merge revision(s) ade56737e2273847426214035c0ff2340b43799a: [Backport #20190]

	Fix coderange of invalid_encoding_string.<<(ord)

	Appending valid encoding character can change coderange from invalid to valid.
	Example: "\x95".force_encoding('sjis')<<0x5C will be a valid string "\x{955C}"
	---
	 string.c                 | 6 +++++-
	 test/ruby/test_string.rb | 3 +++
	 2 files changed, 8 insertions(+), 1 deletion(-)

3 files changed, 9 insertions, 2 deletions

diff --git a/string.c b/string.c
index 923460a8f5..1f7321a1ce 100644
--- a/string.c
+++ b/string.c
@@ -3502,8 +3502,12 @@ rb_str_concat(VALUE str1, VALUE str2)
         }
         rb_str_resize(str1, pos+len);
         memcpy(RSTRING_PTR(str1) + pos, buf, len);
-        if (cr == ENC_CODERANGE_7BIT && code > 127)
+        if (cr == ENC_CODERANGE_7BIT && code > 127) {
             cr = ENC_CODERANGE_VALID;
+        }
+        else if (cr == ENC_CODERANGE_BROKEN) {
+            cr = ENC_CODERANGE_UNKNOWN;
+        }
         ENC_CODERANGE_SET(str1, cr);
     }
     return str1;
diff --git a/test/ruby/test_string.rb b/test/ruby/test_string.rb
index 069813e681..24527a527f 100644
--- a/test/ruby/test_string.rb
+++ b/test/ruby/test_string.rb
@@ -301,6 +301,9 @@ CODE
     assert_raise(RangeError, bug) {S("a".force_encoding(Encoding::UTF_8)) << -1}
     assert_raise(RangeError, bug) {S("a".force_encoding(Encoding::UTF_8)) << 0x81308130}
     assert_nothing_raised {S("a".force_encoding(Encoding::GB18030)) << 0x81308130}
+
+    s = "\x95".force_encoding(Encoding::SJIS).tap(&:valid_encoding?)
+    assert_predicate(s << 0x5c, :valid_encoding?)
   end
 
   def test_MATCH # '=~'
diff --git a/version.h b/version.h
index e88fd44241..72fc289522 100644
--- a/version.h
+++ b/version.h
@@ -11,7 +11,7 @@
 # define RUBY_VERSION_MINOR RUBY_API_VERSION_MINOR
 #define RUBY_VERSION_TEENY 3
 #define RUBY_RELEASE_DATE RUBY_RELEASE_YEAR_STR"-"RUBY_RELEASE_MONTH_STR"-"RUBY_RELEASE_DAY_STR
-#define RUBY_PATCHLEVEL 163
+#define RUBY_PATCHLEVEL 164
 
 #include "ruby/version.h"
 #include "ruby/internal/abi.h"