Oracle 12 - Reporting on Roles
If you want to list all the roles of a particular user:


select granted_role,admin_option,default_role from dba_role_privs where grantee='&user';


If you want to list all users with all roles assigned:


select b.username,a.granted_role,a.admin_option,a.default_role from dba_role_privs a join dba_users b on (a.grantee=b.username);