Add types for Regexp::Parser#parse in regexp_parser gem

.gitmodules

@@ -202,6 +202,9 @@
 [submodule "gems/recaptcha/5.15/_src"]
 	path = gems/recaptcha/5.15/_src
 	url = https://github.com/ambethia/recaptcha.git
+[submodule "gems/regexp_parser/2.8/_src"]
+	path = gems/regexp_parser/2.8/_src
+	url = https://github.com/ammar/regexp_parser.git
 [submodule "gems/rack-oauth2/2.2/_src"]
 	path = gems/rack-oauth2/2.2/_src
 	url = https://github.com/nov/rack-oauth2.git

gems/regexp_parser/2.8/_scripts/test

@@ -0,0 +1,21 @@
+#!/usr/bin/env bash
+
+# Exit command with non-zero status code, Output logs of every command executed, Treat unset variables as an error when substituting.
+set -eou pipefail
+# Internal Field Separator - Linux shell variable
+IFS=$'\n\t'
+# Print shell input lines
+set -v
+
+# Set RBS_DIR variable to change directory to execute type checks using `steep check`
+RBS_DIR=$(cd $(dirname $0)/..; pwd)
+# Set REPO_DIR variable to validate RBS files added to the corresponding folder
+REPO_DIR=$(cd $(dirname $0)/../../..; pwd)
+# Validate RBS files, using the bundler environment present
+bundle exec rbs --repo $REPO_DIR -r regexp_parser:2.8 validate --silent
+
+cd ${RBS_DIR}/_test
+# Run type checks
+bundle exec steep check
+
+$(git rev-parse --show-toplevel)/bin/check-untyped-call.rb

gems/regexp_parser/2.8/_test/Steepfile

@@ -0,0 +1,11 @@
+D = Steep::Diagnostic
+
+target :test do
+  check "."
+  signature "."
+
+  repo_path "../../../"
+  library "regexp_parser"
+
+  configure_code_diagnostics(D::Ruby.all_error)
+end

gems/regexp_parser/2.8/_test/test.rb

@@ -0,0 +1,13 @@
+# Write Ruby code to test the RBS.
+# It is type checked by `steep check` command.
+
+require "regexp_parser"
+
+regex = /a?(b+(c)d)*(?<name>[0-9]+)/i
+Regexp::Parser.parse(regex, 'ruby/2.1') do |token|
+  puts token.inspect
+end
+Regexp::Parser.parse(
+  'a+ # Recognizes a and A...',
+  options: ::Regexp::EXTENDED | ::Regexp::IGNORECASE
+)

gems/regexp_parser/2.8/regexp_parser.rbs

@@ -0,0 +1,17 @@
+class Regexp::Parser
+  def parse: (Regexp | String input, ?String? syntax, ?options: Integer?) { (Regexp::Expression::Root) -> untyped } -> untyped
+           | (Regexp | String input, ?String? syntax, ?options: Integer?) -> Regexp::Expression::Root
+  def self.parse: (Regexp | String input, ?String? syntax, ?options: Integer?) { (Regexp::Expression::Root) -> untyped } -> untyped
+                | (Regexp | String input, ?String? syntax, ?options: Integer?) -> Regexp::Expression::Root
+end
+
+module Regexp::Expression
+  class Root < Subexpression
+  end
+
+  class Subexpression < Base
+  end
+
+  class Base
+  end
+end