// RUN: %clang_cc1 -std=c++2a -verify=expected,cxx20 %s -DNEW=__builtin_operator_new -DDELETE=__builtin_operator_delete
// RUN: %clang_cc1 -std=c++2a -verify=expected,cxx20 %s "-DNEW=operator new" "-DDELETE=operator delete"
// RUN: %clang_cc1 -std=c++2a -verify=expected,cxx20 %s "-DNEW=::operator new" "-DDELETE=::operator delete"
// RUN: %clang_cc1 -std=c++2c -verify=expected,cxx26 %s "-DNEW=::operator new" "-DDELETE=::operator delete"
constexpr bool alloc_from_user_code() {
void *p = NEW(sizeof(int)); // expected-note {{cannot allocate untyped memory in a constant expression; use 'std::allocator<T>::allocate'}}
DELETE(p);
return true;
}
static_assert(alloc_from_user_code()); // expected-error {{constant expression}} expected-note {{in call}}
namespace std {
using size_t = decltype(sizeof(0));
// FIXME: It would be preferable to point these notes at the location of the call to allocator<...>::[de]allocate instead
template<typename T> struct allocator {
constexpr T *allocate(size_t N) {
return (T*)NEW(sizeof(T) * N); // expected-note 3{{heap allocation}} expected-note {{not deallocated}}
}
constexpr void deallocate(void *p) {
DELETE(p); // #dealloc expected-note 2{{'std::allocator<...>::deallocate' used to delete pointer to object allocated with 'new'}}
}
};
}
constexpr bool alloc_via_std_allocator() {
std::allocator<int> alloc;
int *p = alloc.allocate(1);
alloc.deallocate(p);
return true;
}
static_assert(alloc_via_std_allocator());
template<> struct std::allocator<void()> {
constexpr void *allocate() { return NEW(8); } // expected-note {{cannot allocate memory of function type 'void ()'}}
};
constexpr void *fn = std::allocator<void()>().allocate(); // expected-error {{constant expression}} expected-note {{in call}}
struct Incomplete;
template<> struct std::allocator<Incomplete> {
constexpr void *allocate() { return NEW(8); } // expected-note {{cannot allocate memory of incomplete type 'Incomplete'}}
};
constexpr void *incomplete = std::allocator<Incomplete>().allocate(); // expected-error {{constant expression}} expected-note {{in call}}
struct WrongSize { char x[5]; };
static_assert(sizeof(WrongSize) == 5);
template<> struct std::allocator<WrongSize> {
constexpr void *allocate() { return NEW(7); } // expected-note {{allocated size 7 is not a multiple of size 5 of element type 'WrongSize'}}
};
constexpr void *wrong_size = std::allocator<WrongSize>().allocate(); // expected-error {{constant expression}} expected-note {{in call}}
constexpr bool mismatched(int alloc_kind, int dealloc_kind) {
int *p;
switch (alloc_kind) {
case 0:
p = new int; // expected-note {{heap allocation}}
break;
case 1:
p = new int[1]; // expected-note {{heap allocation}}
break;
case 2:
p = std::allocator<int>().allocate(1);
break;
}
switch (dealloc_kind) {
case 0:
delete p; // expected-note {{'delete' used to delete pointer to object allocated with 'std::allocator<...>::allocate'}}
break;
case 1:
delete[] p; // expected-note {{'delete' used to delete pointer to object allocated with 'std::allocator<...>::allocate'}}
break;
case 2:
std::allocator<int>().deallocate(p); // expected-note 2{{in call}}
break;
}
return true;
}
static_assert(mismatched(0, 2)); // expected-error {{constant expression}} expected-note {{in call}}
static_assert(mismatched(1, 2)); // expected-error {{constant expression}} expected-note {{in call}}
static_assert(mismatched(2, 0)); // expected-error {{constant expression}} expected-note {{in call}}
static_assert(mismatched(2, 1)); // expected-error {{constant expression}} expected-note {{in call}}
static_assert(mismatched(2, 2));
constexpr int *escape = std::allocator<int>().allocate(3); // expected-error {{constant expression}} expected-note {{pointer to subobject of heap-allocated}}
constexpr int leak = (std::allocator<int>().allocate(3), 0); // expected-error {{constant expression}}
constexpr int no_lifetime_start = (*std::allocator<int>().allocate(1) = 1); // expected-error {{constant expression}} expected-note {{assignment to object outside its lifetime}}
constexpr int no_deallocate_nullptr = (std::allocator<int>().deallocate(nullptr), 1); // expected-error {{constant expression}} expected-note {{in call}}
