NA and NaN representation on mips64el

[Rafael Laboissière <rafael@debian.org>]

Dear mips porters,

I need some advice on an FTBFS problem with package octave mapping on the 
mips64el architecture. Here is the log for the failed build:

https://buildd.debian.org/status/fetch.php?pkg=octave-mapping&arch=mips64el&ver=1.4.3-1&stamp=1746884958&raw=0

It also FTBFS on riscv64, for the same reason: the unit tests for 
degrees2dm and degrees2dms fail with this error:

 ***** assert (degrees2dm (NA), [NA NA]) !!!!! test failed ASSERT errors for:  assert (degrees2dm (NA), [NA,NA])

   Location  |  Observed  |  Expected  |  Reason
     (1)          NaN           NA        'NA' mismatch
     (2)          NaN           NA        'NA' mismatch

It seems to be a problem related to how floating point NA and NaN are 
represented.

Strangely, I cannot reproduce this problem. I built the package manually 
on a mips64el porterbox using schroot and everything worked fine.

We discussed a similar issue on the upstream bug tracking system for 
Octave back in 2021: https://savannah.gnu.org/bugs/?59830

One of the upstream authors seems to suggest that this problem is related 
to cross-compiling.

Do you know if there is a way to work around this?

Best,

Rafael Laboissière