llvm-project/clang/test/SemaCXX/constant-expression-cxx2a.cpp

551 lines
17 KiB
C++

// RUN: %clang_cc1 -std=c++2a -verify %s -fcxx-exceptions -triple=x86_64-linux-gnu
#include "Inputs/std-compare.h"
namespace std {
struct type_info;
};
namespace ThreeWayComparison {
struct A {
int n;
constexpr friend int operator<=>(const A &a, const A &b) {
return a.n < b.n ? -1 : a.n > b.n ? 1 : 0;
}
};
static_assert(A{1} <=> A{2} < 0);
static_assert(A{2} <=> A{1} > 0);
static_assert(A{2} <=> A{2} == 0);
static_assert(1 <=> 2 < 0);
static_assert(2 <=> 1 > 0);
static_assert(1 <=> 1 == 0);
constexpr int k = (1 <=> 1, 0);
// expected-warning@-1 {{three-way comparison result unused}}
static_assert(std::strong_ordering::equal == 0);
constexpr void f() {
void(1 <=> 1);
}
struct MemPtr {
void foo() {}
void bar() {}
int data;
int data2;
long data3;
};
struct MemPtr2 {
void foo() {}
void bar() {}
int data;
int data2;
long data3;
};
using MemPtrT = void (MemPtr::*)();
using FnPtrT = void (*)();
void FnPtr1() {}
void FnPtr2() {}
#define CHECK(...) ((__VA_ARGS__) ? void() : throw "error")
#define CHECK_TYPE(...) static_assert(__is_same(__VA_ARGS__));
constexpr bool test_constexpr_success = [] {
{
auto &EQ = std::strong_ordering::equal;
auto &LESS = std::strong_ordering::less;
auto &GREATER = std::strong_ordering::greater;
using SO = std::strong_ordering;
auto eq = (42 <=> 42);
CHECK_TYPE(decltype(eq), SO);
CHECK(eq.test_eq(EQ));
auto less = (-1 <=> 0);
CHECK_TYPE(decltype(less), SO);
CHECK(less.test_eq(LESS));
auto greater = (42l <=> 1u);
CHECK_TYPE(decltype(greater), SO);
CHECK(greater.test_eq(GREATER));
}
{
using PO = std::partial_ordering;
auto EQUIV = PO::equivalent;
auto LESS = PO::less;
auto GREATER = PO::greater;
auto eq = (42.0 <=> 42.0);
CHECK_TYPE(decltype(eq), PO);
CHECK(eq.test_eq(EQUIV));
auto less = (39.0 <=> 42.0);
CHECK_TYPE(decltype(less), PO);
CHECK(less.test_eq(LESS));
auto greater = (-10.123 <=> -101.1);
CHECK_TYPE(decltype(greater), PO);
CHECK(greater.test_eq(GREATER));
}
{
using SE = std::strong_equality;
auto EQ = SE::equal;
auto NEQ = SE::nonequal;
MemPtrT P1 = &MemPtr::foo;
MemPtrT P12 = &MemPtr::foo;
MemPtrT P2 = &MemPtr::bar;
MemPtrT P3 = nullptr;
auto eq = (P1 <=> P12);
CHECK_TYPE(decltype(eq), SE);
CHECK(eq.test_eq(EQ));
auto neq = (P1 <=> P2);
CHECK_TYPE(decltype(eq), SE);
CHECK(neq.test_eq(NEQ));
auto eq2 = (P3 <=> nullptr);
CHECK_TYPE(decltype(eq2), SE);
CHECK(eq2.test_eq(EQ));
}
{
using SE = std::strong_equality;
auto EQ = SE::equal;
auto NEQ = SE::nonequal;
FnPtrT F1 = &FnPtr1;
FnPtrT F12 = &FnPtr1;
FnPtrT F2 = &FnPtr2;
FnPtrT F3 = nullptr;
auto eq = (F1 <=> F12);
CHECK_TYPE(decltype(eq), SE);
CHECK(eq.test_eq(EQ));
auto neq = (F1 <=> F2);
CHECK_TYPE(decltype(neq), SE);
CHECK(neq.test_eq(NEQ));
}
{ // mixed nullptr tests
using SO = std::strong_ordering;
using SE = std::strong_equality;
int x = 42;
int *xp = &x;
MemPtrT mf = nullptr;
MemPtrT mf2 = &MemPtr::foo;
auto r3 = (mf <=> nullptr);
CHECK_TYPE(decltype(r3), std::strong_equality);
CHECK(r3.test_eq(SE::equal));
}
return true;
}();
template <auto LHS, auto RHS, bool ExpectTrue = false>
constexpr bool test_constexpr() {
using nullptr_t = decltype(nullptr);
using LHSTy = decltype(LHS);
using RHSTy = decltype(RHS);
// expected-note@+1 {{subexpression not valid in a constant expression}}
auto Res = (LHS <=> RHS);
if constexpr (__is_same(LHSTy, nullptr_t) || __is_same(RHSTy, nullptr_t)) {
CHECK_TYPE(decltype(Res), std::strong_equality);
}
if (ExpectTrue)
return Res == 0;
return Res != 0;
}
int dummy = 42;
int dummy2 = 101;
constexpr bool tc1 = test_constexpr<nullptr, &dummy>();
constexpr bool tc2 = test_constexpr<&dummy, nullptr>();
// OK, equality comparison only
constexpr bool tc3 = test_constexpr<&MemPtr::foo, nullptr>();
constexpr bool tc4 = test_constexpr<nullptr, &MemPtr::foo>();
constexpr bool tc5 = test_constexpr<&MemPtr::foo, &MemPtr::bar>();
constexpr bool tc6 = test_constexpr<&MemPtr::data, nullptr>();
constexpr bool tc7 = test_constexpr<nullptr, &MemPtr::data>();
constexpr bool tc8 = test_constexpr<&MemPtr::data, &MemPtr::data2>();
// expected-error@+1 {{must be initialized by a constant expression}}
constexpr bool tc9 = test_constexpr<&dummy, &dummy2>(); // expected-note {{in call}}
template <class T, class R, class I>
constexpr T makeComplex(R r, I i) {
T res{r, i};
return res;
};
template <class T, class ResultT>
constexpr bool complex_test(T x, T y, ResultT Expect) {
auto res = x <=> y;
CHECK_TYPE(decltype(res), ResultT);
return res.test_eq(Expect);
}
static_assert(complex_test(makeComplex<_Complex double>(0.0, 0.0),
makeComplex<_Complex double>(0.0, 0.0),
std::weak_equality::equivalent));
static_assert(complex_test(makeComplex<_Complex double>(0.0, 0.0),
makeComplex<_Complex double>(1.0, 0.0),
std::weak_equality::nonequivalent));
static_assert(complex_test(makeComplex<_Complex double>(0.0, 0.0),
makeComplex<_Complex double>(0.0, 1.0),
std::weak_equality::nonequivalent));
static_assert(complex_test(makeComplex<_Complex int>(0, 0),
makeComplex<_Complex int>(0, 0),
std::strong_equality::equal));
static_assert(complex_test(makeComplex<_Complex int>(0, 0),
makeComplex<_Complex int>(1, 0),
std::strong_equality::nonequal));
// TODO: defaulted operator <=>
} // namespace ThreeWayComparison
constexpr bool for_range_init() {
int k = 0;
for (int arr[3] = {1, 2, 3}; int n : arr) k += n;
return k == 6;
}
static_assert(for_range_init());
namespace Virtual {
struct NonZeroOffset { int padding = 123; };
// Ensure that we pick the right final overrider during construction.
struct A {
virtual constexpr char f() const { return 'A'; }
char a = f();
};
struct NoOverrideA : A {};
struct B : NonZeroOffset, NoOverrideA {
virtual constexpr char f() const { return 'B'; }
char b = f();
};
struct NoOverrideB : B {};
struct C : NonZeroOffset, A {
virtual constexpr char f() const { return 'C'; }
A *pba;
char c = ((A*)this)->f();
char ba = pba->f();
constexpr C(A *pba) : pba(pba) {}
};
struct D : NonZeroOffset, NoOverrideB, C { // expected-warning {{inaccessible}}
virtual constexpr char f() const { return 'D'; }
char d = f();
constexpr D() : C((B*)this) {}
};
constexpr D d;
static_assert(((B&)d).a == 'A');
static_assert(((C&)d).a == 'A');
static_assert(d.b == 'B');
static_assert(d.c == 'C');
// During the construction of C, the dynamic type of B's A is B.
