Ah, that might explain it. So the module seems to implement that convention as well.
iex(48)> args = ["-co", "foo"]
["-co", "foo"]
iex(49)> {switches, _, _} = OptionParser.parse(
...(49)> args,
...(49)> switches: [
...(49)> debug: :boolean,
...(49)> config_override: :string
...(49)> ],
...(49)> aliases: [
...(49)> o: :config_override
...(49)> ]
...(49)> )
{[config_override: "foo"], [], [{"-c", nil}]}
As you said, -c is ignored.
