Re: Bug: org-2ft and/or float-time is wrong [9.1.2 (9.1.2-22-ga2a034-elpaplus @ ~/.emacs.d/elpa/org-plus-contrib-20171023/)]

[Allen Li <vianchielfaura@gmail.com>]

I found another one (It is 2017-11-01 in local time for me)

(org-time= "<2017-11-01>" "<today>")
nil

This is also local timezone dependent.

Tim made the point that these floats are not intended to be Unix
timestamps and only used for comparison, but this implementation
detail leaks quite heavily.  Furthermore, the value returned by
org-2ft for these comparisons isn't even constant.

For example (org-2ft "<2017-10-10 10:00:00>") returns 1507629600.0 for
me today, but in four days it will return a different value,
1507626000.0.  Surprise, the offset from local time to UTC is not
constant, even on the same machine in the same timezone.

The most immediate impact of this is that all of Org mode's time
comparison functions will be wrong when called during a local time
offset change.  For those of us who are lucky, this may be twice a
year, but for others who are unlucky, it may be multiple times per
year or month, up to the whims of the local government.

This is one of the reasons I think "we're just using them for
comparisons" doesn't excuse org-2ft doing its little time shift.  The
other reason is all of the regressions that change caused, including
this current bug, and yet another is my gut instinct that this is a
poor design choice from a technical perspective as a software
engineer.