From c23d00078c8801d2bc215bf0554899cc871bba33 Mon Sep 17 00:00:00 2001 From: Edward Welbourne Date: Fri, 18 Aug 2023 17:15:37 +0200 Subject: [PATCH] Let QDateTime::offsetFromUtc() work for invalid date-times MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The implementation previously worked for non-short date-times, where the offset has been remembered since construction. This included the case of zoned times (and local times more than 2^55 msec away from the start of 1970) that hit a spring-forward's gap; but excluded local times that did the same (within 2^55 msec of the epoch). This precluded an offset check in a spring-forward test, now added. We can in fact determine the offset whenever we got a valid date and time (we do so in the course of initializing the object, and when asked for toMSecsSinceEpoch(), even when invalid), and we should not use the value of the recorded offset if we didn't get a valid date and time, so amend to always return 0 if we didn't get valid date and time and always report the correct offset otherwise. In the process, amend offsetFromUtc()'s computation to directly resolve the date-time, rather than doing so via toMSecsSinceEpoch(), which has to repeat decision-making offsetFromUtc() has already done by the time it calls it. Also amend toMSecsSinceEpoch() to return 0 if we didn't have a valid date and time to begin with, so it only attempts to produce a useful result in the case where construction attempted to resolve the date-time. Change-Id: I6574e362275ccc4fbd8de6f0fa875d2e50f3bffe Reviewed-by: Mårten Nordheim --- src/corelib/time/qdatetime.cpp | 27 ++++++++++++------- .../corelib/time/qdatetime/tst_qdatetime.cpp | 1 + 2 files changed, 18 insertions(+), 10 deletions(-) diff --git a/src/corelib/time/qdatetime.cpp b/src/corelib/time/qdatetime.cpp index eb65d428ed..f338201f67 100644 --- a/src/corelib/time/qdatetime.cpp +++ b/src/corelib/time/qdatetime.cpp @@ -3744,16 +3744,18 @@ QTimeZone QDateTime::timeZone() const int QDateTime::offsetFromUtc() const { + const auto status = getStatus(d); + if (!status.testFlags(QDateTimePrivate::ValidDate | QDateTimePrivate::ValidTime)) + return 0; + // But allow invalid date-time (e.g. gap's resolution) to report its offset. if (!d.isShort()) return d->m_offsetFromUtc; - if (!isValid()) - return 0; - auto spec = getSpec(d); + auto spec = extractSpec(status); if (spec == Qt::LocalTime) { - // we didn't cache the value, so we need to calculate it now... - qint64 msecs = getMSecs(d); - return (msecs - toMSecsSinceEpoch()) / MSECS_PER_SEC; + // We didn't cache the value, so we need to calculate it: + auto dst = extractDaylightStatus(status); + return QDateTimePrivate::localStateAtMillis(getMSecs(d), dst).offset; } Q_ASSERT(spec == Qt::UTC); @@ -3964,8 +3966,13 @@ qint64 QDateTime::toMSecsSinceEpoch() const // Note: QDateTimeParser relies on this producing a useful result, even when // !isValid(), at least when the invalidity is a time in a fall-back (that // we'll have adjusted to lie outside it, but marked invalid because it's - // not what was asked for). Other things may be doing similar. - switch (getSpec(d)) { + // not what was asked for). Other things may be doing similar. But that's + // only relevant when we got enough data for resolution to find it invalid. + const auto status = getStatus(d); + if (!status.testFlags(QDateTimePrivate::ValidDate | QDateTimePrivate::ValidTime)) + return 0; + + switch (extractSpec(status)) { case Qt::UTC: return getMSecs(d); @@ -3974,9 +3981,9 @@ qint64 QDateTime::toMSecsSinceEpoch() const return d->m_msecs - d->m_offsetFromUtc * MSECS_PER_SEC; case Qt::LocalTime: - if (d.isShort()) { + if (status.testFlag(QDateTimePrivate::ShortData)) { // Short form has nowhere to cache the offset, so recompute. - auto dst = extractDaylightStatus(getStatus(d)); + auto dst = extractDaylightStatus(status); auto state = QDateTimePrivate::localStateAtMillis(getMSecs(d), dst); return state.when - state.offset * MSECS_PER_SEC; } diff --git a/tests/auto/corelib/time/qdatetime/tst_qdatetime.cpp b/tests/auto/corelib/time/qdatetime/tst_qdatetime.cpp index 4e81476e65..71719a183e 100644 --- a/tests/auto/corelib/time/qdatetime/tst_qdatetime.cpp +++ b/tests/auto/corelib/time/qdatetime/tst_qdatetime.cpp @@ -4229,6 +4229,7 @@ void tst_QDateTime::timeZones() const inGap = QDateTime(QDate(2013, 3, 31), QTime(2, 30)); QVERIFY(!inGap.isValid()); QCOMPARE(inGap.date(), QDate(2013, 3, 31)); + QCOMPARE(inGap.offsetFromUtc(), 7200); QCOMPARE(inGap.time(), QTime(3, 30)); }