github.com/go-asm/go@v1.21.1-0.20240213172139-40c5ead50c48/types/testdata/check/const0.go (about) 1 // Copyright 2012 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 // constant declarations 6 7 package const0 8 9 import "unsafe" 10 11 // constants declarations must be initialized by constants 12 var x = 0 13 const c0 = x /* ERROR "not constant" */ 14 15 // typed constants must have constant types 16 const _ interface /* ERROR "invalid constant type" */ {} = 0 17 18 func _ () { 19 const _ interface /* ERROR "invalid constant type" */ {} = 0 20 for i := 0; i < 10; i++ {} // don't crash with non-nil iota here 21 } 22 23 // untyped constants 24 const ( 25 // boolean values 26 ub0 = false 27 ub1 = true 28 ub2 = 2 < 1 29 ub3 = ui1 == uf1 30 ub4 = true == 0 /* ERROR "mismatched types untyped bool and untyped int" */ 31 32 // integer values 33 ui0 = 0 34 ui1 = 1 35 ui2 = 42 36 ui3 = 3141592653589793238462643383279502884197169399375105820974944592307816406286 37 ui4 = -10 38 39 ui5 = ui0 + ui1 40 ui6 = ui1 - ui1 41 ui7 = ui2 * ui1 42 ui8 = ui3 / ui3 43 ui9 = ui3 % ui3 44 45 ui10 = 1 / 0 /* ERROR "division by zero" */ 46 ui11 = ui1 / 0 /* ERROR "division by zero" */ 47 ui12 = ui3 / ui0 /* ERROR "division by zero" */ 48 ui13 = 1 % 0 /* ERROR "division by zero" */ 49 ui14 = ui1 % 0 /* ERROR "division by zero" */ 50 ui15 = ui3 % ui0 /* ERROR "division by zero" */ 51 52 ui16 = ui2 & ui3 53 ui17 = ui2 | ui3 54 ui18 = ui2 ^ ui3 55 ui19 = 1 /* ERROR "invalid operation" */ % 1.0 56 57 // floating point values 58 uf0 = 0. 59 uf1 = 1. 60 uf2 = 4.2e1 61 uf3 = 3.141592653589793238462643383279502884197169399375105820974944592307816406286 62 uf4 = 1e-1 63 64 uf5 = uf0 + uf1 65 uf6 = uf1 - uf1 66 uf7 = uf2 * uf1 67 uf8 = uf3 / uf3 68 uf9 = uf3 /* ERROR "not defined" */ % uf3 69 70 uf10 = 1 / 0 /* ERROR "division by zero" */ 71 uf11 = uf1 / 0 /* ERROR "division by zero" */ 72 uf12 = uf3 / uf0 /* ERROR "division by zero" */ 73 74 uf16 = uf2 /* ERROR "not defined" */ & uf3 75 uf17 = uf2 /* ERROR "not defined" */ | uf3 76 uf18 = uf2 /* ERROR "not defined" */ ^ uf3 77 78 // complex values 79 uc0 = 0.i 80 uc1 = 1.i 81 uc2 = 4.2e1i 82 uc3 = 3.141592653589793238462643383279502884197169399375105820974944592307816406286i 83 uc4 = 1e-1i 84 85 uc5 = uc0 + uc1 86 uc6 = uc1 - uc1 87 uc7 = uc2 * uc1 88 uc8 = uc3 / uc3 89 uc9 = uc3 /* ERROR "not defined" */ % uc3 90 91 uc10 = 1 / 0 /* ERROR "division by zero" */ 92 uc11 = uc1 / 0 /* ERROR "division by zero" */ 93 uc12 = uc3 / uc0 /* ERROR "division by zero" */ 94 95 uc16 = uc2 /* ERROR "not defined" */ & uc3 96 uc17 = uc2 /* ERROR "not defined" */ | uc3 97 uc18 = uc2 /* ERROR "not defined" */ ^ uc3 98 ) 99 100 type ( 101 mybool bool 102 myint int 103 myfloat float64 104 mycomplex complex128 105 ) 106 107 // typed constants 108 const ( 109 // boolean values 110 tb0 bool = false 111 tb1 bool = true 112 tb2 mybool = 2 < 1 113 tb3 mybool = ti1 == tf1 /* ERROR "mismatched types" */ 114 115 // integer values 116 ti0 int8 = ui0 117 ti1 int32 = ui1 118 ti2 int64 = ui2 119 ti3 myint = ui3 /* ERROR "overflows" */ 120 ti4 myint = ui4 121 122 ti5 = ti0 /* ERROR "mismatched types" */ + ti1 123 ti6 = ti1 - ti1 124 ti7 = ti2 /* ERROR "mismatched types" */ * ti1 125 ti8 = ti3 / ti3 126 ti9 = ti3 % ti3 127 128 ti10 = 1 / 0 /* ERROR "division by zero" */ 129 ti11 = ti1 / 0 /* ERROR "division by zero" */ 130 ti12 = ti3 /* ERROR "mismatched types" */ / ti0 131 ti13 = 1 % 0 /* ERROR "division by zero" */ 132 ti14 = ti1 % 0 /* ERROR "division by zero" */ 133 ti15 = ti3 /* ERROR "mismatched types" */ % ti0 134 135 ti16 = ti2 /* ERROR "mismatched types" */ & ti3 136 ti17 = ti2 /* ERROR "mismatched types" */ | ti4 137 ti18 = ti2 ^ ti5 // no mismatched types error because the type of ti5 is unknown 138 139 // floating point values 140 tf0 float32 = 0. 