654 lines
31 KiB
C++
654 lines
31 KiB
C++
// RUN: %clang_cc1 -fsyntax-only -std=c++11 -pedantic -verify=expected,cxx11 -fcxx-exceptions %s -fconstexpr-depth 128 -triple i686-pc-linux-gnu
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// RUN: %clang_cc1 -fsyntax-only -std=c++2a -pedantic -verify=expected,cxx20 -fcxx-exceptions %s -fconstexpr-depth 128 -triple i686-pc-linux-gnu
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// A conditional-expression is a core constant expression unless it involves one
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// of the following as a potentially evaluated subexpression [...]:
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// - this (5.1.1 [expr.prim.general]) [Note: when evaluating a constant
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// expression, function invocation substitution (7.1.5 [dcl.constexpr])
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// replaces each occurrence of this in a constexpr member function with a
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// pointer to the class object. -end note];
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struct This {
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int this1 : this1; // expected-error {{undeclared}}
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int this2 : this->this1; // expected-error {{invalid}}
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void this3() {
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int n1[this->this1]; // expected-warning {{variable length array}} expected-note {{'this'}}
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int n2[this1]; // expected-warning {{variable length array}} expected-note {{'this'}}
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(void)n1, (void)n2;
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}
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};
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// - an invocation of a function other than a constexpr constructor for a
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// literal class or a constexpr function [ Note: Overload resolution (13.3)
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// is applied as usual - end note ];
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struct NonConstexpr1 {
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static int f() { return 1; } // expected-note {{here}}
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int n : f(); // expected-error {{constant expression}} expected-note {{non-constexpr function 'f' cannot be used in a constant expression}}
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};
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struct NonConstexpr2 {
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constexpr NonConstexpr2(); // expected-note {{here}}
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int n;
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};
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struct NonConstexpr3 {
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NonConstexpr3();
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int m : NonConstexpr2().n; // expected-error {{constant expression}} expected-note {{undefined constructor 'NonConstexpr2'}}
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};
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struct NonConstexpr4 {
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NonConstexpr4();
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int n;
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};
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struct NonConstexpr5 {
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int n : NonConstexpr4().n; // expected-error {{constant expression}} expected-note {{non-literal type 'NonConstexpr4' cannot be used in a constant expression}}
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};
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// - an invocation of an undefined constexpr function or an undefined
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// constexpr constructor;
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struct UndefinedConstexpr {
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constexpr UndefinedConstexpr();
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static constexpr int undefinedConstexpr1(); // expected-note {{here}}
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int undefinedConstexpr2 : undefinedConstexpr1(); // expected-error {{constant expression}} expected-note {{undefined function 'undefinedConstexpr1' cannot be used in a constant expression}}
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};
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// - an invocation of a constexpr function with arguments that, when substituted
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// by function invocation substitution (7.1.5), do not produce a core constant
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// expression;
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namespace NonConstExprReturn {
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static constexpr const int &id_ref(const int &n) {
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return n;
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}
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struct NonConstExprFunction {
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int n : id_ref(16); // ok
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};
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constexpr const int *address_of(const int &a) {
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return &a;
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}
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constexpr const int *return_param(int n) {
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return address_of(n);
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}
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struct S {
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int n : *return_param(0); // expected-error {{constant expression}} expected-note {{read of object outside its lifetime}}
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};
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}
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// - an invocation of a constexpr constructor with arguments that, when
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// substituted by function invocation substitution (7.1.5), do not produce all
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// constant expressions for the constructor calls and full-expressions in the
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// mem-initializers (including conversions);
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namespace NonConstExprCtor {
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struct T {
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constexpr T(const int &r) :
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r(r) {
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}
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const int &r;
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};
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constexpr int n = 0;
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constexpr T t1(n); // ok
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constexpr T t2(0); // expected-error {{must be initialized by a constant expression}} expected-note {{temporary created here}} expected-note {{reference to temporary is not a constant expression}}
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struct S {
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int n : T(4).r; // ok
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};
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}
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// - an invocation of a constexpr function or a constexpr constructor that would
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// exceed the implementation-defined recursion limits (see Annex B);
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namespace RecursionLimits {
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constexpr int RecurseForever(int n) {