static_assert(d.ba == 'B');
static_assert(d.d == 'D');
static_assert(d.f() == 'D');
constexpr const A &a = (B&)d;
constexpr const B &b = d;
static_assert(a.f() == 'D');
static_assert(b.f() == 'D');
// FIXME: It is unclear whether this should be permitted.
D d_not_constexpr;
static_assert(d_not_constexpr.f() == 'D'); // expected-error {{constant expression}} expected-note {{virtual function called on object 'd_not_constexpr' whose dynamic type is not constant}}
// Check that we apply a proper adjustment for a covariant return type.
struct Covariant1 {
D d;
virtual const A *f() const;
};
template<typename T>
struct Covariant2 : Covariant1 {
virtual const T *f() const;
};
template<typename T>
struct Covariant3 : Covariant2<T> {
constexpr virtual const D *f() const { return &this->d; }
};
constexpr Covariant3<B> cb;
constexpr Covariant3<C> cc;
constexpr const Covariant1 *cb1 = &cb;
constexpr const Covariant2<B> *cb2 = &cb;
static_assert(cb1->f()->a == 'A');
static_assert(cb1->f() == (B*)&cb.d);
static_assert(cb1->f()->f() == 'D');
static_assert(cb2->f()->b == 'B');
static_assert(cb2->f() == &cb.d);
static_assert(cb2->f()->f() == 'D');
constexpr const Covariant1 *cc1 = &cc;
constexpr const Covariant2<C> *cc2 = &cc;
static_assert(cc1->f()->a == 'A');
static_assert(cc1->f() == (C*)&cc.d);
static_assert(cc1->f()->f() == 'D');
static_assert(cc2->f()->c == 'C');
static_assert(cc2->f() == &cc.d);
static_assert(cc2->f()->f() == 'D');
static_assert(cb.f()->d == 'D');
static_assert(cc.f()->d == 'D');
struct Abstract {
constexpr virtual void f() = 0; // expected-note {{declared here}}
constexpr Abstract() { do_it(); } // expected-note {{in call to}}
constexpr void do_it() { f(); } // expected-note {{pure virtual function 'Virtual::Abstract::f' called}}
};
struct PureVirtualCall : Abstract { void f(); }; // expected-note {{in call to 'Abstract}}
constexpr PureVirtualCall pure_virtual_call; // expected-error {{constant expression}} expected-note {{in call to 'PureVirtualCall}}
}
namespace DynamicCast {
struct A2 { virtual void a2(); };
struct A : A2 { virtual void a(); };
struct B : A {};
struct C2 { virtual void c2(); };
struct C : A, C2 { A *c = dynamic_cast<A*>(static_cast<C2*>(this)); };
struct D { virtual void d(); };
struct E { virtual void e(); };
struct F : B, C, D, private E { void *f = dynamic_cast<void*>(static_cast<D*>(this)); };
struct Padding { virtual void padding(); };
struct G : Padding, F {};
constexpr G g;
// During construction of C, A is unambiguous subobject of dynamic type C.
static_assert(g.c == (C*)&g);
// ... but in the complete object, the same is not true, so the runtime fails.
static_assert(dynamic_cast<const A*>(static_cast<const C2*>(&g)) == nullptr);
// dynamic_cast<void*> produces a pointer to the object of the dynamic type.
static_assert(g.f == (void*)(F*)&g);
static_assert(dynamic_cast<const void*>(static_cast<const D*>(&g)) == &g);
// expected-note@+1 {{reference dynamic_cast failed: 'DynamicCast::A' is an ambiguous base class of dynamic type 'DynamicCast::G' of operand}}
constexpr int d_a = (dynamic_cast<const A&>(static_cast<const D&>(g)), 0); // expected-error {{}}
// Can navigate from A2 to its A...
static_assert(&dynamic_cast<A&>((A2&)(B&)g) == &(A&)(B&)g);
// ... and from B to its A ...
static_assert(&dynamic_cast<A&>((B&)g) == &(A&)(B&)g);
// ... but not from D.
