support charsets with mbminlen > 1

Author: vuvova

mysql-test/main/func_sformat.result

@@ -417,3 +417,23 @@ sformat('{:p}', '50')
 NULL
 Warnings:
 Warning	4183	SFORMAT error: invalid type specifier
+#
+# ucs2 test
+#
+select sformat('={}=', _ucs2 x'006100620063');
+sformat('={}=', _ucs2 x'006100620063')
+=abc=
+set names utf8;
+select sformat(_ucs2 x'003D007B007D003D', _ucs2 x'0442043504410442');
+sformat(_ucs2 x'003D007B007D003D', _ucs2 x'0442043504410442')
+=тест=
+select hex(sformat(_ucs2 x'003D007B007D003D', _ucs2 x'0442043504410442'));
+hex(sformat(_ucs2 x'003D007B007D003D', _ucs2 x'0442043504410442'))
+003D0442043504410442003D
+create table t1 as select sformat(_ucs2 x'003D007B007D003D', _ucs2 x'0442043504410442') as x;
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `x` varchar(8) CHARACTER SET ucs2 DEFAULT NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+drop table t1;

mysql-test/main/func_sformat.test

@@ -188,3 +188,14 @@ echo #;
 echo # Unsupported/disabled features;
 echo #;
 select sformat('{:p}', '50');
+
+echo #;
+echo # ucs2 test;
+echo #;
+select sformat('={}=', _ucs2 x'006100620063');
+set names utf8;
+select sformat(_ucs2 x'003D007B007D003D', _ucs2 x'0442043504410442');
+select hex(sformat(_ucs2 x'003D007B007D003D', _ucs2 x'0442043504410442'));
+create table t1 as select sformat(_ucs2 x'003D007B007D003D', _ucs2 x'0442043504410442') as x;
+show create table t1;
+drop table t1;

sql/item_strfunc.cc

@@ -1311,7 +1311,20 @@ bool Item_func_sformat::fix_length_and_dec()
 {
   ulonglong char_length= 0;
 
-  if (agg_arg_charsets_for_string_result(collation, args, arg_count))
+  uint flags= MY_COLL_ALLOW_SUPERSET_CONV |
+              MY_COLL_ALLOW_COERCIBLE_CONV |
+              MY_COLL_ALLOW_NUMERIC_CONV;
+
+  if (Type_std_attributes::agg_item_collations(collation, func_name_cstring(),
+        args, arg_count, flags, 1))
+    return TRUE;
+
+  DTCollation c= collation;
+  if (c.collation->mbminlen > 1)
+    c.collation= &my_charset_utf8mb4_bin;
+
+  if (Type_std_attributes::agg_item_set_converter(c, func_name_cstring(), args,
+                                                  arg_count, flags, 1))
     return TRUE;
 
   for (uint i=0 ; i < arg_count ; i++)
@@ -1406,7 +1419,7 @@ String *Item_func_sformat::val_str(String *res)
                              fmt::format_args(vargs, arg_count-1));
     res->length(0);
     res->set_charset(collation.collation);
-    res->append(text.c_str(), text.size());
+    res->append(text.c_str(), text.size(), fmt_arg->charset());
   }
   catch (const fmt::format_error &ex)
   {