gh-76007: Deprecate zlib.__version__ attribute

Doc/deprecations/pending-removal-in-3.20.rst

@@ -19,5 +19,6 @@ Pending removal in Python 3.20
   - :mod:`tabnanny`
   - :mod:`tkinter.font`
   - :mod:`tkinter.ttk`
+  - :mod:`zlib`
 
-  (Contributed by Hugo van Kemenade in :gh:`76007`.)
+  (Contributed by Hugo van Kemenade and Stan Ulbrych in :gh:`76007`.)

Doc/whatsnew/3.15.rst

@@ -828,8 +828,9 @@ New deprecations
     - :mod:`tabnanny`
     - :mod:`tkinter.font`
     - :mod:`tkinter.ttk`
+    - :mod:`zlib`
 
-    (Contributed by Hugo van Kemenade in :gh:`76007`.)
+    (Contributed by Hugo van Kemenade and Stan Ulbrych in :gh:`76007`.)
 
 .. Add deprecations above alphabetically, not here at the end.
 

Lib/test/test_zlib.py

@@ -1222,5 +1222,15 @@ def __index__(self):
         return 100
 
 
+class TestModule(unittest.TestCase):
+    def test_deprecated__version__(self):
+        with self.assertWarnsRegex(
+                DeprecationWarning,
+                "'__version__' is deprecated and slated for removal in Python 3.20",
+        ) as cm:
+            getattr(zlib, "__version__")
+        self.assertEqual(cm.filename, __file__)
+
+
 if __name__ == "__main__":
     unittest.main()

Misc/NEWS.d/next/Library/2025-10-14-20-27-06.gh-issue-76007.2NcUbo.rst

@@ -0,0 +1,2 @@
+:mod:`zlib`: Deprecate ``__version__`` and schedule for removal in Python
+3.20.

Modules/zlibmodule.c

@@ -2137,6 +2137,30 @@ zlib_free(void *mod)
     zlib_clear((PyObject *)mod);
 }
 
+static PyObject *
+zlib_getattr(PyObject *self, PyObject *args)
+{
+    PyObject *name;
+    if (!PyArg_UnpackTuple(args, "__getattr__", 1, 1, &name)) {
+        return NULL;
+    }
+
+    if (PyUnicode_Check(name)) {
+        const char *name_str = PyUnicode_AsUTF8(name);
+        if (name_str && strcmp(name_str, "__version__") == 0) {
+            if (PyErr_WarnEx(PyExc_DeprecationWarning,
+                             "'__version__' is deprecated and slated for removal in Python 3.20",
+                             1) < 0) {
+                return NULL;
+            }
+            return PyUnicode_FromString("1.0");
+        }
+    }
+
+    PyErr_Format(PyExc_AttributeError, "module 'zlib' has no attribute %R", name);
+    return NULL;
+}
+
 static int
 zlib_exec(PyObject *mod)
 {
@@ -2221,9 +2245,17 @@ zlib_exec(PyObject *mod)
         return -1;
     }
 #endif
-    if (PyModule_AddStringConstant(mod, "__version__", "1.0") < 0) {
+    static PyMethodDef getattr_method = {"__getattr__", zlib_getattr, METH_VARARGS, "Module __getattr__"};
+    PyObject *getattr_func = PyCFunction_New(&getattr_method, mod);
+    if (getattr_func == NULL) {
+        return -1;
+    }
+
+    if (PyModule_AddObjectRef(mod, "__getattr__", getattr_func) < 0) {
+        Py_DECREF(getattr_func);
         return -1;
     }
+    Py_DECREF(getattr_func);
     return 0;
 }