// expected-note@+1 {{reference dynamic_cast failed: 'DynamicCast::A' is an ambiguous base class of dynamic type 'DynamicCast::G' of operand}}
static_assert(&dynamic_cast<A&>((D&)g) == &(A&)(B&)g); // expected-error {{}}
// Can cast from A2 to sibling class D.
static_assert(&dynamic_cast<D&>((A2&)(B&)g) == &(D&)g);
// Cannot cast from private base E to derived class F.
// expected-note@+1 {{reference dynamic_cast failed: static type 'DynamicCast::E' of operand is a non-public base class of dynamic type 'DynamicCast::G'}}
constexpr int e_f = (dynamic_cast<F&>((E&)g), 0); // expected-error {{}}
// Cannot cast from B to private sibling E.
// expected-note@+1 {{reference dynamic_cast failed: 'DynamicCast::E' is a non-public base class of dynamic type 'DynamicCast::G' of operand}}
constexpr int b_e = (dynamic_cast<E&>((B&)g), 0); // expected-error {{}}
struct Unrelated { virtual void unrelated(); };
// expected-note@+1 {{reference dynamic_cast failed: dynamic type 'DynamicCast::G' of operand does not have a base class of type 'DynamicCast::Unrelated'}}
constexpr int b_unrelated = (dynamic_cast<Unrelated&>((B&)g), 0); // expected-error {{}}
// expected-note@+1 {{reference dynamic_cast failed: dynamic type 'DynamicCast::G' of operand does not have a base class of type 'DynamicCast::Unrelated'}}
constexpr int e_unrelated = (dynamic_cast<Unrelated&>((E&)g), 0); // expected-error {{}}
}
namespace TypeId {
struct A {
const std::type_info &ti = typeid(*this);
};
struct A2 : A {};
static_assert(&A().ti == &typeid(A));
static_assert(&typeid((A2())) == &typeid(A2));
extern A2 extern_a2;
static_assert(&typeid(extern_a2) == &typeid(A2));
constexpr A2 a2;
constexpr const A &a1 = a2;
static_assert(&typeid(a1) == &typeid(A));
struct B {
virtual void f();
const std::type_info &ti1 = typeid(*this);
};
struct B2 : B {
const std::type_info &ti2 = typeid(*this);
};
static_assert(&B2().ti1 == &typeid(B));
static_assert(&B2().ti2 == &typeid(B2));
extern B2 extern_b2;
// expected-note@+1 {{typeid applied to object 'extern_b2' whose dynamic type is not constant}}
static_assert(&typeid(extern_b2) == &typeid(B2)); // expected-error {{constant expression}}
constexpr B2 b2;
constexpr const B &b1 = b2;
static_assert(&typeid(b1) == &typeid(B2));
constexpr bool side_effects() {
// Not polymorphic nor a glvalue.
bool OK = true;
(void)typeid(OK = false, A2()); // expected-warning {{has no effect}}
if (!OK) return false;
// Not polymorphic.
A2 a2;
(void)typeid(OK = false, a2); // expected-warning {{has no effect}}
if (!OK) return false;
// Not a glvalue.
(void)typeid(OK = false, B2()); // expected-warning {{has no effect}}
if (!OK) return false;
// Polymorphic glvalue: operand evaluated.
