mypy: Set disallow_any_generics

See #6100

25 files changed, 125 insertions, 69 deletions

diff --git a/.mypy.ini b/.mypy.ini
index b1cd8967c..289f3eb87 100644
--- a/.mypy.ini
+++ b/.mypy.ini
@@ -3,7 +3,7 @@ python_version = 3.6
 
 ### --strict
 warn_unused_configs = True
-# disallow_any_generics = True
+disallow_any_generics = True
 disallow_subclassing_any = True
 # disallow_untyped_calls = True
 # disallow_untyped_defs = True
@@ -83,6 +83,10 @@ disallow_untyped_defs = True
 [mypy-qutebrowser.config.*]
 disallow_untyped_defs = True
 
+[mypy-qutebrowser.config.configtypes]
+# Needs some major work to use specific generics
+disallow_any_generics = False
+
 [mypy-qutebrowser.api.*]
 disallow_untyped_defs = True
 
diff --git a/qutebrowser/api/cmdutils.py b/qutebrowser/api/cmdutils.py
index 85a700c43..73c6a1bc5 100644
--- a/qutebrowser/api/cmdutils.py
+++ b/qutebrowser/api/cmdutils.py
@@ -105,6 +105,9 @@ def check_exclusive(flags: Iterable[bool], names: Iterable[str]) -> None:
         raise CommandError("Only one of {} can be given!".format(argstr))
 
 
+_CmdHandlerType = Callable[..., Any]
+
+
 class register:  # noqa: N801,N806 pylint: disable=invalid-name
 
     """Decorator to register a new command handler."""
@@ -130,7 +133,7 @@ class register:  # noqa: N801,N806 pylint: disable=invalid-name
         # The arguments to pass to Command.
         self._kwargs = kwargs
 
-    def __call__(self, func: Callable) -> Callable:
+    def __call__(self, func: _CmdHandlerType) -> _CmdHandlerType:
         """Register the command before running the function.
 
         Gets called when a function should be decorated.
@@ -222,7 +225,7 @@ class argument:  # noqa: N801,N806 pylint: disable=invalid-name
         self._argname = argname   # The name of the argument to handle.
         self._kwargs = kwargs  # Valid ArgInfo members.
 
-    def __call__(self, func: Callable) -> Callable:
+    def __call__(self, func: _CmdHandlerType) -> _CmdHandlerType:
         funcname = func.__name__
 
         if self._argname not in inspect.signature(func).parameters:
diff --git a/qutebrowser/api/hook.py b/qutebrowser/api/hook.py
index eadc310f3..884d6c67f 100644
--- a/qutebrowser/api/hook.py
+++ b/qutebrowser/api/hook.py
@@ -22,13 +22,13 @@
 """Hooks for extensions."""
 
 import importlib
-from typing import Callable
+from typing import Callable, Any
 
 
 from qutebrowser.extensions import loader
 
 
-def _add_module_info(func: Callable) -> loader.ModuleInfo:
+def _add_module_info(func: Callable[..., Any]) -> loader.ModuleInfo:
     """Add module info to the given function."""
     module = importlib.import_module(func.__module__)
     return loader.add_module_info(module)
@@ -48,7 +48,7 @@ class init:
             message.info("Extension initialized.")
     """
 
-    def __call__(self, func: Callable) -> Callable:
+    def __call__(self, func: loader.InitHookType) -> loader.InitHookType:
         info = _add_module_info(func)
         if info.init_hook is not None:
             raise ValueError("init hook is already registered!")
@@ -86,7 +86,10 @@ class config_changed:
     def __init__(self, option_filter: str = None) -> None:
         self._filter = option_filter
 
