Previously, requesting a time that got repeated - on the given date,
due to a fall-back transition - would get one of the two repeats,
giving the caller (no hint that there was a choice and) no way to
select the other. Add a flags parameter that captures the available
ways to resolve such ambiguity or select a suitable time near a gap.
Add such a parameter to relevant QDateTime methods, including
constructors, to enable callers to indicate their preference in the
same way. This replaces DST-hint parameters in various internal
functions, including QTimeZonePrivate's dataForLocalTime(). Adapted
tst_QDateTime to test the new feature.
Adapt to gap-times no longer being invalid (by default; or, when they
are, no longer having a useful toMSecsSinceEpoch() value). Instead,
they don't match what was asked for. Amend documentation to reflect
that. Most of the code change for this is to QDTParser and QDTEdit.
[ChangeLog][QtCore][QDateTime] Added a TransitionResolution parameter
to various QDateTime methods to enable the caller to indicate, when
the indicated datetime falls in a time-zone transition, which side of
the transition to fall or whether to produce an invalid result.
[ChangeLog][QtCore][Possibly Significant Behavior Change] When
QDateTime is instantiated for a combination of date and time that was
skipped, by local time or a time-zone, for example during a
spring-forward DST transition, the result is no longer marked invalid.
Whether the selected nearby date-time is before or after the skipped
interval may have changed on some platforms; unless overridden by an
explicit TransitionResolution, it is now a date-time as long after the
previous day's noon as a naive reading of the requested date and time
would expect. This was the prior behavior at least on Linux.
Fixes: QTBUG-79923
Change-Id: I11d5339abef9e7125c4e0dc95a09a7cd4f169dab
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
a49ccc08c3