dateOnly property
Is this constructing a pure date.
This is important because some locales change times at midnight, e.g. Brazil. So if we try to create a DateTime representing a date at midnight on the day of transition it will jump forward or back 1 hour. If it jumps forward that's mostly harmless if we only care about the date. But if it jumps backwards that will change the date, which is bad. Compensate by adjusting the time portion forward. But only do that when we're explicitly trying to construct a date, which we can tell from the format.
Implementation
// We do set it, the analyzer just can't tell.
// ignore: prefer_final_fields
var dateOnly = false;