[tz] zdump new option -i for easier-to-review output

Paul Eggert eggert at cs.ucla.edu
Mon Dec 19 18:03:17 UTC 2016

On 08/21/2016 03:42 AM, Paul Eggert wrote:
> Jon Skeet wrote:
>> I'd stlil argue for
>> colons in offsets (RFC5322 uses a horrible format in general; I see no
>> reason to copy mistakes of the past)
> Tim argued for that as well, so let's do that. 

After having used it for a while, the colons output by zic are getting 
in the way of my manual audits of zdump -i output. The tz database omits 
":" in numeric time zone abbreviations, not only because of longstanding 
tradition exemplified by Internet RFC 5322, but also because the POSIX 
TZ format does not allow ":" there. "zic -i Asia/Colombo" therefore 
outputs lines like this:

2006-04-15    00    +05:30    "+0530"

where the quoted string indicates that something is amiss because the 
abbreviation is not alphabetic and does not match the computed 
abbreviation. To fix this, the attached proposed patch causes zic to 
compute the abbreviation "+0530" instead, causing its output line to 
look like this:

2006-04-15    00    +0530

which makes it clearer that the situation is expected and does not need 
further attention.

It may be that we'll need at some point to have a way to add colons to 
the tz database's time zone abbreviations, for people who prefer that 
style and are not worried about POSIX compatibility. I suppose this can 
be a topic for a future patch. It would need to be done carefully as it 
would likely require a change to the version number in compiled tzdata 
files, as it would change the format of their embedded TZ strings.
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