diff --git a/src/_pytest/_code/code.py b/src/_pytest/_code/code.py
index a40b23470..121ef3a9b 100644
--- a/src/_pytest/_code/code.py
+++ b/src/_pytest/_code/code.py
@@ -928,8 +928,13 @@ class TerminalRepr:
         raise NotImplementedError()
 
 
+# This class is abstract -- only subclasses are instantiated.
 @attr.s(**{ATTRS_EQ_FIELD: False})  # type: ignore
 class ExceptionRepr(TerminalRepr):
+    # Provided by in subclasses.
+    reprcrash = None  # type: Optional[ReprFileLocation]
+    reprtraceback = None  # type: ReprTraceback
+
     def __attrs_post_init__(self):
         self.sections = []  # type: List[Tuple[str, str, str]]
 
diff --git a/src/_pytest/assertion/rewrite.py b/src/_pytest/assertion/rewrite.py
index cec0c5501..e77b1b0b8 100644
--- a/src/_pytest/assertion/rewrite.py
+++ b/src/_pytest/assertion/rewrite.py
@@ -23,6 +23,8 @@ from typing import Set
 from typing import Tuple
 from typing import Union
 
+import py
+
 from _pytest._io.saferepr import saferepr
 from _pytest._version import version
 from _pytest.assertion import util
@@ -177,10 +179,10 @@ class AssertionRewritingHook(importlib.abc.MetaPathFinder, importlib.abc.Loader)
         """
         if self.session is not None and not self._session_paths_checked:
             self._session_paths_checked = True
-            for path in self.session._initialpaths:
+            for initial_path in self.session._initialpaths:
                 # Make something as c:/projects/my_project/path.py ->
                 #     ['c:', 'projects', 'my_project', 'path.py']
-                parts = str(path).split(os.path.sep)
+                parts = str(initial_path).split(os.path.sep)
                 # add 'path' to basenames to be checked.
                 self._basenames_to_check_rewrite.add(os.path.splitext(parts[-1])[0])
 
@@ -213,7 +215,7 @@ class AssertionRewritingHook(importlib.abc.MetaPathFinder, importlib.abc.Loader)
             return True
 
         if self.session is not None:
-            if self.session.isinitpath(fn):
+            if self.session.isinitpath(py.path.local(fn)):
                 state.trace(
                     "matched test file (was specified on cmdline): {!r}".format(fn)
                 )
diff --git a/src/_pytest/cacheprovider.py b/src/_pytest/cacheprovider.py
index 9baee1d4e..967272ca6 100755
--- a/src/_pytest/cacheprovider.py
+++ b/src/_pytest/cacheprovider.py
@@ -464,8 +464,7 @@ def pytest_cmdline_main(config: Config) -> Optional[Union[int, ExitCode]]:
 
 @pytest.hookimpl(tryfirst=True)
 def pytest_configure(config: Config) -> None:
-    # Type ignored: pending mechanism to store typed objects scoped to config.
-    config.cache = Cache.for_config(config)  # type: ignore # noqa: F821
+    config.cache = Cache.for_config(config)
     config.pluginmanager.register(LFPlugin(config), "lfplugin")
     config.pluginmanager.register(NFPlugin(config), "nfplugin")
 
@@ -496,7 +495,7 @@ def pytest_report_header(config: Config) -> Optional[str]:
         # starting with .., ../.. if sensible
 
         try:
-            displaypath = cachedir.relative_to(config.rootdir)
+            displaypath = cachedir.relative_to(str(config.rootdir))
         except ValueError:
             displaypath = cachedir
         return "cachedir: {}".format(displaypath)
diff --git a/src/_pytest/capture.py b/src/_pytest/capture.py
index 041041284..daded6395 100644
--- a/src/_pytest/capture.py
+++ b/src/_pytest/capture.py
@@ -519,11 +519,10 @@ class MultiCapture:
     def pop_outerr_to_orig(self):
         """ pop current snapshot out/err capture and flush to orig streams. """
         out, err = self.readouterr()
-        # TODO: Fix type ignores.
         if out:
-            self.out.writeorg(out)  # type: ignore[union-attr] # noqa: F821
+            self.out.writeorg(out)
         if err:
-            self.err.writeorg(err)  # type: ignore[union-attr] # noqa: F821
+            self.err.writeorg(err)
         return out, err
 
     def suspend_capturing(self, in_: bool = False) -> None:
@@ -543,8 +542,7 @@ class MultiCapture:
         if self.err:
             self.err.resume()
         if self._in_suspended:
-            # TODO: Fix type ignore.
-            self.in_.resume()  # type: ignore[union-attr] # noqa: F821
+            self.in_.resume()
             self._in_suspended = False
 
     def stop_capturing(self) -> None:
@@ -751,11 +749,11 @@ class CaptureManager:
             yield
 
     @pytest.hookimpl(tryfirst=True)
-    def pytest_keyboard_interrupt(self, excinfo):
+    def pytest_keyboard_interrupt(self) -> None:
         self.stop_global_capturing()
 
     @pytest.hookimpl(tryfirst=True)
-    def pytest_internalerror(self, excinfo):
+    def pytest_internalerror(self) -> None:
         self.stop_global_capturing()
 
 
diff --git a/src/_pytest/config/__init__.py b/src/_pytest/config/__init__.py
index 6e26bf15c..b77968110 100644
--- a/src/_pytest/config/__init__.py
+++ b/src/_pytest/config/__init__.py
@@ -48,6 +48,7 @@ from _pytest.warning_types import PytestConfigWarning
 if TYPE_CHECKING:
     from typing import Type
 
+    from _pytest._code.code import _TracebackStyle
     from .argparsing import Argument
 
