gcc/testsuite/go.test/test/blank.go

   1 // run
   2
   3 // Copyright 2009 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 // Test behavior of the blank identifier (_).
   8
   9 package main
  10
  11 import (
  12         "os"
  13         "unsafe"
  14 )
  15
  16 import _ "fmt"
  17
  18 var call string
  19
  20 type T struct {
  21         _, _, _ int
  22 }
  23
  24 func (T) _() {
  25 }
  26
  27 func (T) _() {
  28 }
  29
  30 type U struct {
  31         _ struct{ a, b, c int }
  32 }
  33
  34 const (
  35         c0 = iota
  36         _
  37         _
  38         _
  39         c4
  40 )
  41
  42 var ints = []string{
  43         "1",
  44         "2",
  45         "3",
  46 }
  47
  48 func f() (int, int) {
  49         call += "f"
  50         return 1, 2
  51 }
  52
  53 func g() (float64, float64) {
  54         call += "g"
  55         return 3, 4
  56 }
  57
  58 func h(_ int, _ float64) {
  59 }
  60
  61 func i() int {
  62         call += "i"
  63         return 23
  64 }
  65
  66 var _ = i()
  67
  68 func main() {
  69         if call != "i" {
  70                 panic("init did not run")
  71         }
  72         call = ""
  73         _, _ = f()
  74         a, _ := f()
  75         if a != 1 {
  76                 panic(a)
  77         }
  78         b, _ := g()
  79         if b != 3 {
  80                 panic(b)
  81         }
  82         _, a = f()
  83         if a != 2 {
  84                 panic(a)
  85         }
  86         _, b = g()
  87         if b != 4 {
  88                 panic(b)
  89         }
  90         _ = i()
  91         if call != "ffgfgi" {
  92                 panic(call)
  93         }
  94         if c4 != 4 {
  95                 panic(c4)
  96         }
  97
  98         out := ""
  99         for _, s := range ints {
 100                 out += s
 101         }
 102         if out != "123" {
 103                 panic(out)
 104         }
 105
 106         sum := 0
 107         for s := range ints {
 108                 sum += s
 109         }
 110         if sum != 3 {
 111                 panic(sum)
 112         }
 113
 114         // go.tools/ssa/interp cannot support unsafe.Pointer.
 115         if os.Getenv("GOSSAINTERP") == "" {
 116                 type T1 struct{ x, y, z int }
 117                 t1 := *(*T)(unsafe.Pointer(&T1{1, 2, 3}))
 118                 t2 := *(*T)(unsafe.Pointer(&T1{4, 5, 6}))
 119                 if t1 != t2 {
 120                         panic("T{} != T{}")
 121                 }
 122
 123                 var u1, u2 interface{}
 124                 u1 = *(*U)(unsafe.Pointer(&T1{1, 2, 3}))
 125                 u2 = *(*U)(unsafe.Pointer(&T1{4, 5, 6}))
 126                 if u1 != u2 {
 127                         panic("U{} != U{}")
 128                 }
 129         }
 130
 131         h(a, b)
 132
 133         m()
 134 }
 135
 136 type I interface {
 137         M(_ int, y int)
 138 }
 139
 140 type TI struct{}
 141
 142 func (_ TI) M(x int, y int) {
 143         if x != y {
 144                 println("invalid M call:", x, y)
 145                 panic("bad M")
 146         }
 147 }
 148
 149 var fp = func(_ int, y int) {}
 150
 151 func init() {
 152         fp = fp1
 153 }
 154
 155 func fp1(x, y int) {
 156         if x != y {
 157                 println("invalid fp1 call:", x, y)
 158                 panic("bad fp1")
 159         }
 160 }
 161
 162 func m() {
 163         var i I
 164
 165         i = TI{}
 166         i.M(1, 1)
 167         i.M(2, 2)
 168
 169         fp(1, 1)
 170         fp(2, 2)
 171 }
 172
 173 // useless but legal
 174 var _ int = 1
 175 var _ = 2
 176 var _, _ = 3, 4
 177
 178 const _ = 3
 179 const _, _ = 4, 5
 180
 181 type _ int
 182
 183 func _() {
 184         panic("oops")
 185 }
 186
 187 func ff() {
 188         var _ int = 1
 189 }