[tz] suggestion: split "backward" into "backward" and "deprecated"

[Philip Paeps]

On 2020-05-05 08:46:52 (+0800), Paul Eggert wrote:
> Getting back to the main point, I'm not sure it's worth deprecating 
> links like 'US/Pacific' any time soon, as so many people use them and 
> their cost is not great.

As far as FreeBSD is concerned: since we haven't installed 'US/Pacific' 
since ca 1994, I'm pretty sure nobody uses it. :-)

Since you mention cost though: installing the backward zones increased 
the footprint of /usr/share/zoneinfo from about 1.8M to about 3.3M.  I 
don't consider that worth losing sleep over in 2020.  People who build 
systems where every megabyte counts probably don't ship 
/usr/share/zoneinfo in the first place.  Or they can trivially patch the 
build system not to install backward zones.

> It might be worth coming up with some division of the existing 
> 'backward' file (e.g., recently-backward names vs older-backward 
> names), although I'm not sure what that would look like.  I suppose we 
> could have a comment associated with each name saying when it became 
> backward, though that'd increase maintenance hassle.

Adding a comment stating when the name became backward isn't a huge 
additional maintenance burden.  Especially since we don't move things to 
backward all that often.

The division into backward and deprecated could be scripted based on 
that comment.  Adding the historical comments would be a bit of work 
though.

We could also split backward as Andrew proposes and start tagging 
additions to backward going forward.

Philip

-- 
Philip Paeps
Senior Reality Engineer
Alternative Enterprises