constant-expression-cxx11.cpp revision 974c5f93d0ce4f0699a6f0a4402f6b367da495e3
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?}} expected-error {{not an integral constant expression}} 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{{extension}} 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(u"constexpr!") == 1768383, ""); 361static_assert(MangleChars(U"constexpr!") == 1768383, ""); 362 363constexpr char c0 = "nought index"[0]; 364constexpr char c1 = "nice index"[10]; 365constexpr 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}} 366// FIXME: block the pointer arithmetic with undefined behavior here 367constexpr char c3 = "negative index"[-1]; // expected-error {{must be initialized by a constant expression}} expected-warning {{is before the beginning}} expected-note {{read of dereferenced one-past-the-end pointer}} 368constexpr char c4 = ((char*)(int*)"no reinterpret_casts allowed")[14]; // expected-error {{must be initialized by a constant expression}} 369 370constexpr const char *p = "test" + 2; 371static_assert(*p == 's', ""); 372 373constexpr const char *max_iter(const char *a, const char *b) { 374 return *a < *b ? b : a; 375} 376constexpr const char *max_element(const char *a, const char *b) { 377 return (a+1 >= b) ? a : max_iter(a, max_element(a+1, b)); 378} 379 380constexpr char str[] = "the quick brown fox jumped over the lazy dog"; 381constexpr const char *max = max_element(begin(str), end(str)); 382static_assert(*max == 'z', ""); 383static_assert(max == str + 38, ""); 384 385static_assert(strcmp_ce("hello world", "hello world") == 0, ""); 386static_assert(strcmp_ce("hello world", "hello clang") > 0, ""); 387static_assert(strcmp_ce("constexpr", "test") < 0, ""); 388static_assert(strcmp_ce("", " ") < 0, ""); 389 390struct S { 391 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}} 392}; 393 394struct T { 395 char c[6]; 396 constexpr T() : c{"foo"} {} 397}; 398constexpr T t; 399 400static_assert(t.c[0] == 'f', ""); 401static_assert(t.c[1] == 'o', ""); 402static_assert(t.c[2] == 'o', ""); 403static_assert(t.c[3] == 0, ""); 404static_assert(t.c[4] == 0, ""); 405static_assert(t.c[5] == 0, ""); 406static_assert(t.c[6] == 0, ""); // expected-error {{constant expression}} expected-note {{one-past-the-end}} 407 408} 409 410namespace Array { 411 412template<typename Iter> 413constexpr auto Sum(Iter begin, Iter end) -> decltype(+*begin) { 414 return begin == end ? 0 : *begin + Sum(begin+1, end); 415} 416 417constexpr int xs[] = { 1, 2, 3, 4, 5 }; 418constexpr int ys[] = { 5, 4, 3, 2, 1 }; 419constexpr int sum_xs = Sum(begin(xs), end(xs)); 420static_assert(sum_xs == 15, ""); 421 422constexpr int ZipFoldR(int (*F)(int x, int y, int c), int n, 423 const int *xs, const int *ys, int c) { 424 return n ? F( 425 *xs, // expected-note {{read of dereferenced one-past-the-end pointer}} 426 *ys, 427 ZipFoldR(F, n-1, xs+1, ys+1, c)) // \ 428 expected-note {{in call to 'ZipFoldR(&SubMul, 2, &xs[4], &ys[4], 1)'}} \ 429 expected-note {{in call to 'ZipFoldR(&SubMul, 1, &xs[5], &ys[5], 1)'}} 430 : c; 431} 432constexpr int MulAdd(int x, int y, int c) { return x * y + c; } 433constexpr int InnerProduct = ZipFoldR(MulAdd, 5, xs, ys, 0); 