141 tf1 float32 = 1. 142 tf2 float64 = 4.2e1 143 tf3 myfloat = 3.141592653589793238462643383279502884197169399375105820974944592307816406286 144 tf4 myfloat = 1e-1 145 146 tf5 = tf0 + tf1 147 tf6 = tf1 - tf1 148 tf7 = tf2 /* ERROR "mismatched types" */ * tf1 149 tf8 = tf3 / tf3 150 tf9 = tf3 /* ERROR "not defined" */ % tf3 151 152 tf10 = 1 / 0 /* ERROR "division by zero" */ 153 tf11 = tf1 / 0 /* ERROR "division by zero" */ 154 tf12 = tf3 /* ERROR "mismatched types" */ / tf0 155 156 tf16 = tf2 /* ERROR "mismatched types" */ & tf3 157 tf17 = tf2 /* ERROR "mismatched types" */ | tf3 158 tf18 = tf2 /* ERROR "mismatched types" */ ^ tf3 159 160 // complex values 161 tc0 = 0.i 162 tc1 = 1.i 163 tc2 = 4.2e1i 164 tc3 = 3.141592653589793238462643383279502884197169399375105820974944592307816406286i 165 tc4 = 1e-1i 166 167 tc5 = tc0 + tc1 168 tc6 = tc1 - tc1 169 tc7 = tc2 * tc1 170 tc8 = tc3 / tc3 171 tc9 = tc3 /* ERROR "not defined" */ % tc3 172 173 tc10 = 1 / 0 /* ERROR "division by zero" */ 174 tc11 = tc1 / 0 /* ERROR "division by zero" */ 175 tc12 = tc3 / tc0 /* ERROR "division by zero" */ 176 177 tc16 = tc2 /* ERROR "not defined" */ & tc3 178 tc17 = tc2 /* ERROR "not defined" */ | tc3 179 tc18 = tc2 /* ERROR "not defined" */ ^ tc3 180 ) 181 182 // initialization cycles 183 const ( 184 a /* ERROR "initialization cycle" */ = a 185 b /* ERROR "initialization cycle" */ , c /* ERROR "initialization cycle" */, d, e = e, d, c, b // TODO(gri) should only have one cycle error 186 f float64 = d 187 ) 188 189 // multiple initialization 190 const ( 191 a1, a2, a3 = 7, 3.1415926, "foo" 192 b1, b2, b3 = b3, b1, 42 193 c1, c2, c3 /* ERROR "missing init expr for c3" */ = 1, 2 194 d1, d2, d3 = 1, 2, 3, 4 /* ERROR "extra init expr 4" */ 195 _p0 = assert(a1 == 7) 196 _p1 = assert(a2 == 3.1415926) 197 _p2 = assert(a3 == "foo") 198 _p3 = assert(b1 == 42) 199 _p4 = assert(b2 == 42) 200 _p5 = assert(b3 == 42) 201 ) 202 203 func _() { 204 const ( 205 a1, a2, a3 = 7, 3.1415926, "foo" 206 b1, b2, b3 = b3, b1, 42 207 c1, c2, c3 /* ERROR "missing init expr for c3" */ = 1, 2 208 d1, d2, d3 = 1, 2, 3, 4 /* ERROR "extra init expr 4" */ 209 _p0 = assert(a1 == 7) 210 _p1 = assert(a2 == 3.1415926) 211 _p2 = assert(a3 == "foo") 212 _p3 = assert(b1 == 42) 213 _p4 = assert(b2 == 42) 214 _p5 = assert(b3 == 42) 215 ) 216 } 217 218 // iota 219 const ( 220 iota0 = iota 221 iota1 = iota 222 iota2 = iota*2 223 _a0 = assert(iota0 == 0) 224 _a1 = assert(iota1 == 1) 225 _a2 = assert(iota2 == 4) 226 iota6 = iota*3 227 228 iota7 229 iota8 230 _a3 = assert(iota7 == 21) 231 _a4 = assert(iota8 == 24) 232 ) 233 234 const ( 235 _b0 = iota 236 _b1 = assert(iota + iota2 == 5) 237 _b2 = len([iota]int{}) // iota may appear in a type! 238 _b3 = assert(_b2 == 2) 239 _b4 = len(A{}) 240 ) 241 242 type A [iota /* ERROR "cannot use iota" */ ]int 243 244 // constant expressions with operands across different 245 // constant declarations must use the right iota values 246 const ( 247 _c0 = iota 248 _c1 249 _c2 250 _x = _c2 + _d1 + _e0 // 3 251 ) 252 253 const ( 254 _d0 = iota 255 _d1 256 ) 257 258 const ( 259 _e0 = iota 260 ) 261 262 var _ = assert(_x == 3) 263 264 // special cases 