Various mypy related fixes.

Author: jonathanslenders

mypy.ini

@@ -15,4 +15,6 @@ strict_optional = True
 warn_redundant_casts = True
 warn_return_any = True
 warn_unused_configs = True
-warn_unused_ignores = True
+
+# We have a 'type:ignore' that's not needed on Python 3.6.
+warn_unused_ignores = False

src/prompt_toolkit/application/application.py

@@ -22,6 +22,7 @@
     Any,
     Awaitable,
     Callable,
+    Coroutine,
     Dict,
     FrozenSet,
     Generator,
@@ -1017,7 +1018,7 @@ def trace_dispatch(
         CustomPdb(stdout=sys.__stdout__).set_trace(frame)
 
     def create_background_task(
-        self, coroutine: Awaitable[None]
+        self, coroutine: Coroutine[Any, Any, None]
     ) -> "asyncio.Task[None]":
         """
         Start a background task (coroutine) for the running application. When
@@ -1029,7 +1030,7 @@ def create_background_task(
 
         Not threadsafe.
         """
-        task = get_event_loop().create_task(coroutine)
+        task: asyncio.Task[None] = get_event_loop().create_task(coroutine)
         self.background_tasks.append(task)
         return task
 

src/prompt_toolkit/buffer.py

@@ -17,6 +17,7 @@
     Any,
     Awaitable,
     Callable,
+    Coroutine,
     Deque,
     Iterable,
     List,
@@ -1692,7 +1693,7 @@ def start_completion(
             )
         )
 
-    def _create_completer_coroutine(self) -> Callable[..., Awaitable[None]]:
+    def _create_completer_coroutine(self) -> Callable[..., Coroutine[Any, Any, None]]:
         """
         Create function for asynchronous autocompletion.
 
@@ -1822,7 +1823,7 @@ def proceed() -> bool:
 
         return async_completer
 
-    def _create_auto_suggest_coroutine(self) -> Callable[[], Awaitable[None]]:
+    def _create_auto_suggest_coroutine(self) -> Callable[[], Coroutine[Any, Any, None]]:
         """
         Create function for asynchronous auto suggestion.
         (This can be in another thread.)
@@ -1849,7 +1850,9 @@ async def async_suggestor() -> None:
 
         return async_suggestor
 
-    def _create_auto_validate_coroutine(self) -> Callable[[], Awaitable[None]]:
+    def _create_auto_validate_coroutine(
+        self,
+    ) -> Callable[[], Coroutine[Any, Any, None]]:
         """
         Create a function for asynchronous validation while typing.
         (This can be in another thread.)

src/prompt_toolkit/contrib/telnet/server.py

@@ -245,7 +245,7 @@ def _run_in_terminal(self, func: Callable[[], None]) -> None:
         # Make sure that when an application was active for this connection,
         # that we print the text above the application.
         if self.context:
-            self.context.run(run_in_terminal, func)
+            self.context.run(run_in_terminal, func)  # type: ignore
         else:
             raise RuntimeError("Called _run_in_terminal outside `run_application`.")
 

src/prompt_toolkit/eventloop/dummy_contextvars.py

@@ -4,18 +4,25 @@
 As long as there is only one application running at a time, we don't need the
 real contextvars. So, stuff like the telnet-server and so on requires 3.7.
 """
-from typing import Any, Callable, Generic, Optional, TypeVar
+from typing import TYPE_CHECKING, Any, Callable, Generic, Optional, TypeVar
+
+if TYPE_CHECKING:
+    from typing_extensions import ParamSpec
 
 
 def copy_context() -> "Context":
     return Context()
 
 
+if TYPE_CHECKING:
+    _P = ParamSpec("_P")
 _T = TypeVar("_T")
 
 
 class Context:
-    def run(self, callable: Callable[..., _T], *args: Any, **kwargs: Any) -> _T:
+    def run(
+        self, callable: "Callable[_P, _T]", *args: "_P.args", **kwargs: "_P.kwargs"
+    ) -> _T:
         return callable(*args, **kwargs)
 
     def copy(self) -> "Context":

src/prompt_toolkit/layout/menus.py

@@ -7,6 +7,7 @@
     Iterable,
     List,
     Optional,
+    Sequence,
     Tuple,
     TypeVar,
     Union,
@@ -406,7 +407,7 @@ def create_content(self, width: int, height: int) -> UIContent:
 
         def grouper(
             n: int, iterable: Iterable[_T], fillvalue: Optional[_T] = None
-        ) -> Iterable[List[_T]]:
+        ) -> Iterable[Sequence[Optional[_T]]]:
             "grouper(3, 'ABCDEFG', 'x') --> ABC DEF Gxx"
             args = [iter(iterable)] * n
             return zip_longest(fillvalue=fillvalue, *args)

src/prompt_toolkit/widgets/base.py

@@ -892,7 +892,7 @@ class Checkbox(CheckboxList[str]):
 
     def __init__(self, text: AnyFormattedText = "", checked: bool = False) -> None:
         values = [("value", text)]
-        CheckboxList.__init__(self, values=values)
+        super().__init__(values=values)
         self.checked = checked
 
     @property