On Mon, May 26, 2014 at 02:17:47PM +0000, J. Vuletich (mail lists) wrote:
> Hi David, Folks,
> 
> Quoting "David T. Lewis" <lewis at mail.msen.com>:
> 
> >I have been working on a variation of class DateAndTime that replaces its
> >instance variables (seconds offset jdn nanos) with two instance variables,
> >utcMicroseconds to represent microseconds elapsed since the Posix epoch, 
> >and
> >localOffsetSeconds to represent the local time zone offset. When  
> >instantiating
> >the time now, A single call primitiveUtcWithOffset is used to obtain these
> >two values atomically as reported by the underlying platform.
> >
> >There are several advantages to this representation of DateAndTime, the 
> >most
> >important of which is that its magnitude is unambiguous regardless  
> >of daylight
> >savings transitions in local time zones.
> >
> >This is my attempt to address some historical baggage in Squeak. The VM
> >reports time related to the local time zone, and the image attempts to
> >convert to UTC (sometimes incorrectly). A UTC based representation makes 
> >the
> >implementation of time zone tables more straightforward (see for example
> >the Olson time zone tables in TimeZoneDatabase on SqueakMap).
> >...
> >Dave
> 
> I very much support this approach. I did a bit of testing of  
> <primitive: 'primitiveUtcWithOffset'> . I found that on a Mac, with  
> 'Croquet Closure Cog VM [CoInterpreter VMMaker.oscog-eem.331] Squeak  
> Cog 4.0.2776' 'Mac OS' 'intel' '1092' (from Eliot's site), the second  
> element I get (time zone offset) is -140473411.
> 
> The correct value would be -10800, as answered in Windows. I could not  
> test on Linux yet (could not get the vm to run in Ubuntu 14.04 64 bit  
> :( ).
> 
> Any clue on what's wrong on Mac OS?
> 
> BTW, which would be the current non-Cog VMs to try?
>

Oops, I mistakenly said that the Cog VMs could be used. But it looks like
there is a regression or code merge problem of some sort. I'm afraid that
I was testing with my own locally compiled Cog VM and did not notice the
problem.

A unix Mac VM from squeakvm.org/unix should demonstrate the correct behavior.

CC to vm-dev list:

Eliot, the fix for this was here (but it seems to have been overridden by
a more recent change):

   Name: VMMaker.oscog-dtl.286
   Author: dtl
   Time: 4 May 2013, 11:29:25.237 am
   UUID: 8be237d9-7812-4792-9723-90f9cff0c2e9
   Ancestors: VMMaker.oscog-eem.285
   
   Replace broken primitiveUtcWithOffset with a version that works.

Dave