Fix unexpected exception when a role has an empty argument_specs.yml (#75604)

* Fix role with empty argument_specs.yml

* Use try/except and add changelog fragment

* Always return a dict

* Add test for empty argument_specs key

changelogs/fragments/75604-empty-argument-specs.yml

@@ -0,0 +1,3 @@
+---
+bugfixes:
+  - roles - fix unexpected ``AttributeError`` when an empty ``argument_specs.yml`` is present (https://github.com/ansible/ansible/pull/75604).

lib/ansible/playbook/role/__init__.py

@@ -294,7 +294,10 @@ class Role(Base, Conditional, Taggable, CollectionSearch):
             if self._loader.path_exists(full_path):
                 # Note: _load_role_yaml() takes care of rebuilding the path.
                 argument_specs = self._load_role_yaml('meta', main='argument_specs')
-                return argument_specs.get('argument_specs', {})
+                try:
+                    return argument_specs.get('argument_specs') or {}
+                except AttributeError:
+                    return {}
 
         # We did not find the meta/argument_specs.[yml|yaml] file, so use the spec
         # dict from the role meta data, if it exists. Ansible 2.11 and later will

test/integration/targets/roles_arg_spec/roles/empty_argspec/meta/argument_specs.yml

@@ -0,0 +1,2 @@
+---
+argument_specs:

test/integration/targets/roles_arg_spec/roles/empty_argspec/tasks/main.yml

@@ -0,0 +1,3 @@
+---
+- debug:
+    msg: "Role with empty argument_specs key"

test/integration/targets/roles_arg_spec/roles/empty_file/meta/argument_specs.yml

@@ -0,0 +1 @@
+---

test/integration/targets/roles_arg_spec/roles/empty_file/tasks/main.yml

@@ -0,0 +1,3 @@
+---
+- debug:
+    msg: "Role with empty argument_specs.yml"

test/integration/targets/roles_arg_spec/test.yml

@@ -338,3 +338,19 @@
         - debug: var=ansible_failed_result
         - fail:
             msg: "Should not get here"
+
+- name: "New play to reset vars: Test empty argument_specs.yml"
+  hosts: localhost
+  gather_facts: false
+  tasks:
+    - name: Import role with an empty argument_specs.yml
+      import_role:
+        name: empty_file
+
+- name: "New play to reset vars: Test empty argument_specs key"
+  hosts: localhost
+  gather_facts: false
+  tasks:
+    - name: Import role with an empty argument_specs key
+      import_role:
+        name: empty_argspec