Deprecate co_lnotab instead of removing it

Doc/whatsnew/3.12.rst

@@ -516,6 +516,12 @@ Pending Removal in Python 3.14
   functions that have been deprecated since Python 2 but only gained a
   proper :exc:`DeprecationWarning` in 3.12. Remove them in 3.14.
 
+* Accessing ``co_lnotab`` was deprecated in :pep:`626` since 3.10
+  and was planned to be removed in 3.12
+  but it only got a proper :exc:`DeprecationWarning` in 3.12.
+  Remove it in 3.14.
+  (Contributed by Nikita Sobolev in :gh:`101866`.)
+
 Pending Removal in Future Versions
 ----------------------------------
 

Lib/test/test_code.py

@@ -338,6 +338,13 @@ def func():
         new_code = code = func.__code__.replace(co_linetable=b'')
         self.assertEqual(list(new_code.co_lines()), [])
 
+    def test_co_lnotab_is_deprecated(self):  # TODO: remove in 3.14
+        def func():
+            pass
+
+        with self.assertWarns(DeprecationWarning):
+            func.__code__.co_lnotab
+
     def test_invalid_bytecode(self):
         def foo():
             pass

Misc/NEWS.d/next/Core and Builtins/2023-02-21-17-22-06.gh-issue-101865.fwrTOA.rst

@@ -0,0 +1,2 @@
+Deprecate ``co_lnotab`` in code objects, schedule it for removal in Python
+3.14

Objects/codeobject.c

@@ -1884,6 +1884,13 @@ static PyMemberDef code_memberlist[] = {
 static PyObject *
 code_getlnotab(PyCodeObject *code, void *closure)
 {
+    if (PyErr_WarnEx(PyExc_DeprecationWarning,
+                     "co_lnotab is deprecated since Python 3.12 "
+                     "and will be removed in Python 3.14, "
+                     "use co_lines instead.",
+                     1) < 0) {
+        return NULL;
+    }
     return decode_linetable(code);
 }