It turns out that almost all operators in Perl get optimized away in this manner. 'Constant folding', as it's called, is a very common optimization.

% perl -MO=Deparse
print 15 + 1, 15 - 1, 15 * 1, 15 % 1, 15 & 1, 15 ^ 1, 15 << 1,
  !15, 15 || $x, 15 . 1, 15 < 1, 15 <=> 1, 15 ? $x : $y;
__END__
print 16, 14, 15, 0, 1, 14, 30, 0, 15, '151', 0, 1, $x;
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In fact, the only operator I've found that could have this optimization but doesn't is x.