p2-0x.cpp revision b04035a7b1a3c9b93cea72ae56dd2ea6e787bae9
13a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org// RUN: %clang_cc1 -fsyntax-only -std=c++11 -pedantic -verify -fcxx-exceptions %s -fconstexpr-depth 128 23a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org 33a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org// A conditional-expression is a core constant expression unless it involves one 43a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org// of the following as a potentially evaluated subexpression [...]: 53a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org 63a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org// - this (5.1.1 [expr.prim.general]) [Note: when evaluating a constant 73a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org// expression, function invocation substitution (7.1.5 [dcl.constexpr]) 83a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org// replaces each occurrence of this in a constexpr member function with a 93a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org// pointer to the class object. -end note]; 103a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.orgstruct This { 113a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org int this1 : this1; // expected-error {{undeclared}} 123a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org int this2 : this->this1; // expected-error {{invalid}} 133a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org void this3() { 143a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org int n1[this->this1]; // expected-warning {{variable length array}} 153a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org int n2[this1]; // expected-warning {{variable length array}} 163a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org (void)n1, (void)n2; 173a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org } 183a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org}; 193a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org 203a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org// - an invocation of a function other than a constexpr constructor for a 213a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org// literal class or a constexpr function [ Note: Overload resolution (13.3) 223a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org// is applied as usual - end note ]; 233a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.orgstruct NonConstexpr1 { 243a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org static int f() { return 1; } // expected-note {{here}} 253a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org int n : f(); // expected-error {{constant expression}} expected-note {{non-constexpr function 'f' cannot be used in a constant expression}} 26760fd893ba809a7a5daa25c2749ff502f7186e83kbr@chromium.org}; 273a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.orgstruct NonConstexpr2 { 283a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr NonConstexpr2(); // expected-note {{here}} 293a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org int n; 303a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org}; 313a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.orgstruct NonConstexpr3 { 323a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org NonConstexpr3(); 333a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org int m : NonConstexpr2().n; // expected-error {{constant expression}} expected-note {{undefined constructor 'NonConstexpr2'}} 343a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org}; 353a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.orgstruct NonConstexpr4 { 363a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org NonConstexpr4(); // expected-note {{declared here}} 373a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org int n; 383a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org}; 393a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.orgstruct NonConstexpr5 { 403a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org int n : NonConstexpr4().n; // expected-error {{constant expression}} expected-note {{non-constexpr constructor 'NonConstexpr4' cannot be used in a constant expression}} 413a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org}; 423a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org 433a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org// - an invocation of an undefined constexpr function or an undefined 443a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org// constexpr constructor; 453a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.orgstruct UndefinedConstexpr { 463a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr UndefinedConstexpr(); 473a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org static constexpr int undefinedConstexpr1(); // expected-note {{here}} 483a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org int undefinedConstexpr2 : undefinedConstexpr1(); // expected-error {{constant expression}} expected-note {{undefined function 'undefinedConstexpr1' cannot be used in a constant expression}} 493a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org}; 503a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org 513a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org// - an invocation of a constexpr function with arguments that, when substituted 523a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org// by function invocation substitution (7.1.5), do not produce a constant 533a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org// expression; 543a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.orgnamespace NonConstExprReturn { 553a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org static constexpr const int &id_ref(const int &n) { 563a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org