1 // RUN: %clang_cc1 -triple i686-linux -Wno-string-plus-int -fsyntax-only -verify -std=c++11 -pedantic %s -Wno-comment 2 3 namespace StaticAssertFoldTest { 4 5 int x; 6 static_assert(++x, "test"); // expected-error {{not an integral constant expression}} 7 static_assert(false, "test"); // expected-error {{test}} 8 9 } 10 11 typedef decltype(sizeof(char)) size_t; 12 13 template<typename T> constexpr T id(const T &t) { return t; } 14 template<typename T> constexpr T min(const T &a, const T &b) { 15 return a < b ? a : b; 16 } 17 template<typename T> constexpr T max(const T &a, const T &b) { 18 return a < b ? b : a; 19 } 20 template<typename T, size_t N> constexpr T *begin(T (&xs)[N]) { return xs; } 21 template<typename T, size_t N> constexpr T *end(T (&xs)[N]) { return xs + N; } 22 23 struct MemberZero { 24 constexpr int zero() { return 0; } 25 }; 26 27 namespace DerivedToVBaseCast { 28 29 struct U { int n; }; 30 struct V : U { int n; }; 31 struct A : virtual V { int n; }; 32 struct Aa { int n; }; 33 struct B : virtual A, Aa {}; 34 struct C : virtual A, Aa {}; 35 struct D : B, C {}; 36 37 D d; 38 constexpr B *p = &d; 39 constexpr C *q = &d; 40 41 static_assert((void*)p != (void*)q, ""); 42 static_assert((A*)p == (A*)q, ""); 43 static_assert((Aa*)p != (Aa*)q, ""); 44 45 constexpr B &pp = d; 46 constexpr C &qq = d; 47 static_assert((void*)&pp != (void*)&qq, ""); 48 static_assert(&(A&)pp == &(A&)qq, ""); 49 static_assert(&(Aa&)pp != &(Aa&)qq, ""); 50 51 constexpr V *v = p; 52 constexpr V *w = q; 53 constexpr V *x = (A*)p; 54 static_assert(v == w, ""); 55 static_assert(v == x, ""); 56 57 static_assert((U*)&d == p, ""); 58 static_assert((U*)&d == q, ""); 59 static_assert((U*)&d == v, ""); 60 static_assert((U*)&d == w, ""); 61 static_assert((U*)&d == x, ""); 62 63 struct X {}; 64 struct Y1 : virtual X {}; 65 struct Y2 : X {}; 66 struct Z : Y1, Y2 {}; 67 Z z; 68 static_assert((X*)(Y1*)&z != (X*)(Y2*)&z, ""); 69 } 70 71 namespace ConstCast { 72 73 constexpr int n1 = 0; 74 constexpr int n2 = const_cast<int&>(n1); 75 constexpr int *n3 = const_cast<int*>(&n1); 76 constexpr int n4 = *const_cast<int*>(&n1); 77 constexpr const int * const *n5 = const_cast<const int* const*>(&n3); 78 constexpr int **n6 = const_cast<int**>(&n3); 79 constexpr int n7 = **n5; 80 constexpr int n8 = **n6; 81 82 } 83 84 namespace TemplateArgumentConversion { 85 template<int n> struct IntParam {}; 86 87 using IntParam0 = IntParam<0>; 88 using IntParam0 = IntParam<id(0)>; 89 using IntParam0 = IntParam<MemberZero().zero>; // expected-error {{did you mean to call it with no arguments?}} 90 } 91 92 namespace CaseStatements { 93 void f(int n) { 94 switch (n) { 95 case MemberZero().zero: // expected-error {{did you mean to call it with no arguments?}} expected-note {{previous}} 96 case id(0): // expected-error {{duplicate case value '0'}} 97 return; 98 } 99 } 100 } 101 102 extern int &Recurse1; 103 int &Recurse2 = Recurse1; // expected-note {{declared here}} 104 int &Recurse1 = Recurse2; 105 constexpr int &Recurse3 = Recurse2; // expected-error {{must be initialized by a constant expression}} expected-note {{initializer of 'Recurse2' is not a constant expression}} 106 107 extern const int RecurseA; 108 const int RecurseB = RecurseA; // expected-note {{declared here}} 109 const int RecurseA = 10; 110 constexpr int RecurseC = RecurseB; // expected-error {{must be initialized by a constant expression}} expected-note {{initializer of 'RecurseB' is not a constant expression}} 111 112 namespace MemberEnum { 113 struct WithMemberEnum { 114 enum E { A = 42 }; 115 } wme; 116 117 static_assert(wme.A == 42, ""); 118 } 119 120 namespace DefaultArguments { 121 122 const int z = int(); 123 constexpr int Sum(int a = 0, const int &b = 0, const int *c = &z, char d = 0) { 124 return a + b + *c + d; 125 } 126 const int four = 4; 127 constexpr int eight = 8; 128 constexpr const int twentyseven = 27; 129 static_assert(Sum() == 0, ""); 130 static_assert(Sum(1) == 1, ""); 131 static_assert(Sum(1, four) == 5, ""); 132 static_assert(Sum(1, eight, &twentyseven) == 36, ""); 133 static_assert(Sum(1, 2, &four, eight) == 15, ""); 134 135 } 136 137 namespace Ellipsis { 138 139 // Note, values passed through an ellipsis can't actually be used. 140 constexpr int F(int a, ...) { return a; } 141 static_assert(F(0) == 0, ""); 142 static_assert(F(1, 0) == 1, ""); 143 static_assert(F(2, "test") == 2, ""); 144 static_assert(F(3, &F) == 3, ""); 145 int k = 0; // expected-note {{here}} 146 static_assert(F(4, k) == 3, ""); // expected-error {{constant expression}} expected-note {{read of non-const variable 'k'}} 147 148 } 149 150 namespace Recursion { 151 constexpr int fib(int n) { return n > 1 ? fib(n-1) + fib(n-2) : n; } 152 static_assert(fib(11) == 89, ""); 153 154 constexpr int gcd_inner(int a, int b) { 155 return b == 0 ? a : gcd_inner(b, a % b); 156 } 157 constexpr int gcd(int a, int b) { 158 return gcd_inner(max(a, b), min(a, b)); 159 } 160 161 static_assert(gcd(1749237, 5628959) == 7, ""); 162 } 163 164 namespace FunctionCast { 165 // When folding, we allow functions to be cast to different types. Such 166 // cast functions cannot be called, even if they're constexpr. 