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ID | Category | Severity | Type | Date Submitted | Last Update | ||||||||
0001816 | [Issue 8 drafts] System Interfaces | Objection | Error | 2024-02-23 08:54 | 2024-04-29 15:48 | ||||||||
Reporter | eggert | View Status | public | ||||||||||
Assigned To | |||||||||||||
Priority | normal | Resolution | Accepted As Marked | ||||||||||
Status | Resolved | Product Version | Draft 4.1 | ||||||||||
Name | Paul Eggert | ||||||||||||
Organization | UCLA Computer Science | ||||||||||||
User Reference | |||||||||||||
Section | daylight, timezone, tzname | ||||||||||||
Page Number | 2310-2311 | ||||||||||||
Line Number | 75175-75207 | ||||||||||||
Final Accepted Text | See Note: 0006774. | ||||||||||||
Summary | 0001816: daylight, timezone, tzname do not work with location-based TZ | ||||||||||||
Description |
Although the external variables daylight, timezone, and tzname have well-defined values for POSIX.1-2017 TZ settings, they do not work with location-based TZ settings. For example, with TZ="Europe/Moscow", since 1970 there have been four distinct abbreviations "EET", "EEST", "MSK" and "MSD", and MSK has sometimes stood for +0300 and sometimes for +0400. In practice, I think implementations that support location-based TZ settings set these external variables haphazardly, since the TZif representation doesn't correspond to POSIX.1-2017. User code should therefore not rely on these variables' values when location-based settings are used. The proposed action attempts to change the standard to describe this situation. It continues to require traditional POSIX behavior for traditional TZ settings (which it calls "stdoffsettish timezones" for lack of a better term). It also gives FUTURE DIRECTIONS in which these external variables will be removed. It does not propose marking the variables as obsolescent because, as I understand it, it's too late to do that in this go-round of the standard. |
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Desired Action |
8.3 Other Environment Variables, TZ, page 176 line 6219 Prepend the following text to line 6219, and put "stdoffsettish timezone" into the index. A stdoffsettish timezone" is one that is defined by a TZ of the second format. <time.h> FUTURE DIRECTIONS page 454 line 15856 Change "None" to "The variables daylight, timezone, and tzname are planned to be removed, as they have unspecified values unless the timezone is stdoffsettish." daylight page 801 lines 27442-27448 (the entire page) Remove this page, since 'daylight' is already documented under tzset(), and there's no reason to give it a separate page (there is no page for the related variable tzname). Alternately, add a FUTURE DIRECTIONS section saying "This variable is planned to be removed, as it has an unspecified value unless the timezone is stdoffsettish." Similarly for timezone, page 2279 lines 74379-74385 (the entire page). strptime APPLICATION USAGE page 2160 line 70602: Change "If this name matches" to "If the local timezone is stdoffsettish and this name matches". line 70604: Likewise. tzset DESCRIPTION page 2310 line 75175: Prepend "If the local timezone is stdoffsetish," line 75179: Also prepend "If the local timezone is stdoffsetish," Line 75182: Append the following paragraph: If the local timezone is not stdoffsettish, the tzset() function may set the external variables tzname, daylight and timezone to unspecified values. line 75199 (APPLICATION USAGE) Append the following paragraph: The values of the variables daylight, timezone, and tzname should be used only if the local timezone is known to be stdoffsettish. page 2311 line 75207 (FUTURE DIRECTIONS): Change "None" to "The variables daylight, timezone, and tzname are planned to be removed, as they have unspecified values unless the local timezone is stdoffsettish." |
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Tags | tc1-2024 | ||||||||||||
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Issue History | |||
Date Modified | Username | Field | Change |
2024-02-23 08:54 | eggert | New Issue | |
2024-02-23 08:54 | eggert | Name | => Paul Eggert |
2024-02-23 08:54 | eggert | Organization | => UCLA Computer Science |
2024-02-23 08:54 | eggert | Section | => daylight, timezone, tzname |
2024-02-23 08:54 | eggert | Page Number | => 2310-2311 |
2024-02-23 08:54 | eggert | Line Number | => 75175-75207 |
2024-02-25 07:07 | kre | Note Added: 0006678 | |
2024-02-26 18:06 | eggert | Note Added: 0006687 | |
2024-02-26 19:23 | eblake | Relationship added | related to 0001797 |
2024-04-29 15:42 | Don Cragun | Note Added: 0006774 | |
2024-04-29 15:46 | Don Cragun | Note Edited: 0006774 | |
2024-04-29 15:47 | Don Cragun | Note Edited: 0006774 | |
2024-04-29 15:48 | Don Cragun | Final Accepted Text | => See Note: 0006774. |
2024-04-29 15:48 | Don Cragun | Status | New => Resolved |
2024-04-29 15:48 | Don Cragun | Resolution | Open => Accepted As Marked |
2024-04-29 15:50 | Don Cragun | Tag Attached: tc1-2024 | |
2024-04-29 17:15 | Don Cragun | Note Edited: 0006774 |
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