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