The output would have been empty then; it is apparently not considered a NOP either:

$ perl -MO=Deparse,x7 -e'1;'
'???';
-e syntax OK
[download]

('???' is what B::Deparse produces when something gets optimized away.) I'm guessing that's because a sort may have side effects f.ex with tied arrays or inside the callback (if there is one), or something to that effect.

Makeshifts last the longest.