// RUN: %clang_cc1 -triple x86_64-linux -Wno-string-plus-int -Wno-pointer-arith -Wno-zero-length-array -Wno-c99-designator -fsyntax-only -fcxx-exceptions -verify -std=c++11 -pedantic %s -Wno-comment -Wno-tautological-pointer-compare -Wno-bool-conversion namespace StaticAssertFoldTest { int x; static_assert(++x, "test"); // expected-error {{not an integral constant expression}} static_assert(false, "test"); // expected-error {{test}} } typedef decltype(sizeof(char)) size_t; template constexpr T id(const T &t) { return t; } template constexpr T min(const T &a, const T &b) { return a < b ? a : b; } template constexpr T max(const T &a, const T &b) { return a < b ? b : a; } template constexpr T *begin(T (&xs)[N]) { return xs; } template constexpr T *end(T (&xs)[N]) { return xs + N; } struct MemberZero { constexpr int zero() const { return 0; } }; namespace DerivedToVBaseCast { struct U { int n; }; struct V : U { int n; }; struct A : virtual V { int n; }; struct Aa { int n; }; struct B : virtual A, Aa {}; struct C : virtual A, Aa {}; struct D : B, C {}; D d; constexpr B *p = &d; constexpr C *q = &d; static_assert((void*)p != (void*)q, ""); static_assert((A*)p == (A*)q, ""); static_assert((Aa*)p != (Aa*)q, ""); constexpr B &pp = d; constexpr C &qq = d; static_assert((void*)&pp != (void*)&qq, ""); static_assert(&(A&)pp == &(A&)qq, ""); static_assert(&(Aa&)pp != &(Aa&)qq, ""); constexpr V *v = p; constexpr V *w = q; constexpr V *x = (A*)p; static_assert(v == w, ""); static_assert(v == x, ""); static_assert((U*)&d == p, ""); static_assert((U*)&d == q, ""); static_assert((U*)&d == v, ""); static_assert((U*)&d == w, ""); static_assert((U*)&d == x, ""); struct X {}; struct Y1 : virtual X {}; struct Y2 : X {}; struct Z : Y1, Y2 {}; Z z; static_assert((X*)(Y1*)&z != (X*)(Y2*)&z, ""); } namespace ConstCast { constexpr int n1 = 0; constexpr int n2 = const_cast(n1); constexpr int *n3 = const_cast(&n1); constexpr int n4 = *const_cast(&n1); constexpr const int * const *n5 = const_cast(&n3); constexpr int **n6 = const_cast(&n3); constexpr int n7 = **n5; constexpr int n8 = **n6; // const_cast from prvalue to xvalue. struct A { int n; }; constexpr int n9 = (const_cast(A{123})).n; static_assert(n9 == 123, ""); } namespace TemplateArgumentConversion { template struct IntParam {}; using IntParam0 = IntParam<0>; using IntParam0 = IntParam; using IntParam0 = IntParam; // expected-error {{did you mean to call it with no arguments?}} } namespace CaseStatements { int x; void f(int n) { switch (n) { case MemberZero().zero: // expected-error {{did you mean to call it with no arguments?}} expected-note {{previous}} case id(0): // expected-error {{duplicate case value '0'}} return; case __builtin_constant_p(true) ? (__SIZE_TYPE__)&x : 0:; // expected-error {{constant}} } } } extern int &Recurse1; int &Recurse2 = Recurse1; // expected-note {{declared here}} int &Recurse1 = Recurse2; constexpr int &Recurse3 = Recurse2; // expected-error {{must be initialized by a constant expression}} expected-note {{initializer of 'Recurse2' is not a constant expression}} extern const int RecurseA; const int RecurseB = RecurseA; // expected-note {{declared here}} const int RecurseA = 10; constexpr int RecurseC = RecurseB; // expected-error {{must be initialized by a constant expression}} expected-note {{initializer of 'RecurseB' is not a constant expression}} namespace MemberEnum { struct WithMemberEnum { enum E { A = 42 }; } wme; static_assert(wme.A == 42, ""); } namespace DefaultArguments { const int z = int(); constexpr int Sum(int a = 0, const int &b = 0, const int *c = &z, char d = 0) { return a + b + *c + d; } const int four = 4; constexpr int eight = 8; constexpr const int twentyseven = 27; static_assert(Sum() == 0, ""); static_assert(Sum(1) == 1, ""); static_assert(Sum(1, four) == 5, ""); static_assert(Sum(1, eight, &twentyseven) == 36, ""); static_assert(Sum(1, 2, &four, eight) == 15, ""); } namespace Ellipsis { // Note, values passed through an ellipsis can't actually be used. constexpr int F(int a, ...) { return a; } static_assert(F(0) == 0, ""); static_assert(F(1, 0) == 1, ""); static_assert(F(2, "test") == 2, ""); static_assert(F(3, &F) == 3, ""); int k = 0; // expected-note {{here}} static_assert(F(4, k) == 3, ""); // expected-error {{constant expression}} expected-note {{read of non-const variable 'k'}} } namespace Recursion { constexpr int fib(int n) { return n > 1 ? fib(n-1) + fib(n-2) : n; } static_assert(fib(11) == 89, ""); constexpr int gcd_inner(int a, int b) { return b == 0 ? a : gcd_inner(b, a % b); } constexpr int gcd(int a, int b) { return gcd_inner(max(a, b), min(a, b)); } static_assert(gcd(1749237, 5628959) == 7, ""); } namespace FunctionCast { // When folding, we allow functions to be cast to different types. Such // cast functions cannot be called, even if they're constexpr. constexpr int f() { return 1; } typedef double (*DoubleFn)(); typedef int (*IntFn)(); int a[(int)DoubleFn(f)()]; // expected-error {{variable length array}} expected-warning{{C99 feature}} int b[(int)IntFn(f)()]; // ok } namespace StaticMemberFunction { struct S { static constexpr int k = 42; static constexpr int f(int n) { return n * k + 2; } } s; constexpr int n = s.f(19); static_assert(S::f(19) == 800, ""); static_assert(s.f(19) == 800, ""); static_assert(n == 800, ""); constexpr int (*sf1)(int) = &S::f; constexpr int (*sf2)(int) = &s.f; constexpr const int *sk = &s.k; // Note, out_of_lifetime returns an invalid pointer value, but we don't do // anything with it (other than copy it around), so there's no UB there. constexpr S *out_of_lifetime(S s) { return &s; } // expected-warning {{address of stack}} static_assert(out_of_lifetime({})->k == 42, ""); static_assert(out_of_lifetime({})->f(3) == 128, ""); // Similarly, using an inactive union member breaks no rules. union U { int n; S s; }; constexpr U u = {0}; static_assert(u.s.k == 42, ""); static_assert(u.s.f(1) == 44, ""); // And likewise for a past-the-end pointer. static_assert((&s)[1].k == 42, ""); static_assert((&s)[1].f(1) == 44, ""); } namespace ParameterScopes { const int k = 42; constexpr const int &ObscureTheTruth(const int &a) { return a; } constexpr const int &MaybeReturnJunk(bool b, const int a) { return ObscureTheTruth(b ? a : k); } static_assert(MaybeReturnJunk(false, 0) == 42, ""); // ok constexpr int a = MaybeReturnJunk(true, 0); // expected-error {{constant expression}} expected-note {{read of object outside its lifetime}} constexpr const int MaybeReturnNonstaticRef(bool b, const int a) { return ObscureTheTruth(b ? a : k); } static_assert(MaybeReturnNonstaticRef(false, 0) == 42, ""); // ok constexpr int b = MaybeReturnNonstaticRef(true, 0); // ok constexpr int InternalReturnJunk(int n) { return MaybeReturnJunk(true, n); // expected-note {{read of object outside its lifetime}} } constexpr int n3 = InternalReturnJunk(0); // expected-error {{must be initialized by a constant expression}} expected-note {{in call to 'InternalReturnJunk(0)'}} constexpr int LToR(int &n) { return n; } constexpr int GrabCallersArgument(bool which, int a, int b) { return LToR(which ? b : a); } static_assert(GrabCallersArgument(false, 1, 2) == 1, ""); static_assert(GrabCallersArgument(true, 4, 8) == 8, ""); } namespace Pointers { constexpr int f(int n, const int *a, const int *b, const int *c) { return n == 0 ? 0 : *a + f(n-1, b, c, a); } const int x = 1, y = 10, z = 100; static_assert(f(23, &x, &y, &z) == 788, ""); constexpr int g(int n, int a, int b, int c) { return f(n, &a, &b, &c); } static_assert(g(23, x, y, z) == 788, ""); } namespace FunctionPointers { constexpr int Double(int n) { return 2 * n; } constexpr int Triple(int n) { return 3 * n; } constexpr int Twice(int (*F)(int), int n) { return F(F(n)); } constexpr int Quadruple(int n) { return Twice(Double, n); } constexpr auto Select(int n) -> int (*)(int) { return n == 2 ? &Double : n == 3 ? &Triple : n == 4 ? &Quadruple : 0; } constexpr int Apply(int (*F)(int), int n) { return F(n); } // expected-note {{subexpression}} static_assert(1 + Apply(Select(4), 5) + Apply(Select(3), 7) == 42, ""); constexpr int Invalid = Apply(Select(0), 0); // expected-error {{must be initialized by a constant expression}} expected-note {{in call to 'Apply(nullptr, 0)'}} } namespace PointerComparison { int x, y; static_assert(&x == &y, "false"); // expected-error {{false}} static_assert(&x != &y, ""); constexpr bool g1 = &x == &y; constexpr bool g2 = &x != &y; constexpr bool g3 = &x <= &y; // expected-error {{must be initialized by a constant expression}} expected-note {{unspecified}} constexpr bool g4 = &x >= &y; // expected-error {{must be initialized by a constant expression}} expected-note {{unspecified}} constexpr bool g5 = &x < &y; // expected-error {{must be initialized by a constant expression}} expected-note {{unspecified}} constexpr bool g6 = &x > &y; // expected-error {{must be initialized by a constant expression}} expected-note {{unspecified}} struct S { int x, y; } s; static_assert(&s.x == &s.y, "false"); // expected-error {{false}} static_assert(&s.x != &s.y, ""); static_assert(&s.x <= &s.y, ""); static_assert(&s.x >= &s.y, "false"); // expected-error {{false}} static_assert(&s.x < &s.y, ""); static_assert(&s.x > &s.y, "false"); // expected-error {{false}} static_assert(0 == &y, "false"); // expected-error {{false}} static_assert(0 != &y, ""); constexpr bool n3 = (int*)0 <= &y; // expected-error {{must be initialized by a constant expression}} expected-note {{unspecified}} constexpr bool n4 = (int*)0 >= &y; // expected-error {{must be initialized by a constant expression}} expected-note {{unspecified}} constexpr bool n5 = (int*)0 < &y; // expected-error {{must be initialized by a constant expression}} expected-note {{unspecified}} constexpr bool n6 = (int*)0 > &y; // expected-error {{must be initialized by a constant expression}} expected-note {{unspecified}} static_assert(&x == 0, "false"); // expected-error {{false}} static_assert(&x != 0, ""); constexpr bool n9 = &x <= (int*)0; // expected-error {{must be initialized by a constant expression}} expected-note {{unspecified}} constexpr bool n10 = &x >= (int*)0; // expected-error {{must be initialized by a constant expression}} expected-note {{unspecified}} constexpr bool n11 = &x < (int*)0; // expected-error {{must be initialized by a constant expression}} expected-note {{unspecified}} constexpr bool n12 = &x > (int*)0; // expected-error {{must be initialized by a constant expression}} expected-note {{unspecified}} static_assert(&x == &x, ""); static_assert(&x != &x, "false"); // expected-error {{false}} static_assert(&x <= &x, ""); static_assert(&x >= &x, ""); static_assert(&x < &x, "false"); // expected-error {{false}} static_assert(&x > &x, "false"); // expected-error {{false}} constexpr S* sptr = &s; constexpr bool dyncast = sptr == dynamic_cast(sptr); // expected-error {{constant expression}} expected-note {{dynamic_cast}} struct U {}; struct Str { int a : dynamic_cast(sptr) == dynamic_cast(sptr); // \ expected-warning {{not an integral constant expression}} \ expected-note {{dynamic_cast is not allowed in a constant expression}} int b : reinterpret_cast(sptr) == reinterpret_cast(sptr); // \ expected-warning {{not an integral constant expression}} \ expected-note {{reinterpret_cast is not allowed in a constant expression}} int c : (S*)(long)(sptr) == (S*)(long)(sptr); // \ expected-warning {{not an integral constant expression}} \ expected-note {{cast that performs the conversions of a reinterpret_cast is not allowed in a constant expression}} int d : (S*)(42) == (S*)(42); // \ expected-warning {{not an integral constant expression}} \ expected-note {{cast that performs the conversions of a reinterpret_cast is not allowed in a constant expression}} int e : (Str*)(sptr) == (Str*)(sptr); // \ expected-warning {{not an integral constant expression}} \ expected-note {{cast that performs the conversions of a reinterpret_cast is not allowed in a constant expression}} int f : &(U&)(*sptr) == &(U&)(*sptr); // \ expected-warning {{not an integral constant expression}} \ expected-note {{cast that performs the conversions of a reinterpret_cast is not allowed in a constant expression}} int g : (S*)(void*)(sptr) == sptr; // \ expected-warning {{not an integral constant expression}} \ expected-note {{cast from 'void *' is not allowed in a constant expression}} }; extern char externalvar[]; constexpr bool constaddress = (void *)externalvar == (void *)0x4000UL; // expected-error {{must be initialized by a constant expression}} expected-note {{reinterpret_cast}} constexpr bool litaddress = "foo" == "foo"; // expected-error {{must be initialized by a constant expression}} static_assert(0 != "foo", ""); } namespace MaterializeTemporary { constexpr int f(const int &r) { return r; } constexpr int n = f(1); constexpr bool same(const int &a, const int &b) { return &a == &b; } constexpr bool sameTemporary(const int &n) { return same(n, n); } static_assert(n, ""); static_assert(!same(4, 4), ""); static_assert(same(n, n), ""); static_assert(sameTemporary(9), ""); struct A { int &&r; }; struct B { A &&a1; A &&a2; }; constexpr B b1 { { 1 }, { 2 } }; // expected-note {{temporary created here}} static_assert(&b1.a1 != &b1.a2, ""); static_assert(&b1.a1.r != &b1.a2.r, ""); // expected-error {{constant expression}} expected-note {{outside the expression that created the temporary}} constexpr B &&b2 { { 3 }, { 4 } }; // expected-note {{temporary created here}} static_assert(&b1 != &b2, ""); static_assert(&b1.a1 != &b2.a1, ""); // expected-error {{constant expression}} expected-note {{outside the expression that created the temporary}} constexpr thread_local B b3 { { 1 }, { 2 } }; // expected-error {{constant expression}} expected-note {{reference to temporary}} expected-note {{here}} void foo() { constexpr static B b1 { { 1 }, { 2 } }; // ok constexpr thread_local B b2 { { 1 }, { 2 } }; // expected-error {{constant expression}} expected-note {{reference to temporary}} expected-note {{here}} constexpr B b3 { { 1 }, { 2 } }; // expected-error {{constant expression}} expected-note {{reference to temporary}} expected-note {{here}} } constexpr B &&b4 = ((1, 2), 3, 4, B { {10}, {{20}} }); static_assert(&b4 != &b2, ""); // Proposed DR: copy-elision doesn't trigger lifetime extension. // expected-warning@+1 2{{temporary whose address is used as value of local variable 'b5' will be destroyed at the end of the full-expression}} constexpr B b5 = B{ {0}, {0} }; // expected-error {{constant expression}} expected-note {{reference to temporary}} expected-note {{here}} namespace NestedNonStatic { // Proposed DR: for a reference constant expression to refer to a static // storage duration temporary, that temporary must itself be initialized // by a constant expression (a core constant expression is not enough). struct A { int &&r; }; struct B { A &&a; }; constexpr B a = { A{0} }; // ok // expected-warning@+1 {{temporary bound to reference member of local variable 'b' will be destroyed at the end of the full-expression}} constexpr B b = { A(A{0}) }; // expected-error {{constant expression}} expected-note {{reference to temporary}} expected-note {{here}} } namespace FakeInitList { struct init_list_3_ints { const int (&x)[3]; }; struct init_list_2_init_list_3_ints { const init_list_3_ints (&x)[2]; }; constexpr init_list_2_init_list_3_ints ils = { { { { 1, 2, 3 } }, { { 4, 5, 6 } } } }; } namespace ConstAddedByReference { const int &r = (0); constexpr int n = r; int &&r2 = 0; // expected-note {{created here}} constexpr int n2 = r2; // expected-error {{constant}} expected-note {{read of temporary}} struct A { constexpr operator int() const { return 0; }}; struct B { constexpr operator const int() const { return 0; }}; const int &ra = A(); const int &rb = B(); constexpr int na = ra; constexpr int nb = rb; struct C { int &&r; }; constexpr C c1 = {1}; constexpr int &c1r = c1.r; constexpr const C &c2 = {2}; constexpr int &c2r = c2.r; constexpr C &&c3 = {3}; // expected-note {{created here}} constexpr int &c3r = c3.r; // expected-error {{constant}} expected-note {{read of temporary}} } } constexpr int strcmp_ce(const char *p, const char *q) { return (!*p || *p != *q) ? *p - *q : strcmp_ce(p+1, q+1); } namespace StringLiteral { template constexpr int MangleChars(const Char *p) { return *p + 3 * (*p ? MangleChars(p+1) : 0); } static_assert(MangleChars("constexpr!") == 1768383, ""); static_assert(MangleChars(u8"constexpr!") == 1768383, ""); static_assert(MangleChars(L"constexpr!") == 1768383, ""); static_assert(MangleChars(u"constexpr!") == 1768383, ""); static_assert(MangleChars(U"constexpr!") == 1768383, ""); constexpr char c0 = "nought index"[0]; constexpr char c1 = "nice index"[10]; constexpr char c2 = "nasty index"[12]; // expected-error {{must be initialized by a constant expression}} expected-note {{read of dereferenced one-past-the-end pointer}} constexpr char c3 = "negative index"[-1]; // expected-error {{must be initialized by a constant expression}} expected-note {{cannot refer to element -1 of array of 15 elements}} constexpr char c4 = ((char*)(int*)"no reinterpret_casts allowed")[14]; // expected-error {{must be initialized by a constant expression}} expected-note {{cast that performs the conversions of a reinterpret_cast}} constexpr const char *p = "test" + 2; static_assert(*p == 's', ""); constexpr const char *max_iter(const char *a, const char *b) { return *a < *b ? b : a; } constexpr const char *max_element(const char *a, const char *b) { return (a+1 >= b) ? a : max_iter(a, max_element(a+1, b)); } constexpr char str[] = "the quick brown fox jumped over the lazy dog"; constexpr const char *max = max_element(begin(str), end(str)); static_assert(*max == 'z', ""); static_assert(max == str + 38, ""); static_assert(strcmp_ce("hello world", "hello world") == 0, ""); static_assert(strcmp_ce("hello world", "hello clang") > 0, ""); static_assert(strcmp_ce("constexpr", "test") < 0, ""); static_assert(strcmp_ce("", " ") < 0, ""); struct S { int n : "foo"[4]; // expected-error {{constant expression}} expected-note {{read of dereferenced one-past-the-end pointer is not allowed in a constant expression}} }; struct T { char c[6]; constexpr T() : c{"foo"} {} }; constexpr T t; static_assert(t.c[0] == 'f', ""); static_assert(t.c[1] == 'o', ""); static_assert(t.c[2] == 'o', ""); static_assert(t.c[3] == 0, ""); static_assert(t.c[4] == 0, ""); static_assert(t.c[5] == 0, ""); static_assert(t.c[6] == 0, ""); // expected-error {{constant expression}} expected-note {{one-past-the-end}} struct U { wchar_t chars[6]; int n; } constexpr u = { { L"test" }, 0 }; static_assert(u.chars[2] == L's', ""); struct V { char c[4]; constexpr V() : c("hi!") {} }; static_assert(V().c[1] == "i"[0], ""); namespace Parens { constexpr unsigned char a[] = ("foo"), b[] = {"foo"}, c[] = {("foo")}, d[4] = ("foo"), e[5] = {"foo"}, f[6] = {("foo")}; static_assert(a[0] == 'f', ""); static_assert(b[1] == 'o', ""); static_assert(c[2] == 'o', ""); static_assert(d[0] == 'f', ""); static_assert(e[1] == 'o', ""); static_assert(f[2] == 'o', ""); static_assert(f[5] == 0, ""); static_assert(f[6] == 0, ""); // expected-error {{constant expression}} expected-note {{one-past-the-end}} } } namespace Array { template constexpr auto Sum(Iter begin, Iter end) -> decltype(+*begin) { return begin == end ? 