167 constexpr int f() { return 1; } 168 typedef double (*DoubleFn)(); 169 typedef int (*IntFn)(); 170 int a[(int)DoubleFn(f)()]; // expected-error {{variable length array}} expected-warning{{C99 feature}} 171 int b[(int)IntFn(f)()]; // ok 172 } 173 174 namespace StaticMemberFunction { 175 struct S { 176 static constexpr int k = 42; 177 static constexpr int f(int n) { return n * k + 2; } 178 } s; 179 180 constexpr int n = s.f(19); 181 static_assert(S::f(19) == 800, ""); 182 static_assert(s.f(19) == 800, ""); 183 static_assert(n == 800, ""); 184 185 constexpr int (*sf1)(int) = &S::f; 186 constexpr int (*sf2)(int) = &s.f; 187 constexpr const int *sk = &s.k; 188 } 189 190 namespace ParameterScopes { 191 192 const int k = 42; 193 constexpr const int &ObscureTheTruth(const int &a) { return a; } 194 constexpr const int &MaybeReturnJunk(bool b, const int a) { // expected-note 2{{declared here}} 195 return ObscureTheTruth(b ? a : k); 196 } 197 static_assert(MaybeReturnJunk(false, 0) == 42, ""); // ok 198 constexpr int a = MaybeReturnJunk(true, 0); // expected-error {{constant expression}} expected-note {{read of variable whose lifetime has ended}} 199 200 constexpr const int MaybeReturnNonstaticRef(bool b, const int a) { 201 return ObscureTheTruth(b ? a : k); 202 } 203 static_assert(MaybeReturnNonstaticRef(false, 0) == 42, ""); // ok 204 constexpr int b = MaybeReturnNonstaticRef(true, 0); // ok 205 206 constexpr int InternalReturnJunk(int n) { 207 return MaybeReturnJunk(true, n); // expected-note {{read of variable whose lifetime has ended}} 208 } 209 constexpr int n3 = InternalReturnJunk(0); // expected-error {{must be initialized by a constant expression}} expected-note {{in call to 'InternalReturnJunk(0)'}} 210 211 constexpr int LToR(int &n) { return n; } 212 constexpr int GrabCallersArgument(bool which, int a, int b) { 213 return LToR(which ? b : a); 214 } 215 static_assert(GrabCallersArgument(false, 1, 2) == 1, ""); 216 static_assert(GrabCallersArgument(true, 4, 8) == 8, ""); 217 218 } 219 220 namespace Pointers { 221 222 constexpr int f(int n, const int *a, const int *b, const int *c) { 223 return n == 0 ? 0 : *a + f(n-1, b, c, a); 224 } 225 226 const int x = 1, y = 10, z = 100; 227 static_assert(f(23, &x, &y, &z) == 788, ""); 228 229 constexpr int g(int n, int a, int b, int c) { 230 return f(n, &a, &b, &c); 231 } 232 static_assert(g(23, x, y, z) == 788, ""); 233 234 } 235 236 namespace FunctionPointers { 237 238 constexpr int Double(int n) { return 2 * n; } 239 constexpr int Triple(int n) { return 3 * n; } 240 constexpr int Twice(int (*F)(int), int n) { return F(F(n)); } 241 constexpr int Quadruple(int n) { return Twice(Double, n); } 242 constexpr auto Select(int n) -> int (*)(int) { 243 return n == 2 ? &Double : n == 3 ? &Triple : n == 4 ? &Quadruple : 0; 244 } 245 constexpr int Apply(int (*F)(int), int n) { return F(n); } // expected-note {{subexpression}} 246 247 static_assert(1 + Apply(Select(4), 5) + Apply(Select(3), 7) == 42, ""); 248 249 constexpr int Invalid = Apply(Select(0), 0); // expected-error {{must be initialized by a constant expression}} expected-note {{in call to 'Apply(0, 0)'}} 250 251 } 252 253 namespace PointerComparison { 254 255 int x, y; 256 static_assert(&x == &y, "false"); // expected-error {{false}} 257 static_assert(&x != &y, ""); 258 constexpr bool g1 = &x == &y; 259 constexpr bool g2 = &x != &y; 260 constexpr bool g3 = &x <= &y; // expected-error {{must be initialized by a constant expression}} 261 constexpr bool g4 = &x >= &y; // expected-error {{must be initialized by a constant expression}} 262 constexpr bool g5 = &x < &y; // expected-error {{must be initialized by a constant expression}} 263 constexpr bool g6 = &x > &y; // expected-error {{must be initialized by a constant expression}} 264 265 struct S { int x, y; } s; 266 static_assert(&s.x == &s.y, "false"); // expected-error {{false}} 267 static_assert(&s.x != &s.y, ""); 268 static_assert(&s.x <= &s.y, ""); 269 static_assert(&s.x >= &s.y, "false"); // expected-error {{false}} 270 static_assert(&s.x < &s.y, ""); 271 static_assert(&s.x > &s.y, "false"); // expected-error {{false}} 272 273 static_assert(0 == &y, "false"); // expected-error {{false}} 274 static_assert(0 != &y, ""); 275 constexpr bool n3 = 0 <= &y; // expected-error {{must be initialized by a constant expression}} 276 constexpr bool n4 = 0 >= &y; // expected-error {{must be initialized by a constant expression}} 277 constexpr bool n5 = 0 < &y; // expected-error {{must be initialized by a constant expression}} 278 constexpr bool n6 = 0 > &y; // expected-error {{must be initialized by a constant expression}} 279 280 static_assert(&x == 0, "false"); // expected-error {{false}} 281 static_assert(&x != 0, ""); 282 constexpr bool n9 = &x <= 0; // expected-error {{must be initialized by a constant expression}} 283 constexpr bool n10 = &x >= 0; // expected-error {{must be initialized by a constant expression}} 284 constexpr bool n11 = &x < 0; // expected-error {{must be initialized by a constant expression}} 285 constexpr bool n12 = &x > 0; // expected-error {{must be initialized by a constant expression}} 286 287 static_assert(&x == &x, ""); 288 static_assert(&x != &x, "false"); // expected-error {{false}} 289 static_assert(&x <= &x, ""); 290 static_assert(&x >= &x, ""); 291 static_assert(&x < &x, "false"); // expected-error {{false}} 292 static_assert(&x > &x, "false"); // expected-error {{false}} 293 294 constexpr S* sptr = &s; 295 constexpr bool dyncast = sptr == dynamic_cast<S*>(sptr); // expected-error {{constant expression}} expected-note {{dynamic_cast}} 296 297 struct U {}; 298 struct Str { 299 int a : dynamic_cast<S*>(sptr) == dynamic_cast<S*>(sptr); // \ 300 expected-warning {{not an integral constant expression}} \ 301 expected-note {{dynamic_cast is not allowed in a constant expression}} 302 int b : reinterpret_cast<S*>(sptr) == reinterpret_cast<S*>(sptr); // \ 303 expected-warning {{not an integral constant expression}} \ 304 expected-note {{reinterpret_cast is not allowed in a constant expression}} 305 int c : (S*)(long)(sptr) == (S*)(long)(sptr); // \ 306 expected-warning {{not an integral constant expression}} \ 307 expected-note {{cast which performs the conversions of a reinterpret_cast is not allowed in a constant expression}} 308 int d : (S*)(42) == (S*)(42); // \ 309 expected-warning {{not an integral constant expression}} \ 310 expected-note {{cast which performs the conversions of a reinterpret_cast is not allowed in a constant expression}} 311 int e : (Str*)(sptr) == (Str*)(sptr); // \ 312 expected-warning {{not an integral constant expression}} \ 313 expected-note {{cast which performs the conversions of a reinterpret_cast is not allowed in a constant expression}} 314 int f : &(U&)(*sptr) == &(U&)(*sptr); // \ 315 expected-warning {{not an integral constant expression}} \ 316 expected-note {{cast which performs the conversions of a reinterpret_cast is not allowed in a constant expression}} 317 int g : (S*)(void*)(sptr) == sptr; // \ 318 expected-warning {{not an integral constant expression}} \ 319 expected-note {{cast from 'void *' is not allowed in a constant expression}} 320 }; 321 322 extern char externalvar[]; 323 constexpr bool constaddress = (void *)externalvar == (void *)0x4000UL; // expected-error {{must be initialized by a constant expression}} 324 constexpr bool litaddress = "foo" == "foo"; // expected-error {{must be initialized by a constant expression}} expected-warning {{unspecified}} 325 static_assert(0 != "foo", ""); 326 327 } 328 329 namespace MaterializeTemporary { 330 331 constexpr int f(const int &r) { return r; } 332 constexpr int n = f(1); 333 334 constexpr bool same(const int &a, const int &b) { return &a == &b; } 335 constexpr bool sameTemporary(const int &n) { return same(n, n); } 336 337 static_assert(n, ""); 338 static_assert(!same(4, 4), ""); 339 static_assert(same(n, n), ""); 340 static_assert(sameTemporary(9), ""); 341 342 } 343 344 constexpr int strcmp_ce(const char *p, const char *q) { 345 return (!*p || *p != *q) ? *p - *q : strcmp_ce(p+1, q+1); 346 } 347 348 namespace StringLiteral { 349 350 template<typename Char> 351 constexpr int MangleChars(const Char *p) { 352 return *p + 3 * (*p ? MangleChars(p+1) : 0); 353 } 354 355 static_assert(MangleChars("constexpr!") == 1768383, ""); 356 static_assert(MangleChars(u8"constexpr!") == 1768383, ""); 357 static_assert(MangleChars(L"constexpr!") == 1768383, ""); 358 static_assert(MangleChars(u"constexpr!") == 1768383, ""); 359 static_assert(MangleChars(U"constexpr!") == 1768383, ""); 360 361 constexpr char c0 = "nought index"[0]; 362 constexpr char c1 = "nice index"[10]; 363 constexpr char c2 = "nasty index"[12]; // expected-error {{must be initialized by a constant expression}} expected-warning {{is past the end}} expected-note {{read of dereferenced one-past-the-end pointer}} 364 constexpr char c3 = "negative index"[-1]; // expected-error {{must be initialized by a constant expression}} expected-warning {{is before the beginning}} expected-note {{cannot refer to element -1 of array of 15 elements}} 365 constexpr char c4 = ((char*)(int*)"no reinterpret_casts allowed")[14]; // expected-error {{must be initialized by a constant expression}} expected-note {{cast which performs the conversions of a reinterpret_cast}} 366 367 constexpr const char *p = "test" + 2; 368 static_assert(*p == 's', ""); 369 370 constexpr const char *max_iter(const char *a, const char *b) { 371 return *a < *b ? b : a; 372 } 373 constexpr const char *max_element(const char *a, const char *b) { 374 return (a+1 >= b) ? a : max_iter(a, max_element(a+1, b)); 375 } 376 377 constexpr char str[] = "the quick brown fox jumped over the lazy dog"; 378 constexpr const char *max = max_element(begin(str), end(str)); 379 static_assert(*max == 'z', ""); 380 static_assert(max == str + 38, ""); 381 382 static_assert(strcmp_ce("hello world", "hello world") == 0, ""); 383 static_assert(strcmp_ce("hello world", "hello clang") > 0, ""); 384 static_assert(strcmp_ce("constexpr", "test") < 0, ""); 385 static_assert(strcmp_ce("", " ") < 0, ""); 386 387 struct S { 388 int n : "foo"[4]; // expected-error {{constant expression}} expected-note {{read of dereferenced one-past-the-end pointer is not allowed in a constant expression}} 389 }; 390 391 struct T { 392 char c[6]; 393 constexpr T() : c{"foo"} {} 394 }; 395 constexpr T t; 396 397 static_assert(t.c[0] == 'f', ""); 398 static_assert(t.c[1] == 'o', ""); 399 static_assert(t.c[2] == 'o', ""); 400 static_assert(t.c[3] == 0, ""); 401 static_assert(t.c[4] == 0, ""); 402 static_assert(t.c[5] == 0, ""); 403 static_assert(t.c[6] == 0, ""); // expected-error {{constant expression}} expected-note {{one-past-the-end}} 404 405 struct U { 406 wchar_t chars[6]; 407 int n; 408 } constexpr u = { { L"test" }, 0 }; 409 static_assert(u.chars[2] == L's', ""); 410 411 struct V { 412 char c[4]; 413 constexpr V() : c("hi!") {} 414 }; 415 static_assert(V().c[1] == "i"[0], ""); 416 417 } 418 419 namespace Array { 420 421 template<typename Iter> 422 constexpr auto Sum(Iter begin, Iter end) -> decltype(+*begin) { 423 return begin == end ? 0 : *begin + Sum(begin+1, end); 424 } 425 426 constexpr int xs[] = { 1, 2, 3, 4, 5 }; 427 constexpr int ys[] = { 5, 4, 3, 2, 1 }; 428 constexpr int sum_xs = Sum(begin(xs), end(xs)); 429 static_assert(sum_xs == 15, ""); 430 431 constexpr int ZipFoldR(int (*F)(int x, int y, int c), int n, 432 const int *xs, const int *ys, int c) { 433 return n ? F( 434 *xs, // expected-note {{read of dereferenced one-past-the-end pointer}} 435 *ys, 436 ZipFoldR(F, n-1, xs+1, ys+1, c)) // \ 437 expected-note {{in call to 'ZipFoldR(&SubMul, 2, &xs[4], &ys[4], 1)'}} \ 438 expected-note {{in call to 'ZipFoldR(&SubMul, 1, &xs[5], &ys[5], 1)'}} 439 : c; 440 } 441 constexpr int MulAdd(int x, int y, int c) { return x * y + c; } 442 constexpr int InnerProduct = ZipFoldR(MulAdd, 5, xs, ys, 0); 443 static_assert(InnerProduct == 35, ""); 444 445 constexpr int SubMul(int x, int y, int c) { return (x - y) * c; } 446 constexpr int DiffProd = ZipFoldR(SubMul, 2, xs+3, ys+3, 1); 447 static_assert(DiffProd == 8, ""); 448 static_assert(ZipFoldR(SubMul, 3, xs+3, ys+3, 1), ""); // \ 449 expected-error {{constant expression}} \ 450 expected-note {{in call to 'ZipFoldR(&SubMul, 3, &xs[3], &ys[3], 1)'}} 451 452 constexpr const int *p = xs + 3; 453 constexpr int xs4 = p[1]; // ok 454 constexpr int xs5 = p[2]; // expected-error {{constant expression}} expected-note {{read of dereferenced one-past-the-end pointer}} 455 constexpr int xs6 = p[3]; // expected-error {{constant expression}} expected-note {{cannot refer to element 6}} 456 constexpr int xs0 = p[-3]; // ok 457 constexpr int xs_1 = p[-4]; // expected-error {{constant expression}} expected-note {{cannot refer to element -1}} 458 459 constexpr int zs[2][2][2][2] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 }; 460 static_assert(zs[0][0][0][0] == 1, ""); 461 static_assert(zs[1][1][1][1] == 16, ""); 462 static_assert(zs[0][0][0][2] == 3, ""); // expected-error {{constant expression}} expected-note {{read of dereferenced one-past-the-end pointer}} 463 static_assert((&zs[0][0][0][2])[-1] == 2, ""); 464 static_assert(**(**(zs + 1) + 1) == 11, ""); 465 static_assert(*(&(&(*(*&(&zs[2] - 1)[0] + 2 - 2))[2])[-1][-1] + 1) == 11, ""); // expected-error {{constant expression}} expected-note {{cannot refer to element -1 of array of 2 elements in a constant expression}} 466 static_assert(*(&(&(*(*&(&zs[2] - 1)[0] + 2 - 2))[2])[-1][2] - 2) == 11, ""); 467 constexpr int err_zs_1_2_0_0 = zs[1][2][0][0]; // expected-error {{constant expression}} expected-note {{cannot access array element of pointer past the end}} 468 469 constexpr int fail(const int &p) { 470 return (&p)[64]; // expected-note {{cannot refer to element 64 of array of 2 elements}} 471 } 472 static_assert(fail(*(&(&(*(*&(&zs[2] - 1)[0] + 2 - 2))[2])[-1][2] - 2)) == 11, ""); // \ 473 expected-error {{static_assert expression is not an integral constant expression}} \ 474 expected-note {{in call to 'fail(zs[1][0][1][0])'}} 475 476 constexpr int arr[40] = { 1, 2, 3, [8] = 4 }; // expected-warning {{C99 feature}} 477 constexpr int SumNonzero(const int *p) { 478 return *p + (*p ? SumNonzero(p+1) : 0); 479 } 480 constexpr int CountZero(const int *p, const int *q) { 481 return p == q ? 0 : (*p == 0) + CountZero(p+1, q); 482 } 483 static_assert(SumNonzero(arr) == 6, ""); 484 static_assert(CountZero(arr, arr + 40) == 36, ""); 485 486 struct ArrayElem { 487 constexpr ArrayElem() : n(0) {} 488 int n; 489 constexpr int f() { return n; } 490 }; 491 struct ArrayRVal { 492 constexpr ArrayRVal() {} 493 ArrayElem elems[10]; 494 }; 495 static_assert(ArrayRVal().elems[3].f() == 0, ""); 496 497 } 498 499 namespace DependentValues { 500 501 struct I { int n; typedef I V[10]; }; 502 I::V x, y; 503 template<bool B> struct S { 504 int k; 505 void f() { 506 I::V &cells = B ? x : y; 507 I &i = cells[k]; 508 switch (i.n) {} 509 } 510 }; 511 512 } 513 514 namespace Class { 515 516 struct A { constexpr A(int a, int b) : k(a + b) {} int k; }; 517 constexpr int fn(const A &a) { return a.k; } 518 static_assert(fn(A(4,5)) == 9, ""); 519 520 struct B { int n; int m; } constexpr b = { 0, b.n }; // expected-warning {{uninitialized}} 521 struct C { 522 constexpr C(C *this_) : m(42), n(this_->m) {} // ok 523 int m, n; 524 }; 525 struct D { 526 C c; 527 constexpr D() : c(&c) {} 528 }; 529 static_assert(D().c.n == 42, ""); 530 531 struct E { 532 constexpr E() : p(&p) {} 533 void *p; 534 }; 535 constexpr const E &e1 = E(); // expected-error {{constant expression}} expected-note {{reference to temporary is not a constant expression}} expected-note {{temporary created here}} 536 // This is a constant expression if we elide the copy constructor call, and 537 // is not a constant expression if we don't! But we do, so it is. 538 constexpr E e2 = E(); 539 static_assert(e2.p == &e2.p, ""); 540 constexpr E e3; 541 static_assert(e3.p == &e3.p, ""); 542 543 extern const class F f; 544 struct F { 545 constexpr F() : p(&f.p) {} 546 const void *p; 547 }; 548 constexpr F f; 549 550 struct G { 551 struct T { 552 constexpr T(T *p) : u1(), u2(p) {} 553 union U1 { 554 constexpr U1() {} 555 int a, b = 42; 556 } u1; 557 union U2 { 558 constexpr U2(T *p) : c(p->u1.b) {} 559 int c, d; 560 } u2; 561 } t; 562 constexpr G() : t(&t) {} 563 } constexpr g; 564 565 static_assert(g.t.u1.a == 42, ""); // expected-error {{constant expression}} expected-note {{read of member 'a' of union with active member 'b'}} 566 static_assert(g.t.u1.b == 42, ""); 567 static_assert(g.t.u2.c == 42, ""); 568 static_assert(g.t.u2.d == 42, ""); // expected-error {{constant expression}} expected-note {{read of member 'd' of union with active member 'c'}} 569 570 struct S { 571 int a, b; 572 const S *p; 573 double d; 574 const char *q; 575 576 constexpr S(int n, const S *p) : a(5), b(n), p(p), d(n), q("hello") {} 577 }; 578 579 S global(43, &global); 580 581 static_assert(S(15, &global).b == 15, ""); 582 583 constexpr bool CheckS(const S &s) { 584 return s.a == 5 && s.b == 27 && s.p == &global && s.d == 27. && s.q[3] == 'l'; 585 } 586 static_assert(CheckS(S(27, &global)), ""); 587 588 struct Arr { 589 char arr[3]; 590 constexpr Arr() : arr{'x', 'y', 'z'} {} 591 }; 592 constexpr int hash(Arr &&a) { 593 return a.arr[0] + a.arr[1] * 0x100 + a.arr[2] * 0x10000; 594 } 595 constexpr int k = hash(Arr()); 596 static_assert(k == 0x007a7978, ""); 597 598 599 struct AggregateInit { 600 const char &c; 601 int n; 602 double d; 603 int arr[5]; 604 void *p; 605 }; 606 607 constexpr AggregateInit agg1 = { "hello"[0] }; 608 609 static_assert(strcmp_ce(&agg1.c, "hello") == 0, ""); 610 static_assert(agg1.n == 0, ""); 611 static_assert(agg1.d == 0.0, ""); 612 static_assert(agg1.arr[-1] == 0, ""); // expected-error {{constant expression}} expected-note {{cannot refer to element -1}} 613 static_assert(agg1.arr[0] == 0, ""); 614 static_assert(agg1.arr[4] == 0, ""); 615 static_assert(agg1.arr[5] == 0, ""); // expected-error {{constant expression}} expected-note {{read of dereferenced one-past-the-end}} 616 static_assert(agg1.p == nullptr, ""); 617 618 static constexpr const unsigned char uc[] = { "foo" }; 619 static_assert(uc[0] == 'f', ""); 620 static_assert(uc[3] == 0, ""); 621 622 namespace SimpleDerivedClass { 623 624 struct B { 625 constexpr B(int n) : a(n) {} 626 int a; 627 }; 628 struct D : B { 629 constexpr D(int n) : B(n) {} 630 }; 631 constexpr D d(3); 632 static_assert(d.a == 3, ""); 633 634 } 635 636 struct Bottom { constexpr Bottom() {} }; 637 struct Base : Bottom { 638 constexpr Base(int a = 42, const char *b = "test") : a(a), b(b) {} 639 int a; 640 const char *b; 641 }; 642 struct Base2 : Bottom { 643 constexpr Base2(const int &r) : r(r) {} 644 int q = 123; 645 const int &r; 646 }; 647 struct Derived : Base, Base2 { 648 constexpr Derived() : Base(76), Base2(a) {} 649 int c = r + b[1]; 650 }; 651 652 constexpr bool operator==(const Base &a, const Base &b) { 653 return a.a == b.a && strcmp_ce(a.b, b.b) == 0; 654 } 655 656 constexpr Base base; 657 constexpr Base base2(76); 658 constexpr Derived derived; 659 static_assert(derived.a == 76, ""); 660 static_assert(derived.b[2] == 's', ""); 661 static_assert(derived.c == 76 + 'e', ""); 662 static_assert(derived.q == 123, ""); 663 static_assert(derived.r == 76, ""); 664 static_assert(&derived.r == &derived.a, ""); 665 666 static_assert(!