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
|
// run
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package main
import (
"fmt"
"unsafe"
)
// size returns the size of type T
func size[T any](x T) uintptr {
return unsafe.Sizeof(x)
}
// size returns the alignment of type T
func align[T any](x T) uintptr {
return unsafe.Alignof(x)
}
type Tstruct[T any] struct {
f1 T
f2 int
}
// offset returns the offset of field f2 in the generic type Tstruct
func (r *Tstruct[T]) offset() uintptr {
return unsafe.Offsetof(r.f2)
}
func main() {
v1 := int(5)
if got, want := size(v1), unsafe.Sizeof(v1); got != want {
panic(fmt.Sprintf("got %d, want %d", got, want))
}
if got, want := align(v1), unsafe.Alignof(v1); got != want {
panic(fmt.Sprintf("got %d, want %d", got, want))
}
v2 := "abc"
if got, want := size(v2), unsafe.Sizeof(v2); got != want {
panic(fmt.Sprintf("got %d, want %d", got, want))
}
if got, want := align(v2), unsafe.Alignof(v2); got != want {
panic(fmt.Sprintf("got %d, want %d", got, want))
}
var v3 Tstruct[int]
if got, want := unsafe.Offsetof(v3.f2), unsafe.Sizeof(v1); got != want {
panic(fmt.Sprintf("got %d, want %d", got, want))
}
var v4 Tstruct[interface{}]
var v5 interface{}
if got, want := unsafe.Offsetof(v4.f2), unsafe.Sizeof(v5); got != want {
panic(fmt.Sprintf("got %d, want %d", got, want))
}
if got, want := v3.offset(), unsafe.Offsetof(v3.f2); got != want {
panic(fmt.Sprintf("got %d, want %d", got, want))
}
if got, want := v4.offset(), unsafe.Offsetof(v4.f2); got != want {
panic(fmt.Sprintf("got %d, want %d", got, want))
}
}
|
