fixtures: remove `getfixtureinfo(funcargs)` in favor of None `func`

Since we already broke plugins using this (private) interface in this
version (pytest-play, pytest-wdl), might as well do a cleanup.

src/_pytest/doctest.py

@@ -592,14 +592,9 @@ class DoctestModule(Module):
 def _setup_fixtures(doctest_item: DoctestItem) -> TopRequest:
     """Used by DoctestTextfile and DoctestItem to setup fixture information."""
 
-    def func() -> None:
-        pass
-
     doctest_item.funcargs = {}  # type: ignore[attr-defined]
     fm = doctest_item.session._fixturemanager
-    fixtureinfo = fm.getfixtureinfo(
-        node=doctest_item, func=func, cls=None, funcargs=False
-    )
+    fixtureinfo = fm.getfixtureinfo(node=doctest_item, func=None, cls=None)
     doctest_item._fixtureinfo = fixtureinfo  # type: ignore[attr-defined]
     doctest_item.fixturenames = fixtureinfo.names_closure  # type: ignore[attr-defined]
     fixture_request = TopRequest(doctest_item, _ispytest=True)  # type: ignore[arg-type]

src/_pytest/fixtures.py

@@ -1460,13 +1460,12 @@ class FixtureManager:
     def getfixtureinfo(
         self,
         node: nodes.Item,
-        func: Callable[..., object],
+        func: Optional[Callable[..., object]],
         cls: Optional[type],
-        funcargs: bool = True,
     ) -> FuncFixtureInfo:
         """Calculate the :class:`FuncFixtureInfo` for an item.
 
-        If ``funcargs`` is false, or if the item sets an attribute
+        If ``func`` is None, or if the item sets an attribute
         ``nofuncargs = True``, then ``func`` is not examined at all.
 
         :param node:
@@ -1475,10 +1474,8 @@ class FixtureManager:
             The item's function.
         :param cls:
             If the function is a method, the method's class.
-        :param funcargs:
-            Whether to look into func's parameters as fixture requests.
         """
-        if funcargs and not getattr(node, "nofuncargs", False):
+        if func is not None and not getattr(node, "nofuncargs", False):
             argnames = getfuncargnames(func, name=node.name, cls=cls)
         else:
             argnames = ()

src/_pytest/python.py

@@ -1800,9 +1800,8 @@ class Function(PyobjMixin, nodes.Item):
             self.keywords.update(keywords)
 
         if fixtureinfo is None:
-            fixtureinfo = self.session._fixturemanager.getfixtureinfo(
-                self, self.obj, self.cls, funcargs=True
-            )
+            fm = self.session._fixturemanager
+            fixtureinfo = fm.getfixtureinfo(self, self.obj, self.cls)
         self._fixtureinfo: FuncFixtureInfo = fixtureinfo
         self.fixturenames = fixtureinfo.names_closure
         self._initrequest()