I took a gander at 2008 IEEE 754 standard and section "9.2.1 Special values"
has this to say:

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pow (x, ±0) is 1 for any x (even a zero, quiet NaN, or infinity)
pow (+1, y) is 1 for any y (even a quiet NaN)
So our behaviour is correct. Rejecting.
On Mon Oct 17 03:05:33 2016, c...@zoffix.com wrote:
> So that leaves nqp::pow_n(1e0, NaN) == 1e0. Is that also part of IEEE?
>
> I see that Perl 5 gives a NaN for NaN**0, but 1 for 1**NaN:
>
> zoffix@VirtualBox:~$ perl -wlE 'say -sin(9**9**9)**0'
> NaN
> zoffix@VirtualBox:~$ perl -wlE 'say 1**-sin(9**9**9)'
> 1
>
>
>
>
> On Mon Oct 17 00:25:15 2016, barto...@gmx.de wrote:
> > On Sun Oct 16 11:07:16 2016, alex.jakime...@gmail.com wrote:
> > > Just for the record, another case:
> > >
> > > Code:
> > > say NaN**0
> > >
> > > Output:
> > > 1
> >
> > There was an earlier RT for this one (coming to the conclusion that 1
> > is a reasonable answer here):
> > https://rt.perl.org/Ticket/Display.html?id=124450. It has a link to a
> > discussion from stackoverflow -- to me the following comment
> > was interesting: http://stackoverflow.com/a/17865226