Bug generating RBI for Rails 6.0.3, Ruby 2.7

[hdoan741]

There are generation errors in Ruby 2.7. It seems to happen in the last few days. I found it out via. Sorbet-rails automated tests.

Sample errors: (notice the double ** and double &&)

sorbet/rbi/gems/activerecord.rbi:2489: unexpected token tAMPER https://srb.help/2001
    2489 |  def rotate(**, &&); end
                            ^
sorbet/rbi/gems/activerecord.rbi:2490: unexpected token tAMPER https://srb.help/2001
    2490 |  def sample(**, &&); end

[jaredbeck]

See also:

• Support 2.7 syntax #2900 - "Support 2.7 syntax" - general issue about 2.7
• srb init fails on Ruby 2.7 because of argument delegation #2771 - "srb init fails on Ruby 2.7 because of argument delegation"

[connorshea]

I did a bit of investigating and found that the behavior indeed differs between versions:

# 2.6:
irb(main):003:0> ActiveRecord::Delegation.instance_method(:rotate).parameters
=> [[:rest, :args], [:block, :block]]

# 2.7:
irb(main):008:0> ActiveRecord::Delegation.instance_method(:rotate).parameters
=> [[:rest, :*], [:block, :&]]

Seems to be caused by this line on Ruby 2.7: https://github.com/rails/rails/blob/1b3a0a0388cea93ba33e6a951a3ac0aa2e4a8ed7/activerecord/lib/active_record/relation/delegation.rb#L64

There's no special parameters return type for the delegation syntax, but there is an issue to create it: https://bugs.ruby-lang.org/issues/16456

We could explicitly add a check for [[:rest, :*] and [:block, :&]] and correct it to *args and &block for now, but it'd be a bit of a hack.

EDIT: Apparently the 'hack' is the expected solution 🤷‍♂️

[bmulholland]

I switched to Tapioca and, with these steps, am successfully using Sorbet with Ruby 2.7. This works because Tapioca generates RBI files with *args and &block instead of the new syntax.

[connorshea]

I also chose to resolve this by switching to Tapioca.

[jez]

Going to close this in favor of Tapioca

https://sorbet.org/blog/2022/07/27/srb-tapioca