 
@@ -307,10 +308,9 @@ class PytestPluginManager(PluginManager):
         self._dirpath2confmods = {}  # type: Dict[Any, List[object]]
         # Maps a py.path.local to a module object.
         self._conftestpath2mod = {}  # type: Dict[Any, object]
-        self._confcutdir = None
+        self._confcutdir = None  # type: Optional[py.path.local]
         self._noconftest = False
-        # Set of py.path.local's.
-        self._duplicatepaths = set()  # type: Set[Any]
+        self._duplicatepaths = set()  # type: Set[py.path.local]
 
         self.add_hookspecs(_pytest.hookspec)
         self.register(self)
@@ -893,9 +893,13 @@ class Config:
 
         return self
 
-    def notify_exception(self, excinfo, option=None):
+    def notify_exception(
+        self,
+        excinfo: ExceptionInfo[BaseException],
+        option: Optional[argparse.Namespace] = None,
+    ) -> None:
         if option and getattr(option, "fulltrace", False):
-            style = "long"
+            style = "long"  # type: _TracebackStyle
         else:
             style = "native"
         excrepr = excinfo.getrepr(
@@ -940,13 +944,12 @@ class Config:
         ns, unknown_args = self._parser.parse_known_and_unknown_args(
             args, namespace=copy.copy(self.option)
         )
-        r = determine_setup(
+        self.rootdir, self.inifile, self.inicfg = determine_setup(
             ns.inifilename,
             ns.file_or_dir + unknown_args,
             rootdir_cmd_arg=ns.rootdir or None,
             config=self,
         )
-        self.rootdir, self.inifile, self.inicfg = r
         self._parser.extra_info["rootdir"] = self.rootdir
         self._parser.extra_info["inifile"] = self.inifile
         self._parser.addini("addopts", "extra command line options", "args")
@@ -994,9 +997,7 @@ class Config:
         package_files = (
             str(file)
             for dist in importlib_metadata.distributions()
-            # Type ignored due to missing stub:
-            # https://github.com/python/typeshed/pull/3795
-            if any(ep.group == "pytest11" for ep in dist.entry_points)  # type: ignore
+            if any(ep.group == "pytest11" for ep in dist.entry_points)
             for file in dist.files or []
         )
 
@@ -1073,6 +1074,11 @@ class Config:
             # Imported lazily to improve start-up time.
             from packaging.version import Version
 
+            if not isinstance(minver, str):
+                raise pytest.UsageError(
+                    "%s: 'minversion' must be a single value" % self.inifile
+                )
+
             if Version(minver) > Version(pytest.__version__):
                 raise pytest.UsageError(
                     "%s: 'minversion' requires pytest-%s, actual pytest-%s'"
@@ -1187,6 +1193,8 @@ class Config:
         #   in this case, we already have a list ready to use
         #
         if type == "pathlist":
+            # TODO: This assert is probably not valid in all cases.
+            assert self.inifile is not None
             dp = py.path.local(self.inifile).dirpath()
             input_values = shlex.split(value) if isinstance(value, str) else value
             return [dp.join(x, abs=True) for x in input_values]
diff --git a/src/_pytest/config/findpaths.py b/src/_pytest/config/findpaths.py
index 796fa9b0a..ae8c5f47f 100644
--- a/src/_pytest/config/findpaths.py
+++ b/src/_pytest/config/findpaths.py
@@ -63,7 +63,7 @@ def load_config_dict_from_file(
     elif filepath.ext == ".toml":
         import toml
 
-        config = toml.load(filepath)
+        config = toml.load(str(filepath))
 
         result = config.get("tool", {}).get("pytest", {}).get("ini_options", None)
         if result is not None:
@@ -161,16 +161,18 @@ def determine_setup(
     args: List[str],
     rootdir_cmd_arg: Optional[str] = None,
     config: Optional["Config"] = None,
-) -> Tuple[py.path.local, Optional[str], Dict[str, Union[str, List[str]]]]:
+) -> Tuple[py.path.local, Optional[py.path.local], Dict[str, Union[str, List[str]]]]:
     rootdir = None
     dirs = get_dirs_from_args(args)
     if inifile:
-        inicfg = load_config_dict_from_file(py.path.local(inifile)) or {}
+        inipath_ = py.path.local(inifile)
+        inipath = inipath_  # type: Optional[py.path.local]
+        inicfg = load_config_dict_from_file(inipath_) or {}
         if rootdir_cmd_arg is None:
             rootdir = get_common_ancestor(dirs)
     else:
         ancestor = get_common_ancestor(dirs)
-        rootdir, inifile, inicfg = locate_config([ancestor])
+        rootdir, inipath, inicfg = locate_config([ancestor])
         if rootdir is None and rootdir_cmd_arg is None:
             for possible_rootdir in ancestor.parts(reverse=True):
                 if possible_rootdir.join("setup.py").exists():
@@ -178,7 +180,7 @@ def determine_setup(
                     break
             else:
                 if dirs != [ancestor]:
-                    rootdir, inifile, inicfg = locate_config(dirs)
+                    rootdir, inipath, inicfg = locate_config(dirs)
                 if rootdir is None:
                     if config is not None:
                         cwd = config.invocation_dir
@@ -196,4 +198,5 @@ def determine_setup(
                     rootdir
                 )
             )
-    return rootdir, inifile, inicfg or {}
+    assert rootdir is not None
+    return rootdir, inipath, inicfg or {}
diff --git a/src/_pytest/debugging.py b/src/_pytest/debugging.py
index 3001db4ec..0567927c0 100644
--- a/src/_pytest/debugging.py
+++ b/src/_pytest/debugging.py
@@ -2,11 +2,13 @@
 import argparse
 import functools
 import sys
+import types
 from typing import Generator
 from typing import Tuple
 from typing import Union
 
 from _pytest import outcomes
+from _pytest._code import ExceptionInfo
 from _pytest.compat import TYPE_CHECKING
 from _pytest.config import Config
 from _pytest.config import ConftestImportFailure
@@ -280,9 +282,10 @@ class PdbInvoke:
             out, err = capman.read_global_capture()
             sys.stdout.write(out)
             sys.stdout.write(err)
+        assert call.excinfo is not None
         _enter_pdb(node, call.excinfo, report)
 
