* NEWS: Mention how the CLDR temporary hack runs afoul of
a bug in zic 2023d through 2026a, and how to work around
the bug by using ‘-b fat’.
---
NEWS | 26 +++++++++++++++++++++-----
1 file changed, 21 insertions(+), 5 deletions(-)
diff --git a/NEWS b/NEWS
index e288e399..0d307a3d 100644
--- a/NEWS
+++ b/NEWS
@@ -15,10 +15,11 @@ Unreleased, experimental changes
Model this with its traditional abbreviation CST. Although the
change to permanent -06 legally took place on 2026-08-21,
temporarily model the change to occur on 2026-11-01 at 02:00
- instead, for the same reason as other recent temporary hacks. This
- only affects America/Inuvik as the rest of the territory is covered
- by America/Edmonton, for which the equivalent change was released in
- 2026c.
+ for the same reason as other recent temporary hacks. (Caution:
+ see “NOTE FOR 2026b TEMPORARY HACK FOR CLDR AND CANADA” below.)
+ This affects only America/Inuvik as the rest of the territory is
+ covered by America/Edmonton, for which the equivalent change was
+ released in 2026c.
The Town of Golden in southeastern British Columbia will rejoin the
bulk of the province on -07 after falling back a final time on
@@ -102,7 +103,8 @@ Release 2026c - 2026-07-08 10:23:58 -0700
CST. Although the change to permanent -06 legally took place on
2026-06-18, temporarily model the change to occur on 2026-11-01 at
02:00 instead, for the same reason we introduced a similarly
- temporary hack for British Columbia in 2026b.
+ temporary hack for British Columbia in 2026b. (Caution: see
+ “NOTE FOR 2026b TEMPORARY HACK FOR CLDR AND CANADA” below.)
As the change affects both America/Edmonton and its backward
compatibility link, the obsolescent setting TZ="Canada/Mountain"
@@ -159,6 +161,7 @@ Release 2026b - 2026-04-22 23:06:43 -0700
Briefly:
British Columbia moved to permanent -07 on 2026-03-09.
+ zic no longer mishandles a last transition to a new time type.
Some more overflow bugs have been fixed in zic.
Changes to future timestamps
@@ -185,6 +188,19 @@ Release 2026b - 2026-04-22 23:06:43 -0700
Changes to code
zic no longer mishandles a last transition to a new time type.
+ NOTE FOR 2026b TEMPORARY HACK FOR CLDR AND CANADA:
+ This zic fix is needed for the temporary hack (mentioned above)
+ that works around the Canadian timekeeping bug in Unicode CLDR.
+ Without the fix, the temporary hack causes zic versions 2023d
+ through 2026a, in their default mode that generates slim output,
+ to generate a TZif file that violates Internet RFC 9636 §3.3.
+ The buggy file in turn causes some TZif readers, including tzcode
+ itself, to ignore America/Vancouver’s 2026-11-01 02:00 transition
+ from PDT (tm_isdst=1) to MST (tm_isdst=0). Although the buggy
+ file does not cause any known TZif reader to mishandle UT offsets,
+ caution is advised when using zic 2023d through 2026a to compile
+ data from more-recent tz releases. To work around this problem
+ when using these older zic versions, use ‘zic -b fat’.
zic no longer overflows a buffer when generating a TZ string like
"PST-167:59:58PDT-167:59:59,M11.5.6/-167:59:59,M12.5.6/-167:59:59",
--
2.53.0
