[defect]: Reference "${dialect}" not found ubuntu 20

[ZohaibBinKhalid]

What type of defect/bug is this?

Non compliance with a standards document

How can the issue be reproduced?

just config rlm_sql_mysql got error

    **dialect = "mysql"**

    #
    #  The driver module used to execute the queries.  Since we
    #  don't know which SQL drivers are being used, the default is
    #  "rlm_sql_null", which just logs the queries to disk via the
    #  "logfile" directive, below.
    #
    #  In order to talk to a real database, delete the next line,
    #  and uncomment the one after it.
    #
    #  If the dialect is "mssql", then the driver should be set to
    #  one of the following values, depending on your system:
    #
    #       rlm_sql_db2
    #       rlm_sql_firebird
    #       rlm_sql_freetds
    #       rlm_sql_iodbc
    #       rlm_sql_unixodbc
    #
    **driver = "rlm_sql_mysql"**

driver = "rlm_sql_${dialect}"

    **server = "localhost"
    port = 3306
    login = "radius"
    password = "radpass"**

Log output from the FreeRADIUS daemon

FreeRADIUS Version 3.0.26
Copyright (C) 1999-2021 The FreeRADIUS server project and contributors
There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE
You may redistribute copies of FreeRADIUS under the terms of the
GNU General Public License
For more information about these matters, see the file named COPYRIGHT
Starting - reading configuration files ...
including dictionary file /usr/share/freeradius/dictionary
including dictionary file /usr/share/freeradius/dictionary.dhcp
including dictionary file /usr/share/freeradius/dictionary.vqp
including dictionary file /etc/freeradius/3.0/dictionary
including configuration file /etc/freeradius/3.0/radiusd.conf
including configuration file /etc/freeradius/3.0/proxy.conf
including configuration file /etc/freeradius/3.0/clients.conf
including configuration file /etc/freeradius/3.0/mods-enabled/sql
/etc/freeradius/3.0/mods-enabled/sql[365]: Reference "${dialect}" not found
Errors reading or parsing /etc/freeradius/3.0/radiusd.conf

Relevant log output from client utilities

No response

Backtrace from LLDB or GDB

No response