The prototy according to MSDN is:
LONG InterlockedCompareExchange(
  LONG volatile* Destination,
  LONG Exchange,
  LONG Comperand
);


But is is used in 
g_atomic_int_compare_and_exchange
with a cast to PVOID in second place and third place. 

The other use in 
g_atomic_pointer_compare_and_exchange
is wrong also IMHO it is called:
gpointer  oldval,
gpointer  newval)

as second and third parameter 

I'd argue this is not correct.

Regards
Friedrich