+ ruby31.y: branch parser.

ruby31.y is based on ruby30.y as Ruby 3.0.1. And Ruby 3.0.0 and 3.0.1 are the same (#791) .

.gitignore

@@ -31,5 +31,6 @@ lib/parser/ruby26.rb
 lib/parser/ruby27.rb
 lib/parser/ruby28.rb
 lib/parser/ruby30.rb
+lib/parser/ruby31.rb
 lib/parser/macruby.rb
 lib/parser/rubymotion.rb

Rakefile

@@ -33,6 +33,7 @@ GENERATED_FILES = %w(lib/parser/lexer.rb
                      lib/parser/ruby26.rb
                      lib/parser/ruby27.rb
                      lib/parser/ruby30.rb
+                     lib/parser/ruby31.rb
                      lib/parser/macruby.rb
                      lib/parser/rubymotion.rb)
 

lib/parser/all.rb

@@ -11,3 +11,4 @@
 require 'parser/ruby26'
 require 'parser/ruby27'
 require 'parser/ruby30'
+require 'parser/ruby31'

lib/parser/current.rb

@@ -92,6 +92,15 @@ def warn_syntax_deviation(feature, version)
     require 'parser/ruby30'
     CurrentRuby = Ruby30
 
+  when /^3\.1\./
+    current_version = '3.1.0'
+    if RUBY_VERSION != current_version
+      warn_syntax_deviation 'parser/ruby31', current_version
+    end
+
+    require 'parser/ruby31'
+    CurrentRuby = Ruby31
+
   else # :nocov:
     # Keep this in sync with released Ruby.
     warn_syntax_deviation 'parser/ruby30', '3.0.x'