c++pointersstatic-assertdouble-pointer

std::is_pointer of dereferenced double pointer

I have some code where i want to check for (accidental) double pointers in static_assert

#include<type_traits>


int main()
{
    using namespace std;
    float* arr[10];
    float ** pp;

    static_assert(!is_pointer<decltype(*arr)>::value, "double pointer detected");
    static_assert(!is_pointer<decltype(*pp)>::value, "double pointer detected");

}

I am curious why this compiles, as i was expecting the static_asserts to give an error.

Solution

  • Both of those decltypes resolve to reference types, and therefore neither are pointers, and hence the static assertions pass. These would also pass:

    static_assert(std::is_pointer<std::remove_reference_t<decltype(*arr)>>::value);
static_assert(std::is_pointer<std::remove_reference_t<decltype(*pp)>>::value);