Improve task decorator type hints with overload (#1631)

Without the overload, the decorated function does not have the proper type of PythonFunctionTask, leading to spurious type errors when attempting to register the task on a FlyteRemote object

Signed-off-by: Matthew Hoffman <[email protected]>

flytekit/core/task.py

@@ -1,6 +1,6 @@
 import datetime as _datetime
 from functools import update_wrapper
-from typing import Any, Callable, Dict, List, Optional, Type, Union
+from typing import Any, Callable, Dict, List, Optional, Type, TypeVar, Union, overload
 
 from flytekit.core.base_task import TaskMetadata, TaskResolverMixin
 from flytekit.core.interface import transform_function_to_interface
@@ -75,9 +75,64 @@ def find_pythontask_plugin(cls, plugin_config_type: type) -> Type[PythonFunction
         return PythonFunctionTask
 
 
+T = TypeVar("T")
+
+
+@overload
+def task(
+    _task_function: None = ...,
+    task_config: Optional[T] = ...,
+    cache: bool = ...,
+    cache_serialize: bool = ...,
+    cache_version: str = ...,
+    retries: int = ...,
+    interruptible: Optional[bool] = ...,
+    deprecated: str = ...,
+    timeout: Union[_datetime.timedelta, int] = ...,
+    container_image: Optional[Union[str, ImageSpec]] = ...,
+    environment: Optional[Dict[str, str]] = ...,
+    requests: Optional[Resources] = ...,
+    limits: Optional[Resources] = ...,
+    secret_requests: Optional[List[Secret]] = ...,
+    execution_mode: PythonFunctionTask.ExecutionBehavior = ...,
+    task_resolver: Optional[TaskResolverMixin] = ...,
+    docs: Optional[Documentation] = ...,
+    disable_deck: bool = ...,
+    pod_template: Optional["PodTemplate"] = ...,
+    pod_template_name: Optional[str] = ...,
+) -> Callable[[Callable[..., Any]], PythonFunctionTask[T]]:
+    ...
+
+
+@overload
+def task(
+    _task_function: Callable[..., Any],
+    task_config: Optional[T] = ...,
+    cache: bool = ...,
+    cache_serialize: bool = ...,
+    cache_version: str = ...,
+    retries: int = ...,
+    interruptible: Optional[bool] = ...,
+    deprecated: str = ...,
+    timeout: Union[_datetime.timedelta, int] = ...,
+    container_image: Optional[Union[str, ImageSpec]] = ...,
+    environment: Optional[Dict[str, str]] = ...,
+    requests: Optional[Resources] = ...,
+    limits: Optional[Resources] = ...,
+    secret_requests: Optional[List[Secret]] = ...,
+    execution_mode: PythonFunctionTask.ExecutionBehavior = ...,
+    task_resolver: Optional[TaskResolverMixin] = ...,
+    docs: Optional[Documentation] = ...,
+    disable_deck: bool = ...,
+    pod_template: Optional["PodTemplate"] = ...,
+    pod_template_name: Optional[str] = ...,
+) -> PythonFunctionTask[T]:
+    ...
+
+
 def task(
-    _task_function: Optional[Callable] = None,
-    task_config: Optional[Any] = None,
+    _task_function: Optional[Callable[..., Any]] = None,
+    task_config: Optional[T] = None,
     cache: bool = False,
     cache_serialize: bool = False,
     cache_version: str = "",
@@ -96,7 +151,7 @@ def task(
     disable_deck: bool = True,
     pod_template: Optional["PodTemplate"] = None,
     pod_template_name: Optional[str] = None,
-) -> Union[Callable, PythonFunctionTask]:
+) -> Union[Callable[[Callable[..., Any]], PythonFunctionTask[T]], PythonFunctionTask[T]]:
     """
     This is the core decorator to use for any task type in flytekit.
 
@@ -190,7 +245,7 @@ def foo2():
     :param pod_template_name: The name of the existing PodTemplate resource which will be used in this task.
     """
 
-    def wrapper(fn) -> PythonFunctionTask:
+    def wrapper(fn: Callable[..., Any]) -> PythonFunctionTask[T]:
         _metadata = TaskMetadata(
             cache=cache,
             cache_serialize=cache_serialize,