Support it (read: It is time to switch to Prism.)

[ParadoxV5]

Late Merry Christmas! Ruby 3.4 is out and–

$ cat ruby.rb; steep check
5.then { it }
# Type checking files:

.F

ruby.rb:1:9: [error] Type `::Object` does not have method `it`
│ Diagnostic ID: Ruby::NoMethod
│
└ 5.then { it }
           ~~

Detected 1 problem from 1 file

The problem:

irb(main):001> require 'parser/current'
warning: parser/current is loading parser/ruby34, which recognizes 3.4.0-compliant syntax, but you are running 3.4.1.
Please see https://github.com/whitequark/parser#compatibility-with-ruby-mri.
=> true
irb(main):002> Parser::CurrentRuby.parse('5.then { it }')
=>
s(:block,
  s(:send,
    s(:int, 5), :then),
  s(:args),
  s(:send, nil, :it))
irb(main):003> Parser::CurrentRuby.parse('5.then { _1 }') # control
=>
s(:numblock,
  s(:send,
    s(:int, 5), :then), 1,
  s(:lvar, :_1))

But should we bother the Parser team?

• Soft deprecation of the project? whitequark/parser#1046

With the conclusion of the Syntax Moratorium, who know what pipeline operators creative sugar the devs of Ruby will come up with.
Combined with syntax bug fixes, Prism the “official” parser will make maintainers new and old lose interest of older alternatives, sooner or later.

irb(main):001> Prism.parse '5.then { it }'
=>
…
              └── block:
                  @ BlockNode (location: (1,7)-(1,13))
                  ├── flags: ∅
                  ├── locals: []
                  ├── parameters:
                  │   @ ItParametersNode (location: (1,7)-(1,13))
                  │   └── flags: ∅
                  ├── body:
…

I can stick with _1s for the time beïng.