// expected-note@#dealloc {{'std::allocator<...>::deallocate' used to delete a null pointer}}
constexpr int no_deallocate_nonalloc = (std::allocator<int>().deallocate((int*)&no_deallocate_nonalloc), 1); // expected-error {{constant expression}} expected-note {{in call}}
// expected-note@#dealloc {{delete of pointer '&no_deallocate_nonalloc' that does not point to a heap-allocated object}}
// expected-note@-2 {{declared here}}
void *operator new(std::size_t, void *p) { return p; }
void* operator new[] (std::size_t, void* p) {return p;}
constexpr bool no_placement_new_in_user_code() { // cxx20-error {{constexpr function never produces a constant expression}}
int a;
new (&a) int(42); // cxx20-note {{this placement new expression is not supported in constant expressions before C++2c}}
return a == 42;
}
namespace std {
constexpr bool placement_new_in_stdlib() {
int a;
new (&a) int(42);
return a == 42;
}
}
static_assert(std::placement_new_in_stdlib());
namespace std {
template<typename T, typename ...Args>
constexpr void construct_at(void *p, Args &&...args) {
new (p) T((Args&&)args...); // #new
}
}
constexpr bool call_std_construct_at() {
int *p = std::allocator<int>().allocate(3);
std::construct_at<int>(p, 1);
std::construct_at<int>(p + 1, 2);
std::construct_at<int>(p + 2, 3);
bool good = p[0] + p[1] + p[2] == 6;
std::allocator<int>().deallocate(p);
return good;
}
static_assert(call_std_construct_at());
constexpr bool bad_construct_at_type() {
int a;
// expected-note@#new {{placement new would change type of storage from 'int' to 'float'}}
std::construct_at<float>(&a, 1.0f); // expected-note {{in call}}
return true;
}
static_assert(bad_construct_at_type()); // expected-error{{}} expected-note {{in call}}
constexpr bool bad_construct_at_subobject() {
struct X { int a, b; };
union A {
int a;
X x;
};
A a = {1};
// expected-note@#new {{construction of subobject of member 'x' of union with active member 'a' is not allowed in a constant expression}}
std::construct_at<int>(&a.x.a, 1); // expected-note {{in call}}
return true;
}
static_assert(bad_construct_at_subobject()); // expected-error{{}} expected-note {{in call}}
constexpr bool change_union_member() {
union U {
int a;
int b;
};
U u = {.a = 1};
std::construct_at<int>(&u.b, 2);
return u.b == 2;
}
static_assert(change_union_member());
int external;
// expected-note@#new {{visible outside}}
static_assert((std::construct_at<int>(&external, 1), true)); // expected-error{{}} expected-note {{in call}}
constexpr int &&temporary = 0; // expected-note {{created here}}
// expected-note@#new {{construction of temporary is not allowed in a constant expression outside the expression that created the temporary}}
static_assert((std::construct_at<int>(&temporary, 1), true)); // expected-error{{}} expected-note {{in call}}
constexpr bool construct_after_lifetime() {
int *p = new int;
delete p;
// expected-note@#new {{construction of heap allocated object that has been deleted}}
std::construct_at<int>(p); // expected-note {{in call}}
return true;
}
static_assert(construct_after_lifetime()); // expected-error {{}} expected-note {{in call}}
constexpr bool construct_after_lifetime_2() {
struct A { struct B {} b; };
A a;
a.~A();
std::construct_at<A::B>(&a.b); // expected-note {{in call}}
// expected-note@#new {{construction of subobject of object outside its lifetime is not allowed in a constant expression}}
return true;
}
static_assert(construct_after_lifetime_2()); // expected-error {{}} expected-note {{in call}}
namespace PR48606 {
struct A { mutable int n = 0; };
constexpr bool f() {
A a;
A *p = &a;
p->~A();
std::construct_at<A>(p);
return true;
}
static_assert(f());
constexpr bool g() {
A *p = new A;
p->~A();
std::construct_at<A>(p);
delete p;
return true;
}
static_assert(g());
constexpr bool h() {
std::allocator<A> alloc;
A *p = alloc.allocate(1);
std::construct_at<A>(p);
p->~A();
std::construct_at<A>(p);
p->~A();
alloc.deallocate(p);
return true;
}
static_assert(h());
}
namespace GH62462 {
class string {
public:
char *mem;
constexpr string() {
this->mem = new char(1);
}
constexpr ~string() {
delete this->mem;
}
constexpr unsigned size() const { return 4; }
};
template <unsigned N>
void test() {};
void f() {
test<string().size()>();
}
}
Codebase Browser
llvm