(derived == base), ""); 667 static_assert(derived == base2, ""); 668 669 constexpr Bottom &bot1 = (Base&)derived; 670 constexpr Bottom &bot2 = (Base2&)derived; 671 static_assert(&bot1 != &bot2, ""); 672 673 constexpr Bottom *pb1 = (Base*)&derived; 674 constexpr Bottom *pb2 = (Base2*)&derived; 675 static_assert(&pb1 != &pb2, ""); 676 static_assert(pb1 == &bot1, ""); 677 static_assert(pb2 == &bot2, ""); 678 679 constexpr Base2 &fail = (Base2&)bot1; // expected-error {{constant expression}} expected-note {{cannot cast object of dynamic type 'const Class::Derived' to type 'Class::Base2'}} 680 constexpr Base &fail2 = (Base&)*pb2; // expected-error {{constant expression}} expected-note {{cannot cast object of dynamic type 'const Class::Derived' to type 'Class::Base'}} 681 constexpr Base2 &ok2 = (Base2&)bot2; 682 static_assert(&ok2 == &derived, ""); 683 684 constexpr Base2 *pfail = (Base2*)pb1; // expected-error {{constant expression}} expected-note {{cannot cast object of dynamic type 'const Class::Derived' to type 'Class::Base2'}} 685 constexpr Base *pfail2 = (Base*)&bot2; // expected-error {{constant expression}} expected-note {{cannot cast object of dynamic type 'const Class::Derived' to type 'Class::Base'}} 686 constexpr Base2 *pok2 = (Base2*)pb2; 687 static_assert(pok2 == &derived, ""); 688 static_assert(&ok2 == pok2, ""); 689 static_assert((Base2*)(Derived*)(Base*)pb1 == pok2, ""); 690 static_assert((Derived*)(Base*)pb1 == (Derived*)pok2, ""); 691 692 constexpr Base *nullB = 42 - 6 * 7; 693 static_assert((Bottom*)nullB == 0, ""); 694 static_assert((Derived*)nullB == 0, ""); 695 static_assert((void*)(Bottom*)nullB == (void*)(Derived*)nullB, ""); 696 697 namespace ConversionOperators { 698 699 struct T { 700 constexpr T(int n) : k(5*n - 3) {} 701 constexpr operator int() { return k; } 702 int k; 703 }; 704 705 struct S { 706 constexpr S(int n) : k(2*n + 1) {} 707 constexpr operator int() { return k; } 708 constexpr operator T() { return T(k); } 709 int k; 710 }; 711 712 constexpr bool check(T a, T b) { return a == b.k; } 713 714 static_assert(S(5) == 11, ""); 715 static_assert(check(S(5), 11), ""); 716 717 } 718 719 } 720 721 namespace Temporaries { 722 723 struct S { 724 constexpr S() {} 725 constexpr int f(); 726 }; 727 struct T : S { 728 constexpr T(int n) : S(), n(n) {} 729 int n; 730 }; 731 constexpr int S::f() { 732 // 'this' must be the postfix-expression in a class member access expression, 733 // so we can't just use 734 // return static_cast<T*>(this)->n; 735 return this->*(int(S::*))&T::n; 736 } 737 // The T temporary is implicitly cast to an S subobject, but we can recover the 738 // T full-object via a base-to-derived cast, or a derived-to-base-casted member 739 // pointer. 740 static_assert(T(3).f() == 3, ""); 741 742 constexpr int f(const S &s) { 743 return static_cast<const T&>(s).n; 744 } 745 constexpr int n = f(T(5)); 746 static_assert(f(T(5)) == 5, ""); 747 748 constexpr bool b(int n) { return &n; } 749 static_assert(b(0), ""); 750 751 } 752 753 namespace Union { 754 755 union U { 756 int a; 757 int b; 758 }; 759 760 constexpr U u[4] = { { .a = 0 }, { .b = 1 }, { .a = 2 }, { .b = 3 } }; // expected-warning 4{{C99 feature}} 761 static_assert(u[0].a == 0, ""); 762 static_assert(u[0].b, ""); // expected-error {{constant expression}} expected-note {{read of member 'b' of union with active member 'a'}} 763 static_assert(u[1].b == 1, ""); 764 static_assert((&u[1].b)[1] == 2, ""); // expected-error {{constant expression}} expected-note {{read of dereferenced one-past-the-end pointer}} 765 static_assert(*(&(u[1].b) + 1 + 1) == 3, ""); // expected-error {{constant expression}} expected-note {{cannot refer to element 2 of non-array object}} 766 static_assert((&(u[1]) + 1 + 1)->b == 3, ""); 767 768 constexpr U v = {}; 769 static_assert(v.a == 0, ""); 770 771 union Empty {}; 772 constexpr Empty e = {}; 773 774 // Make sure we handle trivial copy constructors for unions. 775 constexpr U x = {42}; 776 constexpr U y = x; 777 static_assert(y.a == 42, ""); 778 static_assert(y.b == 42, ""); // expected-error {{constant expression}} expected-note {{'b' of union with active member 'a'}} 779 780 } 781 782 namespace MemberPointer { 783 struct A { 784 constexpr A(int n) : n(n) {} 785 int n; 786 constexpr int f() { return n + 3; } 787 }; 788 constexpr A a(7); 789 static_assert(A(5).*&A::n == 5, ""); 790 static_assert((&a)->*&A::n == 7, ""); 791 static_assert((A(8).*&A::f)() == 11, ""); 792 static_assert(((&a)->*&A::f)() == 10, ""); 793 794 struct B : A { 795 constexpr B(int n, int m) : A(n), m(m) {} 796 int m; 797 constexpr int g() { return n + m + 1; } 798 }; 799 constexpr B b(9, 13); 800 static_assert(B(4, 11).*&A::n == 4, ""); 801 static_assert(B(4, 11).*&B::m == 11, ""); 802 static_assert(B(4, 11).*(int(A::*))&B::m == 11, ""); 803 static_assert((&b)->*&A::n == 9, ""); 804 static_assert((&b)->*&B::m == 13, ""); 805 static_assert((&b)->*(int(A::*))&B::m == 13, ""); 806 static_assert((B(4, 11).*&A::f)() == 7, ""); 807 static_assert((B(4, 11).*&B::g)() == 16, ""); 808 static_assert((B(4, 11).*(int(A::*)()const)&B::g)() == 16, ""); 809 static_assert(((&b)->*&A::f)() == 12, ""); 810 static_assert(((&b)->*&B::g)() == 23, ""); 811 static_assert(((&b)->*(int(A::*)()const)&B::g)() == 23, ""); 812 813 struct S { 814 constexpr S(int m, int n, int (S::*pf)() const, int S::*pn) : 815 m(m), n(n), pf(pf), pn(pn) {} 816 constexpr S() : m(), n(), pf(&S::f), pn(&S::n) {} 817 818 constexpr int f() { return this->*pn; } 819 virtual int g() const; 820 821 int m, n; 822 int (S::*pf)() const; 823 int S::*pn; 824 }; 825 826 constexpr int S::*pm = &S::m; 827 constexpr int S::*pn = &S::n; 828 constexpr int (S::*pf)() const = &S::f; 829 constexpr int (S::*pg)() const = &S::g; 830 831 constexpr S s(2, 5, &S::f, &S::m); 832 833 static_assert((s.