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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}}
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}
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struct AlsoRecurseForever {
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constexpr AlsoRecurseForever(int n) :
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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}}
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{}
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int n;
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};
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struct S {
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int k : RecurseForever(0); // expected-error {{constant expression}} expected-note {{in call to}}
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int l : AlsoRecurseForever(0).n; // expected-error {{constant expression}} expected-note {{in call to}}
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};
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}
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// DR1458: taking the address of an object of incomplete class type
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namespace IncompleteClassTypeAddr {
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struct S;
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extern S s;
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constexpr S *p = &s; // ok
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static_assert(p, "");
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extern S sArr[];
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constexpr S (*p2)[] = &sArr; // ok
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struct S {
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constexpr S *operator&() const { return nullptr; }
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};
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constexpr S *q = &s; // ok
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static_assert(!q, "");
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}
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// - an operation that would have undefined behavior [Note: including, for
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// example, signed integer overflow (Clause 5 [expr]), certain pointer
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// arithmetic (5.7 [expr.add]), division by zero (5.6 [expr.mul]), or certain
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// shift operations (5.8 [expr.shift]) -end note];
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namespace UndefinedBehavior {
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void f(int n) {
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switch (n) {
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case (int)4.4e9: // expected-error {{constant expression}} expected-note {{value 4.4E+9 is outside the range of representable values of type 'int'}}
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case (int)0x80000000u: // ok
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case (int)10000000000ll: // expected-note {{here}}
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case (unsigned int)10000000000ll: // expected-error {{duplicate case value}}
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case (int)(unsigned)(long long)4.4e9: // ok
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case (int)(float)1e300: // expected-error {{constant expression}} expected-note {{value +Inf is outside the range of representable values of type 'int'}}
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case (int)((float)1e37 / 1e30): // ok
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case (int)(__fp16)65536: // expected-error {{constant expression}} expected-note {{value +Inf is outside the range of representable values of type 'int'}}
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break;
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}
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}
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constexpr int int_min = ~0x7fffffff;
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constexpr int minus_int_min = -int_min; // expected-error {{constant expression}} expected-note {{value 2147483648 is outside the range}}
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constexpr int div0 = 3 / 0; // expected-error {{constant expression}} expected-note {{division by zero}}
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constexpr int mod0 = 3 % 0; // expected-error {{constant expression}} expected-note {{division by zero}}
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constexpr int int_min_div_minus_1 = int_min / -1; // expected-error {{constant expression}} expected-note {{value 2147483648 is outside the range}}
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constexpr int int_min_mod_minus_1 = int_min % -1; // expected-error {{constant expression}} expected-note {{value 2147483648 is outside the range}}
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constexpr int shl_m1 = 0 << -1; // expected-error {{constant expression}} expected-note {{negative shift count -1}}
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constexpr int shl_0 = 0 << 0; // ok
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constexpr int shl_31 = 0 << 31; // ok
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constexpr int shl_32 = 0 << 32; // expected-error {{constant expression}} expected-note {{shift count 32 >= width of type 'int' (32}}
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constexpr int shl_unsigned_negative = unsigned(-3) << 1; // ok
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constexpr int shl_unsigned_into_sign = 1u << 31; // ok
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constexpr int shl_unsigned_overflow = 1024u << 31; // ok
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constexpr int shl_signed_negative = (-3) << 1; // cxx11-error {{constant expression}} cxx11-note {{left shift of negative value -3}}
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constexpr int shl_signed_ok = 1 << 30; // ok
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constexpr int shl_signed_into_sign = 1 << 31; // ok (DR1457)
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constexpr int shl_signed_into_sign_2 = 0x7fffffff << 1; // ok (DR1457)
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constexpr int shl_signed_off_end = 2 << 31; // cxx11-error {{constant expression}} cxx11-note {{signed left shift discards bits}} expected-warning {{signed shift result (0x100000000) requires 34 bits to represent, but 'int' only has 32 bits}}
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constexpr int shl_signed_off_end_2 = 0x7fffffff << 2; // cxx11-error {{constant expression}} cxx11-note {{signed left shift discards bits}} expected-warning {{signed shift result (0x1FFFFFFFC) requires 34 bits to represent, but 'int' only has 32 bits}}
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constexpr int shl_signed_overflow = 1024 << 31; // cxx11-error {{constant expression}} cxx11-note {{signed left shift discards bits}} expected-warning {{requires 43 bits to represent}}
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constexpr int shl_signed_ok2 = 1024 << 20; // ok
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constexpr int shr_m1 = 0 >> -1; // expected-error {{constant expression}} expected-note {{negative shift count -1}}
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constexpr int shr_0 = 0 >> 0; // ok
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constexpr int shr_31 = 0 >> 31; // ok
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constexpr int shr_32 = 0 >> 32; // expected-error {{constant expression}} expected-note {{shift count 32 >= width of type}}
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struct S {
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int m;
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};
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constexpr S s = { 5 };
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constexpr const int *p = &s.m + 1;
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constexpr const int &f(const int *q) {