0 : *begin + Sum(begin+1, end); } constexpr int xs[] = { 1, 2, 3, 4, 5 }; constexpr int ys[] = { 5, 4, 3, 2, 1 }; constexpr int sum_xs = Sum(begin(xs), end(xs)); static_assert(sum_xs == 15, ""); constexpr int ZipFoldR(int (*F)(int x, int y, int c), int n, const int *xs, const int *ys, int c) { return n ? F( *xs, // expected-note {{read of dereferenced one-past-the-end pointer}} *ys, ZipFoldR(F, n-1, xs+1, ys+1, c)) // \ expected-note {{in call to 'ZipFoldR(&SubMul, 2, &xs[4], &ys[4], 1)'}} \ expected-note {{in call to 'ZipFoldR(&SubMul, 1, &xs[5], &ys[5], 1)'}} : c; } constexpr int MulAdd(int x, int y, int c) { return x * y + c; } constexpr int InnerProduct = ZipFoldR(MulAdd, 5, xs, ys, 0); static_assert(InnerProduct == 35, ""); constexpr int SubMul(int x, int y, int c) { return (x - y) * c; } constexpr int DiffProd = ZipFoldR(SubMul, 2, xs+3, ys+3, 1); static_assert(DiffProd == 8, ""); static_assert(ZipFoldR(SubMul, 3, xs+3, ys+3, 1), ""); // \ expected-error {{constant expression}} \ expected-note {{in call to 'ZipFoldR(&SubMul, 3, &xs[3], &ys[3], 1)'}} constexpr const int *p = xs + 3; constexpr int xs4 = p[1]; // ok constexpr int xs5 = p[2]; // expected-error {{constant expression}} expected-note {{read of dereferenced one-past-the-end pointer}} constexpr int xs6 = p[3]; // expected-error {{constant expression}} expected-note {{cannot refer to element 6}} constexpr int xs0 = p[-3]; // ok constexpr int xs_1 = p[-4]; // expected-error {{constant expression}} expected-note {{cannot refer to element -1}} constexpr int zs[2][2][2][2] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 }; static_assert(zs[0][0][0][0] == 1, ""); static_assert(zs[1][1][1][1] == 16, ""); static_assert(zs[0][0][0][2] == 3, ""); // expected-error {{constant expression}} expected-note {{read of dereferenced one-past-the-end pointer}} static_assert((&zs[0][0][0][2])[-1] == 2, ""); static_assert(**(**(zs + 1) + 1) == 11, ""); static_assert(*(&(&(*(*&(&zs[2] - 1)[0] + 2 - 2))[2])[-1][-1] + 1) == 11, ""); // expected-error {{constant expression}} expected-note {{cannot refer to element -1 of array of 2 elements in a constant expression}} static_assert(*(&(&(*(*&(&zs[2] - 1)[0] + 2 - 2))[2])[-1][2] - 2) == 11, ""); constexpr int err_zs_1_2_0_0 = zs[1][2][0][0]; // \ expected-error {{constant expression}} \ expected-note {{cannot access array element of pointer past the end}} constexpr int fail(const int &p) { return (&p)[64]; // expected-note {{cannot refer to element 64 of array of 2 elements}} } static_assert(fail(*(&(&(*(*&(&zs[2] - 1)[0] + 2 - 2))[2])[-1][2] - 2)) == 11, ""); // \ expected-error {{static_assert expression is not an integral constant expression}} \ expected-note {{in call to 'fail(zs[1][0][1][0])'}} constexpr int arr[40] = { 1, 2, 3, [8] = 4 }; constexpr int SumNonzero(const int *p) { return *p + (*p ? SumNonzero(p+1) : 0); } constexpr int CountZero(const int *p, const int *q) { return p == q ? 0 : (*p == 0) + CountZero(p+1, q); } static_assert(SumNonzero(arr) == 6, ""); static_assert(CountZero(arr, arr + 40) == 36, ""); struct ArrayElem { constexpr ArrayElem() : n(0) {} int n; constexpr int f() const { return n; } }; struct ArrayRVal { constexpr ArrayRVal() {} ArrayElem elems[10]; }; static_assert(ArrayRVal().elems[3].f() == 0, ""); namespace CopyCtor { struct A { constexpr A() {} constexpr A(const A &) {} }; struct B { A a; int arr[10]; }; constexpr B b{{}, {1, 2, 3, 4, 5}}; constexpr B c = b; static_assert(c.arr[2] == 3, ""); static_assert(c.arr[7] == 0, ""); // OK: the copy ctor for X doesn't read any members. struct X { struct Y {} y; } x1; constexpr X x2 = x1; } constexpr int selfref[2][2][2] = { 1, selfref[0][0][0] + 1, 1, selfref[0][1][0] + 1, 1, selfref[0][1][1] + 1 }; static_assert(selfref[0][0][0] == 1, ""); static_assert(selfref[0][0][1] == 2, ""); static_assert(selfref[0][1][0] == 1, ""); static_assert(selfref[0][1][1] == 2, ""); static_assert(selfref[1][0][0] == 1, ""); static_assert(selfref[1][0][1] == 3, ""); static_assert(selfref[1][1][0] == 0, ""); static_assert(selfref[1][1][1] == 0, ""); constexpr int badselfref[2][2][2] = { // expected-error {{constant expression}} badselfref[1][0][0] // expected-note {{outside its lifetime}} }; struct TrivialDefCtor { int n; }; typedef TrivialDefCtor TDCArray[2][2]; static_assert(TDCArray{}[1][1].n == 0, ""); struct NonAggregateTDC : TrivialDefCtor {}; typedef NonAggregateTDC NATDCArray[2][2]; static_assert(NATDCArray{}[1][1].n == 0, ""); } // Per current CWG direction, we reject any cases where pointer arithmetic is // not statically known to be valid. namespace ArrayOfUnknownBound { extern int arr[]; constexpr int *a = arr; constexpr int *b = &arr[0]; static_assert(a == b, ""); constexpr int *c = &arr[1]; // expected-error {{constant}} expected-note {{indexing of array without known bound}} constexpr int *d = &a[1]; // expected-error {{constant}} expected-note {{indexing of array without known bound}} constexpr int *e = a + 1; // expected-error {{constant}} expected-note {{indexing of array without known bound}} struct X { int a; int b[]; // expected-warning {{C99}} }; extern X x; constexpr int *xb = x.b; // expected-error {{constant}} expected-note {{not supported}} struct Y { int a; }; extern Y yarr[]; constexpr Y *p = yarr; constexpr int *q = &p->a; extern const int carr[]; // expected-note {{here}} constexpr int n = carr[0]; // expected-error {{constant}} expected-note {{non-constexpr variable}} constexpr int local_extern[] = {1, 2, 3}; void f() { extern const int local_extern[]; } static_assert(local_extern[1] == 2, ""); } namespace DependentValues { struct I { int n; typedef I V[10]; }; I::V x, y; int g(); // expected-note {{declared here}} template struct S : T { int k; void f() { I::V &cells = B ? x : y; I &i = cells[k]; switch (i.n) {} constexpr int n = g(); // expected-error {{must be initialized by a constant expression}} expected-note {{non-constexpr function 'g'}} constexpr int m = this->g(); // ok, could be constexpr } }; extern const int n; // expected-note {{declared here}} template void f() { // This is ill-formed, because a hypothetical instantiation at the point of // template definition would be ill-formed due to a construct that does not // depend on a template parameter. constexpr int k = n; // expected-error {{must be initialized by a constant expression}} expected-note {{initializer of 'n' is unknown}} } // It doesn't matter that the instantiation could later become valid: constexpr int n = 4; template void f(); } namespace Class { struct A { constexpr A(int a, int b) : k(a + b) {} int k; }; constexpr int fn(const A &a) { return a.k; } static_assert(fn(A(4,5)) == 9, ""); struct B { int n; int m; } constexpr b = { 0, b.n }; struct C { constexpr C(C *this_) : m(42), n(this_->m) {} // ok int m, n; }; struct D { C c; constexpr D() : c(&c) {} }; static_assert(D().c.n == 42, ""); struct E { constexpr E() : p(&p) {} void *p; }; constexpr const E &e1 = E(); // This is a constant expression if we elide the copy constructor call, and // is not a constant expression if we don't! But we do, so it is. constexpr E e2 = E(); static_assert(e2.p == &e2.p, ""); constexpr E e3; static_assert(e3.p == &e3.p, ""); extern const class F f; struct F { constexpr F() : p(&f.p) {} const void *p; }; constexpr F f; struct G { struct T { constexpr T(T *p) : u1(), u2(p) {} union U1 { constexpr U1() {} int a, b = 42; } u1; union U2 { constexpr U2(T *p) : c(p->u1.b) {} int c, d; } u2; } t; constexpr G() : t(&t) {} } constexpr g; static_assert(g.t.u1.a == 42, ""); // expected-error {{constant expression}} expected-note {{read of member 'a' of union with active member 'b'}} static_assert(g.t.u1.b == 42, ""); static_assert(g.t.u2.c == 42, ""); static_assert(g.t.u2.d == 42, ""); // expected-error {{constant expression}} expected-note {{read of member 'd' of union with active member 'c'}} struct S { int a, b; const S *p; double d; const char *q; constexpr S(int n, const S *p) : a(5), b(n), p(p), d(n), q("hello") {} }; S global(43, &global); static_assert(S(15, &global).b == 15, ""); constexpr bool CheckS(const S &s) { return s.a == 5 && s.b == 27 && s.p == &global && s.d == 27. && s.q[3] == 'l'; } static_assert(CheckS(S(27, &global)), ""); struct Arr { char arr[3]; constexpr Arr() : arr{'x', 'y', 'z'} {} }; constexpr int hash(Arr &&a) { return a.arr[0] + a.arr[1] * 0x100 + a.arr[2] * 0x10000; } constexpr int k = hash(Arr()); static_assert(k == 0x007a7978, ""); struct AggregateInit { const char &c; int n; double d; int arr[5]; void *p; }; constexpr AggregateInit agg1 = { "hello"[0] }; static_assert(strcmp_ce(&agg1.c, "hello") == 0, ""); static_assert(agg1.n == 0, ""); static_assert(agg1.d == 0.0, ""); static_assert(agg1.arr[-1] == 0, ""); // expected-error {{constant expression}} expected-note {{cannot refer to element -1}} static_assert(agg1.arr[0] == 0, ""); static_assert(agg1.arr[4] == 0, ""); static_assert(agg1.arr[5] == 0, ""); // expected-error {{constant expression}} expected-note {{read of dereferenced one-past-the-end}} static_assert(agg1.p == nullptr, ""); static constexpr const unsigned char uc[] = { "foo" }; static_assert(uc[0] == 'f', ""); static_assert(uc[3] == 0, ""); namespace SimpleDerivedClass { struct B { constexpr B(int n) : a(n) {} int a; }; struct D : B { constexpr D(int n) : B(n) {} }; constexpr D d(3); static_assert(d.a == 3, ""); } struct Bottom { constexpr Bottom() {} }; struct Base : Bottom { constexpr Base(int a = 42, const char *b = "test") : a(a), b(b) {} int a; const char *b; }; struct Base2 : Bottom { constexpr Base2(const int &r) : r(r) {} int q = 123; const int &r; }; struct Derived : Base, Base2 { constexpr Derived() : Base(76), Base2(a) {} int c = r + b[1]; }; constexpr bool operator==(const Base &a, const Base &b) { return a.a == b.a && strcmp_ce(a.b, b.b) == 0; } constexpr Base base; constexpr Base base2(76); constexpr Derived derived; static_assert(derived.a == 76, ""); static_assert(derived.b[2] == 's', ""); static_assert(derived.c == 76 + 'e', ""); static_assert(derived.q == 123, ""); static_assert(derived.r == 76, ""); static_assert(&derived.r == &derived.a, ""); static_assert(!