MDEV-35614: JSON_UNQUOTE doesn't work with emojis

emojis are a 4 byte utf sequence. Fix the conversion in JSON_UNQUOTE
to utf8mb4_bin by default.

Author: grooverdan

mysql-test/main/func_json.result

@@ -1766,6 +1766,43 @@ FROM JSON_TABLE (@data, '$[*]' COLUMNS (data text PATH '$.Data')) AS t;
 data
 <root language="de"></root>
 #
+# MDEV-35614 JSON_UNQUOTE doesn't work with emojis
+#
+SELECT HEX(JSON_UNQUOTE('"\\ud83d\\ude0a"')) as hex_smiley;
+hex_smiley
+F09F988A
+set names utf8mb4;
+SELECT JSON_UNQUOTE('"\\ud83d\\ude0a"') as smiley;
+smiley
+😊
+SELECT JSON_UNQUOTE('"\\ud83d\\ude0a"') = JSON_UNQUOTE('"\\ud83d\\ude0a"') as equal_smileys;
+equal_smileys
+1
+SELECT JSON_UNQUOTE('"\\ud83d\\ude0a"') <= JSON_UNQUOTE('"\\ud83d\\ude0a"') as less_or_equal_smileys;
+less_or_equal_smileys
+1
+set @v='{ "color":"😊" }';
+select @v as v, collation(@v) as collation_v;
+v	collation_v
+{ "color":"😊" }	utf8mb4_general_ci
+select json_valid(@v) as valid;
+valid
+1
+select json_extract(@v,'$.color') as color_extraction, collation(json_extract(@v,'$.color')) as color_extraction_collation;
+color_extraction	color_extraction_collation
+"😊"	utf8mb4_general_ci
+select json_unquote(json_extract(@v,'$.color')) as unquoted, collation(json_unquote(json_extract(@v,'$.color'))) as unquoted_collation;
+unquoted	unquoted_collation
+😊	utf8mb4_bin
+SELECT JSON_UNQUOTE('"\\uc080\\ude0a"') as invalid_utf8mb4;
+invalid_utf8mb4
+"\uc080\ude0a"
+Warnings:
+Warning	4035	Broken JSON string in argument 1 to function 'json_unquote' at position 13
+show warnings;
+Level	Code	Message
+Warning	4035	Broken JSON string in argument 1 to function 'json_unquote' at position 13
+#
 # End of 10.6 tests
 #
 #

mysql-test/main/func_json.test

@@ -1194,6 +1194,7 @@ SELECT JSON_EXTRACT('{"a": 1,"b": 2}','$.a');
 
 SET @@collation_connection= @save_collation_connection;
 
+
 --echo #
 --echo # End of 10.5 tests
 --echo #
@@ -1231,6 +1232,27 @@ SELECT
   data
 FROM JSON_TABLE (@data, '$[*]' COLUMNS (data text PATH '$.Data')) AS t;
 
+
+--echo #
+--echo # MDEV-35614 JSON_UNQUOTE doesn't work with emojis
+--echo #
+
+SELECT HEX(JSON_UNQUOTE('"\\ud83d\\ude0a"')) as hex_smiley;
+set names utf8mb4;
+SELECT JSON_UNQUOTE('"\\ud83d\\ude0a"') as smiley;
+
+SELECT JSON_UNQUOTE('"\\ud83d\\ude0a"') = JSON_UNQUOTE('"\\ud83d\\ude0a"') as equal_smileys;
+SELECT JSON_UNQUOTE('"\\ud83d\\ude0a"') <= JSON_UNQUOTE('"\\ud83d\\ude0a"') as less_or_equal_smileys;
+
+set @v='{ "color":"😊" }';
+select @v as v, collation(@v) as collation_v;
+select json_valid(@v) as valid;
+select json_extract(@v,'$.color') as color_extraction, collation(json_extract(@v,'$.color')) as color_extraction_collation;
+select json_unquote(json_extract(@v,'$.color')) as unquoted, collation(json_unquote(json_extract(@v,'$.color'))) as unquoted_collation;
+
+SELECT JSON_UNQUOTE('"\\uc080\\ude0a"') as invalid_utf8mb4;
+show warnings;
+
 --echo #
 --echo # End of 10.6 tests
 --echo #

mysql-test/suite/json/r/json_no_table.result

@@ -2886,7 +2886,7 @@ json_unquote(json_compact('["a", "b", "c"]'))
 ["a", "b", "c"]
 select charset(json_unquote('"abc"'));
 charset(json_unquote('"abc"'))
-utf8mb3
+utf8mb4
 select json_quote(convert(X'e68891' using utf8));
 json_quote(convert(X'e68891' using utf8))
 "我"

sql/item_jsonfunc.cc

@@ -851,7 +851,7 @@ String *Item_func_json_quote::val_str(String *str)
 
 bool Item_func_json_unquote::fix_length_and_dec(THD *thd)
 {
-  collation.set(&my_charset_utf8mb3_general_ci,
+  collation.set(&my_charset_utf8mb4_bin,
                 DERIVATION_COERCIBLE, MY_REPERTOIRE_ASCII);
   max_length= args[0]->max_char_length() * collation.collation->mbmaxlen;
   set_maybe_null();
@@ -894,12 +894,12 @@ String *Item_func_json_unquote::val_str(String *str)
     return js;
 
   str->length(0);
-  str->set_charset(&my_charset_utf8mb3_general_ci);
+  str->set_charset(&my_charset_utf8mb4_bin);
 
   if (str->realloc_with_extra_if_needed(je.value_len) ||
       (c_len= json_unescape(js->charset(),
         je.value, je.value + je.value_len,
-        &my_charset_utf8mb3_general_ci,
+        &my_charset_utf8mb4_bin,
         (uchar *) str->ptr(), (uchar *) (str->ptr() + je.value_len))) < 0)
     goto error;