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return q[0];
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}
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constexpr int n = (f(p), 0); // ok
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struct T {
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int n : f(p); // expected-error {{not an integral constant expression}} expected-note {{read of dereferenced one-past-the-end pointer}}
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};
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namespace Ptr {
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struct A {};
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struct B : A { int n; };
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B a[3][3];
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constexpr B *p = a[0] + 4; // expected-error {{constant expression}} expected-note {{element 4 of array of 3 elements}}
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B b = {};
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constexpr A *pa = &b + 1; // expected-error {{constant expression}} expected-note {{base class of pointer past the end}}
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constexpr B *pb = (B*)((A*)&b + 1); // expected-error {{constant expression}} expected-note {{derived class of pointer past the end}}
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constexpr const int *pn = &(&b + 1)->n; // expected-error {{constant expression}} expected-note {{field of pointer past the end}}
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constexpr B *parr = &a[3][0]; // expected-error {{constant expression}} expected-note {{array element of pointer past the end}}
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constexpr A *na = nullptr;
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constexpr B *nb = nullptr;
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constexpr A &ra = *nb; // expected-error {{constant expression}} expected-note {{cannot access base class of null pointer}}
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constexpr B &rb = (B&)*na; // expected-error {{constant expression}} expected-note {{cannot access derived class of null pointer}}
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static_assert((A*)nb == 0, "");
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static_assert((B*)na == 0, "");
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constexpr const int &nf = nb->n; // expected-error {{constant expression}} expected-note {{cannot access field of null pointer}}
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constexpr const int *np1 = (int*)nullptr + 0; // ok
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constexpr const int *np2 = &(*(int(*)[4])nullptr)[0]; // ok
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constexpr const int *np3 = &(*(int(*)[4])nullptr)[2]; // expected-error {{constant expression}} expected-note {{cannot perform pointer arithmetic on null pointer}}
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struct C {
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constexpr int f() const { return 0; }
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} constexpr c = C();
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constexpr int k1 = c.f(); // ok
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constexpr int k2 = ((C*)nullptr)->f(); // expected-error {{constant expression}} expected-note {{member call on dereferenced null pointer}}
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constexpr int k3 = (&c)[1].f(); // expected-error {{constant expression}} expected-note {{member call on dereferenced one-past-the-end pointer}}
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C c2;
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constexpr int k4 = c2.f(); // ok!
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constexpr int diff1 = &a[2] - &a[0];
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constexpr int diff2 = &a[1][3] - &a[1][0];
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constexpr int diff3 = &a[2][0] - &a[1][0]; // expected-error {{constant expression}} expected-note {{subtracted pointers are not elements of the same array}}
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static_assert(&a[2][0] == &a[1][3], "");
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constexpr int diff4 = (&b + 1) - &b;
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constexpr int diff5 = &a[1][2].n - &a[1][0].n; // expected-error {{constant expression}} expected-note {{subtracted pointers are not elements of the same array}}
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constexpr int diff6 = &a[1][2].n - &a[1][2].n;
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constexpr int diff7 = (A*)&a[0][1] - (A*)&a[0][0]; // expected-error {{constant expression}} expected-note {{subtracted pointers are not elements of the same array}}
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}
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namespace Overflow {
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// Signed int overflow.
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constexpr int n1 = 2 * 3 * 3 * 7 * 11 * 31 * 151 * 331; // ok
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constexpr int n2 = 65536 * 32768; // expected-error {{constant expression}} expected-note {{value 2147483648 is outside the range of }}
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constexpr int n3 = n1 + 1; // ok
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constexpr int n4 = n3 + 1; // expected-error {{constant expression}} expected-note {{value 2147483648 is outside the range of }}
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constexpr int n5 = -65536 * 32768; // ok
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constexpr int n6 = 3 * -715827883; // expected-error {{constant expression}} expected-note {{value -2147483649 is outside the range of }}
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constexpr int n7 = -n3 + -1; // ok
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constexpr int n8 = -1 + n7; // expected-error {{constant expression}} expected-note {{value -2147483649 is outside the range of }}
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constexpr int n9 = n3 - 0; // ok
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constexpr int n10 = n3 - -1; // expected-error {{constant expression}} expected-note {{value 2147483648 is outside the range of }}
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constexpr int n11 = -1 - n3; // ok
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constexpr int n12 = -2 - n3; // expected-error {{constant expression}} expected-note {{value -2147483649 is outside the range of }}
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constexpr int n13 = n5 + n5; // expected-error {{constant expression}} expected-note {{value -4294967296 is outside the range of }}
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constexpr int n14 = n3 - n5; // expected-error {{constant expression}} expected-note {{value 4294967295 is outside the range of }}
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constexpr int n15 = n5 * n5; // expected-error {{constant expression}} expected-note {{value 4611686018427387904 is outside the range of }}
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constexpr signed char c1 = 100 * 2; // ok expected-warning{{changes value}}
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constexpr signed char c2 = '\x64' * '\2'; // also ok expected-warning{{changes value}}
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constexpr long long ll1 = 0x7fffffffffffffff; // ok
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constexpr long long ll2 = ll1 + 1; // expected-error {{constant}} expected-note {{ 9223372036854775808 }}
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constexpr long long ll3 = -ll1 - 1; // ok
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constexpr long long ll4 = ll3 - 1; // expected-error {{constant}} expected-note {{ -9223372036854775809 }}
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constexpr long long ll5 = ll3 * ll3; // expected-error {{constant}} expected-note {{ 85070591730234615865843651857942052864 }}
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// Yikes.
