Ruby

[ruby/prism] Fix a token incompatibility for Prism::Translation::Parser::Lexer

This PR fixes a token incompatibility between Parser gem and Prism::Translation::Parser for double splat argument.

Parser gem (Expected)¶

Returns tDSTAR token:

$ bundle exec ruby -Ilib -rparser/ruby33 -ve \
'buf = Parser::Source::Buffer.new("example.rb"); buf.source = "def f(**foo) end"; p Parser::Ruby33.new.tokenize(buf)[2]'
ruby 3.4.0dev (2024-09-01T11:00:13Z master https://github.com/ruby/prism/commit/eb144ef91e) [x86_64-darwin23]
[[:kDEF, ["def", #<Parser::Source::Range example.rb 0...3>]], [:tIDENTIFIER, ["f", #<Parser::Source::Range example.rb 4...5>]],
[:tLPAREN2, ["(", #<Parser::Source::Range example.rb 5...6>]], [:tDSTAR, ["**", #<Parser::Source::Range example.rb 6...8>]],
[:tIDENTIFIER, ["foo", #<Parser::Source::Range example.rb 8...11>]], [:tRPAREN, [")", #<Parser::Source::Range example.rb 11...12>]],
[:kEND, ["end", #<Parser::Source::Range example.rb 13...16>]]]

Prism::Translation::Parser (Actual)¶

Previously, the parser returned tPOW token when parsing the following:

$ bundle exec ruby -Ilib -rprism -rprism/translation/parser33 -ve \
'buf = Parser::Source::Buffer.new("example.rb"); buf.source = "def f(**foo) end"; p Prism::Translation::Parser33.new.tokenize(buf)[2]'
ruby 3.4.0dev (2024-09-01T11:00:13Z master https://github.com/ruby/prism/commit/eb144ef91e) [x86_64-darwin23]
[[:kDEF, ["def", #<Parser::Source::Range example.rb 0...3>]], [:tIDENTIFIER, ["f", #<Parser::Source::Range example.rb 4...5>]],
[:tLPAREN2, ["(", #<Parser::Source::Range example.rb 5...6>]], [:tPOW, ["**", #<Parser::Source::Range example.rb 6...8>]],
[:tIDENTIFIER, ["foo", #<Parser::Source::Range example.rb 8...11>]], [:tRPAREN, [")", #<Parser::Source::Range example.rb 11...12>]],
[:kEND, ["end", #<Parser::Source::Range example.rb 13...16>]]]

After the update, the parser now returns tDSTAR token for the same input:

$ bundle exec ruby -Ilib -rprism -rprism/translation/parser33 -ve \
'buf = Parser::Source::Buffer.new("example.rb"); buf.source = "def f(**foo) end"; p Prism::Translation::Parser33.new.tokenize(buf)[2]'
ruby 3.4.0dev (2024-09-01T11:00:13Z master https://github.com/ruby/prism/commit/eb144ef91e) [x86_64-darwin23]
[[:kDEF, ["def", #<Parser::Source::Range example.rb 0...3>]], [:tIDENTIFIER, ["f", #<Parser::Source::Range example.rb 4...5>]],
[:tLPAREN2, ["(", #<Parser::Source::Range example.rb 5...6>]], [:tDSTAR, ["**", #<Parser::Source::Range example.rb 6...8>]],
[:tIDENTIFIER, ["foo", #<Parser::Source::Range example.rb 8...11>]], [:tRPAREN, [")", #<Parser::Source::Range example.rb 11...12>]],
[:kEND, ["end", #<Parser::Source::Range example.rb 13...16>]]]

With this change, the following code could be removed from test/prism/ruby/parser_test.rb:

-          when :tPOW
-            actual_token[0] = expected_token[0] if expected_token[0] == :tDSTAR

tPOW is the token type for the behavior of a ** b, and its behavior remains unchanged:

$ bundle exec ruby -Ilib -rprism -rprism/translation/parser33 -ve \
'buf = Parser::Source::Buffer.new("example.rb"); buf.source = "a ** b"; p Prism::Translation::Parser33.new.tokenize(buf)[2]'
ruby 3.4.0dev (2024-09-01T11:00:13Z master https://github.com/ruby/prism/commit/eb144ef91e) [x86_64-darwin23]
[[:tIDENTIFIER, ["a", #<Parser::Source::Range example.rb 0...1>]], [:tPOW, ["**", #<Parser::Source::Range example.rb 2...4>]],
[:tIDENTIFIER, ["b", #<Parser::Source::Range example.rb 5...6>]]]

https://github.com/ruby/prism/commit/66bde35a44