function f/0
  for 1 to 1 as \1
    return
  end for
  "dead code"
end function

# (function (@ 1 0-8) ‘f/0’
#   (.inner
#     (for (@ 2 2-5) ‘1’ ‘1’ (.variable ‘\1’)
#       (.inner
#         (return (@ 3 4-10))
#       )
#     )
#   )
# )
# :5:2–13: warning: statement is unreachable
#    "dead code"
#    ^^^^^^^^^^^
#