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char melchizedek[2200000000];
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typedef decltype(melchizedek[1] - melchizedek[0]) ptrdiff_t;
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constexpr ptrdiff_t d1 = &melchizedek[0x7fffffff] - &melchizedek[0]; // ok
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constexpr ptrdiff_t d2 = &melchizedek[0x80000000u] - &melchizedek[0]; // expected-error {{constant expression}} expected-note {{ 2147483648 }}
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constexpr ptrdiff_t d3 = &melchizedek[0] - &melchizedek[0x80000000u]; // ok
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constexpr ptrdiff_t d4 = &melchizedek[0] - &melchizedek[0x80000001u]; // expected-error {{constant expression}} expected-note {{ -2147483649 }}
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// Unsigned int overflow.
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static_assert(65536u * 65536u == 0u, ""); // ok
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static_assert(4294967295u + 1u == 0u, ""); // ok
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static_assert(0u - 1u == 4294967295u, ""); // ok
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static_assert(~0u * ~0u == 1u, ""); // ok
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template<typename T> constexpr bool isinf(T v) { return v && v / 2 == v; }
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// Floating-point overflow and NaN.
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constexpr float f1 = 1e38f * 3.4028f; // ok
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constexpr float f2 = 1e38f * 3.4029f; // ok, +inf is in range of representable values
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constexpr float f3 = 1e38f / -.2939f; // ok
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constexpr float f4 = 1e38f / -.2938f; // ok, -inf is in range of representable values
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constexpr float f5 = 2e38f + 2e38f; // ok, +inf is in range of representable values
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constexpr float f6 = -2e38f - 2e38f; // ok, -inf is in range of representable values
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constexpr float f7 = 0.f / 0.f; // expected-error {{constant expression}} expected-note {{division by zero}}
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constexpr float f8 = 1.f / 0.f; // expected-error {{constant expression}} expected-note {{division by zero}}
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constexpr float f9 = 1e308 / 1e-308; // ok, +inf
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constexpr float f10 = f2 - f2; // expected-error {{constant expression}} expected-note {{produces a NaN}}
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constexpr float f11 = f2 + f4; // expected-error {{constant expression}} expected-note {{produces a NaN}}
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constexpr float f12 = f2 / f2; // expected-error {{constant expression}} expected-note {{produces a NaN}}
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#pragma float_control(push)
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#pragma float_control(except, on)
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constexpr float pi = 3.14f;
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constexpr unsigned ubig = 0xFFFFFFFF;
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constexpr float ce = 1.0 / 3.0; // not-expected-error {{constant expression}} not-expected-note {{floating point arithmetic suppressed in strict evaluation modes}}
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constexpr int ci = (int) pi;
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constexpr float fbig = (float) ubig; // not-expected-error {{constant expression}} not-expected-note {{floating point arithmetic suppressed in strict evaluation modes}}
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constexpr float fabspi = __builtin_fabs(pi); // no error expected
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constexpr float negpi = -pi; // expect no error on unary operator
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#pragma float_control(pop)
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static_assert(!isinf(f1), "");
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static_assert(isinf(f2), "");
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static_assert(!isinf(f3), "");
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static_assert(isinf(f4), "");
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static_assert(isinf(f5), "");
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static_assert(isinf(f6), "");
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static_assert(isinf(f9), "");
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}
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}
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// - a lambda-expression (5.1.2);
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struct Lambda {
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int n : []{ return 1; }(); // cxx11-error {{constant expression}} cxx11-error {{integral constant expression}} cxx11-note {{non-literal type}}
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};