434static_assert(InnerProduct == 35, ""); 435 436constexpr int SubMul(int x, int y, int c) { return (x - y) * c; } 437constexpr int DiffProd = ZipFoldR(SubMul, 2, xs+3, ys+3, 1); 438static_assert(DiffProd == 8, ""); 439static_assert(ZipFoldR(SubMul, 3, xs+3, ys+3, 1), ""); // \ 440 expected-error {{constant expression}} \ 441 expected-note {{in call to 'ZipFoldR(&SubMul, 3, &xs[3], &ys[3], 1)'}} 442 443constexpr const int *p = xs + 3; 444constexpr int xs4 = p[1]; // ok 445constexpr int xs5 = p[2]; // expected-error {{constant expression}} expected-note {{read of dereferenced one-past-the-end pointer}} 446constexpr int xs0 = p[-3]; // ok 447// FIXME: check pointer arithmetic here 448constexpr int xs_1 = p[-4]; // expected-error {{constant expression}} expected-note {{read of dereferenced one-past-the-end pointer}} 449 450constexpr int zs[2][2][2][2] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 }; 451static_assert(zs[0][0][0][0] == 1, ""); 452static_assert(zs[1][1][1][1] == 16, ""); 453static_assert(zs[0][0][0][2] == 3, ""); // expected-error {{constant expression}} expected-note {{read of dereferenced one-past-the-end pointer}} 454static_assert((&zs[0][0][0][2])[-1] == 2, ""); 455static_assert(**(**(zs + 1) + 1) == 11, ""); 456static_assert(*(&(&(*(*&(&zs[2] - 1)[0] + 2 - 2))[2])[-1][-1] + 1) == 11, ""); 457 458constexpr int fail(const int &p) { 459 return (&p)[64]; // expected-note {{read of dereferenced one-past-the-end pointer}} 460} 461static_assert(fail(*(&(&(*(*&(&zs[2] - 1)[0] + 2 - 2))[2])[-1][-1] + 1)) == 11, ""); // \ 462expected-error {{static_assert expression is not an integral constant expression}} \ 463expected-note {{in call to 'fail(zs[1][0][1][0])'}} 464 465constexpr int arr[40] = { 1, 2, 3, [8] = 4 }; // expected-warning {{extension}} 466constexpr int SumNonzero(const int *p) { 467 return *p + (*p ? SumNonzero(p+1) : 0); 468} 469constexpr int CountZero(const int *p, const int *q) { 470 return p == q ? 0 : (*p == 0) + CountZero(p+1, q); 471} 472static_assert(SumNonzero(arr) == 6, ""); 473static_assert(CountZero(arr, arr + 40) == 36, ""); 474 475struct ArrayElem { 476 constexpr ArrayElem() : n(0) {} 477 int n; 478 constexpr int f() { return n; } 479}; 480struct ArrayRVal { 481 constexpr ArrayRVal() {} 482 ArrayElem elems[10]; 483}; 484static_assert(ArrayRVal().elems[3].f() == 0, ""); 485 486} 487 488namespace DependentValues { 489 490struct I { int n; typedef I V[10]; }; 491I::V x, y; 492template<bool B> struct S { 493 int k; 494 void f() { 495 I::V &cells = B ? x : y; 496 I &i = cells[k]; 497 switch (i.n) {} 498 } 499}; 500 501} 502 503namespace Class { 504 505struct A { constexpr A(int a, int b) : k(a + b) {} int k; }; 506constexpr int fn(const A &a) { return a.k; } 507static_assert(fn(A(4,5)) == 9, ""); 508 509struct B { int n; int m; } constexpr b = { 0, b.n }; // expected-warning {{uninitialized}} 510struct C { 511 constexpr C(C *this_) : m(42), n(this_->m) {} // ok 512 int m, n; 513}; 514struct D { 515 C c; 516 constexpr D() : c(&c) {} 517}; 518static_assert(D().c.n == 42, ""); 519 520struct E { // expected-note {{here}} 521 constexpr E() : p(&p) {} // expected-note {{pointer to temporary cannot be used to initialize a member in a constant expression}} 522 void *p; 523}; 524constexpr const E &e1 = E(); // expected-error {{constant expression}} expected-note {{in call to 'E()'}} expected-note {{temporary created here}} 525// This is a constant expression if we elide the copy constructor call, and 526// is not a constant expression if we don't! But we do, so it is. 527// FIXME: The move constructor is not currently implicitly defined as constexpr. 