Parser and emit_forward_arg

[marcandre]

I'd like to use the latest version of parser with emit_forward_arg turned on.

We could avoid this "hack" of redefining to_a as different from children

$ ruby-parse --legacy-forward-arg -e "def foo(...);end; def bar(*rest); end"
(begin
  (def :foo
    (forward-args) nil)
  (def :bar
    (args
      (restarg :rest)) nil))

$ ruby-parse -e "def foo(...);end; def bar(*rest); end"
(begin
  (def :foo
    (args
      (forward-arg)) nil)
  (def :bar
    (args
      (restarg :rest)) nil))

The later form is much improved as an argument signature is always inside an args node.

I doubt it would be much incompatibility, but v1 would be perfect for this.

Comments / objections?

[bbatsov]

Fine by me.