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// - an lvalue-to-rvalue conversion (4.1) unless it is applied to
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namespace LValueToRValue {
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// - a non-volatile glvalue of integral or enumeration type that refers to a
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// non-volatile const object with a preceding initialization, initialized
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// with a constant expression [Note: a string literal (2.14.5 [lex.string])
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// corresponds to an array of such objects. -end note], or
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volatile const int vi = 1; // expected-note 2{{here}}
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const int ci = 1;
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volatile const int &vrci = ci;
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static_assert(vi, ""); // expected-error {{constant expression}} expected-note {{read of volatile-qualified type}}
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static_assert(const_cast<int&>(vi), ""); // expected-error {{constant expression}} expected-note {{read of volatile object 'vi'}}
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static_assert(vrci, ""); // expected-error {{constant expression}} expected-note {{read of volatile-qualified type}}
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// - a non-volatile glvalue of literal type that refers to a non-volatile
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// object defined with constexpr, or that refers to a sub-object of such an
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// object, or
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struct V {
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constexpr V() : v(1) {}
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volatile int v; // expected-note {{not literal because}}
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};
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constexpr V v; // expected-error {{non-literal type}}
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struct S {
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constexpr S(int=0) : i(1), v(const_cast<volatile int&>(vi)) {}
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constexpr S(const S &s) : i(2), v(const_cast<volatile int&>(vi)) {}
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int i;
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volatile int &v;
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};
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constexpr S s; // ok
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constexpr volatile S vs; // expected-note {{here}}
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constexpr const volatile S &vrs = s; // ok
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static_assert(s.i, "");
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static_assert(s.v, ""); // expected-error {{constant expression}} expected-note {{read of volatile-qualified type}}
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static_assert(const_cast<int&>(s.v), ""); // expected-error {{constant expression}} expected-note {{read of volatile object 'vi'}}
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static_assert(vs.i, ""); // expected-error {{constant expression}} expected-note {{read of volatile-qualified type}}
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static_assert(const_cast<int&>(vs.i), ""); // expected-error {{constant expression}} expected-note {{read of volatile object 'vs'}}
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static_assert(vrs.i, ""); // expected-error {{constant expression}} expected-note {{read of volatile-qualified type}}
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// - a non-volatile glvalue of literal type that refers to a non-volatile
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// temporary object whose lifetime has not ended, initialized with a
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// constant expression;
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constexpr volatile S f() { return S(); }
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static_assert(f().i, ""); // expected-error {{constant expression}} expected-note {{read of volatile-qualified type}}
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static_assert(((volatile const S&&)(S)0).i, ""); // expected-error {{constant expression}} expected-note {{read of volatile-qualified type}}
|
|
}
|
|
|
|
// DR1312: The proposed wording for this defect has issues, so we ignore this
|
|
// bullet and instead prohibit casts from pointers to cv void (see core-20842
|
|
// and core-20845).
|
|
//
|
|
// - an lvalue-to-rvalue conversion (4.1 [conv.lval]) that is applied to a
|
|
// glvalue of type cv1 T that refers to an object of type cv2 U, where T and U
|
|
// are neither the same type nor similar types (4.4 [conv.qual]);
|
|
|
|
// - an lvalue-to-rvalue conversion (4.1) that is applied to a glvalue that
|
|
// refers to a non-active member of a union or a subobject thereof;
|
|
namespace LValueToRValueUnion {
|
|
// test/SemaCXX/constant-expression-cxx11.cpp contains more thorough testing
|
|
// of this.