528constexpr E e2 = E(); // unexpected-error {{constant expression}} unexpected-note {{here}} unexpected-note {{non-constexpr constructor 'E' cannot be used in a constant expression}} 529static_assert(e2.p == &e2.p, ""); // unexpected-error {{constant expression}} unexpected-note {{initializer of 'e2' is not a constant expression}} 530constexpr E e3; 531static_assert(e3.p == &e3.p, ""); 532 533extern const class F f; 534struct F { 535 constexpr F() : p(&f.p) {} 536 const void *p; 537}; 538constexpr F f; 539 540struct G { 541 struct T { 542 constexpr T(T *p) : u1(), u2(p) {} 543 union U1 { 544 constexpr U1() {} 545 int a, b = 42; 546 } u1; 547 union U2 { 548 constexpr U2(T *p) : c(p->u1.b) {} 549 int c, d; 550 } u2; 551 } t; 552 constexpr G() : t(&t) {} 553} constexpr g; 554 555static_assert(g.t.u1.a == 42, ""); // expected-error {{constant expression}} expected-note {{read of member 'a' of union with active member 'b'}} 556static_assert(g.t.u1.b == 42, ""); 557static_assert(g.t.u2.c == 42, ""); 558static_assert(g.t.u2.d == 42, ""); // expected-error {{constant expression}} expected-note {{read of member 'd' of union with active member 'c'}} 559 560struct S { 561 int a, b; 562 const S *p; 563 double d; 564 const char *q; 565 566 constexpr S(int n, const S *p) : a(5), b(n), p(p), d(n), q("hello") {} 567}; 568 569S global(43, &global); 570 571static_assert(S(15, &global).b == 15, ""); 572 573constexpr bool CheckS(const S &s) { 574 return s.a == 5 && s.b == 27 && s.p == &global && s.d == 27. && s.q[3] == 'l'; 575} 576static_assert(CheckS(S(27, &global)), ""); 577 578struct Arr { 579 char arr[3]; 580 constexpr Arr() : arr{'x', 'y', 'z'} {} 581}; 582constexpr int hash(Arr &&a) { 583 return a.arr[0] + a.arr[1] * 0x100 + a.arr[2] * 0x10000; 584} 585constexpr int k = hash(Arr()); 586static_assert(k == 0x007a7978, ""); 587 588 589struct AggregateInit { 590 const char &c; 591 int n; 592 double d; 593 int arr[5]; 594 void *p; 595}; 596 597constexpr AggregateInit agg1 = { "hello"[0] }; 598 599static_assert(strcmp_ce(&agg1.c, "hello") == 0, ""); 600static_assert(agg1.n == 0, ""); 601static_assert(agg1.d == 0.0, ""); 602// FIXME: check pointer arithmetic here. 603static_assert(agg1.arr[-1] == 0, ""); // expected-error {{constant expression}} expected-note {{read of dereferenced one-past-the-end}} 604static_assert(agg1.arr[0] == 0, ""); 605static_assert(agg1.arr[4] == 0, ""); 606static_assert(agg1.arr[5] == 0, ""); // expected-error {{constant expression}} expected-note {{read of dereferenced one-past-the-end}} 607static_assert(agg1.p == nullptr, ""); 608 609namespace SimpleDerivedClass { 610 611struct B { 612 constexpr B(int n) : a(n) {} 613 int a; 614}; 615struct D : B { 616 constexpr D(int n) : B(n) {} 617}; 618constexpr D d(3); 