265 const ( 266 _n0 = nil /* ERROR "not constant" */ 267 _n1 = [ /* ERROR "not constant" */ ]int{} 268 ) 269 270 // iotas must not be usable in expressions outside constant declarations 271 type _ [iota /* ERROR "iota outside constant decl" */ ]byte 272 var _ = iota /* ERROR "iota outside constant decl" */ 273 func _() { 274 _ = iota /* ERROR "iota outside constant decl" */ 275 const _ = iota 276 _ = iota /* ERROR "iota outside constant decl" */ 277 } 278 279 func _() { 280 iota := 123 281 const x = iota /* ERROR "is not constant" */ 282 var y = iota 283 _ = y 284 } 285 286 // iotas are usable inside closures in constant declarations (#22345) 287 const ( 288 _ = iota 289 _ = len([iota]byte{}) 290 _ = unsafe.Sizeof(iota) 291 _ = unsafe.Sizeof(func() { _ = iota }) 292 _ = unsafe.Sizeof(func() { var _ = iota }) 293 _ = unsafe.Sizeof(func() { const _ = iota }) 294 _ = unsafe.Sizeof(func() { type _ [iota]byte }) 295 _ = unsafe.Sizeof(func() { func() int { return iota }() }) 296 ) 297 298 // verify inner and outer const declarations have distinct iotas 299 const ( 300 zero = iota 301 one = iota 302 _ = unsafe.Sizeof(func() { 303 var x [iota]int // [2]int 304 const ( 305 Zero = iota 306 One 307 Two 308 _ = unsafe.Sizeof([iota-1]int{} == x) // assert types are equal 309 _ = unsafe.Sizeof([Two]int{} == x) // assert types are equal 310 ) 311 var z [iota]int // [2]int 312 _ = unsafe.Sizeof([2]int{} == z) // assert types are equal 313 }) 314 three = iota // the sequence continues 315 ) 316 var _ [three]int = [3]int{} // assert 'three' has correct value 317 318 var ( 319 _ = iota /* ERROR "iota outside constant decl" */ 320 _ = unsafe.Sizeof(iota /* ERROR "iota outside constant decl" */ ) 321 _ = unsafe.Sizeof(func() { _ = iota /* ERROR "iota outside constant decl" */ }) 322 _ = unsafe.Sizeof(func() { var _ = iota /* ERROR "iota outside constant decl" */ }) 323 _ = unsafe.Sizeof(func() { type _ [iota /* ERROR "iota outside constant decl" */ ]byte }) 324 _ = unsafe.Sizeof(func() { func() int { return iota /* ERROR "iota outside constant decl" */ }() }) 325 ) 326 327 // constant arithmetic precision and rounding must lead to expected (integer) results 328 var _ = []int64{ 329 0.0005 * 1e9, 330 0.001 * 1e9, 331 0.005 * 1e9, 332 0.01 * 1e9, 333 0.05 * 1e9, 334 0.1 * 1e9, 335 0.5 * 1e9, 336 1 * 1e9, 337 5 * 1e9, 338 } 339 340 const _ = unsafe.Sizeof(func() { 341 const _ = 0 342 _ = iota 343 344 const ( 345 zero = iota 346 one 347 ) 348 assert(one == 1) 349 assert(iota == 0) 350 }) 351 352 // issue #52438 353 const i1 = iota 354 const i2 = iota 355 const i3 = iota 356 357 func _() { 358 assert(i1 == 0) 359 assert(i2 == 0) 360 assert(i3 == 0) 361 362 const i4 = iota 363 const i5 = iota 364 const i6 = iota 365 366 assert(i4 == 0) 367 assert(i5 == 0) 368 assert(i6 == 0) 369 } 370 371 // untyped constants must not get arbitrarily large 372 const prec = 512 // internal maximum precision for integers 373 const maxInt = (1<<(prec/2) - 1) * (1<<(prec/2) + 1) // == 1<<prec - 1 374 375 const _ = maxInt + /* ERROR "constant addition overflow" */ 1 376 const _ = -maxInt - /* ERROR "constant subtraction overflow" */ 1 377 const _ = maxInt ^ /* ERROR "constant bitwise XOR overflow" */ -1 378 const _ = maxInt * /* ERROR "constant multiplication overflow" */ 2 379 const _ = maxInt << /* ERROR "constant shift overflow" */ 2 380 const _ = 1 << /* ERROR "constant shift overflow" */ prec 381 382 const _ = ^ /* ERROR "constant bitwise complement overflow" */ maxInt