(derived == base), ""); static_assert(derived == base2, ""); constexpr Bottom &bot1 = (Base&)derived; constexpr Bottom &bot2 = (Base2&)derived; static_assert(&bot1 != &bot2, ""); constexpr Bottom *pb1 = (Base*)&derived; constexpr Bottom *pb2 = (Base2*)&derived; static_assert(&pb1 != &pb2, ""); static_assert(pb1 == &bot1, ""); static_assert(pb2 == &bot2, ""); constexpr Base2 &fail = (Base2&)bot1; // expected-error {{constant expression}} expected-note {{cannot cast object of dynamic type 'const Class::Derived' to type 'Class::Base2'}} constexpr Base &fail2 = (Base&)*pb2; // expected-error {{constant expression}} expected-note {{cannot cast object of dynamic type 'const Class::Derived' to type 'Class::Base'}} constexpr Base2 &ok2 = (Base2&)bot2; static_assert(&ok2 == &derived, ""); constexpr Base2 *pfail = (Base2*)pb1; // expected-error {{constant expression}} expected-note {{cannot cast object of dynamic type 'const Class::Derived' to type 'Class::Base2'}} constexpr Base *pfail2 = (Base*)&bot2; // expected-error {{constant expression}} expected-note {{cannot cast object of dynamic type 'const Class::Derived' to type 'Class::Base'}} constexpr Base2 *pok2 = (Base2*)pb2; static_assert(pok2 == &derived, ""); static_assert(&ok2 == pok2, ""); static_assert((Base2*)(Derived*)(Base*)pb1 == pok2, ""); static_assert((Derived*)(Base*)pb1 == (Derived*)pok2, ""); // Core issue 903: we do not perform constant evaluation when checking for a // null pointer in C++11. Just check for an integer literal with value 0. constexpr Base *nullB = 42 - 6 * 7; // expected-error {{cannot initialize a variable of type 'Class::Base *const' with an rvalue of type 'int'}} constexpr Base *nullB1 = 0; static_assert((Bottom*)nullB == 0, ""); static_assert((Derived*)nullB1 == 0, ""); static_assert((void*)(Bottom*)nullB1 == (void*)(Derived*)nullB1, ""); Base *nullB2 = '\0'; // expected-error {{cannot initialize a variable of type 'Class::Base *' with an rvalue of type 'char'}} Base *nullB3 = (0); Base *nullB4 = false; // expected-error {{cannot initialize a variable of type 'Class::Base *' with an rvalue of type 'bool'}} Base *nullB5 = ((0ULL)); Base *nullB6 = 0.; // expected-error {{cannot initialize a variable of type 'Class::Base *' with an rvalue of type 'double'}} enum Null { kNull }; Base *nullB7 = kNull; // expected-error {{cannot initialize a variable of type 'Class::Base *' with an rvalue of type 'Class::Null'}} static_assert(nullB1 == (1 - 1), ""); // expected-error {{comparison between pointer and integer}} namespace ConversionOperators { struct T { constexpr T(int n) : k(5*n - 3) {} constexpr operator int() const { return k; } int k; }; struct S { constexpr S(int n) : k(2*n + 1) {} constexpr operator int() const { return k; } constexpr operator T() const { return T(k); } int k; }; constexpr bool check(T a, T b) { return a == b.k; } static_assert(S(5) == 11, ""); static_assert(check(S(5), 11), ""); namespace PR14171 { struct X { constexpr (operator int)() const { return 0; } }; static_assert(X() == 0, ""); } } struct This { constexpr int f() const { return 0; } static constexpr int g() { return 0; } void h() { constexpr int x = f(); // expected-error {{must be initialized by a constant}} // expected-note@-1 {{implicit use of 'this' pointer is only allowed within the evaluation of a call to a 'constexpr' member function}} constexpr int y = this->f(); // expected-error {{must be initialized by a constant}} // expected-note-re@-1 {{{{^}}use of 'this' pointer}} constexpr int z = g(); static_assert(z == 0, ""); } }; } namespace Temporaries { struct S { constexpr S() {} constexpr int f() const; constexpr int g() const; }; struct T : S { constexpr T(int n) : S(), n(n) {} int n; }; constexpr int S::f() const { return static_cast(this)->n; // expected-note {{cannot cast}} } constexpr int S::g() const { // FIXME: Better diagnostic for this. return this->*(int(S::*))&T::n; // expected-note {{subexpression}} } // The T temporary is implicitly cast to an S subobject, but we can recover the // T full-object via a base-to-derived cast, or a derived-to-base-casted member // pointer. static_assert(S().f(), ""); // expected-error {{constant expression}} expected-note {{in call to '&Temporaries::S()->f()'}} static_assert(S().g(), ""); // expected-error {{constant expression}} expected-note {{in call to '&Temporaries::S()->g()'}} static_assert(T(3).f() == 3, ""); static_assert(T(4).g() == 4, ""); constexpr int f(const S &s) { return static_cast(s).n; } constexpr int n = f(T(5)); static_assert(f(T(5)) == 5, ""); constexpr bool b(int n) { return &n; } static_assert(b(0), ""); struct NonLiteral { NonLiteral(); int f(); }; constexpr int k = NonLiteral().f(); // expected-error {{constant expression}} expected-note {{non-literal type 'Temporaries::NonLiteral'}} } namespace Union { union U { int a; int b; }; constexpr U u[4] = { { .a = 0 }, { .b = 1 }, { .a = 2 }, { .b = 3 } }; static_assert(u[0].a == 0, ""); static_assert(u[0].b, ""); // expected-error {{constant expression}} expected-note {{read of member 'b' of union with active member 'a'}} static_assert(u[1].b == 1, ""); static_assert((&u[1].b)[1] == 2, ""); // expected-error {{constant expression}} expected-note {{read of dereferenced one-past-the-end pointer}} static_assert(*(&(u[1].b) + 1 + 1) == 3, ""); // expected-error {{constant expression}} expected-note {{cannot refer to element 2 of non-array object}} static_assert((&(u[1]) + 1 + 1)->b == 3, ""); constexpr U v = {}; static_assert(v.a == 0, ""); union Empty {}; constexpr Empty e = {}; // Make sure we handle trivial copy constructors for unions. constexpr U x = {42}; constexpr U y = x; static_assert(y.a == 42, ""); static_assert(y.b == 42, ""); // expected-error {{constant expression}} expected-note {{'b' of union with active member 'a'}} } namespace MemberPointer { struct A { constexpr A(int n) : n(n) {} int n; constexpr int f() const { return n + 3; } }; constexpr A a(7); static_assert(A(5).*&A::n == 5, ""); static_assert((&a)->*&A::n == 7, ""); static_assert((A(8).*&A::f)() == 11, ""); static_assert(((&a)->*&A::f)() == 10, ""); struct B : A { constexpr B(int n, int m) : A(n), m(m) {} int m; constexpr int g() const { return n + m + 1; } }; constexpr B b(9, 13); static_assert(B(4, 11).*&A::n == 4, ""); static_assert(B(4, 11).*&B::m == 11, ""); static_assert(B(4, 11).*(int(A::*))&B::m == 11, ""); static_assert((&b)->*&A::n == 9, ""); static_assert((&b)->*&B::m == 13, ""); static_assert((&b)->*(int(A::*))&B::m == 13, ""); static_assert((B(4, 11).*&A::f)() == 7, ""); static_assert((B(4, 11).*&B::g)() == 16, ""); static_assert((B(4, 11).*(int(A::*)()const)&B::g)() == 16, ""); static_assert(((&b)->*&A::f)() == 12, ""); static_assert(((&b)->*&B::g)() == 23, ""); static_assert(((&b)->*(int(A::*)()const)&B::g)() == 23, ""); struct S { constexpr S(int m, int n, int (S::*pf)() const, int S::*pn) : m(m), n(n), pf(pf), pn(pn) {} constexpr S() : m(), n(), pf(&S::f), pn(&S::n) {} constexpr int f() const { return this->*pn; } virtual int g() const; int m, n; int (S::*pf)() const; int S::*pn; }; constexpr int S::*pm = &S::m; constexpr int S::*pn = &S::n; constexpr int (S::*pf)() const = &S::f; constexpr int (S::*pg)() const = &S::g; constexpr S s(2, 5, &S::f, &S::m); static_assert((s.*&S::f)() == 2, ""); static_assert((s.*s.pf)() == 2, ""); static_assert(pf == &S::f, ""); static_assert(pf == s.*&S::pf, ""); static_assert(pm == &S::m, ""); static_assert(pm != pn, ""); static_assert(s.pn != pn, ""); static_assert(s.pn == pm, ""); static_assert(pg != nullptr, ""); static_assert(pf != nullptr, ""); static_assert((int S::*)nullptr == nullptr, ""); static_assert(pg == pg, ""); // expected-error {{constant expression}} expected-note {{comparison of pointer to virtual member function 'g' has unspecified value}} static_assert(pf != pg, ""); // expected-error {{constant expression}} expected-note {{comparison of pointer to virtual member function 'g' has unspecified value}} template struct T : T {}; template<> struct T<0> { int n; }; template<> struct T<30> : T<29> { int m; }; T<17> t17; T<30> t30; constexpr int (T<10>::*deepn) = &T<0>::n; static_assert(&(t17.*deepn) == &t17.n, ""); static_assert(deepn == &T<2>::n, ""); constexpr int (T<15>::*deepm) = (int(T<10>::*))&T<30>::m; constexpr int *pbad = &(t17.*deepm); // expected-error {{constant expression}} static_assert(&(t30.*deepm) == &t30.m, ""); static_assert(deepm == &T<50>::m, ""); static_assert(deepm != deepn, ""); constexpr T<5> *p17_5 = &t17; constexpr T<13> *p17_13 = (T<13>*)p17_5; constexpr T<23> *p17_23 = (T<23>*)p17_13; // expected-error {{constant expression}} expected-note {{cannot cast object of dynamic type 'T<17>' to type 'T<23>'}} static_assert(&(p17_5->*(int(T<3>::*))deepn) == &t17.n, ""); static_assert(&(p17_13->*deepn) == &t17.n, ""); constexpr int *pbad2 = &(p17_13->*(int(T<9>::*))deepm); // expected-error {{constant expression}} constexpr T<5> *p30_5 = &t30; constexpr T<23> *p30_23 = (T<23>*)p30_5; constexpr T<13> *p30_13 = p30_23; static_assert(&(p30_5->*(int(T<3>::*))deepn) == &t30.n, ""); static_assert(&(p30_13->*deepn) == &t30.n, ""); static_assert(&(p30_23->*deepn) == &t30.n, ""); static_assert(&(p30_5->*(int(T<2>::*))deepm) == &t30.m, ""); static_assert(&(((T<17>*)p30_13)->*deepm) == &t30.m, ""); static_assert(&(p30_23->*deepm) == &t30.m, ""); struct Base { int n; }; template struct Mid : Base {}; struct Derived : Mid<0>, Mid<1> {}; static_assert(&Mid<0>::n == &Mid<1>::n, ""); static_assert((int Derived::*)(int Mid<0>::*)&Mid<0>::n != (int Derived::*)(int Mid<1>::*)&Mid<1>::n, ""); static_assert(&Mid<0>::n == (int Mid<0>::*)&Base::n, ""); constexpr int apply(const A &a, int (A::*f)() const) { return (a.*f)(); } static_assert(apply(A(2), &A::f) == 5, ""); } namespace ArrayBaseDerived { struct Base { constexpr Base() {} int n = 0; }; struct Derived : Base { constexpr Derived() {} constexpr const int *f() const { return &n; } }; constexpr Derived a[10]; constexpr Derived *pd3 = const_cast(&a[3]); constexpr Base *pb3 = const_cast(&a[3]); static_assert(pb3 == pd3, ""); // pb3 does not point to an array element. constexpr Base *pb4 = pb3 + 1; // ok, one-past-the-end pointer. constexpr int pb4n = pb4->n; // expected-error {{constant expression}} expected-note {{cannot access field of pointer past the end}} constexpr Base *err_pb5 = pb3 + 2; // expected-error {{constant expression}} expected-note {{cannot refer to element 2}} expected-note {{here}} constexpr int err_pb5n = err_pb5->n; // expected-error {{constant expression}} expected-note {{initializer of 'err_pb5' is not a constant expression}} constexpr Base *err_pb2 = pb3 - 1; // expected-error {{constant expression}} expected-note {{cannot refer to element -1}} expected-note {{here}} constexpr int err_pb2n = err_pb2->n; // expected-error {{constant expression}} expected-note {{initializer of 'err_pb2'}} constexpr Base *pb3a = pb4 - 1; // pb4 does not point to a Derived. constexpr Derived *err_pd4 = (Derived*)pb4; // expected-error {{constant expression}} expected-note {{cannot access derived class of pointer past the end}} constexpr Derived *pd3a = (Derived*)pb3a; constexpr int pd3n = pd3a->n; // pd3a still points to the Derived array. constexpr Derived *pd6 = pd3a + 3; static_assert(pd6 == &a[6], ""); constexpr Derived *pd9 = pd6 + 3; constexpr Derived *pd10 = pd6 + 4; constexpr int pd9n = pd9->n; // ok constexpr int err_pd10n = pd10->n; // expected-error {{constant expression}} expected-note {{cannot access base class of pointer past the end}} constexpr int pd0n = pd10[-10].n; constexpr int err_pdminus1n = pd10[-11].n; // expected-error {{constant expression}} expected-note {{cannot refer to element -1 of}} constexpr Base *pb9 = pd9; constexpr const int *(Base::*pfb)() const = static_cast(&Derived::f); static_assert((pb9->*pfb)() == &a[9].n, ""); } namespace Complex { class complex { int re, im; public: constexpr complex(int re = 0, int im = 0) : re(re), im(im) {} constexpr complex(const complex &o) : re(o.re), im(o.im) {} constexpr complex operator-() const { return complex(-re, -im); } friend constexpr complex operator+(const complex &l, const complex &r) { return complex(l.re + r.re, l.im + r.im); } friend constexpr complex operator-(const complex &l, const complex &r) { return l + -r; } friend constexpr complex operator*(const complex &l, const complex &r) { return complex(l.re * r.re - l.im * r.im, l.re * r.im + l.im * r.re); } friend constexpr bool operator==(const complex &l, const complex &r) { return l.re == r.re && l.im == r.im; } constexpr bool operator!