error: unexpected token kDO

[y-yagi]

It is a bug similar to #466 and #447, but it is reproduced with v2.5.1.0.

# test.rb
check_open = -> *args do
  # ...
end

check_open.call

$ ruby-parse -v
ruby-parse based on parser version 2.5.1.0 

$ ruby-parse test.rb
test.rb:1:23: error: unexpected token kDO
test.rb:1: check_open = -> *args do
test.rb:1:                       ^~ 

$ ruby-parse _2.4.0.2_ test.rb
warning: parser/current is loading parser/ruby25, which recognizes
warning: 2.5.0-compliant syntax, but you are running 2.5.1.
warning: please see https://github.com/whitequark/parser#compatibility-with-ruby-mri.
(begin
  (lvasgn :check_open
    (block
      (lambda)
      (args
        (restarg :args)) nil))
  (send
    (lvar :check_open) :call)) 

$ ruby -vc test.rb
ruby 2.5.1p57 (2018-03-29 revision 63029) [x86_64-linux]
Syntax OK 

[iliabylich]

$ bin/ruby-parse -E test.rb
check_open = -> *args do
^~~~~~~~~~ tIDENTIFIER "check_open"             expr_cmdarg  [0 <= cond] [0 <= cmdarg]
check_open = -> *args do
           ^ tEQL "="                           expr_beg     [0 <= cond] [0 <= cmdarg]
check_open = -> *args do
             ^~ tLAMBDA "->"                    expr_endfn   [0 <= cond] [0 <= cmdarg]
check_open = -> *args do
                ^ tSTAR2 "*"                    expr_value   [0 <= cond] [0 <= cmdarg]
check_open = -> *args do
                 ^~~~ tIDENTIFIER "args"        expr_cmdarg  [0 <= cond] [0 <= cmdarg]
check_open = -> *args do
                      ^~ kDO "do"               expr_value   [0 <= cond] [0 <= cmdarg]
test.rb:1:23: error: unexpected token kDO
test.rb:1: check_open = -> *args do
test.rb:1:                       ^~

At least it's not related to @cmdarg. There's a wrong state after tIDENTIFIER, MRI transitions to EXPR_ARG (and old versions of parser too), so I guess something is wrong with the @command_state and arg_or_cmdarg method. I'll take a look a bit later.