return n; // expected-note {{reference to temporary cannot be returned from a constexpr function}} 573a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org } 583a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org struct NonConstExprFunction { 593a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org int n : id_ref( // expected-error {{constant expression}} expected-note {{in call to 'id_ref(16)'}} 603a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org 16 // expected-note {{temporary created here}} 613a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org ); 623a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org }; 633a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr const int *address_of(const int &a) { 643a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org return &a; // expected-note {{pointer to 'n' cannot be returned from a constexpr function}} 653a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org } 663a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr const int *return_param(int n) { // expected-note {{declared here}} 673a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org return address_of(n); // expected-note {{in call to 'address_of(n)'}} 683a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org } 693a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org struct S { 703a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org int n : *return_param(0); // expected-error {{constant expression}} expected-note {{in call to 'return_param(0)'}} 713a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org }; 723a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org} 733a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org 743a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org// - an invocation of a constexpr constructor with arguments that, when 753a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org// substituted by function invocation substitution (7.1.5), do not produce all 763a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org// constant expressions for the constructor calls and full-expressions in the 773a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org// mem-initializers (including conversions); 783a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.orgnamespace NonConstExprCtor { 793a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org struct T { 803a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr T(const int &r) : 813a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org r(r) { // expected-note 2{{reference to temporary cannot be used to initialize a member in a constant expression}} 823a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org } 833a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org const int &r; 843a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org }; 853a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr int n = 0; 863a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr T t1(n); // ok 873a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org 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)'}} 883a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org 893a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org struct S { 903a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org int n : T(4).r; // expected-error {{constant expression}} expected-note {{temporary created here}} expected-note {{in call to 'T(4)'}} 913a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org }; 923a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org} 933a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org 943a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org// - an invocation of a constexpr function or a constexpr constructor that would 95760fd893ba809a7a5daa25c2749ff502f7186e83kbr@chromium.org// exceed the implementation-defined recursion limits (see Annex B); 963a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.orgnamespace RecursionLimits { 973a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr int RecurseForever(int n) { 983a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org 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}} 993a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org } 1003a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org struct AlsoRecurseForever { 1013a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr AlsoRecurseForever(int n) : 1023a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org 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}} 1033a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org {} 1043a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org int n; 1053a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org }; 1063a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org struct S { 1073a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org int k : RecurseForever(0); // expected-error {{constant expression}} expected-note {{in call to}} 1083a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org int l : AlsoRecurseForever(0).n; // expected-error {{constant expression}} expected-note {{in call to}} 1093a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org }; 1103a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org} 1113a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org 1123a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org// FIXME: 1133a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org// - an operation that would have undefined behavior [Note: including, for 1143a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org// example, signed integer overflow (Clause 5 [expr]), certain pointer 1153a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org// arithmetic (5.7 [expr.add]), division by zero (5.6 [expr.mul]), or certain 