619static_assert(d.a == 3, ""); 620 621} 622 623struct Bottom { constexpr Bottom() {} }; 624struct Base : Bottom { 625 constexpr Base(int a = 42, const char *b = "test") : a(a), b(b) {} 626 int a; 627 const char *b; 628}; 629struct Base2 : Bottom { 630 constexpr Base2(const int &r) : r(r) {} 631 int q = 123; 632 const int &r; 633}; 634struct Derived : Base, Base2 { 635 constexpr Derived() : Base(76), Base2(a) {} 636 int c = r + b[1]; 637}; 638 639constexpr bool operator==(const Base &a, const Base &b) { 640 return a.a == b.a && strcmp_ce(a.b, b.b) == 0; 641} 642 643constexpr Base base; 644constexpr Base base2(76); 645constexpr Derived derived; 646static_assert(derived.a == 76, ""); 647static_assert(derived.b[2] == 's', ""); 648static_assert(derived.c == 76 + 'e', ""); 649static_assert(derived.q == 123, ""); 650static_assert(derived.r == 76, ""); 651static_assert(&derived.r == &derived.a, ""); 652 653static_assert(!(derived == base), ""); 654static_assert(derived == base2, ""); 655 656constexpr Bottom &bot1 = (Base&)derived; 657constexpr Bottom &bot2 = (Base2&)derived; 658static_assert(&bot1 != &bot2, ""); 659 660constexpr Bottom *pb1 = (Base*)&derived; 661constexpr Bottom *pb2 = (Base2*)&derived; 662static_assert(pb1 != pb2, ""); 663static_assert(pb1 == &bot1, ""); 664static_assert(pb2 == &bot2, ""); 665 666constexpr Base2 &fail = (Base2&)bot1; // expected-error {{constant expression}} 667constexpr Base &fail2 = (Base&)*pb2; // expected-error {{constant expression}} 668constexpr Base2 &ok2 = (Base2&)bot2; 669static_assert(&ok2 == &derived, ""); 670 671constexpr Base2 *pfail = (Base2*)pb1; // expected-error {{constant expression}} 672constexpr Base *pfail2 = (Base*)&bot2; // expected-error {{constant expression}} 673constexpr Base2 *pok2 = (Base2*)pb2; 674static_assert(pok2 == &derived, ""); 675static_assert(&ok2 == pok2, ""); 676static_assert((Base2*)(Derived*)(Base*)pb1 == pok2, ""); 677static_assert((Derived*)(Base*)pb1 == (Derived*)pok2, ""); 678 679constexpr Base *nullB = 42 - 6 * 7; 680static_assert((Bottom*)nullB == 0, ""); 681static_assert((Derived*)nullB == 0, ""); 682static_assert((void*)(Bottom*)nullB == (void*)(Derived*)nullB, ""); 683 684} 685 686namespace Temporaries { 687 688struct S { 689 constexpr S() {} 690 constexpr int f(); 691}; 692struct T : S { 693 constexpr T(int n) : S(), n(n) {} 694 int n; 695}; 696constexpr int S::f() { 697 // 'this' must be the postfix-expression in a class member access expression, 698 // so we can't just use 699 // return static_cast<T*>(this)->n; 700 return this->*(int(S::*))&T::n; 701} 702// The T temporary is implicitly cast to an S subobject, but we can recover the 703// T full-object via a base-to-derived cast, or a derived-to-base-casted member 704// pointer. 