This doesn't happen with 5.8.6 here. Whatever, ~0 is binary complement of zero, i.e. indeed a "largish" integer (but not if you're on a 4 bit processor!;-).

I do get the same behaviour if I s/do/require/, so it seems that your perl is interpreting do that way. Maybe checking some perldelta may reveal a change that has occured in the meanwhile.

Try running your script through B::Deparse and maybe that could shed some light on how perl is interpreting it.

Perl v18446744073709551615.0.0 required--this is only v5.6.1, stopped 
+(did you mean v18446744073709551615.0.0?) at -e line 1.
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Hmmm... so you're on a 64-bit machine!! I don't...

$ perl -le 'print~0'
4294967295
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