p2-0x.cpp revision b4e85ed51905fc94378d7b4ff62b06e0d08042b7
1d26147adbbdca85f07dff432025afee0c8614387caryclark@google.com// RUN: %clang_cc1 -fsyntax-only -std=c++11 -pedantic -verify -fcxx-exceptions %s -fconstexpr-depth 128 2d26147adbbdca85f07dff432025afee0c8614387caryclark@google.com 3d26147adbbdca85f07dff432025afee0c8614387caryclark@google.com// A conditional-expression is a core constant expression unless it involves one 4d26147adbbdca85f07dff432025afee0c8614387caryclark@google.com// of the following as a potentially evaluated subexpression [...]: 5d26147adbbdca85f07dff432025afee0c8614387caryclark@google.com 6d26147adbbdca85f07dff432025afee0c8614387caryclark@google.com// - this (5.1.1 [expr.prim.general]) [Note: when evaluating a constant 7d26147adbbdca85f07dff432025afee0c8614387caryclark@google.com// expression, function invocation substitution (7.1.5 [dcl.constexpr]) 8d26147adbbdca85f07dff432025afee0c8614387caryclark@google.com// replaces each occurrence of this in a constexpr member function with a 9d26147adbbdca85f07dff432025afee0c8614387caryclark@google.com// pointer to the class object. -end note]; 10d26147adbbdca85f07dff432025afee0c8614387caryclark@google.comstruct This { 11d26147adbbdca85f07dff432025afee0c8614387caryclark@google.com int this1 : this1; // expected-error {{undeclared}} 12d26147adbbdca85f07dff432025afee0c8614387caryclark@google.com int this2 : this->this1; // expected-error {{invalid}} 13d26147adbbdca85f07dff432025afee0c8614387caryclark@google.com void this3() { 14d26147adbbdca85f07dff432025afee0c8614387caryclark@google.com int n1[this->this1]; // expected-warning {{variable length array}} 15d26147adbbdca85f07dff432025afee0c8614387caryclark@google.com int n2[this1]; // expected-warning {{variable length array}} 16d26147adbbdca85f07dff432025afee0c8614387caryclark@google.com (void)n1, (void)n2; 17d26147adbbdca85f07dff432025afee0c8614387caryclark@google.com } 18d26147adbbdca85f07dff432025afee0c8614387caryclark@google.com}; 19d26147adbbdca85f07dff432025afee0c8614387caryclark@google.com 20d26147adbbdca85f07dff432025afee0c8614387caryclark@google.com// - an invocation of a function other than a constexpr constructor for a 21d26147adbbdca85f07dff432025afee0c8614387caryclark@google.com// literal class or a constexpr function [ Note: Overload resolution (13.3) 22a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com// is applied as usual - end note ]; 23a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.comstruct NonConstexpr1 { 24a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com static int f() { return 1; } // expected-note {{here}} 25a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com int n : f(); // expected-error {{constant expression}} expected-note {{non-constexpr function 'f' cannot be used in a constant expression}} 26a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com}; 27a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.comstruct NonConstexpr2 { 28a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com constexpr NonConstexpr2(); // expected-note {{here}} 29a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com int n; 30a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com}; 31a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.comstruct NonConstexpr3 { 32a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com NonConstexpr3(); 33a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com int m : NonConstexpr2().n; // expected-error {{constant expression}} expected-note {{undefined constructor 'NonConstexpr2'}} 34a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com}; 3572ae6bd24eb72be13d5745129c16058e4d54e2f4scroggo@google.comstruct NonConstexpr4 { 36a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com NonConstexpr4(); // expected-note {{declared here}} 37a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com int n; 38a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com}; 39a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.comstruct NonConstexpr5 { 40a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com int n : NonConstexpr4().n; // expected-error {{constant expression}} expected-note {{non-constexpr constructor 'NonConstexpr4' cannot be used in a constant expression}} 41a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com}; 42a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com 43a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com// - an invocation of an undefined constexpr function or an undefined 44a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com// constexpr constructor; 45088719ecdc89b399dd3a3a65f8cced262e50d951robertphillips@google.comstruct UndefinedConstexpr { 46a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com