A few special C types which would normally be represented by a pointer
type in Go are instead represented by a uintptr.  See the Special
cases section below.

To access a struct, union, or enum type directly, prefix it with
struct_, union_, or enum_, as in C.struct_stat.

The size of any C type T is available as C.sizeof_T, as in
C.sizeof_struct_stat.

A C function may be declared in the Go file with a parameter type of