-    def pytest_internalerror(self, excrepr, excinfo) -> None:
+    def pytest_internalerror(self, excinfo: ExceptionInfo[BaseException]) -> None:
         tb = _postmortem_traceback(excinfo)
         post_mortem(tb)
 
@@ -320,7 +323,9 @@ def maybe_wrap_pytest_function_for_tracing(pyfuncitem):
         wrap_pytest_function_for_tracing(pyfuncitem)
 
 
-def _enter_pdb(node: Node, excinfo, rep: BaseReport) -> BaseReport:
+def _enter_pdb(
+    node: Node, excinfo: ExceptionInfo[BaseException], rep: BaseReport
+) -> BaseReport:
     # XXX we re-use the TerminalReporter's terminalwriter
     # because this seems to avoid some encoding related troubles
     # for not completely clear reasons.
@@ -349,7 +354,7 @@ def _enter_pdb(node: Node, excinfo, rep: BaseReport) -> BaseReport:
     return rep
 
 
-def _postmortem_traceback(excinfo):
+def _postmortem_traceback(excinfo: ExceptionInfo[BaseException]) -> types.TracebackType:
     from doctest import UnexpectedException
 
     if isinstance(excinfo.value, UnexpectedException):
@@ -361,10 +366,11 @@ def _postmortem_traceback(excinfo):
         # Use the underlying exception instead:
         return excinfo.value.excinfo[2]
     else:
+        assert excinfo._excinfo is not None
         return excinfo._excinfo[2]
 
 
-def post_mortem(t) -> None:
+def post_mortem(t: types.TracebackType) -> None:
     p = pytestPDB._init_pdb("post_mortem")
     p.reset()
     p.interaction(None, t)
diff --git a/src/_pytest/hookspec.py b/src/_pytest/hookspec.py
index 18a9fb39a..1c1726d53 100644
--- a/src/_pytest/hookspec.py
+++ b/src/_pytest/hookspec.py
@@ -19,6 +19,8 @@ if TYPE_CHECKING:
     import warnings
     from typing_extensions import Literal
 
+    from _pytest._code.code import ExceptionRepr
+    from _pytest.code import ExceptionInfo
     from _pytest.config import Config
     from _pytest.config import ExitCode
     from _pytest.config import PytestPluginManager
@@ -30,6 +32,7 @@ if TYPE_CHECKING:
     from _pytest.nodes import Collector
     from _pytest.nodes import Item
     from _pytest.nodes import Node
+    from _pytest.outcomes import Exit
     from _pytest.python import Function
     from _pytest.python import Metafunc
     from _pytest.python import Module
@@ -757,11 +760,19 @@ def pytest_doctest_prepare_content(content):
 # -------------------------------------------------------------------------
 
 
-def pytest_internalerror(excrepr, excinfo):
-    """ called for internal errors. """
+def pytest_internalerror(
+    excrepr: "ExceptionRepr", excinfo: "ExceptionInfo[BaseException]",
+) -> Optional[bool]:
+    """Called for internal errors.
+
+    Return True to suppress the fallback handling of printing an
+    INTERNALERROR message directly to sys.stderr.
+    """
 
 
-def pytest_keyboard_interrupt(excinfo):
+def pytest_keyboard_interrupt(
+    excinfo: "ExceptionInfo[Union[KeyboardInterrupt, Exit]]",
+) -> None:
     """ called for keyboard interrupt. """
 
 
diff --git a/src/_pytest/junitxml.py b/src/_pytest/junitxml.py
index e62bc5235..86e8fcf38 100644
--- a/src/_pytest/junitxml.py
+++ b/src/_pytest/junitxml.py
@@ -26,6 +26,7 @@ import pytest
 from _pytest import deprecated
 from _pytest import nodes
 from _pytest import timing
+from _pytest._code.code import ExceptionRepr
 from _pytest.compat import TYPE_CHECKING
 from _pytest.config import Config
 from _pytest.config import filename_arg
@@ -642,7 +643,7 @@ class LogXML:
             else:
                 reporter.append_collect_skipped(report)
 
-    def pytest_internalerror(self, excrepr) -> None:
+    def pytest_internalerror(self, excrepr: ExceptionRepr) -> None:
         reporter = self.node_reporter("internal")
         reporter.attrs.update(classname="pytest", name="internal")
         reporter._add_simple(Junit.error, "internal error", excrepr)
diff --git a/src/_pytest/logging.py b/src/_pytest/logging.py
index ef90c94e8..04bf74b6c 100644
--- a/src/_pytest/logging.py
+++ b/src/_pytest/logging.py
@@ -586,7 +586,7 @@ class LoggingPlugin:
         fpath = Path(fname)
 
         if not fpath.is_absolute():
-            fpath = Path(self._config.rootdir, fpath)
+            fpath = Path(str(self._config.rootdir), fpath)
 
         if not fpath.parent.exists():
             fpath.parent.mkdir(exist_ok=True, parents=True)
diff --git a/src/_pytest/main.py b/src/_pytest/main.py
index 6d008bcaa..2ec9046b0 100644
--- a/src/_pytest/main.py
+++ b/src/_pytest/main.py
@@ -439,7 +439,7 @@ class Session(nodes.FSCollector):
         )  # type: Dict[Tuple[Type[nodes.Collector], str], CollectReport]
 
