constant-expression-cxx11.cpp revision ec789163a42a7be654ac34aadb750b508954d53c
1// RUN: %clang_cc1 -triple i686-linux -fsyntax-only -verify -std=c++11 -pedantic %s -Wno-comment 2 3namespace StaticAssertFoldTest { 4 5int x; 6static_assert(++x, "test"); // expected-error {{not an integral constant expression}} 7static_assert(false, "test"); // expected-error {{test}} 8 9} 10 11typedef decltype(sizeof(char)) size_t; 12 13template<typename T> constexpr T id(const T &t) { return t; } 14template<typename T> constexpr T min(const T &a, const T &b) { 15 return a < b ? a : b; 16} 17template<typename T> constexpr T max(const T &a, const T &b) { 18 return a < b ? b : a; 19} 20template<typename T, size_t N> constexpr T *begin(T (&xs)[N]) { return xs; } 21template<typename T, size_t N> constexpr T *end(T (&xs)[N]) { return xs + N; } 22 23struct MemberZero { 24 constexpr int zero() { return 0; } 25}; 26 27namespace 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 static_assert((void*)p != (void*)q, ""); 41 static_assert((A*)p == (A*)q, ""); 42 static_assert((Aa*)p != (Aa*)q, ""); 43 44 constexpr B &pp = d; 45 constexpr C &qq = d; 46 static_assert((void*)&pp != (void*)&qq, ""); 47 static_assert(&(A&)pp == &(A&)qq, ""); 48 static_assert(&(Aa&)pp != &(Aa&)qq, ""); 49 50 constexpr V *v = p; 51 constexpr V *w = q; 52 constexpr V *x = (A*)p; 53 static_assert(v == w, ""); 54 static_assert(v == x, ""); 55 56 static_assert((U*)&d == p, ""); 57 static_assert((U*)&d == q, ""); 58 static_assert((U*)&d == v, ""); 59 static_assert((U*)&d == w, ""); 60 static_assert((U*)&d == x, ""); 61 62 struct X {}; 63 struct Y1 : virtual X {}; 64 struct Y2 : X {}; 65 struct Z : Y1, Y2 {}; 66 Z z; 67 static_assert((X*)(Y1*)&z != (X*)(Y2*)&z, ""); 68 69} 70 71namespace ConstCast { 72 73constexpr int n1 = 0; 74constexpr int n2 = const_cast<int&>(n1); 75constexpr int *n3 = const_cast<int*>(&n1); 76constexpr int n4 = *const_cast<int*>(&n1); 77constexpr const int * const *n5 = const_cast<const int* const*>(&n3); 78constexpr int **n6 = const_cast<int**>(&n3); 79constexpr int n7 = **n5; 80constexpr int n8 = **n6; 81 82} 83 84namespace 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 92namespace CaseStatements { 93 void f(int n) { 94 switch (n) { 95 // FIXME: Produce the 'add ()' fixit for this. 96 case MemberZero().zero: // desired-error {{did you mean to call it with no arguments?}} expected-error {{not an integer constant expression}} expected-note {{non-literal type '<bound member function type>'}} 97 case id(1): 98 return; 99 } 100 } 101} 102 103extern int &Recurse1; 104int &Recurse2 = Recurse1; // expected-note 2{{declared here}} expected-note {{initializer of 'Recurse1' is not a constant expression}} 105int &Recurse1 = Recurse2; // expected-note {{declared here}} expected-note {{initializer of 'Recurse2' is not a constant expression}} 106constexpr int &Recurse3 = Recurse2; // expected-error {{must be initialized by a constant expression}} expected-note {{initializer of 'Recurse2' is not a constant expression}} 107 108extern const int RecurseA; 109const int RecurseB = RecurseA; // expected-note {{declared here}} 110const int RecurseA = 10; 111constexpr int RecurseC = RecurseB; // expected-error {{must be initialized by a constant expression}} expected-note {{initializer of 'RecurseB' is not a constant expression}} 112 113namespace MemberEnum { 114 struct WithMemberEnum { 115 enum E { A = 42 }; 116 } wme; 117 118 static_assert(wme.A == 42, ""); 119} 120 121namespace DefaultArguments { 122 123const int z = int(); 124constexpr int Sum(int a = 0, const int &b = 0, const int *c = &z, char d = 0) { 125 return a + b + *c + d; 126} 127const int four = 4; 128constexpr int eight = 8; 129constexpr const int twentyseven = 27; 130static_assert(Sum() == 0, ""); 131static_assert(Sum(1) == 1, ""); 132static_assert(Sum(1, four) == 5, ""); 133static_assert(Sum(1, eight, &twentyseven) == 36, ""); 134static_assert(Sum(1, 2, &four, eight) == 15, ""); 135 136} 137 138namespace Ellipsis { 139 140// Note, values passed through an ellipsis can't actually be used. 141constexpr int F(int a, ...) { return a; } 142static_assert(F(0) == 0, ""); 143static_assert(F(1, 0) == 1, ""); 144static_assert(F(2, "test") == 2, ""); 145static_assert(F(3, &F) == 3, ""); 146int k = 0; // expected-note {{here}} 147static_assert(F(4, k) == 3, ""); // expected-error {{constant expression}} expected-note {{read of non-const variable 'k'}} 148 149} 150 151namespace Recursion { 152 constexpr int fib(int n) { return n > 1 ? fib(n-1) + fib(n-2) : n; } 153 static_assert(fib(11) == 89, ""); 154 155 constexpr int gcd_inner(int a, int b) { 156 return b == 0 ? a : gcd_inner(b, a % b); 157 } 158 constexpr int gcd(int a, int b) { 159 return gcd_inner(max(a, b), min(a, b)); 160 } 161 162 static_assert(gcd(1749237, 5628959) == 7, ""); 163} 164 165namespace FunctionCast { 166 // When folding, we allow functions to be cast to different types. Such 167 // cast functions cannot be called, even if they're constexpr. 