test/sizeof.go

   1 // run
   2
   3 // Copyright 2011 The Go Authors. All rights reserved.
   4 // Use of this source code is governed by a BSD-style
   5 // license that can be found in the LICENSE file.
   6
   7 package main
   8
   9 import "unsafe"
  10
  11 type T struct {
  12         X int
  13 }
  14
  15 var t T
  16
  17 func isUintptr(uintptr) {}
  18
  19 type T2 struct {
  20         A int32
  21         U2
  22 }
  23
  24 type U2 struct {
  25         B int32
  26         C int32
  27 }
  28
  29 var t2 T2
  30 var p2 *T2
  31
  32 func main() {
  33         // Test unsafe.Sizeof, unsafe.Alignof, and unsafe.Offsetof all return uintptr.
  34         isUintptr(unsafe.Sizeof(t))
  35         isUintptr(unsafe.Alignof(t))
  36         isUintptr(unsafe.Offsetof(t.X))
  37
  38         // Test correctness of Offsetof with respect to embedded fields (issue 4909).
  39         if unsafe.Offsetof(t2.C) != 8 {
  40                 println(unsafe.Offsetof(t2.C), "!= 8")
  41                 panic("unsafe.Offsetof(t2.C) != 8")
  42         }
  43         if unsafe.Offsetof(p2.C) != 8 {
  44                 println(unsafe.Offsetof(p2.C), "!= 8")
  45                 panic("unsafe.Offsetof(p2.C) != 8")
  46         }
  47         if unsafe.Offsetof(t2.U2.C) != 4 {
  48                 println(unsafe.Offsetof(t2.U2.C), "!= 4")
  49                 panic("unsafe.Offsetof(t2.U2.C) != 4")
  50         }
  51         if unsafe.Offsetof(p2.U2.C) != 4 {
  52                 println(unsafe.Offsetof(p2.U2.C), "!= 4")
  53                 panic("unsafe.Offsetof(p2.U2.C) != 4")
  54         }
  55         testDeep()
  56         testNotEmbedded()
  57 }
  58
  59 type (
  60         S1 struct {
  61                 A int64
  62                 S2
  63         }
  64         S2 struct {
  65                 B int64
  66                 S3
  67         }
  68         S3 struct {
  69                 C int64
  70                 S4
  71         }
  72         S4 struct {
  73                 D int64
  74                 S5
  75         }
  76         S5 struct {
  77                 E int64
  78                 S6
  79         }
  80         S6 struct {
  81                 F int64
  82                 S7
  83         }
  84         S7 struct {
  85                 G int64
  86                 S8
  87         }
  88         S8 struct {
  89                 H int64
  90                 *S1
  91         }
  92 )
  93
  94 func testDeep() {
  95         var s1 S1
  96         switch {
  97         case unsafe.Offsetof(s1.A) != 0:
  98                 panic("unsafe.Offsetof(s1.A) != 0")
  99         case unsafe.Offsetof(s1.B) != 8:
 100                 panic("unsafe.Offsetof(s1.B) != 8")
 101         case unsafe.Offsetof(s1.C) != 16:
 102                 panic("unsafe.Offsetof(s1.C) != 16")
 103         case unsafe.Offsetof(s1.D) != 24:
 104                 panic("unsafe.Offsetof(s1.D) != 24")
 105         case unsafe.Offsetof(s1.E) != 32:
 106                 panic("unsafe.Offsetof(s1.E) != 32")
 107         case unsafe.Offsetof(s1.F) != 40:
 108                 panic("unsafe.Offsetof(s1.F) != 40")
 109         case unsafe.Offsetof(s1.G) != 48:
 110                 panic("unsafe.Offsetof(s1.G) != 48")
 111         case unsafe.Offsetof(s1.H) != 56:
 112                 panic("unsafe.Offsetof(s1.H) != 56")
 113         case unsafe.Offsetof(s1.S1) != 64:
 114                 panic("unsafe.Offsetof(s1.S1) != 64")
 115         case unsafe.Offsetof(s1.S1.S2.S3.S4.S5.S6.S7.S8.S1.S2) != 8:
 116                 panic("unsafe.Offsetof(s1.S1.S2.S3.S4.S5.S6.S7.S8.S1.S2) != 8")
 117         }
 118 }
 119
 120 func testNotEmbedded() {
 121         type T2 struct {
 122                 B int32
 123                 C int32
 124         }
 125         type T1 struct {
 126                 A int32
 127                 T2
 128         }
 129         type T struct {
 130                 Dummy int32
 131                 F     T1
 132                 P     *T1
 133         }
 134
 135         var t T
 136         var p *T
 137         switch {
 138         case unsafe.Offsetof(t.F.B) != 4:
 139                 panic("unsafe.Offsetof(t.F.B) != 4")
 140         case unsafe.Offsetof(t.F.C) != 8:
 141                 panic("unsafe.Offsetof(t.F.C) != 8")
 142
 143         case unsafe.Offsetof(t.P.B) != 4:
 144                 panic("unsafe.Offsetof(t.P.B) != 4")
 145         case unsafe.Offsetof(t.P.C) != 8:
 146                 panic("unsafe.Offsetof(t.P.C) != 8")
 147
 148         case unsafe.Offsetof(p.F.B) != 4:
 149                 panic("unsafe.Offsetof(p.F.B) != 4")
 150         case unsafe.Offsetof(p.F.C) != 8:
 151                 panic("unsafe.Offsetof(p.F.C) != 8")
 152
 153         case unsafe.Offsetof(p.P.B) != 4:
 154                 panic("unsafe.Offsetof(p.P.B) != 4")
 155         case unsafe.Offsetof(p.P.C) != 8:
 156                 panic("unsafe.Offsetof(p.P.C) != 8")
 157         }
 158 }