         # Dirnames of pkgs with dunder-init files.
-        self._collection_pkg_roots = {}  # type: Dict[py.path.local, Package]
+        self._collection_pkg_roots = {}  # type: Dict[str, Package]
 
         self._bestrelpathcache = _bestrelpath_cache(
             config.rootdir
@@ -601,7 +601,7 @@ class Session(nodes.FSCollector):
                             col = self._collectfile(pkginit, handle_dupes=False)
                             if col:
                                 if isinstance(col[0], Package):
-                                    self._collection_pkg_roots[parent] = col[0]
+                                    self._collection_pkg_roots[str(parent)] = col[0]
                                 # always store a list in the cache, matchnodes expects it
                                 self._collection_node_cache1[col[0].fspath] = [col[0]]
 
@@ -623,8 +623,8 @@ class Session(nodes.FSCollector):
                         for x in self._collectfile(pkginit):
                             yield x
                             if isinstance(x, Package):
-                                self._collection_pkg_roots[dirpath] = x
-                if dirpath in self._collection_pkg_roots:
+                                self._collection_pkg_roots[str(dirpath)] = x
+                if str(dirpath) in self._collection_pkg_roots:
                     # Do not collect packages here.
                     continue
 
diff --git a/src/_pytest/mark/structures.py b/src/_pytest/mark/structures.py
index 7abff9b7b..3d512816c 100644
--- a/src/_pytest/mark/structures.py
+++ b/src/_pytest/mark/structures.py
@@ -66,9 +66,7 @@ def get_empty_parameterset_mark(
         fs,
         lineno,
     )
-    # Type ignored because MarkDecorator.__call__() is a bit tough to
-    # annotate ATM.
-    return mark(reason=reason)  # type: ignore[no-any-return] # noqa: F723
+    return mark(reason=reason)
 
 
 class ParameterSet(
diff --git a/src/_pytest/monkeypatch.py b/src/_pytest/monkeypatch.py
index 9d802a625..09f1ac36e 100644
--- a/src/_pytest/monkeypatch.py
+++ b/src/_pytest/monkeypatch.py
@@ -4,17 +4,29 @@ import re
 import sys
 import warnings
 from contextlib import contextmanager
+from typing import Any
 from typing import Generator
+from typing import List
+from typing import MutableMapping
+from typing import Optional
+from typing import Tuple
+from typing import TypeVar
+from typing import Union
 
 import pytest
+from _pytest.compat import overload
 from _pytest.fixtures import fixture
 from _pytest.pathlib import Path
 
 RE_IMPORT_ERROR_NAME = re.compile(r"^No module named (.*)$")
 
 
+K = TypeVar("K")
+V = TypeVar("V")
+
+
 @fixture
-def monkeypatch():
+def monkeypatch() -> Generator["MonkeyPatch", None, None]:
     """The returned ``monkeypatch`` fixture provides these
     helper methods to modify objects, dictionaries or os.environ::
 
@@ -37,7 +49,7 @@ def monkeypatch():
     mpatch.undo()
 
 
-def resolve(name):
+def resolve(name: str) -> object:
     # simplified from zope.dottedname
     parts = name.split(".")
 
@@ -66,7 +78,7 @@ def resolve(name):
     return found
 
 
-def annotated_getattr(obj, name, ann):
+def annotated_getattr(obj: object, name: str, ann: str) -> object:
     try:
         obj = getattr(obj, name)
     except AttributeError:
@@ -78,7 +90,7 @@ def annotated_getattr(obj, name, ann):
     return obj
 
 
-def derive_importpath(import_path, raising):
+def derive_importpath(import_path: str, raising: bool) -> Tuple[str, object]:
     if not isinstance(import_path, str) or "." not in import_path:
         raise TypeError(
             "must be absolute import path string, not {!r}".format(import_path)
@@ -91,7 +103,7 @@ def derive_importpath(import_path, raising):
 
 
 class Notset:
-    def __repr__(self):
+    def __repr__(self) -> str:
         return "<notset>"
 
 
@@ -102,11 +114,13 @@ class MonkeyPatch:
     """ Object returned by the ``monkeypatch`` fixture keeping a record of setattr/item/env/syspath changes.
     """
 
-    def __init__(self):
-        self._setattr = []
-        self._setitem = []
-        self._cwd = None
-        self._savesyspath = None
+    def __init__(self) -> None:
+        self._setattr = []  # type: List[Tuple[object, str, object]]
+        self._setitem = (
+            []
+        )  # type: List[Tuple[MutableMapping[Any, Any], object, object]]
+        self._cwd = None  # type: Optional[str]
+        self._savesyspath = None  # type: Optional[List[str]]
 
     @contextmanager
     def context(self) -> Generator["MonkeyPatch", None, None]:
@@ -133,7 +147,25 @@ class MonkeyPatch:
         finally:
             m.undo()
 
-    def setattr(self, target, name, value=notset, raising=True):
+    @overload
+    def setattr(
+        self, target: str, name: object, value: Notset = ..., raising: bool = ...,
+    ) -> None:
+        raise NotImplementedError()
+
+    @overload  # noqa: F811
+    def setattr(  # noqa: F811
+        self, target: object, name: str, value: object, raising: bool = ...,
+    ) -> None:
+        raise NotImplementedError()
+
+    def setattr(  # noqa: F811
+        self,
+        target: Union[str, object],
+        name: Union[object, str],
+        value: object = notset,
+        raising: bool = True,
+    ) -> None:
         """ Set attribute value on target, memorizing the old value.
         By default raise AttributeError if the attribute did not exist.
 