constexpr UndefinedConstexpr(); 47a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com static constexpr int undefinedConstexpr1(); // expected-note {{here}} 48a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com int undefinedConstexpr2 : undefinedConstexpr1(); // expected-error {{constant expression}} expected-note {{undefined function 'undefinedConstexpr1' cannot be used in a constant expression}} 49d26147adbbdca85f07dff432025afee0c8614387caryclark@google.com}; 50a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com 51a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com// - an invocation of a constexpr function with arguments that, when substituted 52a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com// by function invocation substitution (7.1.5), do not produce a constant 53a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com// expression; 54a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.comnamespace NonConstExprReturn { 55a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com static constexpr const int &id_ref(const int &n) { 56a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com return n; // expected-note {{reference to temporary cannot be returned from a constexpr function}} 57a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com } 58a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com struct NonConstExprFunction { 59a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com int n : id_ref( // expected-error {{constant expression}} expected-note {{in call to 'id_ref(16)'}} 60a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com 16 // expected-note {{temporary created here}} 61a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com ); 6272ae6bd24eb72be13d5745129c16058e4d54e2f4scroggo@google.com }; 63a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com constexpr const int *address_of(const int &a) { 64a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com return &a; // expected-note {{pointer to 'n' cannot be returned from a constexpr function}} 65a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com } 66a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com constexpr const int *return_param(int n) { // expected-note {{declared here}} 67a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com return address_of(n); // expected-note {{in call to 'address_of(n)'}} 68a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com } 69a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com struct S { 70a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com int n : *return_param(0); // expected-error {{constant expression}} expected-note {{in call to 'return_param(0)'}} 71a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com }; 72941ee9303b62163ae08bbdcd7ad514e1a6389bdarobertphillips@google.com} 73a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com 74a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com// - an invocation of a constexpr constructor with arguments that, when 75a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com// substituted by function invocation substitution (7.1.5), do not produce all 76a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com// constant expressions for the constructor calls and full-expressions in the 77a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com// mem-initializers (including conversions); 78a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.comnamespace NonConstExprCtor { 79a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com struct T { 80a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com constexpr T(const int &r) : 81a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com r(r) { // expected-note 2{{reference to temporary cannot be used to initialize a member in a constant expression}} 825370cd969d8f3957e4306068e6195ac1bca3d6cddjsollen@google.com } 835370cd969d8f3957e4306068e6195ac1bca3d6cddjsollen@google.com const int &r; 845370cd969d8f3957e4306068e6195ac1bca3d6cddjsollen@google.com }; 855370cd969d8f3957e4306068e6195ac1bca3d6cddjsollen@google.com constexpr int n = 0; 86a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com constexpr T t1(n); // ok 87a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com constexpr T t2(0); // expected-error {{must be initialized by a constant expression}} expected-note {{temporary created here}} expected-note {{in call to 'T(0)'}} 88a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com 89a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com struct S { 90a2ca41e3afdd8fad5e0e924dec029f33918e0a67djsollen@google.com int n : T(4).r; // expected-error {{constant expression}} expected-note {{temporary created here}} expected-note {{in call