705static_assert(T(3).f() == 3, ""); 706 707constexpr int f(const S &s) { 708 return static_cast<const T&>(s).n; 709} 710constexpr int n = f(T(5)); 711static_assert(f(T(5)) == 5, ""); 712 713} 714 715namespace Union { 716 717union U { 718 int a; 719 int b; 720}; 721 722constexpr U u[4] = { { .a = 0 }, { .b = 1 }, { .a = 2 }, { .b = 3 } }; // expected-warning 4{{extension}} 723static_assert(u[0].a == 0, ""); 724static_assert(u[0].b, ""); // expected-error {{constant expression}} expected-note {{read of member 'b' of union with active member 'a'}} 725static_assert(u[1].b == 1, ""); 726static_assert((&u[1].b)[1] == 2, ""); // expected-error {{constant expression}} expected-note {{read of dereferenced one-past-the-end pointer}} 727static_assert(*(&(u[1].b) + 1 + 1) == 3, ""); // expected-error {{constant expression}} expected-note {{subexpression}} 728static_assert((&(u[1]) + 1 + 1)->b == 3, ""); 729 730} 731 732namespace MemberPointer { 733 struct A { 734 constexpr A(int n) : n(n) {} 735 int n; 736 constexpr int f() { return n + 3; } 737 }; 738 constexpr A a(7); 739 static_assert(A(5).*&A::n == 5, ""); 740 static_assert((&a)->*&A::n == 7, ""); 741 static_assert((A(8).*&A::f)() == 11, ""); 742 static_assert(((&a)->*&A::f)() == 10, ""); 743 744 struct B : A { 745 constexpr B(int n, int m) : A(n), m(m) {} 746 int m; 747 constexpr int g() { return n + m + 1; } 748 }; 749 constexpr B b(9, 13); 750 static_assert(B(4, 11).*&A::n == 4, ""); 751 static_assert(B(4, 11).*&B::m == 11, ""); 752 static_assert(B(4, 11).*(int(A::*))&B::m == 11, ""); 753 static_assert((&b)->*&A::n == 9, ""); 754 static_assert((&b)->*&B::m == 13, ""); 755 static_assert((&b)->*(int(A::*))&B::m == 13, ""); 756 static_assert((B(4, 11).*&A::f)() == 7, ""); 757 static_assert((B(4, 11).*&B::g)() == 16, ""); 758 static_assert((B(4, 11).*(int(A::*)()const)&B::g)() == 16, ""); 759 static_assert(((&b)->*&A::f)() == 12, ""); 760 static_assert(((&b)->*&B::g)() == 23, ""); 761 static_assert(((&b)->*(int(A::*)()const)&B::g)() == 23, ""); 762 763 struct S { 764 constexpr S(int m, int n, int (S::*pf)() const, int S::*pn) : 765 m(m), n(n), pf(pf), pn(pn) {} 766 constexpr S() : m(), n(), pf(&S::f), pn(&S::n) {} 767 768 constexpr int f() { return this->*pn; } 769 virtual int g() const; 770 771 int m, n; 772 int (S::*pf)() const; 773 int S::*pn; 774 }; 775 776 constexpr int S::*pm = &S::m; 777 constexpr int S::*pn = &S::n; 778 constexpr int (S::*pf)() const = &S::f; 779 constexpr int (S::*pg)() const = &S::g; 780 781 constexpr S s(2, 5, &S::f, &S::m); 782 783 static_assert((s.*&S::f)() == 2, ""); 784 static_assert((s.*s.pf)() == 2, ""); 785 786 template<int n> struct T : T<n-1> {}; 787 template<> struct T<0> { int n; }; 788 template<> struct T<30> : T<29> { int m; }; 789 790 T<17> t17; 791 T<30> t30; 792 793 constexpr int (T<10>::*deepn) = &T<0>::n; 794 static_assert(&(t17.*deepn) == &t17.n, ""); 795 796 constexpr int (T<15>::*deepm) = (int(T<10>::*))&T<30>::m; 797 constexpr int *pbad = &(t17.*deepm); // expected-error {{constant expression}} 798 static_assert(&(t30.*deepm) == &t30.m, ""); 799 800 constexpr T<5> *p17_5 = &t17; 801 constexpr T<13> *p17_13 = (T<13>*)p17_5; 802 constexpr T<23> *p17_23 = (T<23>*)p17_13; // expected-error {{constant expression}} 803 static_assert(&(p17_5->*(int(T<3>::*))deepn) == &t17.n, ""); 804 static_assert(&(p17_13->*deepn) == &t17.n, ""); 805 constexpr int *pbad2 = &(p17_13->*(int(T<9>::*))deepm); // expected-error {{constant expression}} 806 807 constexpr T<5> *p30_5 = &t30; 808 constexpr T<23> *p30_23 = (T<23>*)p30_5; 809 constexpr T<13> *p30_13 = p30_23; 810 static_assert(&(p30_5->*(int(T<3>::*))deepn) == &t30.n, ""); 