-    def __call__(self, func: Callable) -> Callable:
+    def __call__(
+        self,
+        func: loader.ConfigChangedHookType,
+    ) -> loader.ConfigChangedHookType:
         info = _add_module_info(func)
         info.config_changed_hooks.append((self._filter, func))
         return func
diff --git a/qutebrowser/browser/browsertab.py b/qutebrowser/browser/browsertab.py
index cbe698009..b3d1e85f7 100644
--- a/qutebrowser/browser/browsertab.py
+++ b/qutebrowser/browser/browsertab.py
@@ -34,9 +34,10 @@ from PyQt5.QtPrintSupport import QPrintDialog, QPrinter
 from PyQt5.QtNetwork import QNetworkAccessManager
 
 if TYPE_CHECKING:
-    from PyQt5.QtWebKit import QWebHistory
+    from PyQt5.QtWebKit import QWebHistory, QWebHistoryItem
     from PyQt5.QtWebKitWidgets import QWebPage
-    from PyQt5.QtWebEngineWidgets import QWebEngineHistory, QWebEnginePage
+    from PyQt5.QtWebEngineWidgets import (
+        QWebEngineHistory, QWebEngineHistoryItem, QWebEnginePage)
 
 from qutebrowser.keyinput import modeman
 from qutebrowser.config import config
@@ -634,8 +635,8 @@ class AbstractHistoryPrivate:
         """Deserialize from a format produced by self.serialize."""
         raise NotImplementedError
 
-    def load_items(self, items: Sequence) -> None:
-        """Deserialize from a list of WebHistoryItems."""
+    def load_items(self, items: Sequence[sessions.TabHistoryItem]) -> None:
+        """Deserialize from a list of TabHistoryItems."""
         raise NotImplementedError
 
 
@@ -651,7 +652,7 @@ class AbstractHistory:
     def __len__(self) -> int:
         raise NotImplementedError
 
-    def __iter__(self) -> Iterable:
+    def __iter__(self) -> Iterable[Union['QWebHistoryItem', 'QWebEngineHistoryItem']]:
         raise NotImplementedError
 
     def _check_count(self, count: int) -> None:
diff --git a/qutebrowser/browser/commands.py b/qutebrowser/browser/commands.py
index e9653ae19..8cd73ae4f 100644
--- a/qutebrowser/browser/commands.py
+++ b/qutebrowser/browser/commands.py
@@ -602,7 +602,7 @@ class CommandDispatcher:
         widget = self._current_widget()
         url = self._current_url()
 
-        handlers: Dict[str, Callable] = {
+        handlers: Dict[str, Callable[..., QUrl]] = {
             'prev': functools.partial(navigate.prevnext, prev=True),
             'next': functools.partial(navigate.prevnext, prev=False),
             'up': navigate.path_up,
diff --git a/qutebrowser/browser/qutescheme.py b/qutebrowser/browser/qutescheme.py
index cfb238188..031b6fe06 100644
--- a/qutebrowser/browser/qutescheme.py
+++ b/qutebrowser/browser/qutescheme.py
@@ -92,7 +92,8 @@ class Redirect(Exception):
 
 # Return value: (mimetype, data) (encoded as utf-8 if a str is returned)
 _HandlerRet = Tuple[str, Union[str, bytes]]
-_Handler = TypeVar('_Handler', bound=Callable[[QUrl], _HandlerRet])
+_HandlerCallable = Callable[[QUrl], _HandlerRet]
+_Handler = TypeVar('_Handler', bound=_HandlerCallable)
 
 
 class add_handler:  # noqa: N801,N806 pylint: disable=invalid-name
@@ -105,7 +106,7 @@ class add_handler:  # noqa: N801,N806 pylint: disable=invalid-name
 
     def __init__(self, name: str) -> None:
         self._name = name
-        self._function: Optional[Callable] = None
+        self._function: Optional[_HandlerCallable] = None
 
     def __call__(self, function: _Handler) -> _Handler:
         self._function = function
diff --git a/qutebrowser/browser/webelem.py b/qutebrowser/browser/webelem.py
index f53ad1afb..11c95e4cd 100644
--- a/qutebrowser/browser/webelem.py
+++ b/qutebrowser/browser/webelem.py
@@ -58,7 +58,7 @@ def css_selector(group: str, url: QUrl) -> str:
     return ','.join(selectors[group])
 
 
-class AbstractWebElement(collections.abc.MutableMapping):
+class AbstractWebElement(collections.abc.MutableMapping[str, str]):
 
     """A wrapper around QtWebKit/QtWebEngine web element."""
 
diff --git a/qutebrowser/browser/webengine/tabhistory.py b/qutebrowser/browser/webengine/tabhistory.py
index d6c795fb2..ab4b05fe9 100644
--- a/qutebrowser/browser/webengine/tabhistory.py
+++ b/qutebrowser/browser/webengine/tabhistory.py
@@ -35,10 +35,10 @@ HISTORY_STREAM_VERSION = 3
 
 
 def _serialize_item(item, stream):
-    """Serialize a single WebHistoryItem into a QDataStream.
+    """Serialize a single TabHistoryItem into a QDataStream.
 