@@ -150,7 +182,7 @@ class MonkeyPatch:
         __tracebackhide__ = True
         import inspect
 
-        if value is notset:
+        if isinstance(value, Notset):
             if not isinstance(target, str):
                 raise TypeError(
                     "use setattr(target, name, value) or "
@@ -159,6 +191,13 @@ class MonkeyPatch:
                 )
             value = name
             name, target = derive_importpath(target, raising)
+        else:
+            if not isinstance(name, str):
+                raise TypeError(
+                    "use setattr(target, name, value) with name being a string or "
+                    "setattr(target, value) with target being a dotted "
+                    "import string"
+                )
 
         oldval = getattr(target, name, notset)
         if raising and oldval is notset:
@@ -170,7 +209,12 @@ class MonkeyPatch:
         self._setattr.append((target, name, oldval))
         setattr(target, name, value)
 
-    def delattr(self, target, name=notset, raising=True):
+    def delattr(
+        self,
+        target: Union[object, str],
+        name: Union[str, Notset] = notset,
+        raising: bool = True,
+    ) -> None:
         """ Delete attribute ``name`` from ``target``, by default raise
         AttributeError it the attribute did not previously exist.
 
@@ -184,7 +228,7 @@ class MonkeyPatch:
         __tracebackhide__ = True
         import inspect
 
-        if name is notset:
+        if isinstance(name, Notset):
             if not isinstance(target, str):
                 raise TypeError(
                     "use delattr(target, name) or "
@@ -204,12 +248,12 @@ class MonkeyPatch:
             self._setattr.append((target, name, oldval))
             delattr(target, name)
 
-    def setitem(self, dic, name, value):
+    def setitem(self, dic: MutableMapping[K, V], name: K, value: V) -> None:
         """ Set dictionary entry ``name`` to value. """
         self._setitem.append((dic, name, dic.get(name, notset)))
         dic[name] = value
 
-    def delitem(self, dic, name, raising=True):
+    def delitem(self, dic: MutableMapping[K, V], name: K, raising: bool = True) -> None:
         """ Delete ``name`` from dict. Raise KeyError if it doesn't exist.
 
         If ``raising`` is set to False, no exception will be raised if the
@@ -222,7 +266,7 @@ class MonkeyPatch:
             self._setitem.append((dic, name, dic.get(name, notset)))
             del dic[name]
 
-    def setenv(self, name, value, prepend=None):
+    def setenv(self, name: str, value: str, prepend: Optional[str] = None) -> None:
         """ Set environment variable ``name`` to ``value``.  If ``prepend``
         is a character, read the current environment variable value
         and prepend the ``value`` adjoined with the ``prepend`` character."""
@@ -241,16 +285,17 @@ class MonkeyPatch:
             value = value + prepend + os.environ[name]
         self.setitem(os.environ, name, value)
 
-    def delenv(self, name, raising=True):
+    def delenv(self, name: str, raising: bool = True) -> None:
         """ Delete ``name`` from the environment. Raise KeyError if it does
         not exist.
 
         If ``raising`` is set to False, no exception will be raised if the
         environment variable is missing.
         """
-        self.delitem(os.environ, name, raising=raising)
+        environ = os.environ  # type: MutableMapping[str, str]
+        self.delitem(environ, name, raising=raising)
 
-    def syspath_prepend(self, path):
+    def syspath_prepend(self, path) -> None:
         """ Prepend ``path`` to ``sys.path`` list of import locations. """
         from pkg_resources import fixup_namespace_packages
 
@@ -272,7 +317,7 @@ class MonkeyPatch:
 
         invalidate_caches()
 
-    def chdir(self, path):
+    def chdir(self, path) -> None:
         """ Change the current working directory to the specified path.
         Path can be a string or a py.path.local object.
         """
@@ -286,7 +331,7 @@ class MonkeyPatch:
         else:
             os.chdir(path)
 
-    def undo(self):
+    def undo(self) -> None:
         """ Undo previous changes.  This call consumes the
         undo stack. Calling it a second time has no effect unless
         you do more monkeypatching after the undo call.
@@ -306,14 +351,14 @@ class MonkeyPatch:
             else:
                 delattr(obj, name)
         self._setattr[:] = []
-        for dictionary, name, value in reversed(self._setitem):
+        for dictionary, key, value in reversed(self._setitem):
             if value is notset:
                 try:
-                    del dictionary[name]
+                    del dictionary[key]
                 except KeyError:
                     pass  # was already deleted, so we have the desired state
             else:
-                dictionary[name] = value
+                dictionary[key] = value
         self._setitem[:] = []
         if self._savesyspath is not None:
             sys.path[:] = self._savesyspath
diff --git a/src/_pytest/nodes.py b/src/_pytest/nodes.py
index 3757e0b27..c6c77f529 100644
--- a/src/_pytest/nodes.py
+++ b/src/_pytest/nodes.py
@@ -393,7 +393,7 @@ class Node(metaclass=NodeMeta):
         # It will be better to just always display paths relative to invocation_dir, but
         # this requires a lot of plumbing (#6428).
         try:
-            abspath = Path(os.getcwd()) != Path(self.config.invocation_dir)
+            abspath = Path(os.getcwd()) != Path(str(self.config.invocation_dir))
         except OSError:
             abspath = True
 
diff --git a/src/_pytest/python.py b/src/_pytest/python.py
index 4b716c616..c52771057 100644
--- a/src/_pytest/python.py
+++ b/src/_pytest/python.py
@@ -656,7 +656,7 @@ class Package(Module):
 
             parts_ = parts(path.strpath)
             if any(
-                pkg_prefix in parts_ and pkg_prefix.join("__init__.py") != path
+                str(pkg_prefix) in parts_ and pkg_prefix.join("__init__.py") != path
                 for pkg_prefix in pkg_prefixes
             ):
                 continue
@@ -1332,7 +1332,7 @@ def _show_fixtures_per_test(config, session):
 
     def get_best_relpath(func):
         loc = getlocation(func, curdir)
-        return curdir.bestrelpath(loc)
+        return curdir.bestrelpath(py.path.local(loc))
 