*&S::f)() == 2, ""); 834 static_assert((s.*s.pf)() == 2, ""); 835 836 static_assert(pf == &S::f, ""); 837 static_assert(pf == s.*&S::pf, ""); 838 static_assert(pm == &S::m, ""); 839 static_assert(pm != pn, ""); 840 static_assert(s.pn != pn, ""); 841 static_assert(s.pn == pm, ""); 842 static_assert(pg != nullptr, ""); 843 static_assert(pf != nullptr, ""); 844 static_assert((int S::*)nullptr == nullptr, ""); 845 static_assert(pg == pg, ""); // expected-error {{constant expression}} expected-note {{comparison of pointer to virtual member function 'g' has unspecified value}} 846 static_assert(pf != pg, ""); // expected-error {{constant expression}} expected-note {{comparison of pointer to virtual member function 'g' has unspecified value}} 847 848 template<int n> struct T : T<n-1> {}; 849 template<> struct T<0> { int n; }; 850 template<> struct T<30> : T<29> { int m; }; 851 852 T<17> t17; 853 T<30> t30; 854 855 constexpr int (T<10>::*deepn) = &T<0>::n; 856 static_assert(&(t17.*deepn) == &t17.n, ""); 857 static_assert(deepn == &T<2>::n, ""); 858 859 constexpr int (T<15>::*deepm) = (int(T<10>::*))&T<30>::m; 860 constexpr int *pbad = &(t17.*deepm); // expected-error {{constant expression}} 861 static_assert(&(t30.*deepm) == &t30.m, ""); 862 static_assert(deepm == &T<50>::m, ""); 863 static_assert(deepm != deepn, ""); 864 865 constexpr T<5> *p17_5 = &t17; 866 constexpr T<13> *p17_13 = (T<13>*)p17_5; 867 constexpr T<23> *p17_23 = (T<23>*)p17_13; // expected-error {{constant expression}} expected-note {{cannot cast object of dynamic type 'T<17>' to type 'T<23>'}} 868 static_assert(&(p17_5->*(int(T<3>::*))deepn) == &t17.n, ""); 869 static_assert(&(p17_13->*deepn) == &t17.n, ""); 870 constexpr int *pbad2 = &(p17_13->*(int(T<9>::*))deepm); // expected-error {{constant expression}} 871 872 constexpr T<5> *p30_5 = &t30; 873 constexpr T<23> *p30_23 = (T<23>*)p30_5; 874 constexpr T<13> *p30_13 = p30_23; 875 static_assert(&(p30_5->*(int(T<3>::*))deepn) == &t30.n, ""); 876 static_assert(&(p30_13->*deepn) == &t30.n, ""); 877 static_assert(&(p30_23->*deepn) == &t30.n, ""); 878 static_assert(&(p30_5->*(int(T<2>::*))deepm) == &t30.m, ""); 879 static_assert(&(((T<17>*)p30_13)->*deepm) == &t30.m, ""); 880 static_assert(&(p30_23->*deepm) == &t30.m, ""); 881 882 struct Base { int n; }; 883 template<int N> struct Mid : Base {}; 884 struct Derived : Mid<0>, Mid<1> {}; 885 static_assert(&Mid<0>::n == &Mid<1>::n, ""); 886 static_assert((int Derived::*)(int Mid<0>::*)&Mid<0>::n != 887 (int Derived::*)(int Mid<1>::*)&Mid<1>::n, ""); 888 static_assert(&Mid<0>::n == (int Mid<0>::*)&Base::n, ""); 889 } 890 891 namespace ArrayBaseDerived { 892 893 struct Base { 894 constexpr Base() {} 895 int n = 0; 896 }; 897 struct Derived : Base { 898 constexpr Derived() {} 899 constexpr const int *f() { return &n; } 900 }; 901 902 constexpr Derived a[10]; 903 constexpr Derived *pd3 = const_cast<Derived*>(&a[3]); 904 constexpr Base *pb3 = const_cast<Derived*>(&a[3]); 905 static_assert(pb3 == pd3, ""); 906 907 // pb3 does not point to an array element. 908 constexpr Base *pb4 = pb3 + 1; // ok, one-past-the-end pointer. 909 constexpr int pb4n = pb4->n; // expected-error {{constant expression}} expected-note {{cannot access field of pointer past the end}} 910 constexpr Base *err_pb5 = pb3 + 2; // expected-error {{constant expression}} expected-note {{cannot refer to element 2}} expected-note {{here}} 911 constexpr int err_pb5n = err_pb5->n; // expected-error {{constant expression}} expected-note {{initializer of 'err_pb5' is not a constant expression}} 912 constexpr Base *err_pb2 = pb3 - 1; // expected-error {{constant expression}} expected-note {{cannot refer to element -1}} expected-note {{here}} 913 constexpr int err_pb2n = err_pb2->n; // expected-error {{constant expression}} expected-note {{initializer of 'err_pb2'}} 914 constexpr Base *pb3a = pb4 - 1; 915 916 // pb4 does not point to a Derived. 917 constexpr Derived *err_pd4 = (Derived*)pb4; // expected-error {{constant expression}} expected-note {{cannot access derived class of pointer past the end}} 918 constexpr Derived *pd3a = (Derived*)pb3a; 919 constexpr int pd3n = pd3a->n; 920 921 // pd3a still points to the Derived array. 922 constexpr Derived *pd6 = pd3a + 3; 923 static_assert(pd6 == &a[6], ""); 924 constexpr Derived *pd9 = pd6 + 3; 925 constexpr Derived *pd10 = pd6 + 4; 926 constexpr int pd9n = pd9->n; // ok 927 constexpr int err_pd10n = pd10->n; // expected-error {{constant expression}} expected-note {{cannot access base class of pointer past the end}} 928 constexpr int pd0n = pd10[-10].n; 929 constexpr int err_pdminus1n = pd10[-11].n; // expected-error {{constant expression}} expected-note {{cannot refer to element -1 of}} 930 931 constexpr Base *pb9 = pd9; 932 constexpr const int *(Base::*pfb)() const = 933 static_cast<const int *(Base::*)() const>(&Derived::f); 934 static_assert((pb9->*pfb)() == &a[9].n, ""); 935 } 936 937 namespace Complex { 938 939 class complex { 940 int re, im; 941 public: 942 constexpr complex(int re = 0, int im = 0) : re(re), im(im) {} 943 constexpr complex(const complex &o) : re(o.re), im(o.im) {} 944 constexpr complex operator-() const { return complex(-re, -im); } 945 friend constexpr complex operator+(const complex &l, const complex &r) { 946 return complex(l.re + r.re, l.im + r.im); 947 } 948 friend constexpr complex operator-(const complex &l, const complex &r) { 949 return l + -r; 950 } 951 friend constexpr complex operator*(const complex &l, const complex &r) { 952 return complex(l.re * r.re - l.im * r.im, l.re * r.im + l.im * r.re); 953 } 954 friend constexpr bool operator==(const complex &l, const complex &r) { 955 return l.re == r.re && l.im == r.im; 956 } 957 constexpr bool operator!