168 constexpr int f() { return 1; } 169 typedef double (*DoubleFn)(); 170 typedef int (*IntFn)(); 171 int a[(int)DoubleFn(f)()]; // expected-error {{variable length array}} expected-warning{{C99 feature}} 172 int b[(int)IntFn(f)()]; // ok 173} 174 175namespace StaticMemberFunction { 176 struct S { 177 static constexpr int k = 42; 178 static constexpr int f(int n) { return n * k + 2; } 179 } s; 180 181 constexpr int n = s.f(19); 182 static_assert(S::f(19) == 800, ""); 183 static_assert(s.f(19) == 800, ""); 184 static_assert(n == 800, ""); 185 186 constexpr int (*sf1)(int) = &S::f; 187 constexpr int (*sf2)(int) = &s.f; 188 constexpr const int *sk = &s.k; 189} 190 191namespace ParameterScopes { 192 193 const int k = 42; 194 constexpr const int &ObscureTheTruth(const int &a) { return a; } // expected-note 3{{reference to 'a' cannot be returned from a constexpr function}} 195 constexpr const int &MaybeReturnJunk(bool b, const int a) { // expected-note 2{{declared here}} 196 return ObscureTheTruth(b ? a : k); // expected-note 2{{in call to 'ObscureTheTruth(a)'}} 197 } 198 static_assert(MaybeReturnJunk(false, 0) == 42, ""); // ok 199 constexpr int a = MaybeReturnJunk(true, 0); // expected-error {{constant expression}} expected-note {{in call to 'MaybeReturnJunk(1, 0)'}} 200 201 constexpr const int MaybeReturnNonstaticRef(bool b, const int a) { // expected-note {{here}} 202 // If ObscureTheTruth returns a reference to 'a', the result is not a 203 // constant expression even though 'a' is still in scope. 204 return ObscureTheTruth(b ? a : k); // expected-note {{in call to 'ObscureTheTruth(a)'}} 205 } 206 static_assert(MaybeReturnNonstaticRef(false, 0) == 42, ""); // ok 207 constexpr int b = MaybeReturnNonstaticRef(true, 0); // expected-error {{constant expression}} expected-note {{in call to 'MaybeReturnNonstaticRef(1, 0)'}} 208 209 constexpr int InternalReturnJunk(int n) { 210 // FIXME: We should reject this: it never produces a constant expression. 211 return MaybeReturnJunk(true, n); // expected-note {{in call to 'MaybeReturnJunk(1, 0)'}} 212 } 213 constexpr int n3 = InternalReturnJunk(0); // expected-error {{must be initialized by a constant expression}} expected-note {{in call to 'InternalReturnJunk(0)'}} 214 215 constexpr int LToR(int &n) { return n; } 216 constexpr int GrabCallersArgument(bool which, int a, int b) { 217 return LToR(which ? b : a); 218 } 219 static_assert(GrabCallersArgument(false, 1, 2) == 1, ""); 220 static_assert(GrabCallersArgument(true, 4, 8) == 8, ""); 221 222} 223 224namespace Pointers { 225 226 constexpr int f(int n, const int *a, const int *b, const int *c) { 227 return n == 0 ? 0 : *a + f(n-1, b, c, a); 228 } 229 230 const int x = 1, y = 10, z = 100; 231 static_assert(f(23, &x, &y, &z) == 788, ""); 232 233 constexpr int g(int n, int a, int b, int c) { 234 return f(n, &a, &b, &c); 235 } 236 static_assert(g(23, x, y, z) == 788, ""); 237 238} 239 240namespace FunctionPointers { 241 242 constexpr int Double(int n) { return 2 * n; } 243 constexpr int Triple(int n) { return 3 * n; } 244 constexpr int Twice(int (*F)(int), int n) { return F(F(n)); } 245 constexpr int Quadruple(int n) { return Twice(Double, n); } 246 constexpr auto Select(int n) -> int (*)(int) { 247 return n == 2 ? &Double : n == 3 ? &Triple : n == 4 ? &Quadruple : 0; 248 } 249 constexpr int Apply(int (*F)(int), int n) { return F(n); } // expected-note {{subexpression}} 250 251 static_assert(1 + Apply(Select(4), 5) + Apply(Select(3), 7) == 42, ""); 252 253 constexpr int Invalid = Apply(Select(0), 0); // expected-error {{must be initialized by a constant expression}} expected-note {{in call to 'Apply(0, 0)'}} 254 255} 256 257namespace PointerComparison { 258 259int x, y; 260static_assert(&x == &y, "false"); // expected-error {{false}} 261static_assert(&x != &y, ""); 262constexpr bool g1 = &x == &y; 263constexpr bool g2 = &x != &y; 264constexpr bool g3 = &x <= &y; // expected-error {{must be initialized by a constant expression}} 265constexpr bool g4 = &x >= &y; // expected-error {{must be initialized by a constant expression}} 266constexpr bool g5 = &x < &y; // expected-error {{must be initialized by a constant expression}} 267constexpr bool g6 = &x > &y; // expected-error {{must be initialized by a constant expression}} 268 269struct S { int x, y; } s; 270static_assert(&s.x == &s.y, "false"); // expected-error {{false}} 271static_assert(&s.x != &s.y, ""); 272static_assert(&s.x <= &s.y, ""); 273static_assert(&s.x >= &s.y, "false"); // expected-error {{false}} 274static_assert(&s.x < &s.y, ""); 275static_assert(&s.x > &s.y, "false"); // expected-error {{false}} 276 277static_assert(0 == &y, "false"); // expected-error {{false}} 278static_assert(0 != &y, ""); 279constexpr bool n3 = 0 <= &y; // expected-error {{must be initialized by a constant expression}} 280constexpr bool n4 = 0 >= &y; // expected-error {{must be initialized by a constant expression}} 281constexpr bool n5 = 0 < &y; // expected-error {{must be initialized by a constant expression}} 282constexpr bool n6 = 0 > &y; // expected-error {{must be initialized by a constant expression}} 283 284static_assert(&x == 0, "false"); // expected-error {{false}} 285static_assert(&x != 0, ""); 286constexpr bool n9 = &x <= 0; // expected-error {{must be initialized by a constant expression}} 287constexpr bool n10 = &x >= 0; // expected-error {{must be initialized by a constant expression}} 288constexpr bool n11 = &x < 0; // expected-error {{must be initialized by a constant expression}} 289constexpr bool n12 = &x > 0; // expected-error {{must be initialized by a constant expression}} 290 291static_assert(&x == &x, ""); 292static_assert(&x != &x, "false"); // expected-error {{false}} 293static_assert(&x <= &x, ""); 294static_assert(&x >= &x, ""); 295static_assert(&x < &x, "false"); // expected-error {{false}} 296static_assert(&x > &x, "false"); // expected-error {{false}} 297 298constexpr S* sptr = &s; 299constexpr bool dyncast = sptr == dynamic_cast<S*>(sptr); // expected-error {{constant expression}} expected-note {{dynamic_cast}} 300 301struct Str { 302 // FIXME: In C++ mode, we should say 'integral' not 'integer' 303 int a : dynamic_cast<S*>(sptr) == dynamic_cast<S*>(sptr); // \ 304 expected-warning {{not integer constant expression}} \ 305 expected-note {{dynamic_cast is not allowed in a constant expression}} 306 int b : reinterpret_cast<S*>(sptr) == reinterpret_cast<S*>(sptr); // \ 307 expected-warning {{not integer constant expression}} \ 308 expected-note {{reinterpret_cast is not allowed in a constant expression}} 309 int c : (S*)(long)(sptr) == (S*)(long)(sptr); // \ 310 expected-warning {{not integer constant expression}} \ 311 expected-note {{cast which performs the conversions of a reinterpret_cast is not allowed in a constant expression}} 312 int d : (S*)(42) == (S*)(42); // \ 313 expected-warning {{not integer constant expression}} \ 314 expected-note {{cast which performs the conversions of a reinterpret_cast is not allowed in a constant expression}} 315 int e : (Str*)(sptr) == (Str*)(sptr); // \ 316 expected-warning {{not integer constant expression}} \ 317 expected-note {{cast which performs the conversions of a reinterpret_cast is not allowed in a constant expression}} 318 int f : &(Str&)(*sptr) == &(Str&)(*sptr); // \ 319 expected-warning {{not integer constant expression}} \ 320 expected-note {{cast which performs the conversions of a reinterpret_cast is not allowed in a constant expression}} 321 int g : (S*)(void*)(sptr) == sptr; // \ 322 expected-warning {{not integer constant expression}} \ 323 expected-note {{cast from 'void *' is not allowed in a constant expression}} 324}; 325 326extern char externalvar[]; 327constexpr bool constaddress = (void *)externalvar == (void *)0x4000UL; // expected-error {{must be initialized by a constant expression}} 328constexpr bool litaddress = "foo" == "foo"; // expected-error {{must be initialized by a constant expression}} expected-warning {{unspecified}} 329static_assert(0 != "foo", ""); 330 331} 332 333namespace MaterializeTemporary { 334 335constexpr int f(const int &r) { return r; } 336constexpr int n = f(1); 337 338constexpr bool same(const int &a, const int &b) { return &a == &b; } 339constexpr bool sameTemporary(const int &n) { return same(n, n); } 340 341static_assert(n, ""); 342static_assert(!same(4, 4), ""); 343static_assert(same(n, n), ""); 344static_assert(sameTemporary(9), ""); 345 346} 347 348constexpr int strcmp_ce(const char *p, const char *q) { 349 return (!