     def write_fixture(fixture_def):
         argname = fixture_def.argname
@@ -1406,7 +1406,7 @@ def _showfixtures_main(config: Config, session: Session) -> None:
                 (
                     len(fixturedef.baseid),
                     fixturedef.func.__module__,
-                    curdir.bestrelpath(loc),
+                    curdir.bestrelpath(py.path.local(loc)),
                     fixturedef.argname,
                     fixturedef,
                 )
diff --git a/src/_pytest/resultlog.py b/src/_pytest/resultlog.py
index c870ef08e..cd6824abf 100644
--- a/src/_pytest/resultlog.py
+++ b/src/_pytest/resultlog.py
@@ -5,6 +5,7 @@ import os
 
 import py
 
+from _pytest._code.code import ExceptionRepr
 from _pytest.config import Config
 from _pytest.config.argparsing import Parser
 from _pytest.reports import CollectReport
@@ -99,9 +100,9 @@ class ResultLog:
                 longrepr = "%s:%d: %s" % report.longrepr  # type: ignore
             self.log_outcome(report, code, longrepr)
 
-    def pytest_internalerror(self, excrepr):
-        reprcrash = getattr(excrepr, "reprcrash", None)
-        path = getattr(reprcrash, "path", None)
-        if path is None:
+    def pytest_internalerror(self, excrepr: ExceptionRepr) -> None:
+        if excrepr.reprcrash is not None:
+            path = excrepr.reprcrash.path
+        else:
             path = "cwd:%s" % py.path.local()
         self.write_log_entry(path, "!", str(excrepr))
diff --git a/src/_pytest/terminal.py b/src/_pytest/terminal.py
index 9c2665fb8..8c2a30739 100644
--- a/src/_pytest/terminal.py
+++ b/src/_pytest/terminal.py
@@ -30,6 +30,8 @@ from more_itertools import collapse
 import pytest
 from _pytest import nodes
 from _pytest import timing
+from _pytest._code import ExceptionInfo
+from _pytest._code.code import ExceptionRepr
 from _pytest._io import TerminalWriter
 from _pytest._io.wcwidth import wcswidth
 from _pytest.compat import order_preserving_dict
@@ -315,6 +317,7 @@ class TerminalReporter:
         self._show_progress_info = self._determine_show_progress_info()
         self._collect_report_last_write = None  # type: Optional[float]
         self._already_displayed_warnings = None  # type: Optional[int]
+        self._keyboardinterrupt_memo = None  # type: Optional[ExceptionRepr]
 
     @property
     def writer(self) -> TerminalWriter:
@@ -377,9 +380,9 @@ class TerminalReporter:
             if self.currentfspath is not None and self._show_progress_info:
                 self._write_progress_information_filling_space()
             self.currentfspath = fspath
-            fspath = self.startdir.bestrelpath(fspath)
+            relfspath = self.startdir.bestrelpath(fspath)
             self._tw.line()
-            self._tw.write(fspath + " ")
+            self._tw.write(relfspath + " ")
         self._tw.write(res, flush=True, **markup)
 
     def write_ensure_prefix(self, prefix, extra: str = "", **kwargs) -> None:
@@ -448,10 +451,10 @@ class TerminalReporter:
         if set_main_color:
             self._set_main_color()
 
-    def pytest_internalerror(self, excrepr):
+    def pytest_internalerror(self, excrepr: ExceptionRepr) -> bool:
         for line in str(excrepr).split("\n"):
             self.write_line("INTERNALERROR> " + line)
-        return 1
+        return True
 
     def pytest_warning_recorded(
         self, warning_message: warnings.WarningMessage, nodeid: str,
@@ -783,7 +786,7 @@ class TerminalReporter:
             self.write_sep("!", str(session.shouldfail), red=True)
         if exitstatus == ExitCode.INTERRUPTED:
             self._report_keyboardinterrupt()
-            del self._keyboardinterrupt_memo
+            self._keyboardinterrupt_memo = None
         elif session.shouldstop:
             self.write_sep("!", str(session.shouldstop), red=True)
         self.summary_stats()
@@ -799,15 +802,17 @@ class TerminalReporter:
         # Display any extra warnings from teardown here (if any).
         self.summary_warnings()
 
-    def pytest_keyboard_interrupt(self, excinfo) -> None:
+    def pytest_keyboard_interrupt(self, excinfo: ExceptionInfo[BaseException]) -> None:
         self._keyboardinterrupt_memo = excinfo.getrepr(funcargs=True)
 
     def pytest_unconfigure(self) -> None:
-        if hasattr(self, "_keyboardinterrupt_memo"):
+        if self._keyboardinterrupt_memo is not None:
             self._report_keyboardinterrupt()
 
     def _report_keyboardinterrupt(self) -> None:
         excrepr = self._keyboardinterrupt_memo
+        assert excrepr is not None
+        assert excrepr.reprcrash is not None
         msg = excrepr.reprcrash.message
         self.write_sep("!", msg)
         if "KeyboardInterrupt" in msg:
diff --git a/testing/acceptance_test.py b/testing/acceptance_test.py
index 7dfd588a0..686fe1b98 100644
--- a/testing/acceptance_test.py
+++ b/testing/acceptance_test.py
@@ -580,8 +580,9 @@ class TestInvocationVariants:
         assert res.ret == 0
         res.stdout.fnmatch_lines(["*1 passed*"])
 
