introducing FunctionDefinition as actual Node/Collector

src/_pytest/_code/code.py

@@ -210,7 +210,11 @@
 
     @property
     def lineno(self) -> int:
-        return self._rawentry.tb_lineno - 1
+        if self._rawentry.tb_lineno is None:
+            # how did i trigger this 😱
+            return -1  # type: ignore[unreachable]
+        else:
+            return self._rawentry.tb_lineno - 1
 
     @property
     def frame(self) -> Frame:

src/_pytest/compat.py

@@ -1,4 +1,3 @@
-# mypy: allow-untyped-defs
 """Python version compatibility code."""
 
 from __future__ import annotations
@@ -12,8 +11,11 @@
 import os
 from pathlib import Path
 import sys
+from types import FunctionType
+from types import MethodType
 from typing import Any
 from typing import Callable
+from typing import cast
 from typing import Final
 from typing import NoReturn
 
@@ -66,7 +68,8 @@ def is_async_function(func: object) -> bool:
     return iscoroutinefunction(func) or inspect.isasyncgenfunction(func)
 
 
-def getlocation(function, curdir: str | os.PathLike[str] | None = None) -> str:
+def getlocation(function: Any, curdir: str | os.PathLike[str] | None = None) -> str:
+    # todo: declare a type alias for function, fixturefunction and callables/generators
     function = get_real_func(function)
     fn = Path(inspect.getfile(function))
     lineno = function.__code__.co_firstlineno
@@ -80,7 +83,7 @@ def getlocation(function, curdir: str | os.PathLike[str] | None = None) -> str:
     return "%s:%d" % (fn, lineno + 1)
 
 
-def num_mock_patch_args(function) -> int:
+def num_mock_patch_args(function: Callable[..., object]) -> int:
     """Return number of arguments used up by mock arguments (if any)."""
     patchings = getattr(function, "patchings", None)
     if not patchings:
@@ -222,7 +225,7 @@ class _PytestWrapper:
     obj: Any
 
 
-def get_real_func(obj):
+def get_real_func(obj: Any) -> Any:
     """Get the real function object of the (possibly) wrapped object by
     functools.wraps or functools.partial."""
     start_obj = obj
@@ -249,7 +252,7 @@ def get_real_func(obj):
     return obj
 
 
-def get_real_method(obj, holder):
+def get_real_method(obj: Any, holder: object) -> Any:
     """Attempt to obtain the real function object that might be wrapping
     ``obj``, while at the same time returning a bound method to ``holder`` if
     the original object was a bound method."""
@@ -263,11 +266,8 @@ def get_real_method(obj, holder):
     return obj
 
 
-def getimfunc(func):
-    try:
-        return func.__func__
-    except AttributeError:
-        return func
+def getimfunc(func: FunctionType | MethodType | Callable[..., Any]) -> FunctionType:
+    return cast(FunctionType, getattr(func, "__func__", func))
 
 
 def safe_getattr(object: Any, name: str, default: Any) -> Any:

src/_pytest/doctest.py

@@ -417,9 +417,10 @@ def _get_continue_on_failure(config: Config) -> bool:
 
 
 class DoctestTextfile(Module):
-    obj = None
+    # todo: this shouldnt be a module
+    obj: None = None  # type: ignore[assignment]
 
-    def collect(self) -> Iterable[DoctestItem]:
+    def collect(self) -> Iterable[DoctestItem]:  # type: ignore[override]
         import doctest
 
         # Inspired by doctest.testfile; ideally we would use it directly,
@@ -497,7 +498,7 @@ def _mock_aware_unwrap(
 
 
 class DoctestModule(Module):
-    def collect(self) -> Iterable[DoctestItem]:
+    def collect(self) -> Iterable[DoctestItem]:  # type: ignore[override]
         import doctest
 
         class MockAwareDocTestFinder(doctest.DocTestFinder):