=(const complex &r) const { return re != r.re || im != r.im; } constexpr int real() const { return re; } constexpr int imag() const { return im; } }; constexpr complex i = complex(0, 1); constexpr complex k = (3 + 4*i) * (6 - 4*i); static_assert(complex(1,0).real() == 1, ""); static_assert(complex(1,0).imag() == 0, ""); static_assert(((complex)1).imag() == 0, ""); static_assert(k.real() == 34, ""); static_assert(k.imag() == 12, ""); static_assert(k - 34 == 12*i, ""); static_assert((complex)1 == complex(1), ""); static_assert((complex)1 != complex(0, 1), ""); static_assert(complex(1) == complex(1), ""); static_assert(complex(1) != complex(0, 1), ""); constexpr complex makeComplex(int re, int im) { return complex(re, im); } static_assert(makeComplex(1,0) == complex(1), ""); static_assert(makeComplex(1,0) != complex(0, 1), ""); class complex_wrap : public complex { public: constexpr complex_wrap(int re, int im = 0) : complex(re, im) {} constexpr complex_wrap(const complex_wrap &o) : complex(o) {} }; static_assert((complex_wrap)1 == complex(1), ""); static_assert((complex)1 != complex_wrap(0, 1), ""); static_assert(complex(1) == complex_wrap(1), ""); static_assert(complex_wrap(1) != complex(0, 1), ""); constexpr complex_wrap makeComplexWrap(int re, int im) { return complex_wrap(re, im); } static_assert(makeComplexWrap(1,0) == complex(1), ""); static_assert(makeComplexWrap(1,0) != complex(0, 1), ""); } namespace PR11595 { struct A { constexpr bool operator==(int x) const { return true; } }; struct B { B(); A& x; }; static_assert(B().x == 3, ""); // expected-error {{constant expression}} expected-note {{non-literal type 'PR11595::B' cannot be used in a constant expression}} constexpr bool f(int k) { // expected-error {{constexpr function never produces a constant expression}} return B().x == k; // expected-note {{non-literal type 'PR11595::B' cannot be used in a constant expression}} } } namespace ExprWithCleanups { struct A { A(); ~A(); int get(); }; constexpr int get(bool FromA) { return FromA ? A().get() : 1; } constexpr int n = get(false); } namespace Volatile { volatile constexpr int n1 = 0; // expected-note {{here}} volatile const int n2 = 0; // expected-note {{here}} int n3 = 37; // expected-note {{declared here}} constexpr int m1 = n1; // expected-error {{constant expression}} expected-note {{read of volatile-qualified type 'const volatile int'}} constexpr int m2 = n2; // expected-error {{constant expression}} expected-note {{read of volatile-qualified type 'const volatile int'}} constexpr int m1b = const_cast(n1); // expected-error {{constant expression}} expected-note {{read of volatile object 'n1'}} constexpr int m2b = const_cast(n2); // expected-error {{constant expression}} expected-note {{read of volatile object 'n2'}} struct T { int n; }; const T t = { 42 }; // expected-note {{declared here}} constexpr int f(volatile int &&r) { return r; // expected-note {{read of volatile-qualified type 'volatile int'}} } constexpr int g(volatile int &&r) { return const_cast(r); // expected-note {{read of volatile temporary is not allowed in a constant expression}} } struct S { int j : f(0); // expected-error {{constant expression}} expected-note {{in call to 'f(0)'}} int k : g(0); // expected-error {{constant expression}} expected-note {{temporary created here}} expected-note {{in call to 'g(0)'}} int l : n3; // expected-error {{constant expression}} expected-note {{read of non-const variable}} int m : t.n; // expected-warning{{width of bit-field 'm' (42 bits)}} expected-warning{{expression is not an integral constant expression}} expected-note{{read of non-constexpr variable 't' is not allowed}} }; } namespace ExternConstexpr { extern constexpr int n = 0; extern constexpr int m; // expected-error {{constexpr variable declaration must be a definition}} void f() { extern constexpr int i; // expected-error {{constexpr variable declaration must be a definition}} constexpr int j = 0; constexpr int k; // expected-error {{default initialization of an object of const type}} } extern const int q; constexpr int g() { return q; } // expected-note {{outside its lifetime}} constexpr int q = g(); // expected-error {{constant expression}} expected-note {{in call}} extern int r; // expected-note {{here}} constexpr int h() { return r; } // expected-error {{never produces a constant}} expected-note {{read of non-const}} struct S { int n; }; extern const S s; constexpr int x() { return s.n; } // expected-note {{outside its lifetime}} constexpr S s = {x()}; // expected-error {{constant expression}} expected-note {{in call}} } namespace ComplexConstexpr { constexpr _Complex float test1 = {}; // expected-warning {{'_Complex' is a C99 extension}} constexpr _Complex float test2 = {1}; // expected-warning {{'_Complex' is a C99 extension}} constexpr _Complex double test3 = {1,2}; // expected-warning {{'_Complex' is a C99 extension}} constexpr _Complex int test4 = {4}; // expected-warning {{'_Complex' is a C99 extension}} constexpr _Complex int test5 = 4; // expected-warning {{'_Complex' is a C99 extension}} constexpr _Complex int test6 = {5,6}; // expected-warning {{'_Complex' is a C99 extension}} typedef _Complex float fcomplex; // expected-warning {{'_Complex' is a C99 extension}} constexpr fcomplex test7 = fcomplex(); constexpr const double &t2r = __real test3; constexpr const double &t2i = __imag test3; static_assert(&t2r + 1 == &t2i, ""); static_assert(t2r == 1.0, ""); static_assert(t2i == 2.0, ""); constexpr const double *t2p = &t2r; static_assert(t2p[-1] == 0.0, ""); // expected-error {{constant expr}} expected-note {{cannot refer to element -1 of array of 2 elements}} static_assert(t2p[0] == 1.0, ""); static_assert(t2p[1] == 2.0, ""); static_assert(t2p[2] == 0.0, ""); // expected-error {{constant expr}} expected-note {{one-past-the-end pointer}} static_assert(t2p[3] == 0.0, ""); // expected-error {{constant expr}} expected-note {{cannot refer to element 3 of array of 2 elements}} constexpr _Complex float *p = 0; // expected-warning {{'_Complex' is a C99 extension}} constexpr float pr = __real *p; // expected-error {{constant expr}} expected-note {{cannot access real component of null}} constexpr float pi = __imag *p; // expected-error {{constant expr}} expected-note {{cannot access imaginary component of null}} constexpr const _Complex double *q = &test3 + 1; // expected-warning {{'_Complex' is a C99 extension}} constexpr double qr = __real *q; // expected-error {{constant expr}} expected-note {{cannot access real component of pointer past the end}} constexpr double qi = __imag *q; // expected-error {{constant expr}} expected-note {{cannot access imaginary component of pointer past the end}} static_assert(__real test6 == 5, ""); static_assert(__imag test6 == 6, ""); static_assert(&__imag test6 == &__real test6 + 1, ""); } // _Atomic(T) is exactly like T for the purposes of constant expression // evaluation.. namespace Atomic { constexpr _Atomic int n = 3; // expected-warning {{'_Atomic' is a C11 extension}} struct S { _Atomic(double) d; }; // expected-warning {{'_Atomic' is a C11 extension}} constexpr S s = { 0.5 }; constexpr double d1 = s.d; constexpr double d2 = n; constexpr _Atomic double d3 = n; // expected-warning {{'_Atomic' is a C11 extension}} constexpr _Atomic(int) n2 = d3; // expected-warning {{'_Atomic' is a C11 extension}} static_assert(d1 == 0.5, ""); static_assert(d3 == 3.0, ""); namespace PR16056 { struct TestVar { _Atomic(int) value; // expected-warning {{'_Atomic' is a C11 extension}} constexpr TestVar(int value) : value(value) {} }; constexpr TestVar testVar{-1}; static_assert(testVar.value == -1, ""); } namespace PR32034 { struct A {}; struct B { _Atomic(A) a; }; // expected-warning {{'_Atomic' is a C11 extension}} constexpr int n = (B(), B(), 0); struct C { constexpr C() {} void *self = this; }; constexpr _Atomic(C) c = C(); // expected-warning {{'_Atomic' is a C11 extension}} } } namespace InstantiateCaseStmt { template constexpr int f() { return x; } template int g(int c) { switch(c) { case f(): return 1; } return 0; } int gg(int c) { return g<4>(c); } } namespace ConvertedConstantExpr { extern int &m; extern int &n; // expected-note 2{{declared here}} constexpr int k = 4; int &m = const_cast(k); // If we have nothing more interesting to say, ensure we don't produce a // useless note and instead just point to the non-constant subexpression. enum class E { em = m, en = n, // expected-error {{not a constant expression}} expected-note {{initializer of 'n' is unknown}} eo = (m + // expected-error {{not a constant expression}} n // expected-note {{initializer of 'n' is unknown}} ), eq = reinterpret_cast((int*)0) // expected-error {{not a constant expression}} expected-note {{reinterpret_cast}} }; } namespace IndirectField { struct S { struct { // expected-warning {{GNU extension}} union { // expected-warning {{declared in an anonymous struct}} struct { // expected-warning {{GNU extension}} expected-warning {{declared in an anonymous union}} int a; int b; }; int c; }; int d; }; union { int e; int f; }; constexpr S(int a, int b, int d, int e) : a(a), b(b), d(d), e(e) {} constexpr S(int c, int d, int f) : c(c), d(d), f(f) {} }; constexpr S s1(1, 2, 3, 4); constexpr S s2(5, 6, 7); // FIXME: The diagnostics here do a very poor job of explaining which unnamed // member