-    def test_equivalence_pytest_pytest(self):
-        assert pytest.main == py.test.cmdline.main
+    def test_equivalence_pytest_pydottest(self) -> None:
+        # Type ignored because `py.test` is not and will not be typed.
+        assert pytest.main == py.test.cmdline.main  # type: ignore[attr-defined]
 
     def test_invoke_with_invalid_type(self):
         with pytest.raises(
diff --git a/testing/test_assertrewrite.py b/testing/test_assertrewrite.py
index 3813993be..38893deb9 100644
--- a/testing/test_assertrewrite.py
+++ b/testing/test_assertrewrite.py
@@ -1258,7 +1258,7 @@ class TestEarlyRewriteBailout:
 
         def spy_find_spec(name, path):
             self.find_spec_calls.append(name)
-            return importlib.machinery.PathFinder.find_spec(name, path)  # type: ignore
+            return importlib.machinery.PathFinder.find_spec(name, path)
 
         hook = AssertionRewritingHook(pytestconfig)
         # use default patterns, otherwise we inherit pytest's testing config
diff --git a/testing/test_config.py b/testing/test_config.py
index a10ac41dd..c77ab1a48 100644
--- a/testing/test_config.py
+++ b/testing/test_config.py
@@ -683,13 +683,14 @@ class TestConfigFromdictargs:
         )
         with cwd.ensure(dir=True).as_cwd():
             config = Config.fromdictargs(option_dict, ())
+            inipath = py.path.local(inifile)
 
         assert config.args == [str(cwd)]
         assert config.option.inifilename == inifile
         assert config.option.capture == "no"
 
         # this indicates this is the file used for getting configuration values
-        assert config.inifile == inifile
+        assert config.inifile == inipath
         assert config.inicfg.get("name") == "value"
         assert config.inicfg.get("should_not_be_set") is None
 
diff --git a/testing/test_monkeypatch.py b/testing/test_monkeypatch.py
index 1a3afbea9..509e72599 100644
--- a/testing/test_monkeypatch.py
+++ b/testing/test_monkeypatch.py
@@ -5,9 +5,12 @@ import textwrap
 from typing import Dict
 from typing import Generator
 
+import py
+
 import pytest
 from _pytest.compat import TYPE_CHECKING
 from _pytest.monkeypatch import MonkeyPatch
+from _pytest.pytester import Testdir
 
 if TYPE_CHECKING:
     from typing import Type
@@ -45,9 +48,12 @@ def test_setattr() -> None:
     monkeypatch.undo()  # double-undo makes no modification
     assert A.x == 5
 
+    with pytest.raises(TypeError):
+        monkeypatch.setattr(A, "y")  # type: ignore[call-overload]
+
 
 class TestSetattrWithImportPath:
-    def test_string_expression(self, monkeypatch):
+    def test_string_expression(self, monkeypatch: MonkeyPatch) -> None:
         monkeypatch.setattr("os.path.abspath", lambda x: "hello2")
         assert os.path.abspath("123") == "hello2"
 
@@ -64,30 +70,31 @@ class TestSetattrWithImportPath:
         assert _pytest.config.Config == 42  # type: ignore
         monkeypatch.delattr("_pytest.config.Config")
 
-    def test_wrong_target(self, monkeypatch):
-        pytest.raises(TypeError, lambda: monkeypatch.setattr(None, None))
+    def test_wrong_target(self, monkeypatch: MonkeyPatch) -> None:
+        with pytest.raises(TypeError):
+            monkeypatch.setattr(None, None)  # type: ignore[call-overload]
 
-    def test_unknown_import(self, monkeypatch):
-        pytest.raises(ImportError, lambda: monkeypatch.setattr("unkn123.classx", None))
+    def test_unknown_import(self, monkeypatch: MonkeyPatch) -> None:
+        with pytest.raises(ImportError):
+            monkeypatch.setattr("unkn123.classx", None)
 
-    def test_unknown_attr(self, monkeypatch):
-        pytest.raises(
-            AttributeError, lambda: monkeypatch.setattr("os.path.qweqwe", None)
-        )
+    def test_unknown_attr(self, monkeypatch: MonkeyPatch) -> None:
+        with pytest.raises(AttributeError):
+            monkeypatch.setattr("os.path.qweqwe", None)
 
     def test_unknown_attr_non_raising(self, monkeypatch: MonkeyPatch) -> None:
         # https://github.com/pytest-dev/pytest/issues/746
         monkeypatch.setattr("os.path.qweqwe", 42, raising=False)
         assert os.path.qweqwe == 42  # type: ignore
 
-    def test_delattr(self, monkeypatch):
+    def test_delattr(self, monkeypatch: MonkeyPatch) -> None:
         monkeypatch.delattr("os.path.abspath")
         assert not hasattr(os.path, "abspath")
         monkeypatch.undo()
         assert os.path.abspath
 
 
-def test_delattr():
+def test_delattr() -> None:
     class A:
         x = 1
 
@@ -107,7 +114,7 @@ def test_delattr():
     assert A.x == 1
 
 
-def test_setitem():
+def test_setitem() -> None:
     d = {"x": 1}
     monkeypatch = MonkeyPatch()
     monkeypatch.setitem(d, "x", 2)
@@ -135,7 +142,7 @@ def test_setitem_deleted_meanwhile() -> None:
 
 
 @pytest.mark.parametrize("before", [True, False])
-def test_setenv_deleted_meanwhile(before):
+def test_setenv_deleted_meanwhile(before: bool) -> None:
     key = "qwpeoip123"
     if before:
         os.environ[key] = "world"
@@ -167,10 +174,10 @@ def test_delitem() -> None:
     assert d == {"hello": "world", "x": 1}
 
 
-def test_setenv():
+def test_setenv() -> None:
     monkeypatch = MonkeyPatch()
     with pytest.warns(pytest.PytestWarning):
-        monkeypatch.setenv("XYZ123", 2)
+        monkeypatch.setenv("XYZ123", 2)  # type: ignore[arg-type]
     import os
 
     assert os.environ["XYZ123"] == "2"
@@ -178,7 +185,7 @@ def test_setenv():
     assert "XYZ123" not in os.environ
 
 
-def test_delenv():
+def test_delenv() -> None:
     name = "xyz1234"
     assert name not in os.environ
     monkeypatch = MonkeyPatch()
@@ -208,31 +215,28 @@ class TestEnvironWarnings:
 