src/_pytest/fixtures.py

@@ -1100,7 +1100,8 @@ def resolve_fixture_function(
 ) -> _FixtureFunc[FixtureValue]:
     """Get the actual callable that can be called to obtain the fixture
     value."""
-    fixturefunc = fixturedef.func
+    # absuing any for the differences between FunctionTpye and Callable
+    fixturefunc: Any = fixturedef.func
     # The fixture function needs to be bound to the actual
     # request.instance so that code working with "fixturedef" behaves
     # as expected.
@@ -1112,11 +1113,11 @@ def resolve_fixture_function(
             instance,
             fixturefunc.__self__.__class__,
         ):
-            return fixturefunc
+            return cast(_FixtureFunc[FixtureValue], fixturefunc)
         fixturefunc = getimfunc(fixturedef.func)
         if fixturefunc != fixturedef.func:
             fixturefunc = fixturefunc.__get__(instance)
-    return fixturefunc
+    return cast(_FixtureFunc[FixtureValue], fixturefunc)
 
 
 def pytest_fixture_setup(

src/_pytest/main.py

@@ -545,6 +545,7 @@ class Session(nodes.Collector):
     ``Session`` collects the initial paths given as arguments to pytest.
     """
 
+    parent: None
     Interrupted = Interrupted
     Failed = Failed
     # Set on the session by runner.pytest_sessionstart.

src/_pytest/nodes.py

@@ -1,4 +1,3 @@
-# mypy: allow-untyped-defs
 from __future__ import annotations
 
 import abc
@@ -20,6 +19,7 @@
 import warnings
 
 import pluggy
+from typing_extensions import Self
 
 import _pytest._code
 from _pytest._code import getfslineno
@@ -54,9 +54,6 @@
 tracebackcutdir = Path(_pytest.__file__).parent
 
 
-_T = TypeVar("_T")
-
-
 def _imply_path(
     node_type: type[Node],
     path: Path | None,
@@ -96,7 +93,7 @@ class NodeMeta(abc.ABCMeta):
     progress on detangling the :class:`Node` classes.
     """
 
-    def __call__(cls, *k, **kw) -> NoReturn:
+    def __call__(cls, *k: object, **kw: object) -> NoReturn:
         msg = (
             "Direct construction of {name} has been deprecated, please use {name}.from_parent.\n"
             "See "
@@ -105,25 +102,6 @@ def __call__(cls, *k, **kw) -> NoReturn:
         ).format(name=f"{cls.__module__}.{cls.__name__}")
         fail(msg, pytrace=False)
 
-    def _create(cls: type[_T], *k, **kw) -> _T:
-        try:
-            return super().__call__(*k, **kw)  # type: ignore[no-any-return,misc]
-        except TypeError:
-            sig = signature(getattr(cls, "__init__"))
-            known_kw = {k: v for k, v in kw.items() if k in sig.parameters}
-            from .warning_types import PytestDeprecationWarning
-
-            warnings.warn(
-                PytestDeprecationWarning(
-                    f"{cls} is not using a cooperative constructor and only takes {set(known_kw)}.\n"
-                    "See https://docs.pytest.org/en/stable/deprecations.html"
-                    "#constructors-of-custom-pytest-node-subclasses-should-take-kwargs "
-                    "for more details."
-                )
-            )
-
-            return super().__call__(*k, **known_kw)  # type: ignore[no-any-return,misc]
-
 
 class Node(abc.ABC, metaclass=NodeMeta):
     r"""Base class of :class:`Collector` and :class:`Item`, the components of
@@ -138,8 +116,13 @@ class Node(abc.ABC, metaclass=NodeMeta):
     #: for methods not migrated to ``pathlib.Path`` yet, such as
     #: :meth:`Item.reportinfo <pytest.Item.reportinfo>`. Will be deprecated in
     #: a future release, prefer using :attr:`path` instead.
+    name: str
+    parent: Node | None
+    config: Config
+    session: Session
     fspath: LEGACY_PATH
 
+    _nodeid: str
     # Use __slots__ to make attribute access faster.
     # Note that __dict__ is still available.
     __slots__ = (
@@ -156,7 +139,7 @@ class Node(abc.ABC, metaclass=NodeMeta):
     def __init__(
         self,
         name: str,
-        parent: Node | None = None,
+        parent: Node | None,
         config: Config | None = None,
         session: Session | None = None,
         fspath: LEGACY_PATH | None = None,
@@ -200,13 +183,9 @@ def __init__(
         #: Allow adding of extra keywords to use for matching.
         self.extra_keyword_matches: set[str] = set()
 
