What types of objects can constexpr pointers point to?

Question

cppreference.com says:

A constexpr specifier used in an object declaration implies const.

But I tried to make a constexpr pointer hold the address of a const object of the same base-type but the compiler gave me an error:

const int a = 1;
int main(){
constexpr int *b = &a;
return 0;
}

So, what types can a constexpr pointer point to?

Answer 1

The issue here is not with constexpr. If you said

int *b = &a;

You'd get the same error. i.e. "invalid conversion from const int* to int*"

We can fix that by making it a pointer to a const int.

int const *b = &a;

Now we can add constexpr, and yes, constexpr does imply const

constexpr int const *b = &a;

where b is in fact const. This is exactly the same as the following

constexpr int const * const b = &a;
                    //^^^^^
// this const is made redundant by the constexpr.

Answer 2

Your example doesn't compile because 'a' is a 'const int', and requires a 'constexpr const int' pointer to point to it.