     VAR_NAME = "PYTEST_INTERNAL_MY_VAR"
 
-    def test_setenv_non_str_warning(self, monkeypatch):
+    def test_setenv_non_str_warning(self, monkeypatch: MonkeyPatch) -> None:
         value = 2
         msg = (
             "Value of environment variable PYTEST_INTERNAL_MY_VAR type should be str, "
             "but got 2 (type: int); converted to str implicitly"
         )
         with pytest.warns(pytest.PytestWarning, match=re.escape(msg)):
-            monkeypatch.setenv(str(self.VAR_NAME), value)
+            monkeypatch.setenv(str(self.VAR_NAME), value)  # type: ignore[arg-type]
 
 
-def test_setenv_prepend():
+def test_setenv_prepend() -> None:
     import os
 
     monkeypatch = MonkeyPatch()
-    with pytest.warns(pytest.PytestWarning):
-        monkeypatch.setenv("XYZ123", 2, prepend="-")
-    assert os.environ["XYZ123"] == "2"
-    with pytest.warns(pytest.PytestWarning):
-        monkeypatch.setenv("XYZ123", 3, prepend="-")
+    monkeypatch.setenv("XYZ123", "2", prepend="-")
+    monkeypatch.setenv("XYZ123", "3", prepend="-")
     assert os.environ["XYZ123"] == "3-2"
     monkeypatch.undo()
     assert "XYZ123" not in os.environ
 
 
-def test_monkeypatch_plugin(testdir):
+def test_monkeypatch_plugin(testdir: Testdir) -> None:
     reprec = testdir.inline_runsource(
         """
         def test_method(monkeypatch):
@@ -243,7 +247,7 @@ def test_monkeypatch_plugin(testdir):
     assert tuple(res) == (1, 0, 0), res
 
 
-def test_syspath_prepend(mp: MonkeyPatch):
+def test_syspath_prepend(mp: MonkeyPatch) -> None:
     old = list(sys.path)
     mp.syspath_prepend("world")
     mp.syspath_prepend("hello")
@@ -255,7 +259,7 @@ def test_syspath_prepend(mp: MonkeyPatch):
     assert sys.path == old
 
 
-def test_syspath_prepend_double_undo(mp: MonkeyPatch):
+def test_syspath_prepend_double_undo(mp: MonkeyPatch) -> None:
     old_syspath = sys.path[:]
     try:
         mp.syspath_prepend("hello world")
@@ -267,24 +271,24 @@ def test_syspath_prepend_double_undo(mp: MonkeyPatch):
         sys.path[:] = old_syspath
 
 
-def test_chdir_with_path_local(mp: MonkeyPatch, tmpdir):
+def test_chdir_with_path_local(mp: MonkeyPatch, tmpdir: py.path.local) -> None:
     mp.chdir(tmpdir)
     assert os.getcwd() == tmpdir.strpath
 
 
-def test_chdir_with_str(mp: MonkeyPatch, tmpdir):
+def test_chdir_with_str(mp: MonkeyPatch, tmpdir: py.path.local) -> None:
     mp.chdir(tmpdir.strpath)
     assert os.getcwd() == tmpdir.strpath
 
 
-def test_chdir_undo(mp: MonkeyPatch, tmpdir):
+def test_chdir_undo(mp: MonkeyPatch, tmpdir: py.path.local) -> None:
     cwd = os.getcwd()
     mp.chdir(tmpdir)
     mp.undo()
     assert os.getcwd() == cwd
 
 
-def test_chdir_double_undo(mp: MonkeyPatch, tmpdir):
+def test_chdir_double_undo(mp: MonkeyPatch, tmpdir: py.path.local) -> None:
     mp.chdir(tmpdir.strpath)
     mp.undo()
     tmpdir.chdir()
@@ -292,7 +296,7 @@ def test_chdir_double_undo(mp: MonkeyPatch, tmpdir):
     assert os.getcwd() == tmpdir.strpath
 
 
-def test_issue185_time_breaks(testdir):
+def test_issue185_time_breaks(testdir: Testdir) -> None:
     testdir.makepyfile(
         """
         import time
@@ -310,7 +314,7 @@ def test_issue185_time_breaks(testdir):
     )
 
 
-def test_importerror(testdir):
+def test_importerror(testdir: Testdir) -> None:
     p = testdir.mkpydir("package")
     p.join("a.py").write(
         textwrap.dedent(
@@ -360,7 +364,7 @@ def test_issue156_undo_staticmethod(Sample: "Type[Sample]") -> None:
     assert Sample.hello()
 
 
-def test_undo_class_descriptors_delattr():
+def test_undo_class_descriptors_delattr() -> None:
     class SampleParent:
         @classmethod
         def hello(_cls):
@@ -387,7 +391,7 @@ def test_undo_class_descriptors_delattr():
     assert original_world == SampleChild.world
 
 
-def test_issue1338_name_resolving():
+def test_issue1338_name_resolving() -> None:
     pytest.importorskip("requests")
     monkeypatch = MonkeyPatch()
     try:
@@ -396,7 +400,7 @@ def test_issue1338_name_resolving():
         monkeypatch.undo()
 
 
-def test_context():
+def test_context() -> None:
     monkeypatch = MonkeyPatch()
 
     import functools
@@ -408,7 +412,9 @@ def test_context():
     assert inspect.isclass(functools.partial)
 
 
-def test_syspath_prepend_with_namespace_packages(testdir, monkeypatch):
+def test_syspath_prepend_with_namespace_packages(
+    testdir: Testdir, monkeypatch: MonkeyPatch
+) -> None:
     for dirname in "hello", "world":
         d = testdir.mkdir(dirname)
         ns = d.mkdir("ns_pkg")