|
|
union U { int a, b; } constexpr u = U();
|
|
static_assert(u.a == 0, "");
|
|
constexpr const int *bp = &u.b;
|
|
constexpr int b = *bp; // expected-error {{constant expression}} expected-note {{read of member 'b' of union with active member 'a'}}
|
|
|
|
extern const U pu;
|
|
constexpr const int *pua = &pu.a;
|
|
constexpr const int *pub = &pu.b;
|
|
constexpr U pu = { .b = 1 }; // cxx11-warning {{C++20 extension}}
|
|
constexpr const int a2 = *pua; // expected-error {{constant expression}} expected-note {{read of member 'a' of union with active member 'b'}}
|
|
constexpr const int b2 = *pub; // ok
|
|
}
|
|
|
|
// - an id-expression that refers to a variable or data member of reference type
|
|
// unless the reference has a preceding initialization, initialized with a
|
|
// constant expression;
|
|
namespace References {
|
|
const int a = 2;
|
|
int &b = *const_cast<int*>(&a);
|
|
int c = 10; // expected-note 2 {{here}}
|
|
int &d = c;
|
|
constexpr int e = 42;
|
|
int &f = const_cast<int&>(e);
|
|
extern int &g; // expected-note {{here}}
|
|
constexpr int &h(); // expected-note {{here}}
|
|
int &i = h(); // expected-note {{here}}
|
|
constexpr int &j() { return b; }
|
|
int &k = j();
|
|
|
|
struct S {
|
|
int A : a;
|
|
int B : b;
|
|
int C : c; // expected-error {{constant expression}} expected-note {{read of non-const variable 'c'}}
|
|
int D : d; // expected-error {{constant expression}} expected-note {{read of non-const variable 'c'}}
|
|
int D2 : &d - &c + 1;
|
|
int E : e / 2;
|
|
int F : f - 11;
|
|
int G : g; // expected-error {{constant expression}} expected-note {{initializer of 'g' is unknown}}
|
|
int H : h(); // expected-error {{constant expression}} expected-note {{undefined function 'h'}}
|
|
int I : i; // expected-error {{constant expression}} expected-note {{initializer of 'i' is not a constant expression}}
|
|
int J : j();
|
|
int K : k;
|
|
};
|
|
}
|
|
|
|
// - a dynamic_cast (5.2.7);
|
|
namespace DynamicCast {
|
|
struct S { int n; };
|
|
constexpr S s { 16 };
|
|
struct T {
|
|
int n : dynamic_cast<const S*>(&s)->n; // cxx11-warning {{constant expression}} cxx11-note {{dynamic_cast}}
|
|
};
|
|
}
|
|
|
|
// - a reinterpret_cast (5.2.10);
|
|
namespace ReinterpretCast {
|
|
struct S { int n; };
|
|
constexpr S s { 16 };
|
|
struct T {
|
|
int n : reinterpret_cast<const S*>(&s)->n; // expected-warning {{constant expression}} expected-note {{reinterpret_cast}}
|
|
};
|
|
struct U {
|
|
int m : (long)(S*)6; // expected-warning {{constant expression}} expected-note {{reinterpret_cast}}
|
|
};
|
|
}
|
|
|
|
// - a pseudo-destructor call (5.2.4);
|
|
namespace PseudoDtor {
|
|
int k;
|
|
typedef int I;
|
|
struct T {
|
|
int n : (k.~I(), 1); // expected-error {{constant expression}} expected-note {{visible outside that expression}}
|
|
};
|
|
|
|
constexpr int f(int a = 1) { // cxx11-error {{constant expression}} expected-note {{destroying object 'a' whose lifetime has already ended}}
|
|
return (
|
|
a.~I(), // cxx11-note {{pseudo-destructor}}
|
|
0);
|
|
}
|
|
static_assert(f() == 0, ""); // expected-error {{constant expression}}
|
|
|
|
// This is OK in C++20: the union has no active member after the
|
|
// pseudo-destructor call, so the union destructor has no effect.
|
|
union U { int x; };
|
|
constexpr int g(U u = {1}) { // cxx11-error {{constant expression}}
|
|
return (
|
|
u.x.~I(), // cxx11-note 2{{pseudo-destructor}}
|
|
0);
|
|
}
|
|
static_assert(g() == 0, ""); // cxx11-error {{constant expression}} cxx11-note {{in call}}
|
|
}
|
|
|
|
// - increment or decrement operations (5.2.6, 5.3.2);
|
|
namespace IncDec {
|
|
int k = 2;
|
|
struct T {
|
|
int n : ++k; // expected-error {{constant expression}} cxx20-note {{visible outside}}
|
|
int m : --k; // expected-error {{constant expression}} cxx20-note {{visible outside}}
|
|
};
|
|
}
|
|
|
|
// - a typeid expression (5.2.8) whose operand is of a polymorphic class type;
|
|
namespace std {
|
|
struct type_info {
|
|
virtual ~type_info();
|
|
const char *name;
|
|
};
|
|
}
|
|
namespace TypeId {
|
|
struct S { virtual void f(); };
|
|
constexpr S *p = 0;
|
|
constexpr const std::type_info &ti1 = typeid(*p); // expected-error {{must be initialized by a constant expression}} cxx11-note {{typeid applied to expression of polymorphic type 'TypeId::S'}} cxx20-note {{dereferenced null pointer}}
|
|
|
|
struct T {} t;
|
|
constexpr const std::type_info &ti2 = typeid(t);
|
|
}
|
|
|
|
// - a new-expression (5.3.4);
|
|
// - a delete-expression (5.3.5);
|
|
namespace NewDelete {
|
|
constexpr int *p = 0;
|
|
struct T {
|
|
int n : *new int(4); // expected-warning {{constant expression}} cxx11-note {{until C++20}} cxx20-note {{was not deallocated}}
|
|
int m : (delete p, 2); // cxx11-warning {{constant expression}} cxx11-note {{until C++20}}
|
|
};
|
|
}
|
|
|
|
// - a relational (5.9) or equality (5.10) operator where the result is
|
|
// unspecified;
|
|
namespace UnspecifiedRelations {
|
|
int a, b;
|
|
constexpr int *p = &a, *q = &b;
|
|
// C++11 [expr.rel]p2: If two pointers p and q of the same type point to
|
|
// different objects that are not members of the same array or to different
|
|
// functions, or if only one of them is null, the results of p<q, p>q, p<=q,
|
|
// and p>=q are unspecified.