=(const complex &r) const { 958 return re != r.re || im != r.im; 959 } 960 constexpr int real() const { return re; } 961 constexpr int imag() const { return im; } 962 }; 963 964 constexpr complex i = complex(0, 1); 965 constexpr complex k = (3 + 4*i) * (6 - 4*i); 966 static_assert(complex(1,0).real() == 1, ""); 967 static_assert(complex(1,0).imag() == 0, ""); 968 static_assert(((complex)1).imag() == 0, ""); 969 static_assert(k.real() == 34, ""); 970 static_assert(k.imag() == 12, ""); 971 static_assert(k - 34 == 12*i, ""); 972 static_assert((complex)1 == complex(1), ""); 973 static_assert((complex)1 != complex(0, 1), ""); 974 static_assert(complex(1) == complex(1), ""); 975 static_assert(complex(1) != complex(0, 1), ""); 976 constexpr complex makeComplex(int re, int im) { return complex(re, im); } 977 static_assert(makeComplex(1,0) == complex(1), ""); 978 static_assert(makeComplex(1,0) != complex(0, 1), ""); 979 980 class complex_wrap : public complex { 981 public: 982 constexpr complex_wrap(int re, int im = 0) : complex(re, im) {} 983 constexpr complex_wrap(const complex_wrap &o) : complex(o) {} 984 }; 985 986 static_assert((complex_wrap)1 == complex(1), ""); 987 static_assert((complex)1 != complex_wrap(0, 1), ""); 988 static_assert(complex(1) == complex_wrap(1), ""); 989 static_assert(complex_wrap(1) != complex(0, 1), ""); 990 constexpr complex_wrap makeComplexWrap(int re, int im) { 991 return complex_wrap(re, im); 992 } 993 static_assert(makeComplexWrap(1,0) == complex(1), ""); 994 static_assert(makeComplexWrap(1,0) != complex(0, 1), ""); 995 996 } 997 998 namespace PR11595 { 999 struct A { constexpr bool operator==(int x) { return true; } }; 1000 struct B { B(); A& x; }; 1001 static_assert(B().x == 3, ""); // expected-error {{constant expression}} expected-note {{non-literal type 'PR11595::B' cannot be used in a constant expression}} 1002 1003 constexpr bool f(int k) { // expected-error {{constexpr function never produces a constant expression}} 1004 return B().x == k; // expected-note {{non-literal type 'PR11595::B' cannot be used in a constant expression}} 1005 } 1006 } 1007 1008 namespace ExprWithCleanups { 1009 struct A { A(); ~A(); int get(); }; 1010 constexpr int get(bool FromA) { return FromA ? A().get() : 1; } 1011 constexpr int n = get(false); 1012 } 1013 1014 namespace Volatile { 1015 1016 volatile constexpr int n1 = 0; // expected-note {{here}} 1017 volatile const int n2 = 0; // expected-note {{here}} 1018 int n3 = 37; // expected-note {{declared here}} 1019 1020 constexpr int m1 = n1; // expected-error {{constant expression}} expected-note {{read of volatile-qualified type 'const volatile int'}} 1021 constexpr int m2 = n2; // expected-error {{constant expression}} expected-note {{read of volatile-qualified type 'const volatile int'}} 1022 constexpr int m1b = const_cast<const int&>(n1); // expected-error {{constant expression}} expected-note {{read of volatile object 'n1'}} 1023 constexpr int m2b = const_cast<const int&>(n2); // expected-error {{constant expression}} expected-note {{read of volatile object 'n2'}} 1024 1025 struct T { int n; }; 1026 const T t = { 42 }; // expected-note {{declared here}} 1027 1028 constexpr int f(volatile int &&r) { 1029 return r; // expected-note {{read of volatile-qualified type 'volatile int'}} 1030 } 1031 constexpr int g(volatile int &&r) { 1032 return const_cast<int&>(r); // expected-note {{read of volatile temporary is not allowed in a constant expression}} 1033 } 1034 struct S { 1035 int j : f(0); // expected-error {{constant expression}} expected-note {{in call to 'f(0)'}} 1036 int k : g(0); // expected-error {{constant expression}} expected-note {{temporary created here}} expected-note {{in call to 'g(0)'}} 1037 int l : n3; // expected-error {{constant expression}} expected-note {{read of non-const variable}} 1038 int m : t.n; // expected-error {{constant expression}} expected-note {{read of non-constexpr variable}} 1039 }; 1040 1041 } 1042 1043 namespace ExternConstexpr { 1044 extern constexpr int n = 0; 1045 extern constexpr int m; // expected-error {{constexpr variable declaration must be a definition}} 1046 void f() { 1047 extern constexpr int i; // expected-error {{constexpr variable declaration must be a definition}} 1048 constexpr int j = 0; 1049 constexpr int k; // expected-error {{default initialization of an object of const type}} 1050 } 1051 } 1052 1053 namespace ComplexConstexpr { 1054 constexpr _Complex float test1 = {}; 1055 constexpr _Complex float test2 = {1}; 1056 constexpr _Complex double test3 = {1,2}; 1057 constexpr _Complex int test4 = {4}; 1058 constexpr _Complex int test5 = 4; 1059 constexpr _Complex int test6 = {5,6}; 1060 typedef _Complex float fcomplex; 1061 constexpr fcomplex test7 = fcomplex(); 1062 1063 constexpr const double &t2r = __real test3; 1064 constexpr const double &t2i = __imag test3; 1065 static_assert(&t2r + 1 == &t2i, ""); 1066 static_assert(t2r == 1.0, ""); 1067 static_assert(t2i == 2.0, ""); 1068 constexpr const double *t2p = &t2r; 1069 static_assert(t2p[-1] == 0.0, ""); // expected-error {{constant expr}} expected-note {{cannot refer to element -1 of array of 2 elements}} 1070 static_assert(t2p[0] == 1.0, ""); 1071 static_assert(t2p[1] == 2.0, ""); 1072 static_assert(t2p[2] == 0.0, ""); // expected-error {{constant expr}} expected-note {{one-past-the-end pointer}} 1073 static_assert(t2p[3] == 0.0, ""); // expected-error {{constant expr}} expected-note {{cannot refer to element 3 of array of 2 elements}} 1074 constexpr _Complex float *p = 0; 1075 constexpr float pr = __real *p; // expected-error {{constant expr}} expected-note {{cannot access real component of null}} 1076 constexpr float pi = __imag *p; // expected-error {{constant expr}} expected-note {{cannot access imaginary component of null}} 1077 constexpr const _Complex double *q = &test3 + 1; 1078 constexpr double qr = __real *q; // expected-error {{constant expr}} expected-note {{cannot access real component of pointer past the end}} 1079 constexpr double qi = __imag *q; // expected-error {{constant expr}} expected-note {{cannot access imaginary component of pointer past the end}} 1080 1081 static_assert(__real test6 == 5, ""); 1082 static_assert(__imag test6 == 6, ""); 1083 static_assert(&__imag test6 == &__real test6 + 1, ""); 1084 } 1085 1086 namespace InstantiateCaseStmt { 1087 template<int x> constexpr int f() { return x; } 1088 template<int x> int g(int c) { switch(c) { case f<x>(): return 1; } return 0; } 1089 int gg(int c) { return g<4>(c); } 1090 } 1091 1092 namespace ConvertedConstantExpr { 1093 extern int &m; 1094 extern int &n; 1095 1096 constexpr int k = 4; 1097 int &m = const_cast<int&>(k); 1098 1099 // If we have nothing more interesting to say, ensure we don't produce a 1100 // useless note and instead just point to the non-constant subexpression. 