-        if nodeid is not None:
-            assert "::()" not in nodeid
-            self._nodeid = nodeid
-        else:
-            if not self.parent:
-                raise TypeError("nodeid or parent must be provided")
-            self._nodeid = self.parent.nodeid + "::" + self.name
+        self._nodeid = self._make_nodeid(
+            name=self.name, parent=self.parent, given=nodeid
+        )
 
         #: A place where plugins can store information on the node for their
         #: own use.
@@ -215,7 +194,38 @@ def __init__(
         self._store = self.stash
 
     @classmethod
-    def from_parent(cls, parent: Node, **kw) -> Self:
+    def _make_nodeid(cls, name: str, parent: Node | None, given: str | None) -> str:
+        if given is not None:
+            assert "::()" not in given
+            return given
+        else:
+            assert parent is not None
+            return f"{parent.nodeid}::{name}"
+
+    @classmethod
+    def _create(cls, *k: object, **kw: object) -> Self:
+        callit = super(type(cls), NodeMeta).__call__  # type: ignore[misc]
+        try:
+            return cast(Self, callit(cls, *k, **kw))
+        except TypeError as e:
+            sig = signature(getattr(cls, "__init__"))
+            known_kw = {k: v for k, v in kw.items() if k in sig.parameters}
+            from .warning_types import PytestDeprecationWarning
+
+            warnings.warn(
+                PytestDeprecationWarning(
+                    f"{cls} is not using a cooperative constructor and only takes {set(known_kw)}.\n"
+                    f"Exception: {e}\n"
+                    "See https://docs.pytest.org/en/stable/deprecations.html"
+                    "#constructors-of-custom-pytest-node-subclasses-should-take-kwargs "
+                    "for more details."
+                )
+            )
+
+            return cast(Self, callit(cls, *k, **known_kw))
+
+    @classmethod
+    def from_parent(cls, parent: Node, **kw: Any) -> Self:
         """Public constructor for Nodes.
 
         This indirection got introduced in order to enable removing
@@ -238,7 +248,7 @@ def ihook(self) -> pluggy.HookRelay:
         return self.session.gethookproxy(self.path)
 
     def __repr__(self) -> str:
-        return "<{} {}>".format(self.__class__.__name__, getattr(self, "name", None))
+        return f'<{self.__class__.__name__} { getattr(self, "name", None)}>'
 
     def warn(self, warning: Warning) -> None:
         """Issue a warning for this Node.
@@ -598,7 +608,6 @@ def __init__(
 
             if nodeid and os.sep != SEP:
                 nodeid = nodeid.replace(os.sep, SEP)
-
         super().__init__(
             name=name,
             parent=parent,
@@ -611,11 +620,11 @@ def __init__(
     @classmethod
     def from_parent(
         cls,
-        parent,
+        parent: Node,
         *,
         fspath: LEGACY_PATH | None = None,
         path: Path | None = None,
-        **kw,
+        **kw: Any,
     ) -> Self:
         """The public constructor."""
         return super().from_parent(parent=parent, fspath=fspath, path=path, **kw)
@@ -646,22 +655,25 @@ class Directory(FSCollector, abc.ABC):
     """
 
 
+class Definition(Collector, abc.ABC):
+    @abc.abstractmethod
+    def collect(self) -> Iterable[Item]: ...
+
+
 class Item(Node, abc.ABC):
     """Base class of all test invocation items.
 
     Note that for a single function there might be multiple test invocation items.
     """
 
-    nextitem = None
-
     def __init__(
         self,
-        name,
-        parent=None,
+        name: str,
+        parent: Node | None = None,
         config: Config | None = None,
         session: Session | None = None,
         nodeid: str | None = None,
-        **kw,
+        **kw: Any,
     ) -> None:
         # The first two arguments are intentionally passed positionally,
         # to keep plugins who define a node type which inherits from