MDEV-26844: DELETE returns ROW_NUMBER=1 for every row upon

ER_TRUNCATED_WRONG_VALUE

Part 1: Fix for DELETE without ORDER BY

Analysis: m_current_row_for_warning doesn't increment and assumes default
value which is then used by ROW_NUMBER.
Fix: Increment m_current_row_for_warning for each processed row.

mysql-test/main/get_diagnostics.result

@@ -1783,3 +1783,31 @@ SELECT @n;
 @n
 4
 DROP TABLE t1;
+#
+# MDEV-26844: DELETE returns ROW_NUMBER=1 for every row upon
+# ER_TRUNCATED_WRONG_VALUE
+#
+# without ORDER BY
+CREATE TABLE t (a VARCHAR(8));
+INSERT INTO t VALUES ('val1'),('val2'),('100'),('val4');
+SELECT * FROM t;
+a
+val1
+val2
+100
+val4
+DELETE FROM t WHERE a = 100;
+Warnings:
+Warning	1292	Truncated incorrect DOUBLE value: 'val1'
+Warning	1292	Truncated incorrect DOUBLE value: 'val2'
+Warning	1292	Truncated incorrect DOUBLE value: 'val4'
+SHOW WARNINGS;
+Level	Code	Message
+Warning	1292	Truncated incorrect DOUBLE value: 'val1'
+Warning	1292	Truncated incorrect DOUBLE value: 'val2'
+Warning	1292	Truncated incorrect DOUBLE value: 'val4'
+GET DIAGNOSTICS CONDITION 3 @n = ROW_NUMBER;
+SELECT @n;
+@n
+4
+DROP TABLE t;

mysql-test/main/get_diagnostics.test

@@ -1667,3 +1667,23 @@ GET DIAGNOSTICS CONDITION 2 @n= ROW_NUMBER;
 SELECT @n;
 
 DROP TABLE t1;
+
+--echo #
+--echo # MDEV-26844: DELETE returns ROW_NUMBER=1 for every row upon
+--echo # ER_TRUNCATED_WRONG_VALUE
+--echo #
+
+--echo # without ORDER BY
+
+CREATE TABLE t (a VARCHAR(8));
+
+INSERT INTO t VALUES ('val1'),('val2'),('100'),('val4');
+SELECT * FROM t;
+
+DELETE FROM t WHERE a = 100;
+SHOW WARNINGS;
+
+GET DIAGNOSTICS CONDITION 3 @n = ROW_NUMBER;
+SELECT @n;
+
+DROP TABLE t;

sql/sql_delete.cc

@@ -795,9 +795,11 @@ bool mysql_delete(THD *thd, TABLE_LIST *table_list, COND *conds,
   THD_STAGE_INFO(thd, stage_updating);
   fix_rownum_pointers(thd, thd->lex->current_select, &deleted);
 
+  thd->get_stmt_da()->reset_current_row_for_warning(0);
   while (likely(!(error=info.read_record())) && likely(!thd->killed) &&
          likely(!thd->is_error()))
   {
+    thd->get_stmt_da()->inc_current_row_for_warning();
     if (delete_while_scanning)
       delete_record= record_should_be_deleted(thd, table, select, explain,
                                               delete_history);
@@ -873,6 +875,7 @@ bool mysql_delete(THD *thd, TABLE_LIST *table_list, COND *conds,
     else
       break;
   }
+  thd->get_stmt_da()->reset_current_row_for_warning(1);
 
 terminate_delete:
   killed_status= thd->killed;