Many details here are above my head, but my instinct that it's related to optimization in Boolean context seems justified.

Just that it's NOT a Boolean context here, just the more general scalar (sic) one.

And that's obvious by the fact that the PV for !!0 is "" and not "0"

So this smells like bug for me...

Just not a big one, because Perl does that quite regularly.¹

Or am I missing something in the flags?

Cheers Rolf
(addicted to the Perl Programming Language :)
see Wikisyntax for the Monastery

Updates

¹) compare code example in Re^2: Reason for this discrepancy with scalar?

In reply to Re^4: Reason for this discrepancy with scalar? by LanX
in thread Reason for this discrepancy with scalar? by kikuchiyo

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