mypy: Fix implicit optional usage

Current versions of mypy run with no-implicit-optional
by default.  This change gets Nova's mypy test environment
to pass again.

Change-Id: Ie50c8d364ad9c339355cc138b560ec4df14fe307

7 files changed, 16 insertions, 11 deletions

diff --git a/nova/pci/request.py b/nova/pci/request.py
index 27ada6c045..8ae2385549 100644
--- a/nova/pci/request.py
+++ b/nova/pci/request.py
@@ -168,7 +168,7 @@ def _get_alias_from_config() -> Alias:
 
 
 def _translate_alias_to_requests(
-    alias_spec: str, affinity_policy: str = None,
+    alias_spec: str, affinity_policy: ty.Optional[str] = None,
 ) -> ty.List['objects.InstancePCIRequest']:
     """Generate complete pci requests from pci aliases in extra_spec."""
     pci_aliases = _get_alias_from_config()
@@ -255,7 +255,7 @@ def get_instance_pci_request_from_vif(
 
 
 def get_pci_requests_from_flavor(
-    flavor: 'objects.Flavor', affinity_policy: str = None,
+    flavor: 'objects.Flavor', affinity_policy: ty.Optional[str] = None,
 ) -> 'objects.InstancePCIRequests':
     """Validate and return PCI requests.
 
diff --git a/nova/pci/stats.py b/nova/pci/stats.py
index 5c5f7c669c..c6e4844b34 100644
--- a/nova/pci/stats.py
+++ b/nova/pci/stats.py
@@ -82,7 +82,7 @@ class PciDeviceStats(object):
         self,
         numa_topology: 'objects.NUMATopology',
         stats: 'objects.PCIDevicePoolList' = None,
-        dev_filter: whitelist.Whitelist = None,
+        dev_filter: ty.Optional[whitelist.Whitelist] = None,
     ) -> None:
         self.numa_topology = numa_topology
         self.pools = (
diff --git a/nova/pci/whitelist.py b/nova/pci/whitelist.py
index 8862a0ef4f..152cc29ca6 100644
--- a/nova/pci/whitelist.py
+++ b/nova/pci/whitelist.py
@@ -33,7 +33,7 @@ class Whitelist(object):
     assignable.
     """
 
-    def __init__(self, whitelist_spec: str = None) -> None:
+    def __init__(self, whitelist_spec: ty.Optional[str] = None) -> None:
         """White list constructor
 
         For example, the following json string specifies that devices whose
diff --git a/nova/scheduler/client/report.py b/nova/scheduler/client/report.py
index 1242752be1..7c14f3d7ef 100644
--- a/nova/scheduler/client/report.py
+++ b/nova/scheduler/client/report.py
@@ -1047,7 +1047,7 @@ class SchedulerReportClient(object):
         context: nova_context.RequestContext,
         rp_uuid: str,
         traits: ty.Iterable[str],
-        generation: int = None
+        generation: ty.Optional[int] = None
     ):
         """Replace a provider's traits with those specified.
 
diff --git a/nova/virt/libvirt/driver.py b/nova/virt/libvirt/driver.py
index 73134d8391..fe48960296 100644
--- a/nova/virt/libvirt/driver.py
+++ b/nova/virt/libvirt/driver.py
@@ -7636,7 +7636,7 @@ class LibvirtDriver(driver.ComputeDriver):
         instance: 'objects.Instance',
         power_on: bool = True,
         pause: bool = False,
-        post_xml_callback: ty.Callable = None,
+        post_xml_callback: ty.Optional[ty.Callable] = None,
     ) -> libvirt_guest.Guest:
         """Create a Guest from XML.
 
@@ -7697,7 +7697,7 @@ class LibvirtDriver(driver.ComputeDriver):
         block_device_info: ty.Optional[ty.Dict[str, ty.Any]],
         power_on: bool = True,
         vifs_already_plugged: bool = False,
-        post_xml_callback: ty.Callable = None,
+        post_xml_callback: ty.Optional[ty.Callable] = None,
         external_events: ty.Optional[ty.List[ty.Tuple[str, str]]] = None,
         cleanup_instance_dir: bool = False,
         cleanup_instance_disks: bool = False,
diff --git a/nova/virt/libvirt/event.py b/nova/virt/libvirt/event.py
index a7d2a3624f..56951dc11c 100644
--- a/nova/virt/libvirt/event.py
+++ b/nova/virt/libvirt/event.py
@@ -9,6 +9,8 @@
 #    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 #    License for the specific language governing permissions and limitations
 #    under the License.
+import typing as ty
+
 from nova.virt import event
 
 
@@ -22,7 +24,10 @@ class LibvirtEvent(event.InstanceEvent):
 class DeviceEvent(LibvirtEvent):
     """Base class for device related libvirt events"""
 
-    def __init__(self, uuid: str, dev: str, timestamp: float = None):
+    def __init__(self,
+                 uuid: str,
+                 dev: str,
+                 timestamp: ty.Optional[float] = None):
         super().__init__(uuid, timestamp)
         self.dev = dev
 
diff --git a/nova/virt/libvirt/utils.py b/nova/virt/libvirt/utils.py
index adb2ec45a1..e1298ee5c8 100644
--- a/nova/virt/libvirt/utils.py
+++ b/nova/virt/libvirt/utils.py
@@ -261,8 +261,8 @@ def copy_image(
     dest: str,
     host: ty.Optional[str] = None,
     receive: bool = False,
-    on_execute: ty.Callable = None,
-    on_completion: ty.Callable = None,
+    on_execute: ty.Optional[ty.Callable] = None,
+    on_completion: ty.Optional[ty.Callable] = None,
     compression: bool = True,
 ) -> None:
     """Copy a disk image to an existing directory
@@ -639,7 +639,7 @@ def mdev_name2uuid(mdev_name: str) -> str:
     return str(uuid.UUID(mdev_uuid))
 
 
-def mdev_uuid2name(mdev_uuid: str, parent: str = None) -> str:
+def mdev_uuid2name(mdev_uuid: str, parent: ty.Optional[str] = None) -> str:
     """Convert an mdev uuid (of the form 8-4-4-4-12) and optionally its parent
     device to a name (of the form mdev_<uuid_with_underscores>[_<pciid>]).