811 static_assert(&(p30_13->*deepn) == &t30.n, ""); 812 static_assert(&(p30_23->*deepn) == &t30.n, ""); 813 static_assert(&(p30_5->*(int(T<2>::*))deepm) == &t30.m, ""); 814 static_assert(&(((T<17>*)p30_13)->*deepm) == &t30.m, ""); 815 static_assert(&(p30_23->*deepm) == &t30.m, ""); 816} 817 818namespace ArrayBaseDerived { 819 820 struct Base { 821 constexpr Base() {} 822 int n = 0; 823 }; 824 struct Derived : Base { 825 constexpr Derived() {} 826 constexpr const int *f() { return &n; } 827 }; 828 829 constexpr Derived a[10]; 830 constexpr Derived *pd3 = const_cast<Derived*>(&a[3]); 831 constexpr Base *pb3 = const_cast<Derived*>(&a[3]); 832 static_assert(pb3 == pd3, ""); 833 834 // pb3 does not point to an array element. 835 constexpr Base *pb4 = pb3 + 1; // ok, one-past-the-end pointer. 836 constexpr int pb4n = pb4->n; // expected-error {{constant expression}} 837 constexpr Base *err_pb5 = pb3 + 2; // FIXME: reject this. 838 constexpr int err_pb5n = err_pb5->n; // expected-error {{constant expression}} 839 constexpr Base *err_pb2 = pb3 - 1; // FIXME: reject this. 840 constexpr int err_pb2n = err_pb2->n; // expected-error {{constant expression}} 841 constexpr Base *pb3a = pb4 - 1; 842 843 // pb4 does not point to a Derived. 844 constexpr Derived *err_pd4 = (Derived*)pb4; // expected-error {{constant expression}} 845 constexpr Derived *pd3a = (Derived*)pb3a; 846 constexpr int pd3n = pd3a->n; 847 848 // pd3a still points to the Derived array. 849 constexpr Derived *pd6 = pd3a + 3; 850 static_assert(pd6 == &a[6], ""); 851 constexpr Derived *pd9 = pd6 + 3; 852 constexpr Derived *pd10 = pd6 + 4; 853 constexpr int pd9n = pd9->n; // ok 854 constexpr int err_pd10n = pd10->n; // expected-error {{constant expression}} expected-note {{read of dereferenced one-past-the-end pointer}} 855 constexpr int pd0n = pd10[-10].n; 856 // FIXME: check pointer arithmetic here. 857 constexpr int err_pdminus1n = pd10[-11].n; // expected-error {{constant expression}} expected-note {{read of dereferenced one-past-the-end pointer}} 858 859 constexpr Base *pb9 = pd9; 860 constexpr const int *(Base::*pfb)() const = 861 static_cast<const int *(Base::*)() const>(&Derived::f); 862 static_assert((pb9->*pfb)() == &a[9].n, ""); 863} 864 865namespace Complex { 866 867class complex { 868 int re, im; 869public: 870 constexpr complex(int re = 0, int im = 0) : re(re), im(im) {} 871 constexpr complex(const complex &o) : re(o.re), im(o.im) {} 872 constexpr complex operator-() const { return complex(-re, -im); } 873 friend constexpr complex operator+(const complex &l, const complex &r) { 874 return complex(l.re + r.re, l.im + r.im); 875 } 876 friend constexpr complex operator-(const complex &l, const complex &r) { 877 return l + -r; 878 } 879 friend constexpr complex operator*(const complex &l, const complex &r) { 880 return complex(l.re * r.re - l.im * r.im, l.re * r.im + l.im * r.re); 881 } 882 friend constexpr bool operator==(const complex &l, const complex &r) { 883 return l.re == r.re && l.im == r.im; 884 } 885 constexpr bool operator!