1163a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org// shift operations (5.8 [expr.shift]) -end note]; 1173a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.orgnamespace UndefinedBehavior { 1183a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org void f(int n) { 1193a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org switch (n) { 1203a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org case (int)4.4e9: // expected-error {{constant expression}} expected-note {{value 4.4E+9 is outside the range of representable values of type 'int'}} 1213a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org case (int)0x80000000u: // ok 1223a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org case (int)10000000000ll: // expected-note {{here}} 1233a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org case (unsigned int)10000000000ll: // expected-error {{duplicate case value}} 1243a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org case (int)(unsigned)(long long)4.4e9: // ok 1253a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org case (int)(float)1e300: // expected-error {{constant expression}} expected-note {{value 1.0E+300 is outside the range of representable values of type 'float'}} 1263a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org case (int)((float)1e37 / 1e30): // ok 1273a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org case (int)(__fp16)65536: // expected-error {{constant expression}} expected-note {{value 65536 is outside the range of representable values of type 'half'}} 1283a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org break; 1293a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org } 1303a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org } 1313a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org 1323a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr int int_min = ~0x7fffffff; 1333a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr int minus_int_min = -int_min; // expected-error {{constant expression}} expected-note {{value 2147483648 is outside the range}} 1343a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr int div0 = 3 / 0; // expected-error {{constant expression}} expected-note {{division by zero}} expected-warning {{undefined}} 1353a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr int mod0 = 3 % 0; // expected-error {{constant expression}} expected-note {{division by zero}} expected-warning {{undefined}} 1363a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr int int_min_div_minus_1 = int_min / -1; // expected-error {{constant expression}} expected-note {{value 2147483648 is outside the range}} 1373a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr int int_min_mod_minus_1 = int_min % -1; // expected-error {{constant expression}} expected-note {{value 2147483648 is outside the range}} 1383a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org 1393a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr int shl_m1 = 0 << -1; // expected-error {{constant expression}} expected-note {{negative shift count -1}} expected-warning {{negative}} 1403a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr int shl_0 = 0 << 0; // ok 1413a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr int shl_31 = 0 << 31; // ok 1423a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr int shl_32 = 0 << 32; // expected-error {{constant expression}} expected-note {{shift count 32 >= width of type 'int' (32}} expected-warning {{>= width of type}} 1433a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr int shl_unsigned_negative = unsigned(-3) << 1; // ok 1443a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr int shl_unsigned_into_sign = 1u << 31; // ok 1453a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr int shl_unsigned_overflow = 1024u << 31; // ok 1463a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr int shl_signed_negative = (-3) << 1; // expected-error {{constant expression}} expected-note {{left shift of negative value -3}} 1473a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr int shl_signed_ok = 1 << 30; // ok 1483a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr int shl_signed_into_sign = 1 << 31; // expected-error {{constant expression}} expected-note {{value 2147483648 is outside the range}} 1493a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr int shl_signed_overflow = 1024 << 31; // expected-error {{constant expression}} expected-note {{value 2199023255552 is outside the range}} expected-warning {{requires 43 bits to represent}} 1503a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr int shl_signed_ok2 = 1024 << 20; // ok 1513a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org 1523a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr int shr_m1 = 0 >> -1; // expected-error {{constant expression}} expected-note {{negative shift count -1}} expected-warning {{negative}} 1533a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr int shr_0 = 0 >> 0; // ok 1543a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr int shr_31 = 0 >> 31; // ok 1553a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr int shr_32 = 0 >> 32; // expected-error {{constant expression}} expected-note {{shift count 32 >= width of type}} expected-warning {{>= width of type}} 1563a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org 1573a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org struct S { 1583a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org int m; 1593a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org }; 1603a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr S s = { 5 }; // expected-note {{declared here}} 1613a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr const int *p = &s.m + 1; 1623a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr const int &f(const int *q) { 1633a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org return q[0]; // expected-note {{dereferenced pointer past the end of subobject of 's' is not a constant expression}} 1643a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org } 1653a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr int n = (f(p), 0); // expected-error {{constant expression}} expected-note {{in call to 'f(&s.m + 1)'}} 1663a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org struct T { 1673a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org int n : f(p); // expected-error {{not an integral constant expression}} expected-note {{read of dereferenced one-past-the-end pointer}} 1683a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org }; 1693a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org 1703a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org namespace Ptr { 1713a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org struct A {}; 1723a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org struct B : A { int n; }; 1733a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org B a[3][3]; 1743a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr B *p = a[0] + 4; // expected-error {{constant expression}} expected-note {{element 4 of array of 3 elements}} 1753a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org B b = {}; 1763a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr A *pa = &b + 1; // expected-error {{constant expression}} expected-note {{base class of pointer past the end}} 1773a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr B *pb = (B*)((A*)&b + 1); // expected-error {{constant expression}} expected-note {{derived class of pointer past the end}} 1783a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr const int *pn = &(&b + 1)->n; // expected-error {{constant expression}} expected-note {{field of pointer past the end}} 179760fd893ba809a7a5daa25c2749ff502f7186e83kbr@chromium.org constexpr B *parr = &a[3][0]; // expected-error {{constant expression}} expected-note {{array element of pointer past the end}} 1803a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org 181760fd893ba809a7a5daa25c2749ff502f7186e83kbr@chromium.org constexpr A *na = nullptr; 182760fd893ba809a7a5daa25c2749ff502f7186e83kbr@chromium.org constexpr B *nb = nullptr; 183760fd893ba809a7a5daa25c2749ff502f7186e83kbr@chromium.org constexpr A &ra = *nb; // expected-error {{constant expression}} expected-note {{cannot access base class of null pointer}} 184760fd893ba809a7a5daa25c2749ff502f7186e83kbr@chromium.org constexpr B &rb = (B&)*na; // expected-error {{constant expression}} expected-note {{cannot access derived class of null pointer}} 185760fd893ba809a7a5daa25c2749ff502f7186e83kbr@chromium.org static_assert((A*)nb == 0, ""); 186760fd893ba809a7a5daa25c2749ff502f7186e83kbr@chromium.org static_assert((B*)na == 0, ""); 187760fd893ba809a7a5daa25c2749ff502f7186e83kbr@chromium.org constexpr const int &nf = nb->n; // expected-error {{constant expression}} expected-note {{cannot access field of null pointer}} 1883a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr const int &np = (*(int(*)[4])nullptr)[2]; // expected-error {{constant expression}} expected-note {{cannot access array element of null pointer}} 1893a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org 1903a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org struct C { 1913a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr int f() { return 0; } 1923a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org } constexpr c = C(); 1933a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr int k1 = c.f(); // ok 1943a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr int k2 = ((C*)nullptr)->f(); // expected-error {{constant expression}} expected-note {{cannot call member function on null pointer}} 1953a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr int k3 = (&c)[1].f(); // expected-error {{constant expression}} expected-note {{cannot call member function on pointer past the end of object}} 1963a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org C c2; 1973a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr int k4 = c2.f(); // ok! 198760fd893ba809a7a5daa25c2749ff502f7186e83kbr@chromium.org } 1993a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org} 2003a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org 2013a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org// - a lambda-expression (5.1.2); 2023a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.orgstruct Lambda { 2033a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org // FIXME: clang crashes when trying to parse this! Revisit this check once 2043a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org // lambdas are fully implemented. 2053a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org //int n : []{ return 1; }(); 2063a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org}; 2073a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org 2083a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org// - an lvalue-to-rvalue conversion (4.1) unless it is applied to 2093a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.orgnamespace LValueToRValue { 2103a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org // - a non-volatile glvalue of integral or enumeration type that refers to a 2113a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org // non-volatile const object with a preceding initialization, initialized 2123a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org // with a constant expression [Note: a string literal (2.14.5 [lex.string]) 2133a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org // corresponds to an array of such objects. -end note], or 2143a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org