Issue python#18287: PyType_Ready() now checks that tp_name is not NULL.

Original patch by Niklas Koep.

Doc/c-api/typeobj.rst

@@ -116,7 +116,8 @@ type objects) *must* have the :attr:`ob_size` field.
    If no dot is present, the entire :c:member:`~PyTypeObject.tp_name` field is made accessible as the
    :attr:`~definition.__name__` attribute, and the :attr:`__module__` attribute is undefined
    (unless explicitly set in the dictionary, as explained above).  This means your
-   type will be impossible to pickle.
+   type will be impossible to pickle.  Additionally, it will not be listed in
+   module documentations created with pydoc.
 
    This field is not inherited by subtypes.
 

Doc/extending/newtypes.rst

@@ -129,7 +129,9 @@ our objects and in some error messages, for example::
 
 Note that the name is a dotted name that includes both the module name and the
 name of the type within the module. The module in this case is :mod:`noddy` and
-the type is :class:`Noddy`, so we set the type name to :class:`noddy.Noddy`. ::
+the type is :class:`Noddy`, so we set the type name to :class:`noddy.Noddy`.
+One side effect of using an undotted name is that the pydoc documentation tool
+will not list the new type in the module documentation. ::
 
    sizeof(noddy_NoddyObject),  /* tp_basicsize */
 

Misc/ACKS

@@ -775,6 +775,7 @@ Jeff Knupp
 Kubilay Kocak
 Greg Kochanski
 Manvisha Kodali
+Niklas Koep
 Damon Kohler
 Marko Kohtala
 Vajrasky Kok

Misc/NEWS

@@ -10,6 +10,9 @@ Release date: TBA
 Core and Builtins
 -----------------
 
+- Issue #18287: PyType_Ready() now checks that tp_name is not NULL.
+  Original patch by Niklas Koep.
+
 - Issue #24098: Fixed possible crash when AST is changed in process of
   compiling it.
 

Objects/typeobject.c

@@ -4820,6 +4820,12 @@ PyType_Ready(PyTypeObject *type)
     _Py_AddToAllObjects((PyObject *)type, 0);
 #endif
 
+    if (type->tp_name == NULL) {
+        PyErr_Format(PyExc_SystemError,
+                     "Type does not define the tp_name field.");
+        goto error;
+    }
+
     /* Initialize tp_base (defaults to BaseObject unless that's us) */
     base = type->tp_base;
     if (base == NULL && type != &PyBaseObject_Type) {