gh-153903: wrap_dll_function: copy doc, etc from wrapped stub

Doc/library/ctypes.rst

@@ -708,8 +708,7 @@ Specifying function pointers using type annotations
 
       @wrap_dll_function(dll_to_wrap)
       def function_ptr_name(arg_name: ctypes_type, ...) -> ctypes_type:
-         # There should be no body
-         pass
+         """Optional docstring. There should be no function body."""
 
    The body of the decorated function is ignored, and any parameters that are
    missing type annotations are skipped. The names of the parameters are ignored

Lib/ctypes/util.py

@@ -590,6 +590,8 @@ def decorator(func):
 
         ptr.restype = restype
         ptr.argtypes = tuple(annotations.values())
+        functools.update_wrapper(ptr, func, updated=())
+
         return ptr
 
     return decorator

Lib/test/test_ctypes/test_funcptr.py

@@ -134,12 +134,14 @@ def test_abstract(self):
     def test_wrap_dll_function(self):
         @wrap_dll_function(ctypes.pythonapi)
         def PyObject_GetAttr(op: ctypes.py_object, attr: ctypes.py_object) -> ctypes.py_object:
+            """Call the PythonAPI function underlying getattr"""
             pass
 
         class Foo:
             a = "abc"
 
         self.assertEqual(PyObject_GetAttr(Foo, "a"), "abc")
+        self.assertEqual(PyObject_GetAttr.__doc__, "Call the PythonAPI function underlying getattr")
 
         with self.assertRaises(AttributeError):
             @wrap_dll_function(ctypes.pythonapi)