|
|
constexpr bool u1 = p < q; // expected-error {{constant expression}} expected-note {{comparison has unspecified value}}
|
|
constexpr bool u2 = p > q; // expected-error {{constant expression}} expected-note {{comparison has unspecified value}}
|
|
constexpr bool u3 = p <= q; // expected-error {{constant expression}} expected-note {{comparison has unspecified value}}
|
|
constexpr bool u4 = p >= q; // expected-error {{constant expression}} expected-note {{comparison has unspecified value}}
|
|
constexpr bool u5 = p < (int*)0; // expected-error {{constant expression}} expected-note {{comparison has unspecified value}}
|
|
constexpr bool u6 = p <= (int*)0; // expected-error {{constant expression}} expected-note {{comparison has unspecified value}}
|
|
constexpr bool u7 = p > (int*)0; // expected-error {{constant expression}} expected-note {{comparison has unspecified value}}
|
|
constexpr bool u8 = p >= (int*)0; // expected-error {{constant expression}} expected-note {{comparison has unspecified value}}
|
|
constexpr bool u9 = (int*)0 < q; // expected-error {{constant expression}} expected-note {{comparison has unspecified value}}
|
|
constexpr bool u10 = (int*)0 <= q; // expected-error {{constant expression}} expected-note {{comparison has unspecified value}}
|
|
constexpr bool u11 = (int*)0 > q; // expected-error {{constant expression}} expected-note {{comparison has unspecified value}}
|
|
constexpr bool u12 = (int*)0 >= q; // expected-error {{constant expression}} expected-note {{comparison has unspecified value}}
|
|
void f(), g();
|
|
|
|
constexpr void (*pf)() = &f, (*pg)() = &g;
|
|
constexpr bool u13 = pf < pg; // expected-error {{constant expression}} expected-note {{comparison has unspecified value}}
|
|
constexpr bool u14 = pf == pg;
|
|
|
|
// If two pointers point to non-static data members of the same object with
|
|
// different access control, the result is unspecified.
|
|
struct A {
|
|
public:
|
|
constexpr A() : a(0), b(0) {}
|
|
int a;
|
|
constexpr bool cmp() const { return &a < &b; } // expected-note {{comparison of address of fields 'a' and 'b' of 'A' with differing access specifiers (public vs private) has unspecified value}}
|
|
private:
|
|
int b;
|
|
};
|
|
static_assert(A().cmp(), ""); // expected-error {{constant expression}} expected-note {{in call}}
|
|
class B {
|
|
public:
|
|
A a;
|
|
constexpr bool cmp() const { return &a.a < &b.a; } // expected-note {{comparison of address of fields 'a' and 'b' of 'B' with differing access specifiers (public vs protected) has unspecified value}}
|
|
protected:
|
|
A b;
|
|
};
|
|
static_assert(B().cmp(), ""); // expected-error {{constant expression}} expected-note {{in call}}
|
|
|
|
// If two pointers point to different base sub-objects of the same object, or
|
|
// one points to a base subobject and the other points to a member, the result
|
|
// of the comparison is unspecified. This is not explicitly called out by
|
|
// [expr.rel]p2, but is covered by 'Other pointer comparisons are
|
|
// unspecified'.