is active and which is requested. static_assert(s1.a == 1, ""); static_assert(s1.b == 2, ""); static_assert(s1.c == 0, ""); // expected-error {{constant expression}} expected-note {{union with active member}} static_assert(s1.d == 3, ""); static_assert(s1.e == 4, ""); static_assert(s1.f == 0, ""); // expected-error {{constant expression}} expected-note {{union with active member}} static_assert(s2.a == 0, ""); // expected-error {{constant expression}} expected-note {{union with active member}} static_assert(s2.b == 0, ""); // expected-error {{constant expression}} expected-note {{union with active member}} static_assert(s2.c == 5, ""); static_assert(s2.d == 6, ""); static_assert(s2.e == 0, ""); // expected-error {{constant expression}} expected-note {{union with active member}} static_assert(s2.f == 7, ""); } // DR1405: don't allow reading mutable members in constant expressions. namespace MutableMembers { struct MM { mutable int n; // expected-note 3{{declared here}} } constexpr mm = { 4 }; constexpr int mmn = mm.n; // expected-error {{constant expression}} expected-note {{read of mutable member 'n' is not allowed in a constant expression}} int x = (mm.n = 1, 3); constexpr int mmn2 = mm.n; // expected-error {{constant expression}} expected-note {{read of mutable member 'n' is not allowed in a constant expression}} // Here's one reason why allowing this would be a disaster... template struct Id { int k = n; }; int f() { constexpr MM m = { 0 }; ++m.n; return Id().k; // expected-error {{not a constant expression}} expected-note {{read of mutable member 'n' is not allowed in a constant expression}} } struct A { int n; }; struct B { mutable A a; }; // expected-note {{here}} struct C { B b; }; constexpr C c[3] = {}; constexpr int k = c[1].b.a.n; // expected-error {{constant expression}} expected-note {{mutable}} struct D { int x; mutable int y; }; // expected-note {{here}} constexpr D d1 = { 1, 2 }; int l = ++d1.y; constexpr D d2 = d1; // expected-error {{constant}} expected-note {{mutable}} expected-note {{in call}} struct E { union { int a; mutable int b; // expected-note {{here}} }; }; constexpr E e1 = {{1}}; constexpr E e2 = e1; // expected-error {{constant}} expected-note {{mutable}} expected-note {{in call}} struct F { union U { }; mutable U u; struct X { }; mutable X x; struct Y : X { X x; U u; }; mutable Y y; int n; }; // This is OK; we don't actually read any mutable state here. constexpr F f1 = {}; constexpr F f2 = f1; struct G { struct X {}; union U { X a; }; mutable U u; // expected-note {{here}} }; constexpr G g1 = {}; constexpr G g2 = g1; // expected-error {{constant}} expected-note {{mutable}} expected-note {{in call}} constexpr G::U gu1 = {}; constexpr G::U gu2 = gu1; union H { mutable G::X gx; // expected-note {{here}} }; constexpr H h1 = {}; constexpr H h2 = h1; // expected-error {{constant}} expected-note {{mutable}} expected-note {{in call}} } namespace Fold { // This macro forces its argument to be constant-folded, even if it's not // otherwise a constant expression. #define fold(x) (__builtin_constant_p(x) ? (x) : (x)) constexpr int n = (long)(char*)123; // expected-error {{constant expression}} expected-note {{reinterpret_cast}} constexpr int m = fold((long)(char*)123); // ok static_assert(m == 123, ""); #undef fold } namespace DR1454 { constexpr const int &f(const int &n) { return n; } constexpr int k1 = f(0); // ok struct Wrap { const int &value; }; constexpr const Wrap &g(const Wrap &w) { return w; } constexpr int k2 = g({0}).value; // ok // The temporary here has static storage duration, so we can bind a constexpr // reference to it. constexpr const int &i = 1; constexpr const int j = i; static_assert(j == 1, ""); // The temporary here is not const, so it can't be read outside the expression // in which it was created (per the C++14 rules, which we use to avoid a C++11 // defect). constexpr int &&k = 1; // expected-note {{temporary created here}} constexpr const int l = k; // expected-error {{constant expression}} expected-note {{read of temporary}} void f() { // The temporary here has automatic storage duration, so we can't bind a // constexpr reference to it. constexpr const int &i = 1; // expected-error {{constant expression}} expected-note 2{{temporary}} } } namespace RecursiveOpaqueExpr { template constexpr auto LastNonzero(Iter p, Iter q) -> decltype(+*p) { return p != q ? (LastNonzero(p+1, q) ?: *p) : 0; // expected-warning {{GNU}} } constexpr int arr1[] = { 1, 0, 0, 3, 0, 2, 0, 4, 0, 0 }; static_assert(LastNonzero(begin(arr1), end(arr1)) == 4, ""); constexpr int arr2[] = { 1, 0, 0, 3, 0, 2, 0, 4, 0, 5 }; static_assert(LastNonzero(begin(arr2), end(arr2)) == 5, ""); constexpr int arr3[] = { 1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }; static_assert(LastNonzero(begin(arr3), end(arr3)) == 2, ""); } namespace VLASizeof { void f(int k) { // expected-note {{here}} int arr[k]; // expected-warning {{C99}} expected-note {{function parameter 'k'}} constexpr int n = 1 + sizeof(arr) // expected-error {{constant expression}} * 3; } } namespace CompoundLiteral { // Matching GCC, file-scope array compound literals initialized by constants // are lifetime-extended. constexpr int *p = (int*)(int[1]){3}; // expected-warning {{C99}} static_assert(*p == 3, ""); static_assert((int[2]){1, 2}[1] == 2, ""); // expected-warning {{C99}} // Other kinds are not. struct X { int a[2]; }; constexpr int *n = (X){1, 2}.a; // expected-warning {{C99}} expected-warning {{temporary}} // expected-error@-1 {{constant expression}} // expected-note@-2 {{pointer to subobject of temporary}} // expected-note@-3 {{temporary created here}} void f() { static constexpr int *p = (int*)(int[1]){3}; // expected-warning {{C99}} expected-warning {{temporary}} // expected-error@-1 {{constant expression}} // expected-note@-2 {{pointer to subobject of temporary}} // expected-note@-3 {{temporary created here}} static_assert((int[2]){1, 2}[1] == 2, ""); // expected-warning {{C99}} } } namespace Vector { typedef int __attribute__((vector_size(16))) VI4; constexpr VI4 f(int n) { return VI4 { n * 3, n + 4, n - 5, n / 6 }; } constexpr auto v1 = f(10); typedef double __attribute__((vector_size(32))) VD4; constexpr VD4 g(int n) { return (VD4) { n / 2.0, n + 1.5, n - 5.4, n * 0.9 }; // expected-warning {{C99}} } constexpr auto v2 = g(4); } // PR12626, redux namespace InvalidClasses { void test0() { struct X; // expected-note {{forward declaration}} struct Y { bool b; X x; }; // expected-error {{field has incomplete type}} Y y; auto& b = y.b; } } namespace NamespaceAlias { constexpr int f() { namespace NS = NamespaceAlias; // expected-warning {{use of this statement in a constexpr function is a C++14 extension}} return &NS::f != nullptr; } } // Constructors can be implicitly constexpr, even for a non-literal type. namespace ImplicitConstexpr { struct Q { Q() = default; Q(const Q&) = default; Q(Q&&) = default; ~Q(); }; // expected-note 3{{here}} struct R { constexpr R() noexcept; constexpr R(const R&) noexcept; constexpr R(R&&) noexcept; ~R() noexcept; }; struct S { R r; }; // expected-note 3{{here}} struct T { T(const T&) noexcept; T(T &&) noexcept; ~T() noexcept; }; struct U { T t; }; // expected-note 3{{here}} static_assert(!__is_literal_type(Q), ""); static_assert(!__is_literal_type(R), ""); static_assert(!__is_literal_type(S), ""); static_assert(!__is_literal_type(T), ""); static_assert(!__is_literal_type(U), ""); struct Test { friend Q::Q() noexcept; // expected-error {{follows constexpr}} friend Q::Q(Q&&) noexcept; // expected-error {{follows constexpr}} friend Q::Q(const Q&) noexcept; // expected-error {{follows constexpr}} friend S::S() noexcept; // expected-error {{follows constexpr}} friend S::S(S&&) noexcept; // expected-error {{follows constexpr}} friend S::S(const S&) noexcept; // expected-error {{follows constexpr}} friend constexpr U::U() noexcept; // expected-error {{follows non-constexpr}} friend constexpr U::U(U&&) noexcept; // expected-error {{follows non-constexpr}} friend constexpr U::U(const U&) noexcept; // expected-error {{follows non-constexpr}} }; } // Indirectly test that an implicit lvalue to xvalue conversion performed for // an NRVO move operation isn't implemented as CK_LValueToRValue. namespace PR12826 { struct Foo {}; constexpr Foo id(Foo x) { return x; } constexpr Foo res(id(Foo())); } namespace PR13273 { struct U { int t; U() = default; }; struct S : U { S() = default; }; // S's default constructor isn't constexpr, because U's default constructor // doesn't initialize 't', but it's trivial, so value-initialization doesn't // actually call it. static_assert(S{}.t == 0, ""); } namespace PR12670 { struct S { constexpr S(int a0) : m(a0) {} constexpr S() : m(6) {} int m; }; constexpr S x[3] = { {4}, 5 }; static_assert(x[0].m == 4, ""); static_assert(x[1].m == 5, ""); static_assert(x[2].m == 6, ""); } // Indirectly test that an implicit lvalue-to-rvalue conversion is performed // when a conditional operator has one argument of type void and where the other // is a glvalue of class type. namespace ConditionalLValToRVal { struct A { constexpr A(int a) : v(a) {} int v; }; constexpr A f(const A &a) { return a.v == 0 ? throw a : a; } constexpr A a(4); static_assert(f(a).v == 4, ""); } namespace TLS { __thread int n; int m; constexpr bool b = &n == &n; constexpr int *p = &n; // expected-error{{constexpr variable 'p' must be initialized by a constant expression}} constexpr int *f() { return &n; } constexpr int *q = f(); // expected-error{{constexpr variable 'q' must be initialized by a constant expression}} constexpr bool c = f() == f(); constexpr int *g() { return &m; } constexpr int *r = g(); } namespace Void { constexpr void f() { return; } // expected-error{{constexpr function's return type 'void' is not a literal type}} void assert_failed(const char *msg, const char *file, int line); // expected-note {{declared here}} #define ASSERT(expr) ((expr) ? static_cast(0) : assert_failed(#expr, __FILE__, __LINE__)) template constexpr T get(T (&a)[S], size_t k) { return ASSERT(k > 0 && k < S), a[k]; // expected-note{{non-constexpr function 'assert_failed'}} } #undef ASSERT template int get(int (&a)[4], size_t); constexpr int arr[] = { 4, 1, 2, 3, 4 }; static_assert(get(arr, 1) == 