I have version 0.4304 of DateTime (the latest). In that version, line 1651 is the return from _compare_overload: 
sub _compare_overload
{
    # note: $_[1]->compare( $_[0] ) is an error when $_[1] is not a
    # DateTime (such as the INFINITY value)
    return $_[2] ? - $_[0]->compare( $_[1] ) : $_[0]->compare( $_[1] )
+;
}

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_compare_overload is overloaded to <=> and cmp for DateTime objects. So a good place to start tracking this down would be any place you compare DateTime objects (recognizing that the offending call/comparison may be coming from some other module that you are using).

In reply to Re: Negation Error by broomduster
in thread Negation Error by Herkum

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