merge revision(s) e86c1f6fc53433ef5c82ed2b7a4cc9a12c153e4c,f6539202c52a051a4e6946a318a1d9cd29002990: [Backport #1205]

	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, 6 insertions, 0 deletions

diff --git a/transcode.c b/transcode.c
index a72afdc44b..d2abd9e0e5 100644
--- a/transcode.c
+++ b/transcode.c
@@ -2719,6 +2719,12 @@ str_transcode0(int argc, VALUE *argv, VALUE *self, int ecflags, VALUE ecopts)
         }
     }
     else {
+        if (senc && denc && !rb_enc_asciicompat(senc) && !rb_enc_asciicompat(denc)) {
+            rb_encoding *utf8 = rb_utf8_encoding();
+            str = rb_str_conv_enc(str, senc, utf8);
+            senc = utf8;
+            sname = "UTF-8";
+        }
         if (encoding_equal(sname, dname)) {
             sname = "";
             dname = "";