volatile const int vi = 1; // expected-note {{here}} 2153a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org const int ci = 1; 2163a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org volatile const int &vrci = ci; 2173a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org static_assert(vi, ""); // expected-error {{constant expression}} expected-note {{read of volatile-qualified type 'const volatile int'}} 2183a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org static_assert(const_cast<int&>(vi), ""); // expected-error {{constant expression}} expected-note {{read of volatile object 'vi'}} 2193a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org static_assert(vrci, ""); // expected-error {{constant expression}} expected-note {{read of volatile-qualified type}} 2203a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org 2213a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org // - a non-volatile glvalue of literal type that refers to a non-volatile 2223a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org // object defined with constexpr, or that refers to a sub-object of such an 2233a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org // object, or 2243a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org struct S { 2253a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr S(int=0) : i(1), v(1) {} 226760fd893ba809a7a5daa25c2749ff502f7186e83kbr@chromium.org constexpr S(const S &s) : i(2), v(2) {} 2273a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org int i; 2283a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org volatile int v; 2293a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org }; 2303a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr S s; 2313a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr volatile S vs; // expected-note {{here}} 2323a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org constexpr const volatile S &vrs = s; 2333a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org static_assert(s.i, ""); 2343a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org static_assert(s.v, ""); // expected-error {{constant expression}} expected-note {{read of volatile-qualified type}} 2353a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org static_assert(vs.i, ""); // expected-error {{constant expression}} expected-note {{read of volatile-qualified type}} 2363a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org static_assert(const_cast<int&>(vs.i), ""); // expected-error {{constant expression}} expected-note {{read of volatile object 'vs'}} 2373a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org static_assert(vrs.i, ""); // expected-error {{constant expression}} expected-note {{read of volatile-qualified type}} 2383a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org 2393a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org // - a non-volatile glvalue of literal type that refers to a non-volatile 2403a0db227ffe90888ad760c61a63226988c974e0apatrick@chromium.org // temporary object whose lifetime has not ended, initialized with a 241 // constant expression; 242 constexpr volatile S f() { return S(); } 243 static_assert(f().i, ""); // ok! there's no lvalue-to-rvalue conversion here! 244 static_assert(((volatile const S&&)(S)0).i, ""); // expected-error {{constant expression}} expected-note {{subexpression}} 245} 246 247// FIXME: 248// 249// DR1312: The proposed wording for this defect has issues, so we ignore this 250// bullet and instead prohibit casts from pointers to cv void (see core-20842 251// and core-20845). 252// 253// - an lvalue-to-rvalue conversion (4.1 [conv.lval]) that is applied to a 254// glvalue of type cv1 T that refers to an object of type cv2 U, where T and U 255// are neither the same type nor similar types (4.4 [conv.qual]); 256 257// FIXME: 258// - an lvalue-to-rvalue conversion (4.1) that is applied to a glvalue that 259// refers to a non-active member of a union or a subobject thereof; 260 261// - an id-expression that refers to a variable or data member of reference type 262// unless the reference has a preceding initialization, initialized with a 263// constant expression; 264namespace References { 265 const int a = 2; 266 int &b = *const_cast<int*>(&a); 267 int c = 10; // expected-note 2 {{here}} 268 int &d = c; 269 constexpr int e = 42; 270 int &f = const_cast<int&>(e); 271 extern int &g; 272 constexpr int &h(); // expected-note 2{{here}} 273 int &i = h(); // expected-note {{here}} expected-note {{undefined function 'h' cannot be used in a constant expression}} 274 constexpr int &j() { return b; } 275 int &k = j(); 276 277 struct S { 278 int A : a; 279 int B : b; 280 int C : c; // expected-error {{constant expression}} expected-note {{read of non-const variable 'c'}} 281 int D : d; // expected-error {{constant expression}} expected-note {{read of non-const variable 'c'}} 282 int D2 : &d - &c + 1; 283 int E : e / 2; 284 int F : f - 11; 285 int G : g; // expected-error {{constant expression}} 286 int H : h(); // expected-error {{constant expression}} expected-note {{undefined function 'h'}} 287 int I : i; // expected-error {{constant expression}} expected-note {{initializer of 'i' is not a constant expression}} 288 int J : j(); 289 int K : k; 290 }; 291} 292 293// - a dynamic_cast (5.2.7); 294namespace DynamicCast { 295 struct S { int n; }; 296 constexpr S s { 16 }; 297 struct T { 298 int n : dynamic_cast<const S*>(&s)->n; // expected-warning {{constant expression}} expected-note {{dynamic_cast}} 299 }; 300} 301 302// - a reinterpret_cast (5.2.10); 303namespace ReinterpretCast { 304 struct S { int n; }; 305 constexpr S s { 16 }; 306 struct T { 307 int n : reinterpret_cast<const S*>(&s)->n; // expected-warning {{constant expression}} expected-note {{reinterpret_cast}} 308 }; 309 struct U { 310 int m : (long)(S*)6; // expected-warning {{constant expression}} expected-note {{reinterpret_cast}} 311 }; 312} 313 314// - a pseudo-destructor call (5.2.4); 315namespace PseudoDtor { 316 int k; 317 typedef int I; 318 struct T { 319 int n : (k.