*p || *p != *q) ? *p - *q : strcmp_ce(p+1, q+1); 350} 351 352namespace StringLiteral { 353 354template<typename Char> 355constexpr int MangleChars(const Char *p) { 356 return *p + 3 * (*p ? MangleChars(p+1) : 0); 357} 358 359static_assert(MangleChars("constexpr!") == 1768383, ""); 360static_assert(MangleChars(u8"constexpr!") == 1768383, ""); 361static_assert(MangleChars(L"constexpr!") == 1768383, ""); 362static_assert(MangleChars(u"constexpr!") == 1768383, ""); 363static_assert(MangleChars(U"constexpr!") == 1768383, ""); 364 365constexpr char c0 = "nought index"[0]; 366constexpr char c1 = "nice index"[10]; 367constexpr 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}} 368constexpr 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}} 369constexpr 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}} 370 371constexpr const char *p = "test" + 2; 372static_assert(*p == 's', ""); 373 374constexpr const char *max_iter(const char *a, const char *b) { 375 return *a < *b ? b : a; 376} 377constexpr const char *max_element(const char *a, const char *b) { 378 return (a+1 >= b) ? a : max_iter(a, max_element(a+1, b)); 379} 380 381constexpr char str[] = "the quick brown fox jumped over the lazy dog"; 382constexpr const char *max = max_element(begin(str), end(str)); 383static_assert(*max == 'z', ""); 384static_assert(max == str + 38, ""); 385 386static_assert(strcmp_ce("hello world", "hello world") == 0, ""); 387static_assert(strcmp_ce("hello world", "hello clang") > 0, ""); 388static_assert(strcmp_ce("constexpr", "test") < 0, ""); 389static_assert(strcmp_ce("", " ") < 0, ""); 390 391struct S { 392 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}} 393}; 394 395struct T { 396 char c[6]; 397 constexpr T() : c{"foo"} {} 398}; 399constexpr T t; 400 401static_assert(t.c[0] == 'f', ""); 402static_assert(t.c[1] == 'o', ""); 403static_assert(t.c[2] == 'o', ""); 404static_assert(t.c[3] == 0, ""); 405static_assert(t.c[4] == 0, ""); 406static_assert(t.c[5] == 0, ""); 407static_assert(t.c[6] == 0, ""); // expected-error {{constant expression}} expected-note {{one-past-the-end}} 408 409struct U { 410 wchar_t chars[6]; 411 int n; 412} constexpr u = { { L"test" }, 0 }; 413static_assert(u.chars[2] == L's', ""); 414 415} 416 417namespace Array { 418 419template<typename Iter> 420constexpr auto Sum(Iter begin, Iter end) -> decltype(+*begin) { 421 return begin == end ? 0 : *begin + Sum(begin+1, end); 422} 423 424constexpr int xs[] = { 1, 2, 3, 4, 5 }; 425constexpr int ys[] = { 5, 4, 3, 2, 1 }; 426constexpr int sum_xs = Sum(begin(xs), end(xs)); 427static_assert(sum_xs == 15, ""); 428 429constexpr int ZipFoldR(int (*F)(int x, int y, int c), int n, 430 const int *xs, const int *ys, int c) { 431 return n ? F( 432 *xs, // expected-note {{read of dereferenced one-past-the-end pointer}} 433 *ys, 434 ZipFoldR(F, n-1, xs+1, ys+1, c)) // \ 435 expected-note {{in call to 'ZipFoldR(&SubMul, 2, &xs[4], &ys[4], 1)'}} \ 436 expected-note {{in call to 'ZipFoldR(&SubMul, 1, &xs[5], &ys[5], 1)'}} 437 : c; 438} 439constexpr int MulAdd(int x, int y, int c) { return x * y + c; } 440constexpr int InnerProduct = ZipFoldR(MulAdd, 5, xs, ys, 0); 441static_assert(InnerProduct == 35, ""); 442 443constexpr int SubMul(int x, int y, int c) { return (x - y) * c; } 444constexpr int DiffProd = ZipFoldR(SubMul, 2, xs+3, ys+3, 1); 445static_assert(DiffProd == 8, ""); 446static_assert(ZipFoldR(SubMul, 3, xs+3, ys+3, 1), ""); // \ 447 expected-error {{constant expression}} \ 448 expected-note {{in call to 'ZipFoldR(&SubMul, 3, &xs[3], &ys[3], 1)'}} 449 450constexpr const int *p = xs + 3; 451constexpr int xs4 = p[1]; // ok 452constexpr int xs5 = p[2]; // expected-error {{constant expression}} expected-note {{read of dereferenced one-past-the-end pointer}} 453constexpr int xs6 = p[3]; // expected-error {{constant expression}} expected-note {{cannot refer to element 6}} 454constexpr int xs0 = p[-3]; // ok 455constexpr int xs_1 = p[-4]; // expected-error {{constant expression}} expected-note {{cannot refer to element -1}} 456 457constexpr int zs[2][2][2][2] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 }; 458static_assert(zs[0][0][0][0] == 1, ""); 459static_assert(zs[1][1][1][1] == 16, ""); 460static_assert(zs[0][0][0][2] == 3, ""); // expected-error {{constant expression}} expected-note {{read of dereferenced one-past-the-end pointer}} 461static_assert((&zs[0][0][0][2])[-1] == 2, ""); 462static_assert(**(**(zs + 1) + 1) == 11, ""); 463static_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}} 464static_assert(*(&(&(*(*&(&zs[2] - 1)[0] + 2 - 2))[2])[-1][2] - 2) == 11, ""); 465constexpr 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}} 466 467constexpr int fail(const int &p) { 468 return (&p)[64]; // expected-note {{cannot refer to element 64 of array of 2 elements}} 469} 470static_assert(fail(*(&(&(*(*&(&zs[2] - 1)[0] + 2 - 2))[2])[-1][2] - 2)) == 11, ""); // \ 471expected-error {{static_assert expression is not an integral constant expression}} \ 472expected-note {{in call to 'fail(zs[1][0][1][0])'}} 473 474constexpr int arr[40] = { 1, 2, 3, [8] = 4 }; // expected-warning {{C99 feature}} 475constexpr int SumNonzero(const int *p) { 476 return *p + (*p ? SumNonzero(p+1) : 0); 477} 478constexpr int CountZero(const int *p, const int *q) { 479 return p == q ? 