1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
|
//@ run-pass
//@ reference: layout.aggregate.struct-offsets
//@ edition: 2018
#[repr(align(64))]
#[derive(Copy, Clone)]
#[allow(dead_code)]
pub struct Overaligned(u8);
#[allow(dead_code)]
struct ReprRustStruct {
x: i32,
y: [u32; 4],
z: f32,
a: u128,
b: Overaligned,
}
macro_rules! span_of {
($ty:ty , $field:tt) => {{
let __field = unsafe { ::core::mem::zeroed::<$ty>() };
(
core::mem::offset_of!($ty, $field),
core::mem::offset_of!($ty, $field) + core::mem::size_of_val(&__field.$field),
)
}};
}
fn test_fields_make_sense(a: &(usize, usize)) {
assert!(a.0 <= a.1);
}
// order is `begin, end`
fn test_non_overlapping(a: &(usize, usize), b: &(usize, usize)) {
assert!((a.1 <= b.0) || (b.1 <= a.0));
}
fn test_fields_non_overlapping() {
let fields = [
span_of!(ReprRustStruct, x),
span_of!(ReprRustStruct, y),
span_of!(ReprRustStruct, z),
span_of!(ReprRustStruct, a),
span_of!(ReprRustStruct, b),
];
test_fields_make_sense(&fields[0]);
test_fields_make_sense(&fields[1]);
test_fields_make_sense(&fields[2]);
test_fields_make_sense(&fields[3]);
test_fields_make_sense(&fields[4]);
test_non_overlapping(&fields[0], &fields[1]);
test_non_overlapping(&fields[0], &fields[2]);
test_non_overlapping(&fields[0], &fields[3]);
test_non_overlapping(&fields[0], &fields[4]);
test_non_overlapping(&fields[1], &fields[2]);
test_non_overlapping(&fields[2], &fields[3]);
test_non_overlapping(&fields[2], &fields[4]);
test_non_overlapping(&fields[3], &fields[4]);
}
fn test_fields_aligned() {
assert_eq!((core::mem::offset_of!(ReprRustStruct, x) % (core::mem::align_of::<i32>())), 0);
assert_eq!((core::mem::offset_of!(ReprRustStruct, y) % (core::mem::align_of::<[u32; 4]>())), 0);
assert_eq!((core::mem::offset_of!(ReprRustStruct, z) % (core::mem::align_of::<f32>())), 0);
assert_eq!((core::mem::offset_of!(ReprRustStruct, a) % (core::mem::align_of::<u128>())), 0);
assert_eq!(
(core::mem::offset_of!(ReprRustStruct, b) % (core::mem::align_of::<Overaligned>())),
0
);
}
fn main() {
test_fields_non_overlapping();
test_fields_aligned();
}
|
