TiDB returns an error when to try select INTERVAL 1 DAY + "1997-12-31"

[espresso98]

Bug Report

TiDB returns an error when to try select INTERVAL 1 DAY + "1997-12-31" but, supports it in the reverse form.

1. Minimal reproduce step (Required)

select INTERVAL 1 DAY + "1997-12-31";

2. What did you expect to see?

mysql> select INTERVAL 1 DAY + "1997-12-31";
+-------------------------------+
| INTERVAL 1 DAY + "1997-12-31" |
+-------------------------------+
| 1998-01-01                    |
+-------------------------------+
1 row in set (0.01 sec)

3. What did you see instead

TiDB> select INTERVAL 1 DAY + "1997-12-31";
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your TiDB version for the right syntax to use line 1 column 17 near "1 DAY + "1997-12-31"


TiDB> select "1997-12-31" + INTERVAL 1 DAY;
+-------------------------------+
| "1997-12-31" + INTERVAL 1 DAY |
+-------------------------------+
| 1998-01-01                    |
+-------------------------------+
1 row in set (0.00 sec)

4. What is your TiDB version? (Required)

tidb_version(): Release Version: v5.2.2
Edition: Community
Git Commit Hash: da1c21fd45a4ea5900ac16d2f4a248143f378d18
Git Branch: heads/refs/tags/v5.2.2
UTC Build Time: 2021-10-20 06:03:29
GoVersion: go1.16.4
Race Enabled: false
TiKV Min Version: v3.0.0-60965b006877ca7234adaced7890d7b029ed1306
Check Table Before Drop: false
1 row in set (0.00 sec)

[kennytm]

adding a parser rule mapping "INTERVAL" Expression TimeUnit '+' BitExpr should be sufficient to fix this.

tidb/parser/parser.y

Line 6626 in 13d0deb

| BitExpr '+' "INTERVAL" Expression TimeUnit %prec '+'

[Defined2014]

/assign

[Defined2014]

/unassign

[Defined2014]

Tried on #30312 , it will cause select INTERVAL(0,1,1,1) parse to fail.
And try to follow mysql, it will have shift/reduce problems.

[bb7133]

I don't think this is a major bug: select INTERVAL 1 DAY + "1997-12-31"; is not a common usecase and it can be workarounded easily.