[ruby-core:124499] [Ruby Feature#21813] Add [:forward, :...] symbol tuple to indicate forwarding arguments when calling `Method#parameters`

13 Jan 2026

      Issue #21813 has been updated by nobu (Nobuyoshi Nakada).

`foo(a: 1)` doesn't print what you expect, I guess.

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Feature #21813: Add  [:forward, :...] symbol tuple to indicate forwarding arguments when calling `Method#parameters`
https://bugs.ruby-lang.org/issues/21813#change-116057

* Author: pabloh (Pablo Herrero)
* Status: Open
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When accessing `Method#parameters` for a method using forwarding parameters, an unexpected behavior arises:

```ruby
def foo(*, **, &)
  binding.eval "print(#{(method(__method__).parameters.dig(0,1))})" # Works fine
end

foo(1,2,3,4) # => 1234

def bar(...)
  binding.eval "print(#{(method(__method__).parameters.dig(0,1))})" # Fails!
end

bar(1,2,3,3) # SyntaxError
```

It's very strange that you can't access the parameters, on `eval`, using the symbols provided at `Method#parameters`.

Adding `[:forward, :...]` or `[:forwarding, :...]` for those cases feels simply natural.

-- 
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