to 'T(4)'}} 91d26147adbbdca85f07dff432025afee0c8614387caryclark@google.com }; 92d26147adbbdca85f07dff432025afee0c8614387caryclark@google.com} 93d26147adbbdca85f07dff432025afee0c8614387caryclark@google.com 94// - an invocation of a constexpr function or a constexpr constructor that would 95// exceed the implementation-defined recursion limits (see Annex B); 96namespace RecursionLimits { 97 constexpr int RecurseForever(int n) { 98 return n + RecurseForever(n+1); // expected-note {{constexpr evaluation exceeded maximum depth of 128 calls}} expected-note 9{{in call to 'RecurseForever(}} expected-note {{skipping 118 calls}} 99 } 100 struct AlsoRecurseForever { 101 constexpr AlsoRecurseForever(int n) : 102 n(AlsoRecurseForever(n+1).n) // expected-note {{constexpr evaluation exceeded maximum depth of 128 calls}} expected-note 9{{in call to 'AlsoRecurseForever(}} expected-note {{skipping 118 calls}} 103 {} 104 int n; 105 }; 106 struct S { 107 int k : RecurseForever(0); // expected-error {{constant expression}} expected-note {{in call to}} 108 int l : AlsoRecurseForever(0).n; // expected-error {{constant expression}} expected-note {{in call to}} 109 }; 110} 111 112// FIXME: 113// - an operation that would have undefined behavior [Note: including, for 114// example, signed integer overflow (Clause 5 [expr]), certain pointer 115// arithmetic (5.7 [expr.add]), division by zero (5.6 [expr.mul]), or certain 116// shift operations (5.8 [expr.shift]) -end note]; 117namespace UndefinedBehavior { 118 void f(int n) { 119 switch (n) { 120 case (int)4.4e9: // expected-error {{constant expression}} expected-note {{value 4.4E+9 is outside the range of representable values of type 'int'}} 121 case (int)(unsigned)(long long)4.4e9: // ok 122 case (float)1e300: // expected-error {{constant expression}} expected-note {{value 1.0E+300 is outside the range of representable values of type 'float'}} 123 case (int)((float)1e37 / 1e30): // ok 124 case (int)(__fp16)65536: // expected-error {{constant expression}} expected-note {{value 65536 is outside the range of representable values of type 'half'}} 125 break; 126 } 127 } 128 129 struct S { 130 int m; 131 }; 132 constexpr S s = { 5 }; // expected-note {{declared here}} 133 constexpr const int *p = &s.m + 1; 134 constexpr const int &f(const int *q) { 135 return q[0]; // expected-note {{dereferenced pointer past the end of subobject of 's' is not a constant expression}} 136 } 137 struct T { 138 int n : f(p); // expected-error {{not an integer constant expression}} expected-note {{in call to 'f(&s.m + 1)'}} 139 }; 140 141 namespace Ptr { 142 struct A {}; 143 struct B : A { int n; }; 144 B a[3][3]; 145 constexpr B *p = a[0] + 4; // expected-error {{constant expression}} expected-note {{element 4 of array of 3 elements}} 146 B b = {}; 147 constexpr A *pa = &b + 1; // expected-error {{constant expression}} expected-note {{base class of pointer past the end}} 148 constexpr B *pb = (B*)((A*)&b + 1); // expected-error {{constant expression}} expected-note {{derived class of pointer past the end}} 149 constexpr const int *pn = &(&b + 1)->n; // expected-error {{constant expression}} expected-note {{field of pointer past the end}} 150 constexpr B *parr = &a[3][0]; // expected-error {{constant expression}} expected-note {{array element of pointer past the end}} 151 152 constexpr A *na = nullptr; 153 constexpr B *nb = nullptr; 154 constexpr A &ra = *nb; // expected-error {{constant expression}} expected-note {{cannot access base class of null pointer}} 155 constexpr B &rb = (B&)*na; // expected-error {{constant expression}} expected-note {{cannot access derived class of null pointer}} 156 static_assert((A*)nb == 0, ""); 157 static_assert((B*)na == 0, ""); 158 constexpr const int &nf = nb->n; // expected-error {{constant expression}} expected-note {{cannot access field of null pointer}} 159 constexpr const int &np = (*(int(*)[4])nullptr)[2]; // expected-error {{constant expression}} expected-note {{cannot access array element of null pointer}} 160 } 161} 162 163// - a lambda-expression (5.1.2); 164struct Lambda { 165 // FIXME: clang crashes when trying to parse this! Revisit this check once 166 // lambdas are fully implemented. 