     Args:
-        item: The WebHistoryItem to write.
+        item: The TabHistoryItem to write.
         stream: The QDataStream to write to.
     """
     # Thanks to Otter Browser:
@@ -108,10 +108,10 @@ def _serialize_item(item, stream):
 
 
 def serialize(items):
-    """Serialize a list of WebHistoryItems to a data stream.
+    """Serialize a list of TabHistoryItems to a data stream.
 
     Args:
-        items: An iterable of WebHistoryItems.
+        items: An iterable of TabHistoryItems.
 
     Return:
         A (stream, data, user_data) tuple.
diff --git a/qutebrowser/browser/webkit/tabhistory.py b/qutebrowser/browser/webkit/tabhistory.py
index c38968b62..a707030d1 100644
--- a/qutebrowser/browser/webkit/tabhistory.py
+++ b/qutebrowser/browser/webkit/tabhistory.py
@@ -64,10 +64,10 @@ def _serialize_item(item):
 
 
 def serialize(items):
-    """Serialize a list of WebHistoryItems to a data stream.
+    """Serialize a list of TabHistoryItems to a data stream.
 
     Args:
-        items: An iterable of WebHistoryItems.
+        items: An iterable of TabHistoryItems.
 
     Return:
         A (stream, data, user_data) tuple.
diff --git a/qutebrowser/config/config.py b/qutebrowser/config/config.py
index 69f3ca2cc..437a54a33 100644
--- a/qutebrowser/config/config.py
+++ b/qutebrowser/config/config.py
@@ -97,7 +97,10 @@ class change_filter:  # noqa: N801,N806 pylint: disable=invalid-name
         else:
             return False
 
-    def __call__(self, func: Callable) -> Callable:
+    def __call__(
+        self,
+        func: Callable[..., None],
+    ) -> Callable[..., None]:
         """Filter calls to the decorated function.
 
         Gets called when a function should be decorated.
@@ -105,7 +108,9 @@ class change_filter:  # noqa: N801,N806 pylint: disable=invalid-name
         Adds a filter which returns if we're not interested in the change-event
         and calls the wrapped function if we are.
 
-        We assume the function passed doesn't take any parameters.
+        We assume the function passed doesn't take any parameters. However, it
+        could take a "self" argument, so we can't cleary express this in the
+        type above.
 
         Args:
             func: The function to be decorated.
@@ -309,7 +314,7 @@ class Config(QObject):
 
     def _init_values(self) -> None:
         """Populate the self._values dict."""
-        self._values: Mapping = {}
+        self._values: Mapping[str, configutils.Values] = {}
         for name, opt in configdata.DATA.items():
             self._values[name] = configutils.Values(opt)
 
diff --git a/qutebrowser/config/configcommands.py b/qutebrowser/config/configcommands.py
index 2084556da..143b02fca 100644
--- a/qutebrowser/config/configcommands.py
+++ b/qutebrowser/config/configcommands.py
@@ -21,7 +21,7 @@
 
 import os.path
 import contextlib
-from typing import TYPE_CHECKING, Iterator, List, Optional
+from typing import TYPE_CHECKING, Iterator, List, Optional, Any, Tuple
 
 from PyQt5.QtCore import QUrl
 
@@ -475,7 +475,7 @@ class ConfigCommands:
             raise cmdutils.CommandError("{} already exists - use --force to "
                                         "overwrite!".format(filename))
 
-        options: List = []
+        options: List[Tuple[Optional[urlmatch.UrlPattern], configdata.Option, Any]] = []
         if defaults:
             options = [(None, opt, opt.default)
                        for _name, opt in sorted(configdata.DATA.items())]
diff --git a/qutebrowser/config/configfiles.py b/qutebrowser/config/configfiles.py
index a3320c5c1..6f0d0b13c 100644
--- a/qutebrowser/config/configfiles.py
+++ b/qutebrowser/config/configfiles.py
@@ -30,7 +30,7 @@ import configparser
 import contextlib
 import re
 from typing import (TYPE_CHECKING, Any, Dict, Iterable, Iterator, List, Mapping,
-                    MutableMapping, Optional, cast)
+                    MutableMapping, Optional, Tuple, cast)
 
 import yaml
 from PyQt5.QtCore import pyqtSignal, pyqtSlot, QObject, QSettings, qVersion
@@ -302,18 +302,18 @@ class YamlConfig(QObject):
         self._validate_names(settings)
         self._build_values(settings)
 
