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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↩
);↩
}↩