Fix POSIX TZ edge cases: midnight fall-back, sub-hour offsets, quoted names, abolished DST - #5
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…s, numeric zone names and abolished DST
- express each transition in the pre-transition wall clock instead of
adjusting hours by +/-1; fixes zones such as Asia/Beirut (M10.5.0/0)
- omit the hour only when it is 02:00, the POSIX default; the old code
omitted it whenever both rules shared an hour
- render offsets with minutes/seconds (IST-5:30) instead of truncating
- quote non-alphabetic abbreviations (<+03>-3) as POSIX requires
- zones that abolished DST no longer get invented rules
- week ordinal 5 ("last") only when no later same weekday exists
- table-driven tests against tzdata strings, incl. southern hemisphere
- CI: gofmt, vet, race tests on Go 1.19 and stable; publish on release
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
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What
FormatTimeZoneproduced wrong strings for several classes of zone. This rewrites the transition logic and adds table-driven tests checked against the POSIX strings in the IANA tzdata footers.EET-2EEST,M3.5.0/0,M10.4.6/24EET-2EEST,M3.5.0/0,M10.5.0/0IST-5IST-5:30+03-3+03,M1.3.2/6:14:07,M1.1.1/0<+03>-3CET-1CEST,M3.5.0/2,M10.5.0/3CET-1CEST,M3.5.0,M10.5.0/3How
h1--/h2++hacks and fixes fall-backs that cross midnight./0,/0.4.Output change
Rule 1 no longer carries an explicit
/2. Both forms are valid POSIX and parsed identically by every TZ parser I know of, but if a consumer string-compares, it will notice.GetPosixOffsetis unchanged and marked deprecated because it truncates minutes.Tests
go test -race ./...on Go 1.19 and stable via the updated workflow: 13 zones incl. Sydney (southern hemisphere), London (01:00 transition), Beirut, Kolkata, Tokyo, Istanbul, São Paulo, UTC.🤖 Generated with Claude Code