Rest (*) character not showing up in macros

[watzon]

Crystal::Macro::Def#args is supposed to list all arguments, but if you include a rest character it only shows up as an empty string.

Example: https://carc.in/#/r/3m9b

[bew]

@watzon a simple wrapper with splat (*) support: https://carc.in/#/r/3mc6

The original idea was to correctly wrap a method, and generate a new method with the exact same signature. But there doesn't seem to be a way without using a lot of boilerplate like:

macro wrap(def_node)
  {% splat_no = def_node.splat_index %}
  def {{ def_node.name }}_wrapped(
    {% for arg, i in def_node.args %}
      {% if i == splat_no %}*{% end %}{{ arg }},
    {% end %}
    {% if double_splat = def_node.double_splat %}
      **{{ double_splat }},
    {% end %}
    {% if block_arg = def_node.block_arg %}
      &{{ block_arg }}
    {% end %}
  )
    # wrapper content!
  end
end

wrap def foo(a : String, *rest : Bool, named : String)
end

wrap def bar(a : String, *, named : String, **kwargs)
end

wrap def baz(arg : Bool, **kwargs, &block : String ->)
end

https://carc.in/#/r/3mc7 (the generated def doesn't parse correctly, fixed in #5737)

It feels overkill to do that just to wrap a method..
It would be nice to have a SplatArg & DoubleSplatArg (and BlockArg?) in the array from def_node.args, that would have the correct to_s for their kind. This way we would only need to do *def_node.args to replicate the def_node's signature.

[watzon]

Thanks @bew, I figured you'd be able to describe it a bit better

[HertzDevil]

Instead of changing the AST grammar, perhaps it is better to have this as part of #13082