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#![allow(clippy::disallowed_names)]
use bytemuck::{offset_of, Zeroable};
#[test]
fn test_offset_of_vertex() {
#[repr(C)]
struct Vertex {
pos: [f32; 2],
uv: [u16; 2],
color: [u8; 4],
}
unsafe impl Zeroable for Vertex {}
let pos = offset_of!(Zeroable::zeroed(), Vertex, pos);
let uv = offset_of!(Zeroable::zeroed(), Vertex, uv);
let color = offset_of!(Zeroable::zeroed(), Vertex, color);
assert_eq!(pos, 0);
assert_eq!(uv, 8);
assert_eq!(color, 12);
}
#[test]
fn test_offset_of_foo() {
#[derive(Default)]
struct Foo {
a: u8,
b: &'static str,
c: i32,
}
let a_offset = offset_of!(Default::default(), Foo, a);
let b_offset = offset_of!(Default::default(), Foo, b);
let c_offset = offset_of!(Default::default(), Foo, c);
assert_ne!(a_offset, b_offset);
assert_ne!(b_offset, c_offset);
// We can't check against hardcoded values for a repr(Rust) type,
// but prove to ourself this way.
let foo = Foo::default();
// Note: offsets are in bytes.
let as_bytes = &foo as *const _ as *const u8;
// we're using wrapping_offset here because it's not worth
// the unsafe block, but it would be valid to use `add` instead,
// as it cannot overflow.
assert_eq!(
&foo.a as *const _ as usize,
as_bytes.wrapping_add(a_offset) as usize
);
assert_eq!(
&foo.b as *const _ as usize,
as_bytes.wrapping_add(b_offset) as usize
);
assert_eq!(
&foo.c as *const _ as usize,
as_bytes.wrapping_add(c_offset) as usize
);
}
|
