Git alias with positional parameters

Basically I’m trying to alias:

git files 9fa3

…to execute the command:

git diff --name-status 9fa3^ 9fa3

but git doesn’t appear to pass positional parameters to the alias command. I have tried:

[alias]
    files = "!git diff --name-status $1^ $1"
    files = "!git diff --name-status {1}^ {1}"

…and a few others but those didn’t work.

The degenerate case would be:

$ git echo_reverse_these_params a b c d e
e d c b a

…how can I make this work?