[Chicken-janitors] Re: #287: timezone fixes (was: seconds->utc-time doesn't zero out its timezone)

[Chicken Trac]

#287: timezone fixes
----------------------------+-----------------------------------------------
 Reporter:  zbigniew        |       Owner:  felix   
     Type:  enhancement     |      Status:  accepted
 Priority:  minor           |   Milestone:  4.6.0   
Component:  core libraries  |     Version:  4.5.x   
 Keywords:                  |  
----------------------------+-----------------------------------------------

Comment(by zbigniew):

 Patch 0002 changes seconds->local-time to use tm_gmtoff for all platforms
 that support it, not just OS X.  As this is a BSD extension (present since
 BSD4.3-Reno) it is widely available.  Currently we just use the local
 timezone, which is incorrect when calculating a time with DST not equal to
 current time  (or if, say, timezone rules changed in the past).  For
 example, on my machine, the second timezone offset should be 21600,
 because DST is in effect:
 {{{
 (seconds->local-time 0) ;=> #(0 0 19 31 11 69 3 364 #f 18000)
 (seconds->local-time) ;=> #(48 45 21 19 6 110 1 199 #t 18000)
 }}}

 (Note that the timezone offset is always inclusive of DST and the dst flag
 is just advisory.

 This does not fix the issue on Windows or some other platforms, but that
 would require more hacks, so I am punting on that.

-- 
Ticket URL: <http://www.irp.oist.jp/trac/chicken/ticket/287#comment:3>
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