167 //int n : []{ return 1; }(); 168}; 169 170// - an lvalue-to-rvalue conversion (4.1) unless it is applied to 171namespace LValueToRValue { 172 // - a non-volatile glvalue of integral or enumeration type that refers to a 173 // non-volatile const object with a preceding initialization, initialized 174 // with a constant expression [Note: a string literal (2.14.5 [lex.string]) 175 // corresponds to an array of such objects. -end note], or 176 volatile const int vi = 1; // expected-note {{here}} 177 const int ci = 1; 178 volatile const int &vrci = ci; 179 static_assert(vi, ""); // expected-error {{constant expression}} expected-note {{read of volatile-qualified type 'const volatile int'}} 180 static_assert(const_cast<int&>(vi), ""); // expected-error {{constant expression}} expected-note {{read of volatile object 'vi'}} 181 static_assert(vrci, ""); // expected-error {{constant expression}} expected-note {{read of volatile-qualified type}} 182 183 // - a non-volatile glvalue of literal type that refers to a non-volatile 184 // object defined with constexpr, or that refers to a sub-object of such an 185 // object, or 186 struct S { 187 constexpr S(int=0) : i(1), v(1) {} 188 constexpr S(const S &s) : i(2), v(2) {} 189 int i; 190 volatile int v; 191 }; 192 constexpr S s; 193 constexpr volatile S vs; // expected-note {{here}} 194 constexpr const volatile S &vrs = s; 195 static_assert(s.i, ""); 196 static_assert(s.v, ""); // expected-error {{constant expression}} expected-note {{read of volatile-qualified type}} 197 static_assert(vs.i, ""); // expected-error {{constant expression}} expected-note {{read of volatile-qualified type}} 198 static_assert(const_cast<int&>(vs.i), ""); // expected-error {{constant expression}} expected-note {{read of volatile object 'vs'}} 199 static_assert(vrs.i, ""); // expected-error {{constant expression}} expected-note {{read of volatile-qualified type}} 200 201 // - a non-volatile glvalue of literal type that refers to a non-volatile 202 // temporary object whose lifetime has not ended, initialized with a 203 // constant expression; 204 constexpr volatile S f() { return S(); } 205 static_assert(f().i, ""); // ok! there's no lvalue-to-rvalue conversion here! 206 static_assert(((volatile const S&&)(S)0).i, ""); // expected-error {{constant expression}} expected-note {{subexpression}} 207} 208 209// FIXME: 210// 211// DR1312: The proposed wording for this defect has issues, so we ignore this 212// bullet and instead prohibit casts from pointers to cv void (see core-20842 213// and core-20845). 214// 215// - an lvalue-to-rvalue conversion (4.1 [conv.lval]) that is applied to a 216// glvalue of type cv1 T that refers to an object of type cv2 U, where T and U 217// are neither the same type nor similar types (4.4 [conv.qual]); 218 219// FIXME: 220// - an lvalue-to-rvalue conversion (4.1) that is applied to a glvalue that 221// refers to a non-active member of a union or a subobject thereof; 222 223// - an id-expression that refers to a variable or data member of reference type 224// unless the reference has a preceding initialization, initialized with a 225// constant expression; 226namespace References { 227 const int a = 2; 228 int &b = *const_cast<int*>(&a); 229 int c = 10; // expected-note 2 {{here}} 230 int &d = c; 231 constexpr int e = 42; 232 int &f = const_cast<int&>(e); 233 extern int &g; 234 constexpr int &h(); // expected-note 2{{here}} 235 int &i = h(); // expected-note {{here}} expected-note {{undefined function 'h' cannot be used in a constant expression}} 236 constexpr int &j() { return b; } 237 int &k = j(); 238 239 struct S { 240 int A : a; 241 int B : b; 242 int C : c; // expected-error {{constant expression}} expected-note {{read of non-const variable 'c'}} 243 int D : d; // expected-error {{constant expression}} expected-note {{read of non-const variable 'c'}} 244 int D2 : &d - &c + 1; 245 int E : e / 2; 246 int F : f - 11; 247 int G : g; // expected-error {{constant expression}} 248 int H : h(); // expected-error {{constant expression}} expected-note {{undefined function 'h'}} 249 int I : i; // expected-error {{constant expression}} expected-note {{initializer of 'i' is not a constant expression}} 250 int J : j(); 251 int K : k; 252 }; 253} 254 255// - a dynamic_cast (5.2.7); 256namespace DynamicCast { 257 struct S { int n; }; 258 constexpr S s { 16 }; 259 struct T { 260 int n : dynamic_cast<const S*>(&s)->n; // expected-warning {{constant expression}} expected-note {{dynamic_cast}} 261 }; 262} 263 264// - a reinterpret_cast (5.2.10); 265namespace ReinterpretCast { 266 struct S { int n; }; 267 constexpr S s { 16 }; 268 struct T { 269 int n : reinterpret_cast<const S*>(&s)->n; // expected-warning {{constant expression}} expected-note {{reinterpret_cast}} 270 }; 271 struct U { 272 int m : (long)(S*)6; // expected-warning {{constant expression}} expected-note {{reinterpret_cast}} 273 }; 274} 275 276// - a pseudo-destructor call (5.2.4); 277namespace PseudoDtor { 278 int k; 279 typedef int I; 280 struct T { 281 int n : (k.