1101 enum class E { 1102 em = m, 1103 en = n, // expected-error {{not a constant expression}} 1104 eo = (m + 1105 n // expected-error {{not a constant expression}} 1106 ), 1107 eq = reinterpret_cast<int>((int*)0) // expected-error {{not a constant expression}} expected-note {{reinterpret_cast}} 1108 }; 1109 } 1110 1111 namespace IndirectField { 1112 struct S { 1113 struct { // expected-warning {{GNU extension}} 1114 union { 1115 struct { // expected-warning {{GNU extension}} 1116 int a; 1117 int b; 1118 }; 1119 int c; 1120 }; 1121 int d; 1122 }; 1123 union { 1124 int e; 1125 int f; 1126 }; 1127 constexpr S(int a, int b, int d, int e) : a(a), b(b), d(d), e(e) {} 1128 constexpr S(int c, int d, int f) : c(c), d(d), f(f) {} 1129 }; 1130 1131 constexpr S s1(1, 2, 3, 4); 1132 constexpr S s2(5, 6, 7); 1133 1134 // FIXME: The diagnostics here do a very poor job of explaining which unnamed 1135 // member is active and which is requested. 1136 static_assert(s1.a == 1, ""); 1137 static_assert(s1.b == 2, ""); 1138 static_assert(s1.c == 0, ""); // expected-error {{constant expression}} expected-note {{union with active member}} 1139 static_assert(s1.d == 3, ""); 1140 static_assert(s1.e == 4, ""); 1141 static_assert(s1.f == 0, ""); // expected-error {{constant expression}} expected-note {{union with active member}} 1142 1143 static_assert(s2.a == 0, ""); // expected-error {{constant expression}} expected-note {{union with active member}} 1144 static_assert(s2.b == 0, ""); // expected-error {{constant expression}} expected-note {{union with active member}} 1145 static_assert(s2.c == 5, ""); 1146 static_assert(s2.d == 6, ""); 1147 static_assert(s2.e == 0, ""); // expected-error {{constant expression}} expected-note {{union with active member}} 1148 static_assert(s2.f == 7, ""); 1149 } 1150 1151 // DR1405: don't allow reading mutable members in constant expressions. 1152 namespace MutableMembers { 1153 struct MM { 1154 mutable int n; // expected-note 3{{declared here}} 1155 } constexpr mm = { 4 }; 1156 constexpr int mmn = mm.n; // expected-error {{constant expression}} expected-note {{read of mutable member 'n' is not allowed in a constant expression}} 1157 int x = (mm.n = 1, 3); 1158 constexpr int mmn2 = mm.n; // expected-error {{constant expression}} expected-note {{read of mutable member 'n' is not allowed in a constant expression}} 1159 1160 // Here's one reason why allowing this would be a disaster... 1161 template<int n> struct Id { int k = n; }; 1162 int f() { 1163 constexpr MM m = { 0 }; 1164 ++m.n; 1165 return Id<m.n>().k; // expected-error {{not a constant expression}} expected-note {{read of mutable member 'n' is not allowed in a constant expression}} 1166 } 1167 1168 struct A { int n; }; 1169 struct B { mutable A a; }; // expected-note {{here}} 1170 struct C { B b; }; 1171 constexpr C c[3] = {}; 1172 constexpr int k = c[1].b.a.n; // expected-error {{constant expression}} expected-note {{mutable}} 1173 } 1174 1175 namespace Fold { 1176 1177 // This macro forces its argument to be constant-folded, even if it's not 1178 // otherwise a constant expression. 1179 #define fold(x) (__builtin_constant_p(x) ? (x) : (x)) 1180 1181 constexpr int n = (int)(char*)123; // expected-error {{constant expression}} expected-note {{reinterpret_cast}} 1182 constexpr int m = fold((int)(char*)123); // ok 1183 static_assert(m == 123, ""); 1184 1185 #undef fold 1186 1187 } 1188 1189 namespace DR1454 { 1190 1191 constexpr const int &f(const int &n) { return n; } 1192 constexpr int k1 = f(0); // ok 1193 1194 struct Wrap { 1195 const int &value; 1196 }; 1197 constexpr const Wrap &g(const Wrap &w) { return w; } 1198 constexpr int k2 = g({0}).value; // ok 1199 1200 constexpr const int &i = 0; // expected-error {{constant expression}} expected-note {{temporary}} expected-note 2{{here}} 1201 constexpr const int j = i; // expected-error {{constant expression}} expected-note {{initializer of 'i' is not a constant expression}} 1202 1203 } 1204 1205 namespace RecursiveOpaqueExpr { 1206 template<typename Iter> 1207 constexpr auto LastNonzero(Iter p, Iter q) -> decltype(+*p) { 1208 return p != q ? (LastNonzero(p+1, q) ?: *p) : 0; // expected-warning {{GNU}} 1209 } 1210 1211 constexpr int arr1[] = { 1, 0, 0, 3, 0, 2, 0, 4, 0, 0 }; 1212 static_assert(LastNonzero(begin(arr1), end(arr1)) == 4, ""); 1213 1214 constexpr int arr2[] = { 1, 0, 0, 3, 0, 2, 0, 4, 0, 5 }; 1215 static_assert(LastNonzero(begin(arr2), end(arr2)) == 5, ""); 1216 } 1217 1218 namespace VLASizeof { 1219 1220 void f(int k) { 1221 int arr[k]; // expected-warning {{C99}} 1222 constexpr int n = 1 + 1223 sizeof(arr) // expected-error {{constant expression}} 1224 * 3; 1225 } 1226 } 1227 1228 namespace CompoundLiteral { 1229 // FIXME: 1230 // We don't model the semantics of this correctly: the compound literal is 1231 // represented as a prvalue in the AST, but actually behaves like an lvalue. 1232 // We treat the compound literal as a temporary and refuse to produce a 1233 // pointer to it. This is OK: we're not required to treat this as a constant 1234 // in C++, and in C we model compound literals as lvalues. 1235 constexpr int *p = (int*)(int[1]){0}; // expected-warning {{C99}} expected-error {{constant expression}} expected-note 2{{temporary}} 1236 } 1237 1238 namespace Vector { 1239 typedef int __attribute__((vector_size(16))) VI4; 1240 constexpr VI4 f(int n) { 1241 return VI4 { n * 3, n + 4, n - 5, n / 6 }; 1242 } 1243 constexpr auto v1 = f(10); 1244 1245 typedef double __attribute__((vector_size(32))) VD4; 1246 constexpr VD4 g(int n) { 1247 return (VD4) { n / 2.0, n + 1.5, n - 5.4, n * 0.9 }; // expected-warning {{C99}} 1248 } 1249 constexpr auto v2 = g(4); 1250 } 1251
