Implementation of addressof

Question

Having previously been unaware of the existence of std::addressof, why it exists makes sense to me: as a way of taking the an address in the presence of an over

Answer 1

The short version:

operator& can't be overloaded for char. So the type is being cast to a char reference to get what's guaranteed to be the true address.

That conversion is done in two casts because of the restrictions on const_cast and reinterpret_cast.

The longer version:

It's performing three sequential casts.

reinterpret_cast

This is effectively casting to a char&. The const and volatile only exist because _Tp may be const or volatile, and reinterpret_cast can add those, but would be unable to remove them.

const_cast

Now the const and volatile have been removed. const_cast may do that.

reinterpret_cast<_Tp*> &(result)

Now the address is taken and the type is converted back to a pointer to the original type.