function f/0
  macro m/0
  end macro
end function

# (function (@ 1 0-8) ‘f/0’
#   (.inner
#     (macro (@ 2 2-7) ‘m/0’
#       (.inner nil)
#     )
#   )
# )
# :2:2–7: error: macro definition inside function definition
#    macro m/0
#    ^^^^^
# :1:0–8: note: outer function definition defined here
#  function f/0
#  ^^^^^^^^