How to loop over a role in Ansible?

Don’t use roles: but tasks: and use the include_role module. For example:

---
# roles/myrole/tasks/main.yml
- debug: var=bla

---
# playbook
- hosts: localhost
  connection: local
  gather_facts: no
  tasks:
   - name: Loop over role
     include_role:
      name: myrole
     vars:
      bla: ""
     with_items:
      - hello world
      - hi