I seem to remember that 0 and 1 in void context are documented as a form of NOP (no operation) in Perl, but I'm failing to find the corresponding perldoc.

edit

ahh, it's in perlop

   No-ops
       Perl doesn't officially have a no-op operator, but the bare con
+stants 0
       and 1 are special-cased to not produce a warning in a void cont
+ext, so
       you can for example safely do

           1 while foo();
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