https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84891
--- Comment #7 from Steve Kargl <sgk at troutmask dot apl.washington.edu> --- On Mon, Mar 19, 2018 at 08:01:17AM -0700, Steve Kargl wrote: > > I can't find anything in the Fortran2008 standard specifying how > > arithmetic on intrinsic complex types work. CCing two Fortran maintainers > > to see whether Fortran requires us to do any changes here. I forgot about what I believe are default setting. '-fcx-fortran-rules' Complex multiplication and division follow Fortran rules. Range reduction is done as part of complex division, but there is no checking whether the result of a complex multiplication or division is 'NaN + I*NaN', with an attempt to rescue the situation in that case. I also believe that '-fcx-limited-range' When enabled, this option states that a range reduction step is not needed when performing complex division. Also, there is no checking whether the result of a complex multiplication or division is 'NaN + I*NaN', with an attempt to rescue the situation in that case. The default is '-fno-cx-limited-range', but is enabled by '-ffast-math'. is active, but I can't find where either is set.