modernc.org/gc@v1.0.1-0.20240304020402-f0dba7c97c2b/testdata/errchk/test/blank.go (about) 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 }