[MariaDB developers] How to debug build/project?

I followed https://mariadb.org/get-involved/getting-started-for-developers/get-code-bui... and am able to run the server and mariadb client. Right now i am trying to debug the project after building and running it but havent been successful. I am trying the issue https://jira.mariadb.org/browse/MDEV-34228 In SQL 2023 we have the use of underscore with numeric literals. Any pointers on how to approach this will be appreciated. Been trying to fiddle around numericliteral.h file. Thank You