0 : (*p == 0) + CountZero(p+1, q); 480} 481static_assert(SumNonzero(arr) == 6, ""); 482static_assert(CountZero(arr, arr + 40) == 36, ""); 483 484struct ArrayElem { 485 constexpr ArrayElem() : n(0) {} 486 int n; 487 constexpr int f() { return n; } 488}; 489struct ArrayRVal { 490 constexpr ArrayRVal() {} 491 ArrayElem elems[10]; 492}; 493static_assert(ArrayRVal().elems[3].f() == 0, ""); 494 495} 496 497namespace DependentValues { 498 499struct I { int n; typedef I V[10]; }; 500I::V x, y; 501template<bool B> struct S { 502 int k; 503 void f() { 504 I::V &cells = B ? x : y; 505 I &i = cells[k]; 506 switch (i.n) {} 507 } 508}; 509 510} 511 512namespace Class { 513 514struct A { constexpr A(int a, int b) : k(a + b) {} int k; }; 515constexpr int fn(const A &a) { return a.k; } 516static_assert(fn(A(4,5)) == 9, ""); 517 518struct B { int n; int m; } constexpr b = { 0, b.n }; // expected-warning {{uninitialized}} 519struct C { 520 constexpr C(C *this_) : m(42), n(this_->m) {} // ok 521 int m, n; 522}; 523struct D { 524 C c; 525 constexpr D() : c(&c) {} 526}; 527static_assert(D().c.n == 42, ""); 528 529struct E { 530 constexpr E() : p(&p) {} // expected-note {{pointer to temporary cannot be used to initialize a member in a constant expression}} 531 void *p; 532}; 533constexpr const E &e1 = E(); // expected-error {{constant expression}} expected-note {{in call to 'E()'}} expected-note {{temporary created here}} 534// This is a constant expression if we elide the copy constructor call, and 535// is not a constant expression if we don't! But we do, so it is. 536constexpr E e2 = E(); 537static_assert(e2.p == &e2.p, ""); 538constexpr E e3; 539static_assert(e3.p == &e3.p, ""); 540 541extern const class F f; 542struct F { 543 constexpr F() : p(&f.p) {} 544 const void *p; 545}; 546constexpr F f; 547 548struct G { 549 struct T { 550 constexpr T(T *p) : u1(), u2(p) {} 551 union U1 { 552 constexpr U1() {} 553 int a, b = 42; 554 } u1; 555 union U2 { 556 constexpr U2(T *p) : c(p->u1.b) {} 557 int c, d; 558 } u2; 559 } t; 560 constexpr G() : t(&t) {} 561} constexpr g; 562 563static_assert(g.t.u1.a == 42, ""); // expected-error {{constant expression}} expected-note {{read of member 'a' of union with active member 'b'}} 564static_assert(g.t.u1.b == 42, ""); 565static_assert(g.t.u2.c == 42, ""); 566static_assert(g.t.u2.d == 42, ""); // expected-error {{constant expression}} expected-note {{read of member 'd' of union with active member 'c'}} 567 568struct S { 569 int a, b; 570 const S *p; 571 double d; 572 const char *q; 573 574 constexpr S(int n, const S *p) : a(5), b(n), p(p), d(n), q("hello") {} 575}; 576 577S global(43, &global); 578 579static_assert(S(15, &global).b == 15, ""); 580 581constexpr bool CheckS(const S &s) { 582 return s.a == 5 && s.b == 27 && s.p == &global && s.d == 27. && s.q[3] == 'l'; 583} 584static_assert(CheckS(S(27, &global)), ""); 585 586struct Arr { 587 char arr[3]; 588 constexpr Arr() : arr{'x', 'y', 'z'} {} 589}; 590constexpr int hash(Arr &&a) { 591 return a.arr[0] + a.arr[1] * 0x100 + a.arr[2] * 0x10000; 592} 593constexpr int k = hash(Arr()); 594static_assert(k == 0x007a7978, ""); 595 596 597struct AggregateInit { 598 const char &c; 599 int n; 600 double d; 601 int arr[5]; 602 void *p; 603}; 604 605constexpr AggregateInit agg1 = { "hello"[0] }; 606 607static_assert(strcmp_ce(&agg1.c, "hello") == 0, ""); 608static_assert(agg1.n == 0, ""); 609static_assert(agg1.d == 0.0, ""); 610static_assert(agg1.arr[-1] == 0, ""); // expected-error {{constant expression}} expected-note {{cannot refer to element -1}} 611static_assert(agg1.arr[0] == 0, ""); 612static_assert(agg1.arr[4] == 0, ""); 613static_assert(agg1.arr[5] == 0, ""); // expected-error {{constant expression}} expected-note {{read of dereferenced one-past-the-end}} 614static_assert(agg1.p == nullptr, ""); 615 616namespace SimpleDerivedClass { 617 618struct B { 619 constexpr B(int n) : a(n) {} 620 int a; 621}; 622struct D : B { 623 constexpr D(int n) : B(n) {} 624}; 625constexpr D d(3); 626static_assert(d.a == 3, ""); 627 628} 629 630struct Bottom { constexpr Bottom() {} }; 631struct Base : Bottom { 632 constexpr Base(int a = 42, const char *b = "test") : a(a), b(b) {} 633 int a; 634 const char *b; 635}; 636struct Base2 : Bottom { 637 constexpr Base2(const int &r) : r(r) {} 638 int q = 123; 639 const int &r; 640}; 641struct Derived : Base, Base2 { 642 constexpr Derived() : Base(76), Base2(a) {} 643 int c = r + b[1]; 644}; 645 646constexpr bool operator==(const Base &a, const Base &b) { 647 return a.a == b.a && strcmp_ce(a.b, b.b) == 0; 648} 649 650constexpr Base base; 651constexpr Base base2(76); 652constexpr Derived derived; 653static_assert(derived.a == 76, ""); 654static_assert(derived.b[2] == 's', ""); 655static_assert(derived.c == 76 + 'e', ""); 656static_assert(derived.q == 123, ""); 657static_assert(derived.r == 76, ""); 658static_assert(&derived.r == &derived.a, ""); 659 660static_assert(!