Remove unicode character encoding from ActiveSupport::JSON.encode

The encoding scheme (e.g. ☠ -> "\u2620") was broken for characters
not in the Basic Multilingual Plane.  It is possible to escape them
for json using the weird encoding scheme of a twelve-character
sequence representing the UTF-16 surrogate pair (e.g. '𠜎' ->
"\u270e\u263a") but this wasn't properly handled in the escaping code.
Since raw UTF-8 is allowed in json, it was decided to simply pass
through the raw bytes rather than attempt to escape them.

Backport of https://github.com/zbskii/rails/commit/9ace3a8820a5270f9b3f37b593f8bbea3e940f73

Conflicts:

	activesupport/CHANGELOG.md
	activesupport/lib/active_support/json/encoding.rb
	activesupport/test/json/encoding_test.rb

1 files changed, 1 insertions, 7 deletions

diff --git a/activesupport/lib/active_support/json/encoding.rb b/activesupport/lib/active_support/json/encoding.rb
index bd2f909ca9..a50e6524c6 100644
--- a/activesupport/lib/active_support/json/encoding.rb
+++ b/activesupport/lib/active_support/json/encoding.rb
@@ -122,13 +122,7 @@ module ActiveSupport
           if string.respond_to?(:force_encoding)
             string = string.encode(::Encoding::UTF_8, :undef => :replace).force_encoding(::Encoding::BINARY)
           end
-          json = string.
-            gsub(escape_regex) { |s| ESCAPED_CHARS[s] }.
-            gsub(/([\xC0-\xDF][\x80-\xBF]|
-                   [\xE0-\xEF][\x80-\xBF]{2}|
-                   [\xF0-\xF7][\x80-\xBF]{3})+/nx) { |s|
-            s.unpack("U*").pack("n*").unpack("H*")[0].gsub(/.{4}/n, '\\\\u\&')
-          }
+          json = string.gsub(escape_regex) { |s| ESCAPED_CHARS[s] }
           json = %("#{json}")
           json.force_encoding(::Encoding::UTF_8) if json.respond_to?(:force_encoding)
           json