[Bug fortran/57749] -ffpe-trap=zero or invalid produces SIGFPE on complex zero ** 1e0

["zeccav at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57749

--- Comment #16 from Vittorio Zecca <zeccav at gmail dot com> ---
You are being a little too hard on me, but so be it.

I believe there is only one special case, base==0,
and that there are only two ifs to put in cpow to avoid the floating exception
and give the expected result(I am simplifying here, also because I do
not use C):

if(base==0)
{
 if(exponent>0) return 0; else raise hell;
}

The actual code where the original issue occurred had the exponentiation
in the deep of nested loops, it would have been rather time consuming
to test base==0
at the Fortran level


And I still do not understand why if the exponent is integer no
exception is raised and
the expected result zero is delivered.
As in the following fragment (with option -ffpe-trap=zero,invalid):
      complex x
      x=cmplx(0e0,0e0)
      i=2
      r=2e0
      print *,x**i ! no exception raised delivers zero
      print *,x**r ! exception raised
      end
The Intel ifort and NAG nagfor compilers raise no exceptions and
deliver the expected result.
With my best wishes of good work to everybody.