Time not representable

[Carsten Dominik <carsten.dominik@gmail.com>]

Hi everyone,

in the Org-mode mailing list, an old issue just came up again:
Some dates are not representable in Emacs when using functions
like encode-time.

The problem has to do with integer representations.

From the past I know that only times between 1970 and 2038 were
representable (that may have been Emacs 20 or something like this).

Recently I have noticed that my system now *can* represent dates
past 2038

   (encode-time 0 0 0 1 1 2040) => (33706 28784)

attesting to the fact that time is represented now with more than
32 bits.

Another data point is that on a different system, Bastien has found
that he can get times before 1970 represented, but not after 2038.
So apparently his system is using something else to represent time.

I can look up all the details about the systems if needed, but the
question I have is more general:

Why is it that these things are different on different systems?  Is
this under the control of Emacs, or does this depend on system
libraries which are being used?

Are there plans to use a time representation which will consistently
allow dates past 2038 and, if possible also before 1970?

Any pointers to educate me about these issues would be appreciated.

Thanks!

- Carsten