For “handle” types (opaque pointers), Microsoft uses the trick of declaring structures and then typedef’ing a pointer to the structure:
#define DECLARE_HANDLE(name) struct name##__ { int unused; }; \
typedef struct name##__ *name
Then instead of
typedef void* FOOHANDLE;
typedef void* BARHANDLE;
They do:
DECLARE_HANDLE(FOOHANDLE);
DECLARE_HANDLE(BARHANDLE);
So now, this works:
FOOHANDLE make_foo();
BARHANDLE make_bar();
void do_bar(BARHANDLE);
FOOHANDLE foo = make_foo(); /* ok */
BARHANDLE bar = foo; /* won't work! */
do_bar(foo); /* won't work! */