(derived == base), ""); 661static_assert(derived == base2, ""); 662 663constexpr Bottom &bot1 = (Base&)derived; 664constexpr Bottom &bot2 = (Base2&)derived; 665static_assert(&bot1 != &bot2, ""); 666 667constexpr Bottom *pb1 = (Base*)&derived; 668constexpr Bottom *pb2 = (Base2*)&derived; 669static_assert(pb1 != pb2, ""); 670static_assert(pb1 == &bot1, ""); 671static_assert(pb2 == &bot2, ""); 672 673constexpr Base2 &fail = (Base2&)bot1; // expected-error {{constant expression}} expected-note {{cannot cast object of dynamic type 'const Class::Derived' to type 'Class::Base2'}} 674constexpr Base &fail2 = (Base&)*pb2; // expected-error {{constant expression}} expected-note {{cannot cast object of dynamic type 'const Class::Derived' to type 'Class::Base'}} 675constexpr Base2 &ok2 = (Base2&)bot2; 676static_assert(&ok2 == &derived, ""); 677 678constexpr Base2 *pfail = (Base2*)pb1; // expected-error {{constant expression}} expected-note {{cannot cast object of dynamic type 'const Class::Derived' to type 'Class::Base2'}} 679constexpr Base *pfail2 = (Base*)&bot2; // expected-error {{constant expression}} expected-note {{cannot cast object of dynamic type 'const Class::Derived' to type 'Class::Base'}} 680constexpr Base2 *pok2 = (Base2*)pb2; 681static_assert(pok2 == &derived, ""); 682static_assert(&ok2 == pok2, ""); 683static_assert((Base2*)(Derived*)(Base*)pb1 == pok2, ""); 684static_assert((Derived*)(Base*)pb1 == (Derived*)pok2, ""); 685 686constexpr Base *nullB = 42 - 6 * 7; 687static_assert((Bottom*)nullB == 0, ""); 688static_assert((Derived*)nullB == 0, ""); 689static_assert((void*)(Bottom*)nullB == (void*)(Derived*)nullB, ""); 690 691} 692 693namespace Temporaries { 694 695struct S { 696 constexpr S() {} 697 constexpr int f(); 698}; 699struct T : S { 700 constexpr T(int n) : S(), n(n) {} 701 int n; 702}; 703constexpr int S::f() { 704 // 'this' must be the postfix-expression in a class member access expression, 705 // so we can't just use 706 // return static_cast<T*>(this)->n; 707 return this->*(int(S::*))&T::n; 708} 709// The T temporary is implicitly cast to an S subobject, but we can recover the 710// T full-object via a base-to-derived cast, or a derived-to-base-casted member 711// pointer. 712static_assert(T(3).f() == 3, ""); 713 714constexpr int f(const S &s) { 715 return static_cast<const T&>(s).n; 716} 717constexpr int n = f(T(5)); 718static_assert(f(T(5)) == 5, ""); 719 720} 721 722namespace Union { 723 724union U { 725 int a; 726 int b; 727}; 728 729constexpr U u[4] = { { .a = 0 }, { .b = 1 }, { .a = 2 }, { .b = 3 } }; // expected-warning 4{{C99 feature}} 730static_assert(u[0].a == 0, ""); 731static_assert(u[0].b, ""); // expected-error {{constant expression}} expected-note {{read of member 'b' of union with active member 'a'}} 732static_assert(u[1].b == 1, ""); 733static_assert((&u[1].b)[1] == 2, ""); // expected-error {{constant expression}} expected-note {{read of dereferenced one-past-the-end pointer}} 734static_assert(*(&(u[1].b) + 1 + 1) == 3, ""); // expected-error {{constant expression}} expected-note {{cannot refer to element 2 of non-array object}} 735static_assert((&(u[1]) + 1 + 1)->b == 3, ""); 736 737constexpr U v = {}; 738static_assert(v.a == 0, ""); 739 740union Empty {}; 741constexpr Empty e = {}; 742 743// Make sure we handle trivial copy constructors for unions. 744constexpr U x = {42}; 745constexpr U y = x; 746static_assert(y.a == 42, ""); 747static_assert(y.b == 42, ""); // expected-error {{constant expression}} expected-note {{'b' of union with active member 'a'}} 748 749} 750 751namespace MemberPointer { 752 struct A { 753 constexpr A(int n) : n(n) {} 754 int n; 755 constexpr int f() { return n + 3; } 756 }; 757 constexpr A a(7); 758 static_assert(A(5).*&A::n == 5, ""); 759 static_assert((&a)->*&A::n == 7, ""); 760 static_assert((A(8).*&A::f)() == 11, ""); 761 static_assert(((&a)->*&A::f)() == 10, ""); 762 763 struct B : A { 764 constexpr B(int n, int m) : A(n), m(m) {} 765 int m; 766 constexpr int g() { return n + m + 1; } 767 }; 768 constexpr B b(9, 13); 769 static_assert(B(4, 11).*&A::n == 4, ""); 770 static_assert(B(4, 11).*&B::m == 11, ""); 771 static_assert(B(4, 11).*(int(A::*))&B::m == 11, ""); 772 static_assert((&b)->*&A::n == 9, ""); 773 static_assert((&b)->*&B::m == 13, ""); 774 static_assert((&b)->*(int(A::*))&B::m == 13, ""); 775 static_assert((B(4, 11).