my_macro(.)
my_macro(. .)

# (macro_call (@ 1 0-8) ‘my_macro/0’
#   (.arguments nil)
# )
# (macro_call (@ 2 0-8) ‘my_macro/0’
#   (.arguments nil)
# )
# :1:9–10: warning: ‘.’ outside alternation has no effect
#  my_macro(.)
#           ^
# :2:9–10: warning: ‘.’ outside alternation has no effect
#  my_macro(. .)
#           ^
# :2:11–12: warning: ‘.’ outside alternation has no effect
#  my_macro(. .)
#             ^