MDEV-8282: crash in filesort() with simple ordered delete

Handle the case where the optimizer decides to use
handler->delete_all_rows(), but then this call returns
HA_ERR_UNSUPPORTED and execution switches to regular
row-by-row deletion.

mysql-test/r/analyze_stmt_orderby.result

@@ -364,3 +364,20 @@ ANALYZE
 }
 drop table t2;
 drop table t0, t1;
+#
+#  MDEV-8282: crash in filesort() with simple ordered delete
+#
+create table t1(a int) engine=innodb;
+delete from t1 order by a;
+# EXPLAIN thinks it will use delete_all_rows():
+explain
+delete from t1 order by a;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	1	Deleting all rows
+# ANALYZE shows that delete_all_rows() didn't work and we deleted rows
+# one-by-one:
+analyze
+delete from t1 order by a;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	r_rows	filtered	r_filtered	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	1	0.00	100.00	100.00	Using filesort
+drop table t1;

mysql-test/t/analyze_stmt_orderby.test

 
+--source include/have_innodb.inc
+
 create table t0(a int);
 insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
 
@@ -91,3 +93,20 @@ select MAX(b) from t2 where mod(a,2)=0 group by c;
 drop table t2;
 drop table t0, t1;
 
+--echo #
+--echo #  MDEV-8282: crash in filesort() with simple ordered delete
+--echo #
+create table t1(a int) engine=innodb;
+delete from t1 order by a;
+
+--echo # EXPLAIN thinks it will use delete_all_rows():
+explain
+delete from t1 order by a;
+
+--echo # ANALYZE shows that delete_all_rows() didn't work and we deleted rows
+--echo # one-by-one:
+analyze
+delete from t1 order by a;
+
+drop table t1;
+

sql/sql_delete.cc

@@ -370,6 +370,7 @@ bool mysql_delete(THD *thd, TABLE_LIST *table_list, COND *conds,
       goto cleanup;
     }
     /* Handler didn't support fast delete; Delete rows one by one */
+    query_plan.cancel_delete_all_rows();
   }
   if (conds)
   {

sql/sql_lex.h

@@ -2372,6 +2372,10 @@ class Delete_plan : public Update_plan
     deleting_all_rows= true;
     scanned_rows= rows_arg;
   }
+  void cancel_delete_all_rows()
+  {
+    deleting_all_rows= false;
+  }
 
   Explain_delete* save_explain_delete_data(MEM_ROOT *mem_root, THD *thd);
 };