-    def _load_settings_object(self, yaml_data: Any) -> '_SettingsType':
+    def _load_settings_object(self, yaml_data: Any) -> _SettingsType:
         """Load the settings from the settings: key."""
         return self._pop_object(yaml_data, 'settings', dict)
 
-    def _load_legacy_settings_object(self, yaml_data: Any) -> '_SettingsType':
+    def _load_legacy_settings_object(self, yaml_data: Any) -> _SettingsType:
         data = self._pop_object(yaml_data, 'global', dict)
         settings = {}
         for name, value in data.items():
             settings[name] = {'global': value}
         return settings
 
-    def _build_values(self, settings: Mapping) -> None:
+    def _build_values(self, settings: Mapping[str, Any]) -> None:
         """Build up self._values from the values in the given dict."""
         errors = []
         for name, yaml_values in settings.items():
@@ -740,9 +740,17 @@ class ConfigPyWriter:
 
     def __init__(
             self,
-            options: List,
+            options: List[
+                Tuple[
+                    Optional[urlmatch.UrlPattern],
+                    configdata.Option,
+                    Any
+                ]
+            ],
             bindings: MutableMapping[str, Mapping[str, Optional[str]]],
-            *, commented: bool) -> None:
+            *,
+            commented: bool,
+    ) -> None:
         self._options = options
         self._bindings = bindings
         self._commented = commented
diff --git a/qutebrowser/config/websettings.py b/qutebrowser/config/websettings.py
index 896f7639c..7556d2b6d 100644
--- a/qutebrowser/config/websettings.py
+++ b/qutebrowser/config/websettings.py
@@ -85,7 +85,11 @@ class AttributeInfo:
 
     """Info about a settings attribute."""
 
-    def __init__(self, *attributes: Any, converter: Callable = None) -> None:
+    def __init__(
+        self,
+        *attributes: Any,
+        converter: Callable[[Any], bool] = None,
+    ) -> None:
         self.attributes = attributes
         if converter is None:
             self.converter = lambda val: val
diff --git a/qutebrowser/extensions/loader.py b/qutebrowser/extensions/loader.py
index 9b704c94d..7ae45023b 100644
--- a/qutebrowser/extensions/loader.py
+++ b/qutebrowser/extensions/loader.py
@@ -39,6 +39,9 @@ from qutebrowser.misc import objects
 # ModuleInfo objects for all loaded plugins
 _module_infos = []
 
+InitHookType = Callable[['InitContext'], None]
+ConfigChangedHookType = Callable[[], None]
+
 
 @dataclasses.dataclass
 class InitContext:
@@ -59,9 +62,13 @@ class ModuleInfo:
     """
 
     skip_hooks: bool = False
-    init_hook: Optional[Callable] = None
-    config_changed_hooks: List[Tuple[Optional[str], Callable]] = dataclasses.field(
-        default_factory=list)
+    init_hook: Optional[InitHookType] = None
+    config_changed_hooks: List[
+        Tuple[
+            Optional[str],
+            ConfigChangedHookType,
+        ]
+    ] = dataclasses.field(default_factory=list)
 
 
 @dataclasses.dataclass
diff --git a/qutebrowser/keyinput/basekeyparser.py b/qutebrowser/keyinput/basekeyparser.py
index d1828791c..7e688dab1 100644
--- a/qutebrowser/keyinput/basekeyparser.py
+++ b/qutebrowser/keyinput/basekeyparser.py
@@ -112,7 +112,7 @@ class BindingTrie:
 
         return lines
 
-    def update(self, mapping: Mapping) -> None:
+    def update(self, mapping: Mapping[keyutils.KeySequence, str]) -> None:
         """Add data from the given mapping to the trie."""
         for key in mapping:
             self[key] = mapping[key]
diff --git a/qutebrowser/keyinput/keyutils.py b/qutebrowser/keyinput/keyutils.py
index ddf818708..6bd8c99b8 100644
--- a/qutebrowser/keyinput/keyutils.py
+++ b/qutebrowser/keyinput/keyutils.py
@@ -458,7 +458,7 @@ class KeySequence:
             assert self
         self._validate()
 