|
|
struct C {
|
|
int c[2];
|
|
};
|
|
struct D {
|
|
int d;
|
|
};
|
|
struct E : C, D {
|
|
struct Inner {
|
|
int f;
|
|
} e;
|
|
} e;
|
|
constexpr bool base1 = &e.c[0] < &e.d; // expected-error {{constant expression}} expected-note {{comparison of addresses of subobjects of different base classes has unspecified value}}
|
|
constexpr bool base2 = &e.c[1] < &e.e.f; // expected-error {{constant expression}} expected-note {{comparison of address of base class subobject 'C' of class 'E' to field 'e' has unspecified value}}
|
|
constexpr bool base3 = &e.e.f < &e.d; // expected-error {{constant expression}} expected-note {{comparison of address of base class subobject 'D' of class 'E' to field 'e' has unspecified value}}
|
|
|
|
// [expr.rel]p3: Pointers to void can be compared [...] if both pointers
|
|
// represent the same address or are both the null pointer [...]; otherwise
|
|
// the result is unspecified.
|
|
struct S { int a, b; } s;
|
|
constexpr void *null = 0;
|
|
constexpr void *pv = (void*)&s.a;
|
|
constexpr void *qv = (void*)&s.b;
|
|
constexpr bool v1 = null < (int*)0;
|
|
constexpr bool v2 = null < pv; // expected-error {{constant expression}} expected-note {{comparison has unspecified value}}
|
|
constexpr bool v3 = null == pv; // ok
|
|
constexpr bool v4 = qv == pv; // ok
|
|
constexpr bool v5 = qv >= pv; // expected-error {{constant expression}} expected-note {{unequal pointers to void}}
|
|
constexpr bool v6 = qv > null; // expected-error {{constant expression}} expected-note {{comparison has unspecified value}}
|
|
constexpr bool v7 = qv <= (void*)&s.b; // ok
|
|
constexpr bool v8 = qv > (void*)&s.a; // expected-error {{constant expression}} expected-note {{unequal pointers to void}}
|
|
}
|
|
|
|
// - an assignment or a compound assignment (5.17); or
|
|
namespace Assignment {
|
|
int k;
|
|
struct T {
|
|
int n : (k = 9); // expected-error {{constant expression}} cxx20-note {{visible outside}}
|
|
int m : (k *= 2); // expected-error {{constant expression}} cxx20-note {{visible outside}}
|
|
};
|
|
|
|
struct Literal {
|
|
constexpr Literal(const char *name) : name(name) {}
|
|
const char *name;
|
|
};
|
|
struct Expr {
|
|
constexpr Expr(Literal l) : IsLiteral(true), l(l) {}
|
|
bool IsLiteral;
|
|
union {
|
|
Literal l;
|
|
// ...
|
|
};
|
|
};
|
|
struct MulEq {
|
|
constexpr MulEq(Expr a, Expr b) : LHS(a), RHS(b) {}
|
|
Expr LHS;
|
|
Expr RHS;
|
|
};
|
|
constexpr MulEq operator*=(Expr a, Expr b) { return MulEq(a, b); }
|
|
Literal a("a");
|
|
Literal b("b");
|
|
MulEq c = a *= b; // ok
|
|
}
|
|
|
|
// - a throw-expression (15.1)
|
|
namespace Throw {
|
|
struct S {
|
|
int n : (throw "hello", 10); // expected-error {{constant expression}}
|
|
};
|
|
}
|
|
|
|
// PR9999
|
|
template<unsigned int v>
|
|
class bitWidthHolding {
|
|
public:
|
|
static const
|
|
unsigned int width = (v == 0 ? 0 : bitWidthHolding<(v >> 1)>::width + 1);
|
|
};
|
|
|
|
static const int width=bitWidthHolding<255>::width;
|
|
|
|
template<bool b>
|
|
struct always_false {
|
|
static const bool value = false;
|
|
};
|
|
|
|
template<bool b>
|
|
struct and_or {
|
|
static const bool and_value = b && and_or<always_false<b>::value>::and_value;
|
|
static const bool or_value = !b || and_or<always_false<b>::value>::or_value;
|
|
};
|
|
|
|
static const bool and_value = and_or<true>::and_value;
|
|
static const bool or_value = and_or<true>::or_value;
|
|
|
|
static_assert(and_value == false, "");
|
|
static_assert(or_value == true, "");
|
|
|
|
namespace rdar13090123 {
|
|
typedef __INTPTR_TYPE__ intptr_t;
|
|
|
|
constexpr intptr_t f(intptr_t x) {
|
|
return (((x) >> 21) * 8);
|
|
}
|
|
|
|
extern "C" int foo;
|
|
|
|
constexpr intptr_t i = f((intptr_t)&foo - 10); // expected-error{{constexpr variable 'i' must be initialized by a constant expression}} \
|
|
// expected-note{{reinterpret_cast}}
|
|
}
|