enum doesn't support collation

[ChenPeng2013]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

new_collations_enabled_on_first_bootstrap = true

use test;
drop table if exists t;
CREATE TABLE `t` (   `a` enum('a','b') DEFAULT NULL ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_general_ci;
insert into t values('a');
select * from t where a = 'A';

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

mysql> select * from t where a = 'A';
+------+
| a    |
+------+
| a    |
+------+
1 row in set (0.00 sec)

3. What did you see instead (Required)

mysql> select * from t where a = 'A';
Empty set (0.00 sec)

4. What is your TiDB version? (Required)

master 0cdd24d and release-4.0 ddba4fe

[XuHuaiyu]

PTAL @wjhuang2016

[sre-bot]

Integrity check:
RCA symptom trigger_condition affect_version fix_version fields are empty

Please comment /info to get template

[ti-srebot]

Please edit this comment to complete the following information

Not a bug

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2. Add notes to indicate why it is not a bug

Duplicate bug

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Bug

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Example for how to fill out the template: #20100

1. Root Cause Analysis (RCA)

enum and set get the wrong coercibility.

2. Symptom

Wrong result

3. All Trigger Conditions

enum or set, new collation

4. Workaround (optional)

5. Affected versions

[v4.0.0:v4.0.7]

6. Fixed versions

unplanned