merge revision(s) 21dced8b01823a991829b66ffdc8ffc635965c76: [Backport #19389]

	[ruby/stringio] [Bug #19389] Fix chomping with longer separator

	https://github.com/ruby/stringio/commit/eb322a9716
	---
	 ext/stringio/stringio.c        | 5 +++--
	 test/stringio/test_stringio.rb | 2 ++
	 2 files changed, 5 insertions(+), 2 deletions(-)

3 files changed, 6 insertions, 3 deletions

diff --git a/ext/stringio/stringio.c b/ext/stringio/stringio.c
index 8df07e80f6..7c34164d31 100644
--- a/ext/stringio/stringio.c
+++ b/ext/stringio/stringio.c
@@ -1233,8 +1233,9 @@ strio_getline(struct getline_arg *arg, struct StringIO *ptr)
 	str = strio_substr(ptr, ptr->pos, e - s - w, enc);
     }
     else {
-	if (n < e - s) {
-	    if (e - s < 1024) {
+	if (n < e - s + arg->chomp) {
+	    /* unless chomping, RS at the end does not matter */
+	    if (e - s < 1024 || n == e - s) {
 		for (p = s; p + n <= e; ++p) {
 		    if (MEMCMP(p, RSTRING_PTR(str), char, n) == 0) {
 			e = p + (arg->chomp ? 0 : n);
diff --git a/test/stringio/test_stringio.rb b/test/stringio/test_stringio.rb
index e0b4504b54..e91a625488 100644
--- a/test/stringio/test_stringio.rb
+++ b/test/stringio/test_stringio.rb
@@ -99,6 +99,8 @@ class TestStringIO < Test::Unit::TestCase
     assert_equal("def", stringio.gets("", chomp: true))
 
     assert_string("", Encoding::UTF_8, StringIO.new("\n").gets(chomp: true))
+
+    assert_equal("", StringIO.new("ab").gets("ab", chomp: true))
   end
 
   def test_gets_chomp_eol
diff --git a/version.h b/version.h
index c1ba27e3b8..410987229f 100644
--- a/version.h
+++ b/version.h
@@ -11,7 +11,7 @@
 # define RUBY_VERSION_MINOR RUBY_API_VERSION_MINOR
 #define RUBY_VERSION_TEENY 4
 #define RUBY_RELEASE_DATE RUBY_RELEASE_YEAR_STR"-"RUBY_RELEASE_MONTH_STR"-"RUBY_RELEASE_DAY_STR
-#define RUBY_PATCHLEVEL 199
+#define RUBY_PATCHLEVEL 200
 
 #define RUBY_RELEASE_YEAR 2023
 #define RUBY_RELEASE_MONTH 3