How to fix conflicting types for built-in function __atomic_* warnings

[Patrick Oppenlander]

Hi,

I'm trying to implement some libatomic functions on an ARM Cortex M0 and 
can't seem to get the function signatures right.

I'm currently trying signatures that look like:

int8_t __atomic_exchange_1(int8_t *object, int8_t desired, memory_order)
{
	...
}

But GCC complains with:

/home/patrick/src/motec/ldm/lib/atomic.c:16:8: warning: conflicting 
types for built-in function '__atomic_exchange_1'
  int8_t __atomic_exchange_1(int8_t *object, int8_t desired, memory_order)
         ^~~~~~~~~~~~~~~~~~~

Specifying "-fno-builtin" makes no difference.

Is there any way to get around this? Or am I missing something obvious.

Many thanks,

		Patrick