REGEX function doesn't support collation

[wjhuang2016]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. What did you do?

DROP TABLE IF EXISTS t1;
CREATE TABLE t1 ( a int, p1 VARCHAR(255) CHARACTER SET utf8 COLLATE utf8_bin,p2 VARCHAR(255) CHARACTER SET utf8 COLLATE utf8_general_ci , p3 VARCHAR(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_bin,p4 VARCHAR(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci ,n1 VARCHAR(255) CHARACTER SET utf8 COLLATE utf8_bin,n2 VARCHAR(255) CHARACTER SET utf8 COLLATE utf8_general_ci , n3 VARCHAR(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_bin,n4 VARCHAR(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci ); 

insert into t1 (a) values (1);
insert into t1 (a,p1,p2,p3,p4,n1,n2,n3,n4) values (2,'0aA1!测试テストמבחן  ','0aA1!测试テストמבחן 	','0aA1!测试テストמבחן 	','0aA1!测试テストמבחן 	','0Aa1!测试テストמבחן','0Aa1!测试テストמבחן','0Aa1!测试テストמבחן','0Aa1!测试テストמבחן');
insert into t1 (a,p1,p2,p3,p4,n1,n2,n3,n4) values (3,'0aA1!测试テストמבחן','0aA1!测试テストמבחן','0aA1!测试テストמבחן','0aA1!测试テストמבחן','0Aa1!测试テストמבחן','0Aa1!测试テストמבחן','0Aa1!测试テストמבחן','0Aa1!测试テストמבחן');
insert into t1 (a,p1,p2,p3,p4,n1,n2,n3,n4) values (4,'0aA1!测试テストמבחן','0aA1!测试テストמבחן','0aA1!测试テストמבחן','0aA1!测试テストמבחן','0Aa1!测试テストמבחן  ','0Aa1!测试テストמבחן  ','0Aa1!测试テストמבחן  ','0Aa1!测试テストמבחן  ');
insert into t1 (a,p1,p2,p3,p4,n1,n2,n3,n4) values (5,'0aA1!测试テストמבחן0aA1!测试','0aA1!测试テストמבחן0aA1!测试','0aA1!测试テストמבחן0aA1!测试','0aA1!测试テストמבחן0aA1!测试','0Aa1!测试','0Aa1!测试','0Aa1!测试','0Aa1!测试');
insert into t1 (a,p1,p2,p3,p4,n1,n2,n3,n4) values (6,'0aA1!测试テストמבחן0aA1!测试','0aA1!测试テストמבחן0aA1!测试','0aA1!测试テストמבחן0aA1!测试','0aA1!测试テストמבחן0aA1!测试','0aA1!测试','0aA1!测试','0aA1!测试','0aA1!测试');
insert into t1 (a,p1,p2,p3,p4,n1,n2,n3,n4) values (7,'0aA1!测试テストמבחן  ','0aA1!测试テストמבחן 	','0aA1!测试テストמבחן 	','0aA1!测试テストמבחן 	','0aA1!测试テストמבחן','0aA1!测试テストמבחן','0aA1!测试テストמבחן','0aA1!测试テストמבחן');
insert into t1 (a,p1,p2,p3,p4,n1,n2,n3,n4) values (8,'0aA1!测试テストמבחן','0aA1!测试テストמבחן','0aA1!测试テストמבחן','0aA1!测试テストמבחן','0aA1!测试テストמבחן  ','0aA1!测试テストמבחן  ','0aA1!测试テストמבחן  ','0aA1!测试テストמבחן  ');

select p1 REGEXP n1 from t1;
select p1 REGEXP n2 from t1;
select p1 REGEXP n3 from t1;
select p1 REGEXP n4 from t1;

select p2 REGEXP n1 from t1;
select p2 REGEXP n2 from t1;
select p2 REGEXP n3 from t1;
select p2 REGEXP n4 from t1;

select p3 REGEXP n1 from t1;
select p3 REGEXP n2 from t1;
select p3 REGEXP n3 from t1;
select p3 REGEXP n4 from t1;

select p4 REGEXP n1 from t1;
select p4 REGEXP n2 from t1;
select p4 REGEXP n3 from t1;
select p4 REGEXP n4 from t1;

DROP TABLE IF EXISTS t1;

2. What did you expect to see?

The result of TiDB is the same as MySQL

Note:
Refer to #16792 and
https://stackoverflow.com/questions/15326421/how-do-i-do-a-case-insensitive-regular-expression-in-go

4. What version of TiDB are you using? (tidb-server -V or run select tidb_version(); on TiDB)

master