From 3743b4c3ef64223bd2e35874d9ab22f46bcf504d Mon Sep 17 00:00:00 2001
From: Alexey Botchkov <holyfoot@askmonty.org>
Date: Tue, 6 Dec 2016 00:34:25 +0400
Subject: [PATCH] MDEV-11468 JSON_UNQUOTE returns incorrect results.

        Now return the argument's value when error.
---
 mysql-test/r/func_json.result | 3 +++
 mysql-test/t/func_json.test   | 1 +
 sql/item_jsonfunc.cc          | 4 ++--
 3 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/mysql-test/r/func_json.result b/mysql-test/r/func_json.result
index 36430973fe7..df34e5b80bc 100644
--- a/mysql-test/r/func_json.result
+++ b/mysql-test/r/func_json.result
@@ -277,6 +277,9 @@ drop table t1;
 select json_unquote('"abc"');
 json_unquote('"abc"')
 abc
+select json_unquote('abc');
+json_unquote('abc')
+abc
 select json_object("a", json_object("b", "abcd"));
 json_object("a", json_object("b", "abcd"))
 {"a": {"b": "abcd"}}
diff --git a/mysql-test/t/func_json.test b/mysql-test/t/func_json.test
index 62853de6ad2..357f223f579 100644
--- a/mysql-test/t/func_json.test
+++ b/mysql-test/t/func_json.test
@@ -121,6 +121,7 @@ drop table t1;
 
 
 select json_unquote('"abc"');
+select json_unquote('abc');
 
 select json_object("a", json_object("b", "abcd"));
 select json_object("a", '{"b": "abcd"}');
diff --git a/sql/item_jsonfunc.cc b/sql/item_jsonfunc.cc
index cb1c174d08d..c3b4bc7b8b5 100644
--- a/sql/item_jsonfunc.cc
+++ b/sql/item_jsonfunc.cc
@@ -359,8 +359,8 @@ String *Item_func_json_unquote::val_str(String *str)
   return str;
 
 error:
-  null_value= 1;
-  return 0;
+  /* We just return the argument's value in the case of error. */
+  return js;
 }