A value of type "const int*" cannot be used to initialize an entity of type "int* const"

Question

I have this code in c++ on vs 2022 community version.

import std;

int main()
{
    constexpr int x = 10;
    constexpr int* p = &x;
    
    
}

I am not allowed to assign the address of x to p because of this: A value of type "const int*" cannot be used to initialize an entity of type "int* const". So I understand that &x means const int* and p is int* const. Why so? I think p is pointer to const int. It seems constexpr applies to p and not to int. Could you clarify?

Answer 1

constexpr int x = 10; implies int const x = 10;.

constexpr int* p = &x; implies int* const p = &x; - p is an unchangeable pointer to a changeable int.

In the generic form constexpr T x = t; implies T const x = t;. It doesn't change a pointee type.

C++ does not allow to assign an address of a const to a pointer that points to a non const.

The proper solution in the global context:

constexpr int x = 10;
constexpr const int* p = &x;

The proper solution in a function local context:

int main() {
  static constexpr int x = 10;
  constexpr const int* p = &x;
}

static is not implied by constexpr and non static constexpr variable is just a usual runtime const variable.