-    def _convert_key(self, key: Qt.Key) -> int:
+    def _convert_key(self, key: Union[int, Qt.KeyboardModifiers]) -> int:
         """Convert a single key for QKeySequence."""
         assert isinstance(key, (int, Qt.KeyboardModifiers)), key
         return int(key)
diff --git a/qutebrowser/misc/debugcachestats.py b/qutebrowser/misc/debugcachestats.py
index f172f0854..2004ad7ab 100644
--- a/qutebrowser/misc/debugcachestats.py
+++ b/qutebrowser/misc/debugcachestats.py
@@ -30,7 +30,7 @@ from typing import Any, Callable, List, Optional, Tuple, TypeVar
 _CACHE_FUNCTIONS: List[Tuple[str, Any]] = []
 
 
-_T = TypeVar('_T', bound=Callable)
+_T = TypeVar('_T', bound=Callable[..., Any])
 
 
 def register(name: Optional[str] = None) -> Callable[[_T], _T]:
diff --git a/qutebrowser/misc/elf.py b/qutebrowser/misc/elf.py
index 307d3b4ac..bf824880a 100644
--- a/qutebrowser/misc/elf.py
+++ b/qutebrowser/misc/elf.py
@@ -65,7 +65,7 @@ import re
 import dataclasses
 import mmap
 import pathlib
-from typing import IO, ClassVar, Dict, Optional, Tuple, cast
+from typing import Any, IO, ClassVar, Dict, Optional, Tuple, cast
 
 from PyQt5.QtCore import QLibraryInfo
 
@@ -93,7 +93,7 @@ class Endianness(enum.Enum):
     big = 2
 
 
-def _unpack(fmt: str, fobj: IO[bytes]) -> Tuple:
+def _unpack(fmt: str, fobj: IO[bytes]) -> Tuple[Any, ...]:
     """Unpack the given struct format from the given file."""
     size = struct.calcsize(fmt)
     data = _safe_read(fobj, size)
diff --git a/qutebrowser/misc/throttle.py b/qutebrowser/misc/throttle.py
index 1beebe1aa..ac565b68d 100644
--- a/qutebrowser/misc/throttle.py
+++ b/qutebrowser/misc/throttle.py
@@ -45,7 +45,7 @@ class Throttle(QObject):
     """
 
     def __init__(self,
-                 func: Callable,
+                 func: Callable[..., None],
                  delay_ms: int,
                  parent: QObject = None) -> None:
         """Constructor.
diff --git a/qutebrowser/utils/debug.py b/qutebrowser/utils/debug.py
index 54fcd5aa9..7d069909a 100644
--- a/qutebrowser/utils/debug.py
+++ b/qutebrowser/utils/debug.py
@@ -35,7 +35,7 @@ from qutebrowser.misc import objects
 from qutebrowser.qt import sip
 
 
-def log_events(klass: Type) -> Type:
+def log_events(klass: Type[QObject]) -> Type[QObject]:
     """Class decorator to log Qt events."""
     old_event = klass.event
 
@@ -46,7 +46,7 @@ def log_events(klass: Type) -> Type:
                                                 qenum_key(QEvent, e.type())))
         return old_event(self, e)
 
-    klass.event = new_event
+    klass.event = new_event  # type: ignore[assignment]
     return klass
 
 
@@ -96,10 +96,13 @@ def log_signals(obj: QObject) -> QObject:
     return obj
 
 
-def qenum_key(base: Type,
-              value: Union[int, sip.simplewrapper],
+_EnumValueType = Union[sip.simplewrapper, int]
+
+
+def qenum_key(base: Type[_EnumValueType],
+              value: _EnumValueType,
               add_base: bool = False,
-              klass: Type = None) -> str:
+              klass: Type[_EnumValueType] = None) -> str:
     """Convert a Qt Enum value to its key as a string.
 