1, ""); static_assert(get(arr, 4) == 4, ""); static_assert(get(arr, 0) == 4, ""); // expected-error{{not an integral constant expression}} \ // expected-note{{in call to 'get(arr, 0)'}} } namespace std { struct type_info; } namespace TypeId { struct A { virtual ~A(); }; A f(); A &g(); constexpr auto &x = typeid(f()); constexpr auto &y = typeid(g()); // expected-error{{constant expression}} \ // expected-note{{typeid applied to expression of polymorphic type 'TypeId::A' is not allowed in a constant expression}} \ // expected-warning {{expression with side effects will be evaluated despite being used as an operand to 'typeid'}} } namespace PR14203 { struct duration { constexpr duration() {} constexpr operator int() const { return 0; } }; // These are valid per P0859R0 (moved as DR). template void f() { constexpr duration d = duration(); } int n = sizeof(short{duration(duration())}); } namespace ArrayEltInit { struct A { constexpr A() : p(&p) {} void *p; }; constexpr A a[10]; static_assert(a[0].p == &a[0].p, ""); static_assert(a[9].p == &a[9].p, ""); static_assert(a[0].p != &a[9].p, ""); static_assert(a[9].p != &a[0].p, ""); constexpr A b[10] = {}; static_assert(b[0].p == &b[0].p, ""); static_assert(b[9].p == &b[9].p, ""); static_assert(b[0].p != &b[9].p, ""); static_assert(b[9].p != &b[0].p, ""); } namespace PR15884 { struct S {}; constexpr S f() { return {}; } constexpr S *p = &f(); // expected-error@-1 {{taking the address of a temporary}} // expected-error@-2 {{constexpr variable 'p' must be initialized by a constant expression}} // expected-note@-3 {{pointer to temporary is not a constant expression}} // expected-note@-4 {{temporary created here}} } namespace AfterError { constexpr int error() { return foobar; // expected-error {{undeclared identifier}} } constexpr int k = error(); // expected-error {{constexpr variable 'k' must be initialized by a constant expression}} } namespace std { typedef decltype(sizeof(int)) size_t; template class initializer_list { const _E* __begin_; size_t __size_; constexpr initializer_list(const _E* __b, size_t __s) : __begin_(__b), __size_(__s) {} public: typedef _E value_type; typedef const _E& reference; typedef const _E& const_reference; typedef size_t size_type; typedef const _E* iterator; typedef const _E* const_iterator; constexpr initializer_list() : __begin_(nullptr), __size_(0) {} constexpr size_t size() const {return __size_;} constexpr const _E* begin() const {return __begin_;} constexpr const _E* end() const {return __begin_ + __size_;} }; } namespace InitializerList { constexpr int sum(const int *b, const int *e) { return b != e ? *b + sum(b+1, e) : 0; } constexpr int sum(std::initializer_list ints) { return sum(ints.begin(), ints.end()); } static_assert(sum({1, 2, 3, 4, 5}) == 15, ""); static_assert(*std::initializer_list{1, 2, 3}.begin() == 1, ""); static_assert(std::initializer_list{1, 2, 3}.begin()[2] == 3, ""); namespace DR2126 { constexpr std::initializer_list il = {1.0, 2.0, 3.0}; static_assert(il.begin()[1] == 2.0, ""); } } namespace StmtExpr { struct A { int k; }; void f() { static_assert(({ const int x = 5; x * 3; }) == 15, ""); // expected-warning {{extension}} constexpr auto a = ({ A(); }); // expected-warning {{extension}} } constexpr int g(int k) { return ({ // expected-warning {{extension}} const int x = k; x * x; }); } static_assert(g(123) == 15129, ""); constexpr int h() { // expected-error {{never produces a constant}} return ({ // expected-warning {{extension}} return 0; // expected-note {{not supported}} 1; }); } } namespace VirtualFromBase { struct S1 { virtual int f() const; }; struct S2 { virtual int f(); }; template struct X : T { constexpr X() {} double d = 0.0; constexpr int f() { return sizeof(T); } // expected-warning {{will not be implicitly 'const' in C++14}} }; // Virtual f(), not OK. constexpr X> xxs1; constexpr X *p = const_cast>*>(&xxs1); static_assert(p->f() == sizeof(X), ""); // expected-error {{constant expression}} expected-note {{virtual function}} // Non-virtual f(), OK. constexpr X> xxs2; constexpr X *q = const_cast>*>(&xxs2); static_assert(q->f() == sizeof(S2), ""); } namespace ConstexprConstructorRecovery { class X { public: enum E : short { headers = 0x1, middlefile = 0x2, choices = 0x4 }; constexpr X() noexcept {}; protected: E val{0}; // expected-error {{cannot initialize a member subobject of type 'ConstexprConstructorRecovery::X::E' with an rvalue of type 'int'}} expected-note {{here}} }; // FIXME: We should avoid issuing this follow-on diagnostic. constexpr X x{}; // expected-error {{constant expression}} expected-note {{not initialized}} } namespace Lifetime { void f() { constexpr int &n = n; // expected-error {{constant expression}} expected-note {{use of reference outside its lifetime}} expected-warning {{not yet bound to a value}} constexpr int m = m; // expected-error {{constant expression}} expected-note {{read of object outside its lifetime}} } constexpr int &get(int &&n) { return n; } constexpr int &&get_rv(int &&n) { return static_cast(n); } struct S { int &&r; int &s; int t; constexpr S() : r(get_rv(0)), s(get(0)), t(r) {} // expected-note {{read of object outside its lifetime}} constexpr S(int) : r(get_rv(0)), s(get(0)), t(s) {} // expected-note {{read of object outside its lifetime}} }; constexpr int k1 = S().t; // expected-error {{constant expression}} expected-note {{in call}} constexpr int k2 = S(0).t; // expected-error {{constant expression}} expected-note {{in call}} struct Q { int n = 0; constexpr int f() const { return 0; } }; constexpr Q *out_of_lifetime(Q q) { return &q; } // expected-warning {{address of stack}} constexpr int k3 = out_of_lifetime({})->n; // expected-error {{constant expression}} expected-note {{read of object outside its lifetime}} constexpr int k4 = out_of_lifetime({})->f(); // expected-error {{constant expression}} expected-note {{member call on object outside its lifetime}} constexpr int null = ((Q*)nullptr)->f(); // expected-error {{constant expression}} expected-note {{member call on dereferenced null pointer}} Q q; Q qa[3]; constexpr int pte0 = (&q)[0].f(); // ok constexpr int pte1 = (&q)[1].f(); // expected-error {{constant expression}} expected-note {{member call on dereferenced one-past-the-end pointer}} constexpr int pte2 = qa[2].f(); // ok constexpr int pte3 = qa[3].f(); // expected-error {{constant expression}} expected-note {{member call on dereferenced one-past-the-end pointer}} constexpr Q cq; constexpr Q cqa[3]; constexpr int cpte0 = (&cq)[0].f(); // ok constexpr int cpte1 = (&cq)[1].f(); // expected-error {{constant expression}} expected-note {{member call on dereferenced one-past-the-end pointer}} constexpr int cpte2 = cqa[2].f(); // ok constexpr int cpte3 = cqa[3].f(); // expected-error {{constant expression}} expected-note {{member call on dereferenced one-past-the-end pointer}} // FIXME: There's no way if we can tell if the first call here is valid; it // depends on the active union member. Should we reject for that reason? union U { int n; Q q; }; U u1 = {0}; constexpr U u2 = {0}; constexpr int union_member1 = u1.q.f(); constexpr int union_member2 = u2.q.f(); // expected-error {{constant expression}} expected-note {{member call on member 'q' of union with active member 'n'}} struct R { // expected-note {{field init}} struct Inner { constexpr int f() const { return 0; } }; int a = b.f(); // expected-warning {{uninitialized}} expected-note 2{{member call on object outside its lifetime}} Inner b; }; constexpr R r; // expected-error {{constant expression}} expected-note {{in call}} expected-note {{implicit default constructor for 'Lifetime::R' first required here}} void rf() { constexpr R r; // expected-error {{constant expression}} expected-note {{in call}} } } namespace Bitfields { struct A { bool b : 1; unsigned u : 5; int n : 5; bool b2 : 3; unsigned u2 : 74; // expected-warning {{exceeds the width of its type}} int n2 : 81; // expected-warning {{exceeds the width of its type}} }; constexpr A a = { false, 33, 31, false, 0xffffffff, 0x7fffffff }; // expected-warning 2{{truncation}} static_assert(a.b == 0 && a.u == 1 && a.n == -1 && a.b2 == 0 && a.u2 + 1 == 0 && a.n2 == 0x7fffffff, "bad truncation of bitfield values"); struct B { int n : 3; constexpr B(int k) : n(k) {} }; static_assert(B(3).n == 3, ""); static_assert(B(4).n == -4, ""); static_assert(B(7).n == -1, ""); static_assert(B(8).n == 0, ""); static_assert(B(-1).n == -1, ""); static_assert(B(-8889).n == -1, ""); namespace PR16755 { struct X { int x : 1; constexpr static int f(int x) { return X{x}.x; } }; static_assert(X::f(3) == -1, "3 should truncate to -1"); } struct HasUnnamedBitfield { unsigned a; unsigned : 20; unsigned b; constexpr HasUnnamedBitfield() : a(), b() {} constexpr HasUnnamedBitfield(unsigned a, unsigned b) : a(a), b(b) {} }; void testUnnamedBitfield() { const HasUnnamedBitfield zero{}; int a = 1 / zero.b; // expected-warning {{division by zero is undefined}} const HasUnnamedBitfield oneZero{1, 0}; int b = 1 / oneZero.b; // expected-warning {{division by zero is undefined}} } union UnionWithUnnamedBitfield { int : 3; int n; }; static_assert(UnionWithUnnamedBitfield().n == 0, ""); static_assert(UnionWithUnnamedBitfield{}.n == 0, ""); static_assert(UnionWithUnnamedBitfield{1}.n == 1, ""); } namespace ZeroSizeTypes { constexpr int (*p1)[0] = 0, (*p2)[0] = 0; constexpr int k = p2 - p1; // expected-error@-1 {{constexpr variable 'k' must be initialized by a constant expression}} // expected-note@-2 {{subtraction of pointers to type 'int [0]' of zero size}} int arr[5][0]; constexpr int f() { // expected-error {{never produces a constant expression}} return &arr[3] - &arr[0]; // expected-note {{subtraction of pointers to type 'int [0]' of zero size}} } } namespace BadDefaultInit { template struct X { static const int n = N; }; struct A { // expected-error {{default member initializer for 'k' needed within definition of enclosing class}} int k = // expected-note {{default member initializer declared here}} X::n; // expected-note {{in evaluation of exception specification for 'BadDefaultInit::A::A' needed here}} }; struct B { constexpr B( int k = X::n) : // expected-error {{default argument to function 'B' that is declared later}} expected-note {{here}} k(k) {} int k; }; } namespace