On 2023-05-17 10:38, Spencer Baugh wrote:
> I think it's because I'm on gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-44),
> and _Generic was added in 4.9?

Thanks for reporting the problem. Since _Generic is used here merely as 
a micro-optimization on 32-bit platforms, it's not worth whatever 
porting hassle you've run into, so I installed the attached patch so 
that modiff no longer uses _Generic.