~I(), 0); // expected-error {{constant expression}} expected-note{{subexpression}} 282 }; 283} 284 285// - increment or decrement operations (5.2.6, 5.3.2); 286namespace IncDec { 287 int k = 2; 288 struct T { 289 int n : ++k; // expected-error {{constant expression}} 290 int m : --k; // expected-error {{constant expression}} 291 }; 292} 293 294// - a typeid expression (5.2.8) whose operand is of a polymorphic class type; 295namespace std { 296 struct type_info { 297 virtual ~type_info(); 298 const char *name; 299 }; 300} 301namespace TypeId { 302 struct S { virtual void f(); }; 303 constexpr S *p = 0; 304 constexpr const std::type_info &ti1 = typeid(*p); // expected-error {{must be initialized by a constant expression}} expected-note {{typeid applied to expression of polymorphic type 'TypeId::S'}} 305 306 struct T {} t; 307 constexpr const std::type_info &ti2 = typeid(t); 308} 309 310// - a new-expression (5.3.4); 311// - a delete-expression (5.3.5); 312namespace NewDelete { 313 int *p = 0; 314 struct T { 315 int n : *new int(4); // expected-error {{constant expression}} expected-note {{subexpression}} 316 int m : (delete p, 2); // expected-error {{constant expression}} expected-note {{subexpression}} 317 }; 318} 319 320// - a relational (5.9) or equality (5.10) operator where the result is 321// unspecified; 322namespace UnspecifiedRelations { 323 int a, b; 324 constexpr int *p = &a, *q = &b; 325 // C++11 [expr.rel]p2: If two pointers p and q of the same type point to 326 // different objects that are not members of the same array or to different 327 // functions, or if only one of them is null, the results of p<q, p>q, p<=q, 328 // and p>=q are unspecified. 329 constexpr bool u1 = p < q; // expected-error {{constant expression}} 330 constexpr bool u2 = p > q; // expected-error {{constant expression}} 331 constexpr bool u3 = p <= q; // expected-error {{constant expression}} 332 constexpr bool u4 = p >= q; // expected-error {{constant expression}} 333 constexpr bool u5 = p < 0; // expected-error {{constant expression}} 334 constexpr bool u6 = p <= 0; // expected-error {{constant expression}} 335 constexpr bool u7 = p > 0; // expected-error {{constant expression}} 336 constexpr bool u8 = p >= 0; // expected-error {{constant expression}} 337 constexpr bool u9 = 0 < q; // expected-error {{constant expression}} 338 constexpr bool u10 = 0 <= q; // expected-error {{constant expression}} 339 constexpr bool u11 = 0 > q; // expected-error {{constant expression}} 340 constexpr bool u12 = 0 >= q; // expected-error {{constant expression}} 341 void f(), g(); 342 343 constexpr void (*pf)() = &f, (*pg)() = &g; 344 constexpr bool u13 = pf < pg; // expected-error {{constant expression}} 345 constexpr bool u14 = pf == pg; 346 347 // FIXME: 348 // If two pointers point to non-static data members of the same object with 349 // different access control, the result is unspecified. 350 351 // FIXME: 352 // [expr.rel]p3: Pointers to void can be compared [...] if both pointers 353 // represent the same address or are both the null pointer [...]; otherwise 354 // the result is unspecified. 355 356 // FIXME: Implement comparisons of pointers to members. 357 // [expr.eq]p2: If either is a pointer to a virtual member function and 358 // neither is null, the result is unspecified. 359} 360 361// - an assignment or a compound assignment (5.17); or 362namespace Assignment { 363 int k; 364 struct T { 365 int n : (k = 9); // expected-error {{constant expression}} 366 int m : (k *= 2); // expected-error {{constant expression}} 367 }; 368 369 struct Literal { 370 constexpr Literal(const char *name) : name(name) {} 371 const char *name; 372 }; 373 struct Expr { 374 constexpr Expr(Literal l) : IsLiteral(true), l(l) {} 375 bool IsLiteral; 376 union { 377 Literal l; 378 // ... 379 }; 380 }; 381 struct MulEq { 382 constexpr MulEq(Expr a, Expr b) : LHS(a), RHS(b) {} 383 Expr LHS; 384 Expr RHS; 385 }; 386 constexpr MulEq operator*=(Expr a, Expr b) { return MulEq(a, b); } 387 Literal a("a"); 388 Literal b("b"); 389 MulEq c = a *= b; // ok 390} 391 392// - a throw-expression (15.1) 393namespace Throw { 394 struct S { 395 int n : (throw "hello", 10); // expected-error {{constant expression}} expected-note {{subexpression}} 396 }; 397} 398 399// PR9999 400template<bool v> 401class bitWidthHolding { 402public: 403 static const 404 unsigned int width = (v == 0 ? 0 : bitWidthHolding<(v >> 1)>::width + 1); 405}; 406 407static const int width=bitWidthHolding<255>::width; 408 409template<bool b> 410struct always_false { 411 static const bool value = false; 412}; 413 414template<bool b> 415struct and_or { 416 static const bool and_value = b && and_or<always_false<b>::value>::and_value; 417 static const bool or_value = !b || and_or<always_false<b>::value>::or_value; 418}; 419 420static const bool and_value = and_or<true>::and_value; 421static const bool or_value = and_or<true>::or_value; 422