Unreasonable behavior when use CTE in view

[guo-shaoge]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

drop table if exists t1;
drop view if exists vv;
create table t1(c1 int primary key);
insert into t1 values(1), (2), (3);
create view vv as with recursive cte1(c1) as (select c1 from t1 where c1 = 2 union select c1 + 1 c1 from cte1 where c1 < 3) select * from cte1;
desc vv;

2. What did you expect to see? (Required)

MySQL:

mysql> desc vv;
+-------+------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+------+------+-----+---------+-------+
| c1    | int  | YES  |     | NULL    |       |
+-------+------+------+-----+---------+-------+
1 row in set (0.11 sec)

3. What did you see instead (Required)

TiDB: It's unreasonable because c1 is NULLABLE and Primary key.

mysql>     desc vv;
+-------+---------+------+------+---------+-------+
| Field | Type    | Null | Key  | Default | Extra |
+-------+---------+------+------+---------+-------+
| c1    | int(11) | YES  | PRI  | NULL    |       |
+-------+---------+------+------+---------+-------+
1 row in set (0.01 sec)

4. What is your TiDB version? (Required)

master