hypot error : '__builtin_choose_expr' requires a constant expression

Hi All,I got errors when I tried to use the function hypot. It said " '__builtin_choose_expr' requires a constant expression". I found the error occurs at "__tg_integer" in tgmath.h. It does not treat "(__typeof__(__e1))1.5 == 1" as a constantexpression. I am confused that why it's not a constant expression, and how should I fix this.

The code is as follows:


#include <tgmath.h>
int main()
{
    double __complex__ z = 0.0;
    hypot(__real__ z, __imag__ z);
    return 0;
}
Looking forward to your reply!
Thanks and Regards,
Chunxia Du