MySQL triggers reporting an unparseable section for trigger SET statements

Search before asking

[X] I searched the issues and found no similar issues.

What Happened

I am attempting to clean up a large MySQL application which uses triggers for compatibility with an older application. This obviously runs hard into https://github.com/sqlfluff/sqlfluff/issues/3599 but I noticed another oddity with SET statements in those triggers - here's a highly-reduced example:

CREATE TRIGGER tr_downloads_i_copy_new_fields BEFORE INSERT
ON downloads
FOR EACH ROW BEGIN

SET NEW.createdate = UNIX_TIMESTAMP(NEW.createdate_m);

END

A little code golfing suggests that the problem is using the SET NEW.<column> form since SQLFluff works fine the more common SET @variable form. As far as I know, that's the only way to do that in MySQL and it's what they use in the examples:

https://dev.mysql.com/doc/refman/8.0/en/trigger-syntax.html

Expected Behaviour

The body of the trigger would be formatted

Observed Behaviour

== [test.sql] FAIL                                                                          
L:   1 | P:   1 |  PRS | Line 1, Position 1: Found unparsable section: 'CREATE
                       | TRIGGER tr_downloadao_i_copy_new_...'
WARNING: Parsing errors found and dialect is set to 'mysql'. Have you configured your dialect correctly?

How to reproduce

sqlfluff lint

Dialect

mysql

Version

3.0.6

Configuration

[sqlfluff] dialect = mysql max_line_length = 120 exclude_rules = L013

[sqlfluff:indentation] tab_space_size = 4

[sqlfluff:rules:capitalisation.keywords] capitalisation_policy = upper [sqlfluff:rules:capitalisation.functions] extended_capitalisation_policy = upper [sqlfluff:rules:capitalisation.types] extended_capitalisation_policy = upper

Are you willing to work on and submit a PR to address the issue?

[ ] Yes I am willing to submit a PR!

Code of Conduct

[X] I agree to follow this project's Code of Conduct

sqlfluff / sqlfluff