Given that DateTime says:

All of the parameters are optional except for "year". The "month" and "day" parameters both default to 1, while the "hour", "minute", "second", and "nanosecond" parameters all default to 0.

the answer would appear to be "no". By the time the object has been created it is too late to determine whether an hour of 0 is by default or by supply.

In reply to Re: Detecting whether DateTime object has a time component or not? by hippo
in thread Detecting whether DateTime object has a time component or not? by perlancar

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