     Args:
@@ -119,8 +122,9 @@ def qenum_key(base: Type,
             raise TypeError("Can't guess enum class of an int!")
 
     try:
-        idx = base.staticMetaObject.indexOfEnumerator(klass.__name__)
-        meta_enum = base.staticMetaObject.enumerator(idx)
+        meta_obj = base.staticMetaObject  # type: ignore[union-attr]
+        idx = meta_obj.indexOfEnumerator(klass.__name__)
+        meta_enum = meta_obj.enumerator(idx)
         ret = meta_enum.valueToKey(int(value))  # type: ignore[arg-type]
     except AttributeError:
         ret = None
@@ -139,10 +143,10 @@ def qenum_key(base: Type,
         return ret
 
 
-def qflags_key(base: Type,
-               value: Union[int, sip.simplewrapper],
+def qflags_key(base: Type[_EnumValueType],
+               value: _EnumValueType,
                add_base: bool = False,
-               klass: Type = None) -> str:
+               klass: Type[_EnumValueType] = None) -> str:
     """Convert a Qt QFlags value to its keys as string.
 
     Note: Passing a combined value (such as Qt.AlignCenter) will get the names
@@ -220,7 +224,7 @@ def signal_name(sig: pyqtBoundSignal) -> str:
     return m.group('name')
 
 
-def format_args(args: Sequence = None, kwargs: Mapping = None) -> str:
+def format_args(args: Sequence[Any] = None, kwargs: Mapping[str, Any] = None) -> str:
     """Format a list of arguments/kwargs to a function-call like string."""
     if args is not None:
         arglist = [utils.compact_text(repr(arg), 200) for arg in args]
@@ -245,9 +249,9 @@ def dbg_signal(sig: pyqtBoundSignal, args: Any) -> str:
     return '{}({})'.format(signal_name(sig), format_args(args))
 
 
-def format_call(func: Callable,
-                args: Sequence = None,
-                kwargs: Mapping = None,
+def format_call(func: Callable[..., Any],
+                args: Sequence[Any] = None,
+                kwargs: Mapping[str, Any] = None,
                 full: bool = True) -> str:
     """Get a string representation of a function calls with the given args.
 
@@ -302,7 +306,7 @@ class log_time:  # noqa: N801,N806 pylint: disable=invalid-name
         self._logger.debug("{} took {} seconds.".format(
             self._action.capitalize(), delta))
 
-    def __call__(self, func: Callable) -> Callable:
+    def __call__(self, func: Callable[..., Any]) -> Callable[..., Any]:
         @functools.wraps(func)
         def wrapped(*args: Any, **kwargs: Any) -> Any:
             """Call the original function."""
diff --git a/qutebrowser/utils/docutils.py b/qutebrowser/utils/docutils.py
index 202fcba95..89e799c89 100644
--- a/qutebrowser/utils/docutils.py
+++ b/qutebrowser/utils/docutils.py
@@ -25,7 +25,7 @@ import inspect
 import os.path
 import collections
 import enum
-from typing import Callable, MutableMapping, Optional, List, Union
+from typing import Any, Callable, MutableMapping, Optional, List, Union
 
 import qutebrowser
 from qutebrowser.utils import log, utils
@@ -88,7 +88,7 @@ class DocstringParser:
         arg_inside = enum.auto()
         misc = enum.auto()
 
-    def __init__(self, func: Callable) -> None:
+    def __init__(self, func: Callable[..., Any]) -> None:
         """Constructor.
 
         Args:
diff --git a/qutebrowser/utils/objreg.py b/qutebrowser/utils/objreg.py
index 99d8a0936..0819a5d0a 100644
--- a/qutebrowser/utils/objreg.py
+++ b/qutebrowser/utils/objreg.py
@@ -55,7 +55,8 @@ class CommandOnlyError(Exception):
 _IndexType = Union[str, int]
 
 
-class ObjectRegistry(collections.UserDict):
+# UserDict is only generic in Python 3.9+
+class ObjectRegistry(collections.UserDict):  # type: ignore[type-arg]
 
     """A registry of long-living objects in qutebrowser.
 