*&A::f)() == 7, ""); 776 static_assert((B(4, 11).*&B::g)() == 16, ""); 777 static_assert((B(4, 11).*(int(A::*)()const)&B::g)() == 16, ""); 778 static_assert(((&b)->*&A::f)() == 12, ""); 779 static_assert(((&b)->*&B::g)() == 23, ""); 780 static_assert(((&b)->*(int(A::*)()const)&B::g)() == 23, ""); 781 782 struct S { 783 constexpr S(int m, int n, int (S::*pf)() const, int S::*pn) : 784 m(m), n(n), pf(pf), pn(pn) {} 785 constexpr S() : m(), n(), pf(&S::f), pn(&S::n) {} 786 787 constexpr int f() { return this->*pn; } 788 virtual int g() const; 789 790 int m, n; 791 int (S::*pf)() const; 792 int S::*pn; 793 }; 794 795 constexpr int S::*pm = &S::m; 796 constexpr int S::*pn = &S::n; 797 constexpr int (S::*pf)() const = &S::f; 798 constexpr int (S::*pg)() const = &S::g; 799 800 constexpr S s(2, 5, &S::f, &S::m); 801 802 static_assert((s.*&S::f)() == 2, ""); 803 static_assert((s.*s.pf)() == 2, ""); 804 805 template<int n> struct T : T<n-1> {}; 806 template<> struct T<0> { int n; }; 807 template<> struct T<30> : T<29> { int m; }; 808 809 T<17> t17; 810 T<30> t30; 811 812 constexpr int (T<10>::*deepn) = &T<0>::n; 813 static_assert(&(t17.*deepn) == &t17.n, ""); 814 815 constexpr int (T<15>::*deepm) = (int(T<10>::*))&T<30>::m; 816 constexpr int *pbad = &(t17.*deepm); // expected-error {{constant expression}} 817 static_assert(&(t30.*deepm) == &t30.m, ""); 818 819 constexpr T<5> *p17_5 = &t17; 820 constexpr T<13> *p17_13 = (T<13>*)p17_5; 821 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>'}} 822 static_assert(&(p17_5->*(int(T<3>::*))deepn) == &t17.n, ""); 823 static_assert(&(p17_13->*deepn) == &t17.n, ""); 824 constexpr int *pbad2 = &(p17_13->*(int(T<9>::*))deepm); // expected-error {{constant expression}} 825 826 constexpr T<5> *p30_5 = &t30; 827 constexpr T<23> *p30_23 = (T<23>*)p30_5; 828 constexpr T<13> *p30_13 = p30_23; 829 static_assert(&(p30_5->*(int(T<3>::*))deepn) == &t30.n, ""); 830 static_assert(&(p30_13->*deepn) == &t30.n, ""); 831 static_assert(&(p30_23->*deepn) == &t30.n, ""); 832 static_assert(&(p30_5->*(int(T<2>::*))deepm) == &t30.m, ""); 833 static_assert(&(((T<17>*)p30_13)->*deepm) == &t30.m, ""); 834 static_assert(&(p30_23->*deepm) == &t30.m, ""); 835} 836 837namespace ArrayBaseDerived { 838 839 struct Base { 840 constexpr Base() {} 841 int n = 0; 842 }; 843 struct Derived : Base { 844 constexpr Derived() {} 845 constexpr const int *f() { return &n; } 846 }; 847 848 constexpr Derived a[10]; 849 constexpr Derived *pd3 = const_cast<Derived*>(&a[3]); 850 constexpr Base *pb3 = const_cast<Derived*>(&a[3]); 851 static_assert(pb3 == pd3, ""); 852 853 // pb3 does not point to an array element. 854 constexpr Base *pb4 = pb3 + 1; // ok, one-past-the-end pointer. 855 constexpr int pb4n = pb4->n; // expected-error {{constant expression}} expected-note {{cannot access field of pointer past the end}} 856 constexpr Base *err_pb5 = pb3 + 2; // expected-error {{constant expression}} expected-note {{cannot refer to element 2}} expected-note {{here}} 857 constexpr int err_pb5n = err_pb5->n; // expected-error {{constant expression}} expected-note {{initializer of 'err_pb5' is not a constant expression}} 858 constexpr Base *err_pb2 = pb3 - 1; // expected-error {{constant expression}} expected-note {{cannot refer to element -1}} expected-note {{here}} 859 constexpr int err_pb2n = err_pb2->n; // expected-error {{constant expression}} expected-note {{initializer of 'err_pb2'}} 860 constexpr Base *pb3a = pb4 - 1; 861 862 // pb4 does not point to a Derived. 863 constexpr Derived *err_pd4 = (Derived*)pb4; // expected-error {{constant expression}} expected-note {{cannot access derived class of pointer past the end}} 864 constexpr Derived *pd3a = (Derived*)pb3a; 865 constexpr int pd3n = pd3a->n; 866 867 // pd3a still points to the Derived array. 868 constexpr Derived *pd6 = pd3a + 3; 869 static_assert(pd6 == &a[6], ""); 870 constexpr Derived *pd9 = pd6 + 3; 871 constexpr Derived *pd10 = pd6 + 4; 872 constexpr int pd9n = pd9->n; // ok 873 constexpr int err_pd10n = pd10->n; // expected-error {{constant expression}} expected-note {{cannot access base class of pointer past the end}} 874 constexpr int pd0n = pd10[-10].n; 875 constexpr int err_pdminus1n = pd10[-11].n; // expected-error {{constant expression}} expected-note {{cannot refer to element -1 of}} 876 877 constexpr Base *pb9 = pd9; 878 constexpr const int *(Base::*pfb)() const = 879 static_cast<const int *(Base::*)() const>(&Derived::f); 880 static_assert((pb9->*pfb)() == &a[9].n, ""); 881} 882 883namespace Complex { 884 885class complex { 886 int re, im; 887public: 888 constexpr complex(int re = 0, int im = 0) : re(re), im(im) {} 889 constexpr complex(const complex &o) : re(o.re), im(o.im) {} 890 constexpr complex operator-() const { return complex(-re, -im); } 891 friend constexpr complex operator+(const complex &l, const complex &r) { 892 return complex(l.re + r.re, l.im + r.im); 893 } 894 friend constexpr complex operator-(const complex &l, const complex &r) { 895 return l + -r; 896 } 897 friend constexpr complex operator*(const complex &l, const complex &r) { 898 return complex(l.re * r.re - l.im * r.im, l.re * r.im + l.im * r.re); 899 } 900 friend constexpr bool operator==(const complex &l, const complex &r) { 901 return l.re == r.re && l.im == r.im; 902 } 903 constexpr bool operator!