merge revision(s) 391abc543cea118a9cd7d6310acadbfa352668ef,e86c1f6fc53433ef5c82ed2b7a4cc9a12c153e4c,f6539202c52a051a4e6946a318a1d9cd29002990: [Backport #12052]

	Scan the coderange in the given encoding

	---
	 ext/-test-/string/enc_str_buf_cat.c       | 14 ++++++++++++++
	 string.c                                  | 32 ++++++++++++++++++++++---------
	 test/-ext-/string/test_enc_str_buf_cat.rb |  9 +++++++++
	 3 files changed, 46 insertions(+), 9 deletions(-)

	Work around issue transcoding issue with non-ASCII compatible
	 encodings and xml escaping

	When using a non-ASCII compatible source and destination encoding
	and xml escaping (the :xml option to String#encode), the resulting
	string was broken, as it used the correct non-ASCII compatible
	encoding, but contained data that was ASCII-compatible instead of
	compatible with the string's encoding.

	Work around this issue by detecting the case where both the
	source and destination encoding are non-ASCII compatible, and
	transcoding the source string from the non-ASCII compatible
	encoding to UTF-8. The xml escaping code will correctly handle
	the UTF-8 source string and the return the correctly encoded
	and escaped value.

	Fixes [Bug #12052]

	Co-authored-by: Nobuyoshi Nakada <nobu@ruby-lang.org>
	---
	 test/ruby/test_transcode.rb | 19 +++++++++++++++++++
	 transcode.c                 |  6 ++++++
	 2 files changed, 25 insertions(+)

	=?UTF-8?q?-=20add=20regression=20tests=20for=20U+6E7F=20(?=
	 =?UTF-8?q?=E6=B9=BF)=20in=20ISO-2022-JP?=
	MIME-Version: 1.0
	Content-Type: text/plain; charset=UTF-8
	Content-Transfer-Encoding: 8bit

	  In ISO-2022-JP, the bytes use to code are the same as those for "<>".
	  This adds regression tests to make sure that these bytes, when representing
	  湿, are NOT　escaped with encode("ISO-2022-JP, xml: :text) or similar.
	  These are additional regression tests for #12052.
	---
	 test/ruby/test_transcode.rb | 3 +++
	 1 file changed, 3 insertions(+)

1 files changed, 14 insertions, 0 deletions

diff --git a/ext/-test-/string/enc_str_buf_cat.c b/ext/-test-/string/enc_str_buf_cat.c
index 9ac4a298be..4c1b262e1e 100644
--- a/ext/-test-/string/enc_str_buf_cat.c
+++ b/ext/-test-/string/enc_str_buf_cat.c
@@ -7,8 +7,22 @@ enc_str_buf_cat(VALUE str, VALUE str2)
     return rb_enc_str_buf_cat(str, RSTRING_PTR(str2), RSTRING_LEN(str2), rb_enc_get(str2));
 }
 
+static VALUE
+str_conv_enc_opts(VALUE str, VALUE from, VALUE to, VALUE ecflags, VALUE ecopts)
+{
+    rb_encoding *from_enc = NIL_P(from) ? NULL : rb_to_encoding(from);
+    rb_encoding *to_enc = NIL_P(to) ? NULL : rb_to_encoding(to);
+    int flags = NUM2INT(ecflags);
+    if (!NIL_P(ecopts)) {
+        Check_Type(ecopts, T_HASH);
+        OBJ_FREEZE(ecopts);
+    }
+    return rb_str_conv_enc_opts(str, from_enc, to_enc, flags, ecopts);
+}
+
 void
 Init_string_enc_str_buf_cat(VALUE klass)
 {
     rb_define_method(klass, "enc_str_buf_cat", enc_str_buf_cat, 1);
+    rb_define_method(klass, "str_conv_enc_opts", str_conv_enc_opts, 4);
 }