Re: recommending AC_SYS_YEAR2038_REQUIRED ?

[Paul Eggert]

On 2023-04-10 14:08, Bruno Haible wrote:
> > Applications like 'ls' and 'date'
> > and even 'grep' need support for timestamps past 2038.
> ... if they are used in hardware that will operate in and beyond 2038.

That's not the only reason year-2038 support is needed. And it's not 
just trivial things like "date -d'now + 15 years'"; it's packages like 
tar and coreutils that need to work even in environments where users 
today can mistakenly (or purposely!) set file timestamps to be 15 years 
from now. A common command like 'grep' or 'find' shouldn't misbehave 
merely because a file timestamp is in the future.

I plan to reword the manual to suggest year2038 over year2038-required 
as you suggested, and to give packagers an out even when 
year2038-required is used. However, for core packages year 2038 support 
really should be opt-out, not opt-in, and for these packages 
year2038-required is more likely to save people trouble down the road.

If we change to AC_YEAR2038_OPT_OUT we can update the manual accordingly 
of course.