NeverConstantTwoWays { // If we see something non-constant but foldable followed by something // non-constant and not foldable, we want the first diagnostic, not the // second. constexpr int f(int n) { // expected-error {{never produces a constant expression}} return (int *)(long)&n == &n ? // expected-note {{reinterpret_cast}} 1 / 0 : // expected-warning {{division by zero}} 0; } constexpr int n = // expected-error {{must be initialized by a constant expression}} (int *)(long)&n == &n ? // expected-note {{reinterpret_cast}} 1 / 0 : 0; } namespace PR17800 { struct A { constexpr int operator()() const { return 0; } }; template constexpr int sink(T ...) { return 0; } template constexpr int run() { return sink(A()() + N ...); } constexpr int k = run<1, 2, 3>(); } namespace BuiltinStrlen { constexpr const char *a = "foo\0quux"; constexpr char b[] = "foo\0quux"; constexpr int f() { return 'u'; } constexpr char c[] = { 'f', 'o', 'o', 0, 'q', f(), 'u', 'x', 0 }; static_assert(__builtin_strlen("foo") == 3, ""); static_assert(__builtin_strlen("foo\0quux") == 3, ""); static_assert(__builtin_strlen("foo\0quux" + 4) == 4, ""); constexpr bool check(const char *p) { return __builtin_strlen(p) == 3 && __builtin_strlen(p + 1) == 2 && __builtin_strlen(p + 2) == 1 && __builtin_strlen(p + 3) == 0 && __builtin_strlen(p + 4) == 4 && __builtin_strlen(p + 5) == 3 && __builtin_strlen(p + 6) == 2 && __builtin_strlen(p + 7) == 1 && __builtin_strlen(p + 8) == 0; } static_assert(check(a), ""); static_assert(check(b), ""); static_assert(check(c), ""); constexpr int over1 = __builtin_strlen(a + 9); // expected-error {{constant expression}} expected-note {{one-past-the-end}} constexpr int over2 = __builtin_strlen(b + 9); // expected-error {{constant expression}} expected-note {{one-past-the-end}} constexpr int over3 = __builtin_strlen(c + 9); // expected-error {{constant expression}} expected-note {{one-past-the-end}} constexpr int under1 = __builtin_strlen(a - 1); // expected-error {{constant expression}} expected-note {{cannot refer to element -1}} constexpr int under2 = __builtin_strlen(b - 1); // expected-error {{constant expression}} expected-note {{cannot refer to element -1}} constexpr int under3 = __builtin_strlen(c - 1); // expected-error {{constant expression}} expected-note {{cannot refer to element -1}} // FIXME: The diagnostic here could be better. constexpr char d[] = { 'f', 'o', 'o' }; // no nul terminator. constexpr int bad = __builtin_strlen(d); // expected-error {{constant expression}} expected-note {{one-past-the-end}} } namespace PR19010 { struct Empty {}; struct Empty2 : Empty {}; struct Test : Empty2 { constexpr Test() {} Empty2 array[2]; }; void test() { constexpr Test t; } } void PR21327(int a, int b) { static_assert(&a + 1 != &b, ""); // expected-error {{constant expression}} } namespace EmptyClass { struct E1 {} e1; union E2 {} e2; // expected-note {{here}} struct E3 : E1 {} e3; // The defaulted copy constructor for an empty class does not read any // members. The defaulted copy constructor for an empty union reads the // object representation. constexpr E1 e1b(e1); constexpr E2 e2b(e2); // expected-error {{constant expression}} expected-note{{read of non-const}} expected-note {{in call}} constexpr E3 e3b(e3); } namespace PR21786 { extern void (*start[])(); extern void (*end[])(); static_assert(&start != &end, ""); // expected-error {{constant expression}} static_assert(&start != nullptr, ""); struct Foo; struct Bar { static const Foo x; static const Foo y; }; static_assert(&Bar::x != nullptr, ""); static_assert(&Bar::x != &Bar::y, ""); } namespace PR21859 { constexpr int Fun() { return; } // expected-error {{non-void constexpr function 'Fun' should return a value}} constexpr int Var = Fun(); template constexpr int FunT1() { return; } // expected-error {{non-void constexpr function 'FunT1' should return a value}} template constexpr int FunT2() { return 0; } template <> constexpr int FunT2() { return 0; } template <> constexpr int FunT2() { return; } // expected-error {{non-void constexpr function 'FunT2' should return a value}} } struct InvalidRedef { int f; // expected-note{{previous definition is here}} constexpr int f(void); // expected-error{{redefinition of 'f'}} expected-warning{{will not be implicitly 'const'}} }; namespace PR17938 { template constexpr T const &f(T const &x) { return x; } struct X {}; struct Y : X {}; struct Z : Y { constexpr Z() {} }; static constexpr auto z = f(Z()); } namespace PR24597 { struct A { int x, *p; constexpr A() : x(0), p(&x) {} constexpr A(const A &a) : x(a.x), p(&x) {} }; constexpr A f() { return A(); } constexpr A g() { return f(); } constexpr int a = *f().p; constexpr int b = *g().p; } namespace IncompleteClass { struct XX { static constexpr int f(XX*) { return 1; } // expected-note {{here}} friend constexpr int g(XX*) { return 2; } // expected-note {{here}} static constexpr int i = f(static_cast(nullptr)); // expected-error {{constexpr variable 'i' must be initialized by a constant expression}} expected-note {{undefined function 'f' cannot be used in a constant expression}} static constexpr int j = g(static_cast(nullptr)); // expected-error {{constexpr variable 'j' must be initialized by a constant expression}} expected-note {{undefined function 'g' cannot be used in a constant expression}} }; } namespace InheritedCtor { struct A { constexpr A(int) {} }; struct B : A { int n; using A::A; }; // expected-note {{here}} constexpr B b(0); // expected-error {{constant expression}} expected-note {{derived class}} struct C : A { using A::A; struct { union { int n, m = 0; }; union { int a = 0; }; int k = 0; }; struct {}; union {}; }; // expected-warning 6{{}} constexpr C c(0); struct D : A { using A::A; // expected-note {{here}} struct { // expected-warning {{extension}} union { // expected-warning {{extension}} int n; }; }; }; constexpr D d(0); // expected-error {{constant expression}} expected-note {{derived class}} struct E : virtual A { using A::A; }; // expected-note {{here}} // We wrap a function around this to avoid implicit zero-initialization // happening first; the zero-initialization step would produce the same // error and defeat the point of this test. void f() { constexpr E e(0); // expected-error {{constant expression}} expected-note {{derived class}} } // FIXME: This produces a note with no source location. //constexpr E e(0); struct W { constexpr W(int n) : w(n) {} int w; }; struct X : W { using W::W; int x = 2; }; struct Y : X { using X::X; int y = 3; }; struct Z : Y { using Y::Y; int z = 4; }; constexpr Z z(1); static_assert(z.w == 1 && z.x == 2 && z.y == 3 && z.z == 4, ""); } namespace PR28366 { namespace ns1 { void f(char c) { //expected-note2{{declared here}} struct X { static constexpr char f() { //expected-error{{never produces a constant expression}} return c; //expected-error{{reference to local}} expected-note{{function parameter}} } }; int I = X::f(); } void g() { const int c = 'c'; static const int d = 'd'; struct X { static constexpr int f() { return c + d; } }; static_assert(X::f() == 'c' + 'd',""); } } // end ns1 } //end ns PR28366 namespace PointerArithmeticOverflow { int n; int a[1]; constexpr int *b = &n + 1 + (long)-1; constexpr int *c = &n + 1 + (unsigned long)-1; // expected-error {{constant expression}} expected-note {{cannot refer to element 1844}} constexpr int *d = &n + 1 - (unsigned long)1; constexpr int *e = a + 1 + (long)-1; constexpr int *f = a + 1 + (unsigned long)-1; // expected-error {{constant expression}} expected-note {{cannot refer to element 1844}} constexpr int *g = a + 1 - (unsigned long)1; constexpr int *p = (&n + 1) + (unsigned __int128)-1; // expected-error {{constant expression}} expected-note {{cannot refer to element 3402}} constexpr int *q = (&n + 1) - (unsigned __int128)-1; // expected-error {{constant expression}} expected-note {{cannot refer to element -3402}} constexpr int *r = &(&n + 1)[(unsigned __int128)-1]; // expected-error {{constant expression}} expected-note {{cannot refer to element 3402}} } namespace PR40430 { struct S { char c[10] = "asdf"; constexpr char foo() const { return c[3]; } }; static_assert(S().foo() == 'f', ""); } namespace PR41854 { struct e { operator int(); }; struct f { e c; }; int a; f &d = reinterpret_cast(a); unsigned b = d.c; } namespace array_size { template struct array { static constexpr int size() { return N; } }; template void f1(T t) { constexpr int k = t.size(); } template void f2(const T &t) { // expected-note 2{{declared here}} constexpr int k = t.size(); // expected-error 2{{constant}} expected-note 2{{function parameter 't' with unknown value cannot be used in a constant expression}} } template void f3(const T &t) { constexpr int k = T::size(); } void g(array<3> a) { f1(a); f2(a); // expected-note {{instantiation of}} f3(a); } template struct array_nonstatic { constexpr int size() const { return N; } }; void h(array_nonstatic<3> a) { f1(a); f2(a); // expected-note {{instantiation of}} } } namespace flexible_array { struct A { int x; char arr[]; }; // expected-warning {{C99}} expected-note {{here}} constexpr A a = {1}; static_assert(a.x == 1, ""); static_assert(&a.arr != nullptr, ""); static_assert(a.arr[0], ""); // expected-error {{constant expression}} expected-note {{array member without known bound}} static_assert(a.arr[1], ""); // expected-error {{constant expression}} expected-note {{array member without known bound}} constexpr A b[] = {{1}, {2}, {3}}; // expected-warning {{flexible array member}} static_assert(b[0].x == 1, ""); static_assert(b[1].x == 2, ""); static_assert(b[2].x == 3, ""); static_assert(b[2].arr[0], ""); // expected-error {{constant expression}} expected-note {{array member without known bound}} // If we ever start to accept this, we'll need to ensure we can // constant-evaluate it properly. constexpr A c = {1, 2, 3}; // expected-error {{initialization of flexible array member}} } void local_constexpr_var() { constexpr int a = 0; // expected-note {{address of non-static constexpr variable 'a' may differ on each invocation of the enclosing function; add 'static' to give it a constant address}} constexpr const int *p = &a; // expected-error {{constant expression}} expected-note {{pointer to 'a' is not a constant expression}} }