refactor: remove unused code

src/_pytest/assertion/rewrite.py

@@ -35,6 +35,7 @@ from _pytest._io.saferepr import saferepr
 from _pytest._version import version
 from _pytest.assertion import util
 from _pytest.config import Config
+from _pytest.fixtures import getfixturemarker
 from _pytest.main import Session
 from _pytest.pathlib import absolutepath
 from _pytest.pathlib import fnmatch_ex
@@ -462,7 +463,7 @@ def _format_assertmsg(obj: object) -> str:
 
 def _should_repr_global_name(obj: object) -> bool:
     if callable(obj):
-        return hasattr(obj, "_fixture_function_marker")
+        return getfixturemarker(obj) is not None
 
     try:
         return not hasattr(obj, "__name__")

src/_pytest/fixtures.py

@@ -1192,9 +1192,6 @@ class FixtureFunctionDefinition:
     ):
         self.name = fixture_function_marker.name or function.__name__
         self.__name__ = self.name
-        # This attribute is used to check if an arbitrary python object is a fixture.
-        # Using isinstance on every object in code might execute code that is not intended to be executed.
-        # Like lazy loaded classes.
         self._fixture_function_marker = fixture_function_marker
         self._fixture_function = function
         self._instance = instance