diff --git a/qutebrowser/utils/qtutils.py b/qutebrowser/utils/qtutils.py
index 01234a42b..ff8983c50 100644
--- a/qutebrowser/utils/qtutils.py
+++ b/qutebrowser/utils/qtutils.py
@@ -31,7 +31,8 @@ Module attributes:
 import io
 import operator
 import contextlib
-from typing import TYPE_CHECKING, BinaryIO, IO, Iterator, Optional, Union, Tuple, cast
+from typing import (Any, AnyStr, TYPE_CHECKING, BinaryIO, IO, Iterator,
+                    Optional, Union, Tuple, cast)
 
 from PyQt5.QtCore import (qVersion, QEventLoop, QDataStream, QByteArray,
                           QIODevice, QFileDevice, QSaveFile, QT_VERSION_STR,
@@ -227,7 +228,7 @@ def savefile_open(
         filename: str,
         binary: bool = False,
         encoding: str = 'utf-8'
-) -> Iterator[IO]:
+) -> Iterator[IO[AnyStr]]:
     """Context manager to easily use a QSaveFile."""
     f = QSaveFile(filename)
     cancelled = False
@@ -239,7 +240,7 @@ def savefile_open(
         dev = cast(BinaryIO, PyQIODevice(f))
 
         if binary:
-            new_f: IO = dev
+            new_f: IO[Any] = dev  # FIXME:mypy Why doesn't AnyStr work?
         else:
             new_f = io.TextIOWrapper(dev, encoding=encoding)
 
@@ -298,7 +299,11 @@ class PyQIODevice(io.BufferedIOBase):
         if not self.writable():
             raise OSError("Trying to write to unwritable file!")
 
-    def open(self, mode: QIODevice.OpenMode) -> contextlib.closing:
+    # contextlib.closing is only generic in Python 3.9+
+    def open(
+        self,
+        mode: QIODevice.OpenMode,
+    ) -> contextlib.closing:  # type: ignore[type-arg]
         """Open the underlying device and ensure opening succeeded.
 
         Raises OSError if opening failed.
diff --git a/qutebrowser/utils/urlmatch.py b/qutebrowser/utils/urlmatch.py
index 8dfd6d273..f14c2083d 100644
--- a/qutebrowser/utils/urlmatch.py
+++ b/qutebrowser/utils/urlmatch.py
@@ -104,7 +104,14 @@ class UrlPattern:
         self._init_path(parsed)
         self._init_port(parsed)
 
-    def _to_tuple(self) -> Tuple:
+    def _to_tuple(self) -> Tuple[
+        bool,  # _match_all
+        bool,  # _match_subdomains
+        Optional[str],  # _scheme
+        Optional[str],  # host
+        Optional[str],  # _path
+        Optional[int],  # _port
+    ]:
         """Get a pattern with information used for __eq__/__hash__."""
         return (self._match_all, self._match_subdomains, self._scheme,
                 self.host, self._path, self._port)
diff --git a/qutebrowser/utils/utils.py b/qutebrowser/utils/utils.py
index 56ebe45c4..fb0165de2 100644
--- a/qutebrowser/utils/utils.py
+++ b/qutebrowser/utils/utils.py
@@ -341,7 +341,7 @@ class prevent_exceptions:  # noqa: N801,N806 pylint: disable=invalid-name
         self._retval = retval
         self._predicate = predicate
 
-    def __call__(self, func: Callable) -> Callable:
+    def __call__(self, func: Callable[..., Any]) -> Callable[..., Any]:
         """Called when a function should be decorated.
 
         Args:
@@ -447,7 +447,7 @@ def qualname(obj: Any) -> str:
 _ExceptionType = Union[Type[BaseException], Tuple[Type[BaseException]]]
 
 
-def raises(exc: _ExceptionType, func: Callable, *args: Any) -> bool:
+def raises(exc: _ExceptionType, func: Callable[..., Any], *args: Any) -> bool:
     """Check if a function raises a given exception.
 
     Args:
@@ -725,7 +725,10 @@ def yaml_dump(data: Any, f: IO[str] = None) -> Optional[str]:
         return yaml_data.decode('utf-8')
 
 
-def chunk(elems: Sequence, n: int) -> Iterator[Sequence]:
+_T = TypeVar('_T')
+
+
+def chunk(elems: Sequence[_T], n: int) -> Iterator[Sequence[_T]]:
     """Yield successive n-sized chunks from elems.
 
     If elems % n != 0, the last chunk will be smaller.