~I(), 0); // expected-error {{constant expression}} expected-note{{subexpression}} 320 }; 321} 322 323// - increment or decrement operations (5.2.6, 5.3.2); 324namespace IncDec { 325 int k = 2; 326 struct T { 327 int n : ++k; // expected-error {{constant expression}} 328 int m : --k; // expected-error {{constant expression}} 329 }; 330} 331 332// - a typeid expression (5.2.8) whose operand is of a polymorphic class type; 333namespace std { 334 struct type_info { 335 virtual ~type_info(); 336 const char *name; 337 }; 338} 339namespace TypeId { 340 struct S { virtual void f(); }; 341 constexpr S *p = 0; 342 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'}} 343 344 struct T {} t; 345 constexpr const std::type_info &ti2 = typeid(t); 346} 347 348// - a new-expression (5.3.4); 349// - a delete-expression (5.3.5); 350namespace NewDelete { 351 int *p = 0; 352 struct T { 353 int n : *new int(4); // expected-error {{constant expression}} expected-note {{subexpression}} 354 int m : (delete p, 2); // expected-error {{constant expression}} expected-note {{subexpression}} 355 }; 356} 357 358// - a relational (5.9) or equality (5.10) operator where the result is 359// unspecified; 360namespace UnspecifiedRelations { 361 int a, b; 362 constexpr int *p = &a, *q = &b; 363 // C++11 [expr.rel]p2: If two pointers p and q of the same type point to 364 // different objects that are not members of the same array or to different 365 // functions, or if only one of them is null, the results of p<q, p>q, p<=q, 366 // and p>=q are unspecified. 367 constexpr bool u1 = p < q; // expected-error {{constant expression}} 368 constexpr bool u2 = p > q; // expected-error {{constant expression}} 369 constexpr bool u3 = p <= q; // expected-error {{constant expression}} 370 constexpr bool u4 = p >= q; // expected-error {{constant expression}} 371 constexpr bool u5 = p < 0; // expected-error {{constant expression}} 372 constexpr bool u6 = p <= 0; // expected-error {{constant expression}} 373 constexpr bool u7 = p > 0; // expected-error {{constant expression}} 374 constexpr bool u8 = p >= 0; // expected-error {{constant expression}} 375 constexpr bool u9 = 0 < q; // expected-error {{constant expression}} 376 constexpr bool u10 = 0 <= q; // expected-error {{constant expression}} 377 constexpr bool u11 = 0 > q; // expected-error {{constant expression}} 378 constexpr bool u12 = 0 >= q; // expected-error {{constant expression}} 379 void f(), g(); 380 381 constexpr void (*pf)() = &f, (*pg)() = &g; 382 constexpr bool u13 = pf < pg; // expected-error {{constant expression}} 383 constexpr bool u14 = pf == pg; 384 385 // FIXME: 386 // If two pointers point to non-static data members of the same object with 387 // different access control, the result is unspecified. 388 389 // [expr.rel]p3: Pointers to void can be compared [...] if both pointers 390 // represent the same address or are both the null pointer [...]; otherwise 391 // the result is unspecified. 392 struct S { int a, b; } s; 393 constexpr void *null = 0; 394 constexpr void *pv = (void*)&s.a; 395 constexpr void *qv = (void*)&s.b; 396 constexpr bool v1 = null < 0; 397 constexpr bool v2 = null < pv; // expected-error {{constant expression}} 398 constexpr bool v3 = null == pv; // ok 399 constexpr bool v4 = qv == pv; // ok 400 constexpr bool v5 = qv >= pv; // expected-error {{constant expression}} expected-note {{unequal pointers to void}} 401 constexpr bool v6 = qv > null; // expected-error {{constant expression}} 402 constexpr bool v7 = qv <= (void*)&s.b; // ok 403 constexpr bool v8 = qv > (void*)&s.a; // expected-error {{constant expression}} expected-note {{unequal pointers to void}} 404 405 // FIXME: Implement comparisons of pointers to members. 406 // [expr.eq]p2: If either is a pointer to a virtual member function and 407 // neither is null, the result is unspecified. 408} 409 410// - an assignment or a compound assignment (5.17); or 411namespace Assignment { 412 int k; 413 struct T { 414 int n : (k = 9); // expected-error {{constant expression}} 415 int m : (k *= 2); // expected-error {{constant expression}} 416 }; 417 418 struct Literal { 419 constexpr Literal(const char *name) : name(name) {} 420 const char *name; 421 }; 422 struct Expr { 423 constexpr Expr(Literal l) : IsLiteral(true), l(l) {} 424 bool IsLiteral; 425 union { 426 Literal l; 427 // ... 428 }; 429 }; 430 struct MulEq { 431 constexpr MulEq(Expr a, Expr b) : LHS(a), RHS(b) {} 432 Expr LHS; 433 Expr RHS; 434 }; 435 constexpr MulEq operator*=(Expr a, Expr b) { return MulEq(a, b); } 436 Literal a("a"); 437 Literal b("b"); 438 MulEq c = a *= b; // ok 439} 440 441// - a throw-expression (15.1) 442namespace Throw { 443 struct S { 444 int n : (throw "hello", 10); // expected-error {{constant expression}} expected-note {{subexpression}} 445 }; 446} 447 448// PR9999 449template<unsigned int v> 450class bitWidthHolding { 451public: 452 static const 453 unsigned int width = (v == 0 ? 0 : bitWidthHolding<(v >> 1)>::width + 1); 454}; 455 456static const int width=bitWidthHolding<255>::width; 457 458template<bool b> 459struct always_false { 460 static const bool value = false; 461}; 462 463template<bool b> 464struct and_or { 465 static const bool and_value = b && and_or<always_false<b>::value>::and_value; 466 static const bool or_value = !b || and_or<always_false<b>::value>::or_value; 467}; 468 469static const bool and_value = and_or<true>::and_value; 470static const bool or_value = and_or<true>::or_value; 471 472static_assert(and_value == false, ""); 473static_assert(or_value == true, ""); 474