
||
|
|
};
|
||
|
|
};
|
||
|
|
}
|
||
|
|
|
||
|
|
// A union is `FromBytes` if:
|
||
|
|
// - all fields are `FromBytes`
|
||
|
|
|
||
|
|
#[derive(Clone, Copy, FromBytes)]
|
||
|
|
union Zst {
|
||
|
|
a: (),
|
||
|
|
}
|
||
|
|
|
||
|
|
is_from_bytes!(Zst);
|
||
|
|
|
||
|
|
#[derive(FromBytes)]
|
||
|
|
union One {
|
||
|
|
a: u8,
|
||
|
|
}
|
||
|
|
|
||
|
|
is_from_bytes!(One);
|
||
|
|
|
||
|
|
#[derive(FromBytes)]
|
||
|
|
union Two {
|
||
|
|
a: u8,
|
||
|
|
b: Zst,
|
||
|
|
}
|
||
|
|
|
||
|
|
is_from_bytes!(Two);
|
||
|
|
|
||
|
|
#[derive(FromBytes)]
|
||
|
|
union TypeParams<'a, T: Copy, I: Iterator>
|
||
|
|
where
|
||
|
|
I::Item: Copy,
|
||
|
|
{
|
||
|
|
a: T,
|
||
|
|
c: I::Item,
|
||
|
|
d: u8,
|
||
|
|
e: PhantomData<&'a [u8]>,
|
||
|
|
f: PhantomData<&'static str>,
|
||
|
|
g: PhantomData<String>,
|
||
|
|
}
|
||
|
|
|
||
|
|
is_from_bytes!(TypeParams<'static, (), IntoIter<()>>);
|