=(const complex &r) const { 904 return re != r.re || im != r.im; 905 } 906 constexpr int real() const { return re; } 907 constexpr int imag() const { return im; } 908}; 909 910constexpr complex i = complex(0, 1); 911constexpr complex k = (3 + 4*i) * (6 - 4*i); 912static_assert(complex(1,0).real() == 1, ""); 913static_assert(complex(1,0).imag() == 0, ""); 914static_assert(((complex)1).imag() == 0, ""); 915static_assert(k.real() == 34, ""); 916static_assert(k.imag() == 12, ""); 917static_assert(k - 34 == 12*i, ""); 918static_assert((complex)1 == complex(1), ""); 919static_assert((complex)1 != complex(0, 1), ""); 920static_assert(complex(1) == complex(1), ""); 921static_assert(complex(1) != complex(0, 1), ""); 922constexpr complex makeComplex(int re, int im) { return complex(re, im); } 923static_assert(makeComplex(1,0) == complex(1), ""); 924static_assert(makeComplex(1,0) != complex(0, 1), ""); 925 926class complex_wrap : public complex { 927public: 928 constexpr complex_wrap(int re, int im = 0) : complex(re, im) {} 929 constexpr complex_wrap(const complex_wrap &o) : complex(o) {} 930}; 931 932static_assert((complex_wrap)1 == complex(1), ""); 933static_assert((complex)1 != complex_wrap(0, 1), ""); 934static_assert(complex(1) == complex_wrap(1), ""); 935static_assert(complex_wrap(1) != complex(0, 1), ""); 936constexpr complex_wrap makeComplexWrap(int re, int im) { 937 return complex_wrap(re, im); 938} 939static_assert(makeComplexWrap(1,0) == complex(1), ""); 940static_assert(makeComplexWrap(1,0) != complex(0, 1), ""); 941 942} 943 944namespace PR11595 { 945 struct A { constexpr bool operator==(int x) { return true; } }; 946 struct B { B(); A& x; }; 947 static_assert(B().x == 3, ""); // expected-error {{constant expression}} expected-note {{non-literal type 'PR11595::B' cannot be used in a constant expression}} 948 949 constexpr bool f(int k) { 950 return B().x == k; // expected-note {{non-literal type 'PR11595::B' cannot be used in a constant expression}} 951 } 952 constexpr int n = f(1); // expected-error {{must be initialized by a constant expression}} expected-note {{in call to 'f(1)'}} 953} 954 955namespace ExprWithCleanups { 956 struct A { A(); ~A(); int get(); }; 957 constexpr int get(bool FromA) { return FromA ? A().get() : 1; } 958 constexpr int n = get(false); 959} 960 961namespace Volatile { 962 963volatile constexpr int n1 = 0; // expected-note {{here}} 964volatile const int n2 = 0; // expected-note {{here}} 965int n3 = 37; // expected-note {{declared here}} 966 967constexpr int m1 = n1; // expected-error {{constant expression}} expected-note {{read of volatile object 'n1'}} 968constexpr int m2 = n2; // expected-error {{constant expression}} expected-note {{read of volatile object 'n2'}} 969 970struct T { int n; }; 971const T t = { 42 }; // expected-note {{declared here}} 972 973constexpr int f(volatile int &&r) { 974 return r; // expected-note {{read of volatile temporary is not allowed in a constant expression}} 975} 976struct S { 977 int k : f(0); // expected-error {{constant expression}} expected-note {{temporary created here}} expected-note {{in call to 'f(0)'}} 978 int l : n3; // expected-error {{constant expression}} expected-note {{read of non-const variable}} 979 int m : t.n; // expected-error {{constant expression}} expected-note {{read of non-constexpr variable}} 980}; 981 982} 983 984namespace ExternConstexpr { 985 extern constexpr int n = 0; 986 extern constexpr int m; // expected-error {{constexpr variable declaration must be a definition}} 987 void f() { 988 extern constexpr int i; // expected-error {{constexpr variable declaration must be a definition}} 989 constexpr int j = 0; 990 constexpr int k; // expected-error {{default initialization of an object of const type}} 991 } 992} 993 994namespace ComplexConstexpr { 995 constexpr _Complex float test1 = {}; 996 constexpr _Complex float test2 = {1}; 997 constexpr _Complex double test3 = {1,2}; 998 constexpr _Complex int test4 = {4}; 999 constexpr _Complex int test5 = 4; 1000 constexpr _Complex int test6 = {5,6}; 1001} 1002