=(const complex &r) const { 886 return re != r.re || im != r.im; 887 } 888 constexpr int real() const { return re; } 889 constexpr int imag() const { return im; } 890}; 891 892constexpr complex i = complex(0, 1); 893constexpr complex k = (3 + 4*i) * (6 - 4*i); 894static_assert(complex(1,0).real() == 1, ""); 895static_assert(complex(1,0).imag() == 0, ""); 896static_assert(((complex)1).imag() == 0, ""); 897static_assert(k.real() == 34, ""); 898static_assert(k.imag() == 12, ""); 899static_assert(k - 34 == 12*i, ""); 900static_assert((complex)1 == complex(1), ""); 901static_assert((complex)1 != complex(0, 1), ""); 902static_assert(complex(1) == complex(1), ""); 903static_assert(complex(1) != complex(0, 1), ""); 904constexpr complex makeComplex(int re, int im) { return complex(re, im); } 905static_assert(makeComplex(1,0) == complex(1), ""); 906static_assert(makeComplex(1,0) != complex(0, 1), ""); 907 908class complex_wrap : public complex { 909public: 910 constexpr complex_wrap(int re, int im = 0) : complex(re, im) {} 911 constexpr complex_wrap(const complex_wrap &o) : complex(o) {} 912}; 913 914static_assert((complex_wrap)1 == complex(1), ""); 915static_assert((complex)1 != complex_wrap(0, 1), ""); 916static_assert(complex(1) == complex_wrap(1), ""); 917static_assert(complex_wrap(1) != complex(0, 1), ""); 918constexpr complex_wrap makeComplexWrap(int re, int im) { 919 return complex_wrap(re, im); 920} 921static_assert(makeComplexWrap(1,0) == complex(1), ""); 922static_assert(makeComplexWrap(1,0) != complex(0, 1), ""); 923 924} 925 926namespace PR11595 { 927 struct A { constexpr bool operator==(int x) { return true; } }; 928 struct B { B(); A& x; }; 929 static_assert(B().x == 3, ""); // expected-error {{constant expression}} expected-note {{non-literal type 'PR11595::B' cannot be used in a constant expression}} 930 931 constexpr bool f(int k) { 932 return B().x == k; // expected-note {{non-literal type 'PR11595::B' cannot be used in a constant expression}} 933 } 934 constexpr int n = f(1); // expected-error {{must be initialized by a constant expression}} expected-note {{in call to 'f(1)'}} 935} 936 937namespace ExprWithCleanups { 938 struct A { A(); ~A(); int get(); }; 939 constexpr int get(bool FromA) { return FromA ? A().get() : 1; } 940 constexpr int n = get(false); 941} 942 943namespace Volatile { 944 945volatile constexpr int n1 = 0; // expected-note {{here}} 946volatile const int n2 = 0; // expected-note {{here}} 947int n3 = 37; // expected-note {{declared here}} 948 949constexpr int m1 = n1; // expected-error {{constant expression}} expected-note {{read of volatile object 'n1'}} 950constexpr int m2 = n2; // expected-error {{constant expression}} expected-note {{read of volatile object 'n2'}} 951 952struct T { int n; }; 953const T t = { 42 }; // expected-note {{declared here}} 954 955constexpr int f(volatile int &&r) { 956 return r; // expected-note {{read of volatile temporary is not allowed in a constant expression}} 957} 958struct S { 959 int k : f(0); // expected-error {{constant expression}} expected-note {{temporary created here}} expected-note {{in call to 'f(0)'}} 960 int l : n3; // expected-error {{constant expression}} expected-note {{read of non-const variable}} 961 int m : t.n; // expected-error {{constant expression}} expected-note {{read of non-constexpr variable}} 962}; 963 964} 965