predefined new function) and the term C pointer means a pointer to
memory allocated by C (such as by a call to C.malloc). Whether a
pointer is a Go pointer or a C pointer is a dynamic property
determined by how the memory was allocated; it has nothing to do with
the type of the pointer.

Note that values of some Go types, other than the type's zero value,
always include Go pointers. This is true of string, slice, interface,