That's not a feature, it's a bug. Here are changes to "zic.c" to eliminate the error message, and to "localtime.c" to ensure correct handling of zones to be treated as if they had long-ago DST (rather like proleptic calendars). --ado ------- zic.c ------- *** /tmp/geta13214 Mon Nov 19 17:41:38 2007 --- /tmp/getb13214 Mon Nov 19 17:41:39 2007 *************** *** 2012,2018 **** } for (i = 0; i < zonecount; ++i) { zp = &zpfirst[i]; ! updateminmax(zp->z_untilrule.r_loyear); for (j = 0; j < zp->z_nrules; ++j) { rp = &zp->z_rules[j]; if (rp->r_lowasnum) --- 2012,2019 ---- } for (i = 0; i < zonecount; ++i) { zp = &zpfirst[i]; ! if (i < zonecount - 1) ! updateminmax(zp->z_untilrule.r_loyear); for (j = 0; j < zp->z_nrules; ++j) { rp = &zp->z_rules[j]; if (rp->r_lowasnum) *************** *** 2043,2050 **** else max_year = INT_MAX; } /* ! ** For the benefit of older systems, generate data through 2037. */ if (max_year < 2037) max_year = 2037; for (i = 0; i < zonecount; ++i) { --- 2044,2054 ---- else max_year = INT_MAX; } /* ! ** For the benefit of older systems, ! ** generate data from 1900 through 2037. */ + if (min_year > 1900) + min_year = 1900; if (max_year < 2037) max_year = 2037; for (i = 0; i < zonecount; ++i) { ------- localtime.c ------- *** /tmp/geta13272 Mon Nov 19 17:43:30 2007 --- /tmp/getb13272 Mon Nov 19 17:43:30 2007 *************** *** 177,182 **** --- 177,183 ---- const struct tm * btmp); static time_t transtime(time_t janfirst, int year, const struct rule * rulep, long offset); + static int typesequiv(const struct state * sp, int a, int b); static int tzload(const char * name, struct state * sp, int doextend); static int tzparse(const char * name, struct state * sp, *************** *** 556,570 **** } i = 2 * YEARSPERREPEAT; sp->goback = sp->goahead = sp->timecnt > i; ! sp->goback = sp->goback && sp->types[i] == sp->types[0] && differ_by_repeat(sp->ats[i], sp->ats[0]); sp->goahead = sp->goahead && ! sp->types[sp->timecnt - 1] == sp->types[sp->timecnt - 1 - i] && differ_by_repeat(sp->ats[sp->timecnt - 1], sp->ats[sp->timecnt - 1 - i]); return 0; } static const int mon_lengths[2][MONSPERYEAR] = { { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }, { 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 } --- 557,598 ---- } i = 2 * YEARSPERREPEAT; sp->goback = sp->goahead = sp->timecnt > i; ! sp->goback = sp->goback && ! typesequiv(sp, sp->types[i], sp->types[0]) && differ_by_repeat(sp->ats[i], sp->ats[0]); sp->goahead = sp->goahead && ! typesequiv(sp, sp->types[sp->timecnt - 1], ! sp->types[sp->timecnt - 1 - i]) && differ_by_repeat(sp->ats[sp->timecnt - 1], sp->ats[sp->timecnt - 1 - i]); return 0; } + static int + typesequiv(sp, a, b) + const struct state * const sp; + const int a; + const int b; + { + register int result; + + if (sp == NULL || + a < 0 || a >= sp->typecnt || + b < 0 || b >= sp->typecnt) + result = FALSE; + else { + register const struct ttinfo * ap = &sp->ttis[a]; + register const struct ttinfo * bp = &sp->ttis[b]; + result = ap->tt_gmtoff == bp->tt_gmtoff && + ap->tt_isdst == bp->tt_isdst && + ap->tt_ttisstd == bp->tt_ttisstd && + ap->tt_ttisgmt == bp->tt_ttisgmt && + strcmp(&sp->chars[ap->tt_abbrind], + &sp->chars[bp->tt_abbrind]) == 0; + } + return result; + } + static const int mon_lengths[2][MONSPERYEAR] = { { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }, { 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }