MySQL 8.0 deprecation warnings

[sbulen]

Description

Receiving the following warnings when restoring an SMF DB using MySQL 8.0.20:

WARNING: mysqli_warning  'utf8' is currently an alias for the character set UTF8MB3, but will be an alias for UTF8MB4 in a future release. Please consider using UTF8MB4 in order to be unambiguous.
WARNING: mysqli_warning  Integer display width is deprecated and will be removed in a future release.
WARNING: mysqli_warning  'NO_ZERO_DATE', 'NO_ZERO_IN_DATE' and 'ERROR_FOR_DIVISION_BY_ZERO' sql modes should be used with strict mode. They will be merged with strict mode in a future release. 

All simple fixes, just tedious. Changes needed throughout installer & upgrader, & also in settings management for $db_character_set.

Steps to reproduce

1. Restore an SMF DB from a mysqldump export into a MySQL 8.0.20 DB

Environment (complete as necessary)

• Version/Git revision: current
• Database Type: MySQL
• Database Version: 8.0.20
• PHP Version: 8.0.13

[sbulen]

I really don't think this is a 2.1.0 requirement. Could we remove or change the milestone?

[sbulen]

I see this as being in 3 parts:

• INT display width cleanup. Soon is good, just not a 2.1.0 dependency.
• STRICT mode cleanup. Soon is good, just not a 2.1.0 dependency.
• UTF8/UTF8MB3/UTF8MB4 clarifications. Should be incorporated into Mysql mb4 #6409 .

[Sesquipedalian]

I'm fine with changing the milestone, so long as no actual database changes will be required to fix this.

[sbulen]

Some more reading regarding these changes:

Today, "utf8" is an alias for "utf8mb3", but that is going to change to "utf8mb4". In fact, utf8mb3 itself - the SMF current default - is being deprecated:
https://dev.mysql.com/doc/refman/8.0/en/charset-unicode-utf8.html

Benefits, including utf8mb4 is faster:
https://dev.mysql.com/blog-archive/mysql-8-0-when-to-use-utf8mb3-over-utf8mb4/

Integer display width is deprecated:
https://dev.mysql.com/worklog/task/?id=13127
https://dev.mysql.com/doc/refman/8.0/en/numeric-type-attributes.html
https://stackoverflow.com/questions/58938358/mysql-warning-1681-integer-display-width-is-deprecated