From 502ca37dde288d20fed6e6ea34f4ab3299de7777 Mon Sep 17 00:00:00 2001
From: Nobuyoshi Nakada <nobu@ruby-lang.org>
Date: Wed, 21 Dec 2022 14:07:54 +0900
Subject: [ruby/optparse] The encoding argument of `Regexp.new` has been
 ignored since 1.9

https://github.com/ruby/optparse/commit/766f567405
---
 lib/optparse.rb                | 19 ++++++++++++++++---
 test/optparse/test_optparse.rb |  3 +++
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/lib/optparse.rb b/lib/optparse.rb
index dc2b8a060f..b9126465e0 100644
--- a/lib/optparse.rb
+++ b/lib/optparse.rb
@@ -2084,10 +2084,23 @@ XXX
       f |= Regexp::IGNORECASE if /i/ =~ o
       f |= Regexp::MULTILINE if /m/ =~ o
       f |= Regexp::EXTENDED if /x/ =~ o
-      k = o.delete("imx")
-      k = nil if k.empty?
+      case o = o.delete("imx")
+      when ""
+      when "u"
+        s = s.encode(Encoding::UTF_8)
+      when "e"
+        s = s.encode(Encoding::EUC_JP)
+      when "s"
+        s = s.encode(Encoding::SJIS)
+      when "n"
+        f |= Regexp::NOENCODING
+      else
+        raise OptionParser::InvalidArgument, "unknown regexp option - #{o}"
+      end
+    else
+      s ||= all
     end
-    Regexp.new(s || all, f, k)
+    Regexp.new(s, f)
   end
 
   #
diff --git a/test/optparse/test_optparse.rb b/test/optparse/test_optparse.rb
index 5a0593d9bb..bfa705ad03 100644
--- a/test/optparse/test_optparse.rb
+++ b/test/optparse/test_optparse.rb
@@ -63,6 +63,9 @@ class TestOptionParser < Test::Unit::TestCase
     assert_equal(/foo/i, @reopt)
     assert_equal(%w"", no_error {@opt.parse!(%w"--regexp=/foo/n")})
     assert_equal(/foo/n, @reopt)
+    assert_equal(%w"", no_error {@opt.parse!(%W"--regexp=/\u{3042}/s")})
+    assert_equal(Encoding::Windows_31J, @reopt.encoding)
+    assert_equal("\x82\xa0".force_encoding(Encoding::Windows_31J), @reopt.source)
   end
 
   def test_into
-- 
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