From: "johnnyshields (Johnny Shields) via ruby-core" <ruby-core@...>
Date: 2024-01-25T05:00:14+00:00
Subject: [ruby-core:116438] [Ruby master Feature#20211] Reconsider introducing 3.2-style support of Anonymous Args/Blocks

Issue #20211 has been reported by johnnyshields (Johnny Shields).

----------------------------------------
Feature #20211: Reconsider introducing 3.2-style support of Anonymous Args/Blocks
https://bugs.ruby-lang.org/issues/20211

* Author: johnnyshields (Johnny Shields)
* Status: Open
* Priority: Normal
----------------------------------------
(My sincere apologies if this issue has already been raised, I didn't see it in Ruby 3.4 backlog.)

As per https://bugs.ruby-lang.org/issues/19370, Ruby 3.3 no longer allows the following:

```ruby
def m(*)
  [1, 2, 3].each { |*| p(*) }
end
m('test', 'test', 'test')
#=> Ruby 3.2: p(*) uses args from m(*) #=> test, test, test
#=> Ruby 3.3: raises SyntaxError: anonymous rest parameter is also used within block
```

I am concerned because Rubocop auto-corrects Ruby 3.1+ code to syntax which is no longer supported in Ruby 3.3. There may be quite a bit of Ruby code in the wild which breaks on 3.3 (my own app broke in about 50 places).
  - [Ruby 3.1+: Naming/BlockForwarding (default true)](https://www.rubydoc.info/gems/rubocop/RuboCop/Cop/Naming/BlockForwarding)
  - [Ruby 3.2+: Style/ArgumentsForwarding with UseAnonymousForwarding (default true)](https://www.rubydoc.info/gems/rubocop/RuboCop/Cop/Style/ArgumentsForwarding)

It would be nice if the Ruby 3.4 syntax could allow the old nested syntax, supporting arg shadowing with different behavior between implicit and explicit |*| usage.

```ruby
def m(*)
  [1, 2, 3].each { p(*) }
end
m('test', 'test', 'test')
#=> Ruby 3.2: p(*) uses args from m(*) #=> test, test, test
#=> Ruby 3.4: p(*) uses args from m(*) #=> test, test, test

def m(*)
  [1, 2, 3].each { |*| p(*) }
end
m('test', 'test', 'test')
#=> Ruby 3.2: p(*) uses args from m(*) #=> test, test, test
#=> Ruby 3.4: p(*) uses args from each #=> 1, 2, 3
```

The same would also apply to anonymous blocks.



-- 
https://bugs.ruby-lang.org/
 ______________________________________________
 ruby-core mailing list -- ruby-core@ml.ruby-lang.org
 To unsubscribe send an email to ruby-core-leave@ml.ruby-lang.org
 ruby-core info -- https://ml.ruby-lang.org/mailman3/postorius/lists/ruby-core.ml.ruby-lang.org/