MDEV-8839 COLUMN_GET() produces warnings with no data

mysql-test/suite/vcol/r/vcol_misc.result

@@ -346,5 +346,24 @@ t1	CREATE TABLE `t1` (
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1
 DROP TABLE t1;
 #
+# MDEV-8839 COLUMN_GET() produces warnings with no data
+#
+SET @aaa= COLUMN_CREATE('price', _binary 0xF0F1F2F3F4F5F6F7);
+SELECT COLUMN_GET(@aaa, 'price' AS DECIMAL) aaa;
+aaa
+0
+Warnings:
+Warning	1918	Encountered illegal value '\xF0\xF1\xF2\xF3\xF4\xF5\xF6\xF7' when converting to DECIMAL
+SELECT COLUMN_GET(@aaa, 'price' AS INT) aaa;
+aaa
+0
+Warnings:
+Warning	1918	Encountered illegal value '\xF0\xF1\xF2\xF3\xF4\xF5\xF6\xF7' when converting to INT
+SELECT COLUMN_GET(@aaa, 'price' AS DOUBLE) aaa;
+aaa
+0
+Warnings:
+Warning	1918	Encountered illegal value '\xF0\xF1\xF2\xF3\xF4\xF5\xF6\xF7' when converting to DOUBLE
+#
 # End of 10.1 tests
 #

mysql-test/suite/vcol/t/vcol_misc.test

@@ -302,6 +302,15 @@ CREATE TABLE t1 (a DATETIME, b TIMESTAMP AS (TIMESTAMP(a)),c TIMESTAMP);
 SHOW CREATE TABLE t1;
 DROP TABLE t1;
 
+--echo #
+--echo # MDEV-8839 COLUMN_GET() produces warnings with no data
+--echo #
+SET @aaa= COLUMN_CREATE('price', _binary 0xF0F1F2F3F4F5F6F7);
+SELECT COLUMN_GET(@aaa, 'price' AS DECIMAL) aaa;
+SELECT COLUMN_GET(@aaa, 'price' AS INT) aaa;
+SELECT COLUMN_GET(@aaa, 'price' AS DOUBLE) aaa;
+
+
 --echo #
 --echo # End of 10.1 tests
 --echo #

sql/item_strfunc.cc

@@ -4963,13 +4963,12 @@ longlong Item_dyncol_get::val_int()
     if (end != org_end || error > 0)
     {
       THD *thd= current_thd;
-      char buff[80];
-      strmake(buff, val.x.string.value.str, MY_MIN(sizeof(buff)-1,
-                                              val.x.string.value.length));
       push_warning_printf(thd, Sql_condition::WARN_LEVEL_WARN,
                           ER_BAD_DATA,
                           ER_THD(thd, ER_BAD_DATA),
-                          buff,
+                          ErrConvString(val.x.string.value.str,
+                                        val.x.string.value.length,
+                                        val.x.string.charset).ptr(),
                           unsigned_flag ? "UNSIGNED INT" : "INT");
     }
     unsigned_flag= error >= 0;
@@ -5028,13 +5027,13 @@ double Item_dyncol_get::val_real()
         error)
     {
       THD *thd= current_thd;
-      char buff[80];
-      strmake(buff, val.x.string.value.str, MY_MIN(sizeof(buff)-1,
-                                              val.x.string.value.length));
       push_warning_printf(thd, Sql_condition::WARN_LEVEL_WARN,
                           ER_BAD_DATA,
                           ER_THD(thd, ER_BAD_DATA),
-                          buff, "DOUBLE");
+                          ErrConvString(val.x.string.value.str,
+                                        val.x.string.value.length,
+                                        val.x.string.charset).ptr(),
+                          "DOUBLE");
     }
     return res;
   }
@@ -5085,9 +5084,6 @@ my_decimal *Item_dyncol_get::val_decimal(my_decimal *decimal_value)
     int rc;
     rc= str2my_decimal(0, val.x.string.value.str, val.x.string.value.length,
                        val.x.string.charset, decimal_value, &end);
-    char buff[80];
-    strmake(buff, val.x.string.value.str, MY_MIN(sizeof(buff)-1,
-                                            val.x.string.value.length));
     if (rc != E_DEC_OK ||
         end != val.x.string.value.str + val.x.string.value.length)
     {
@@ -5095,7 +5091,10 @@ my_decimal *Item_dyncol_get::val_decimal(my_decimal *decimal_value)
       push_warning_printf(thd, Sql_condition::WARN_LEVEL_WARN,
                           ER_BAD_DATA,
                           ER_THD(thd, ER_BAD_DATA),
-                          buff, "DECIMAL");
+                          ErrConvString(val.x.string.value.str,
+                                        val.x.string.value.length,
+                                        val.x.string.charset).ptr(),
+                          "DECIMAL");
     }
     break;
   }