OK = false;
B2 b2;
(void)typeid(OK = true, b2); // expected-warning {{will be evaluated}}
return OK;
}
static_assert(side_effects());
}
namespace Union {
struct Base {
int y; // expected-note {{here}}
};
struct A : Base {
int x;
int arr[3];
union { int p, q; };
};
union B {
A a;
int b;
};
constexpr int read_wrong_member() { // expected-error {{never produces a constant}}
B b = {.b = 1};
return b.a.x; // expected-note {{read of member 'a' of union with active member 'b'}}
}
constexpr int change_member() {
B b = {.b = 1};
b.a.x = 1;
return b.a.x;
}
static_assert(change_member() == 1);
constexpr int change_member_then_read_wrong_member() { // expected-error {{never produces a constant}}
B b = {.b = 1};
b.a.x = 1;
return b.b; // expected-note {{read of member 'b' of union with active member 'a'}}
}
constexpr int read_wrong_member_indirect() { // expected-error {{never produces a constant}}
B b = {.b = 1};
int *p = &b.a.y;
return *p; // expected-note {{read of member 'a' of union with active member 'b'}}
}
constexpr int read_uninitialized() {
B b = {.b = 1};
int *p = &b.a.y;
b.a.x = 1;
return *p; // expected-note {{read of uninitialized object}}
}
static_assert(read_uninitialized() == 0); // expected-error {{constant}} expected-note {{in call}}
constexpr void write_wrong_member_indirect() { // expected-error {{never produces a constant}}
B b = {.b = 1};
int *p = &b.a.y;
*p = 1; // expected-note {{assignment to member 'a' of union with active member 'b'}}
}
constexpr int write_uninitialized() {
B b = {.b = 1};
int *p = &b.a.y;
b.a.x = 1;
*p = 1;
return *p;
}
static_assert(write_uninitialized() == 1);
constexpr int change_member_indirectly() {
B b = {.b = 1};
b.a.arr[1] = 1;
int &r = b.a.y;
r = 123;
b.b = 2;
b.a.y = 3;
b.a.arr[2] = 4;
return b.a.arr[2];
}
static_assert(change_member_indirectly() == 4);
constexpr B return_uninit() {
B b = {.b = 1};
b.a.x = 2;
return b;
}
constexpr B uninit = return_uninit(); // expected-error {{constant expression}} expected-note {{subobject of type 'int' is not initialized}}
static_assert(return_uninit().a.x == 2);
constexpr A return_uninit_struct() {
B b = {.b = 1};
b.a.x = 2;
return b.a;
}
// FIXME: It's unclear that this should be valid. Copying a B involves
// copying the object representation of the union, but copying an A invokes a
// copy constructor that copies the object elementwise, and reading from
// b.a.y is undefined.
static_assert(return_uninit_struct().x == 2);
constexpr B return_init_all() {
B b = {.b = 1};
b.a.x = 2;
b.a.y = 3;
b.a.arr[0] = 4;
b.a.arr[1] = 5;
b.a.arr[2] = 6;
return b;
}
static_assert(return_init_all().a.x == 2);
static_assert(return_init_all().a.y == 3);
static_assert(return_init_all().a.arr[0] == 4);
static_assert(return_init_all().a.arr[1] == 5);
static_assert(return_init_all().a.arr[2] == 6);
static_assert(return_init_all().a.p == 7); // expected-error {{}} expected-note {{read of member 'p' of union with no active member}}
static_assert(return_init_all().a.q == 8); // expected-error {{}} expected-note {{read of member 'q' of union with no active member}}
constexpr B init_all = return_init_all();
constexpr bool test_no_member_change = []{
union U { char dummy = {}; };
U u1;
U u2;
u1 = u2;
return true;
}();
struct S1 {
int n;
};
struct S2 : S1 {};
struct S3 : S2 {};
void f() {
S3 s;
s.n = 0;
}
}
namespace TwosComplementShifts {
using uint32 = __UINT32_TYPE__;
using int32 = __INT32_TYPE__;
static_assert(uint32(int32(0x1234) << 16) == 0x12340000);
static_assert(uint32(int32(0x1234) << 19) == 0x91a00000);
static_assert(uint32(int32(0x1234) << 20) == 0x23400000); // expected-warning {{requires 34 bits}}
static_assert(uint32(int32(0x1234) << 24) == 0x34000000); // expected-warning {{requires 38 bits}}
static_assert(uint32(int32(-1) << 31) == 0x80000000);
static_assert(-1 >> 1 == -1);
static_assert(-1 >> 31 == -1);
static_assert(-2 >> 1 == -1);
static_assert(-3 >> 1 == -2);
static_assert(-4 >> 1 == -2);
}