gh-94673: Add _PyStaticType_InitBuiltin() (#95152)

This is the first of several precursors to storing tp_subclasses (and tp_weaklist) on the interpreter state for static builtin types.

We do the following:

* add `_PyStaticType_InitBuiltin()`
* add `_Py_TPFLAGS_STATIC_BUILTIN`
* set it on all static builtin types in `_PyStaticType_InitBuiltin()`
* shuffle some code around to be able to use _PyStaticType_InitBuiltin()
    * rename `_PyStructSequence_InitType()` to `_PyStructSequence_InitBuiltinWithFlags()`
    * add `_PyStructSequence_InitBuiltin()`.

7 files changed, 99 insertions, 49 deletions

diff --git a/Objects/exceptions.c b/Objects/exceptions.c
index 9aab683..e06a8f4 100644
--- a/Objects/exceptions.c
+++ b/Objects/exceptions.c
@@ -3556,8 +3556,7 @@ _PyExc_InitTypes(PyInterpreterState *interp)
 
     for (size_t i=0; i < Py_ARRAY_LENGTH(static_exceptions); i++) {
         PyTypeObject *exc = static_exceptions[i].exc;
-
-        if (PyType_Ready(exc) < 0) {
+        if (_PyStaticType_InitBuiltin(exc) < 0) {
             return -1;
         }
     }
diff --git a/Objects/floatobject.c b/Objects/floatobject.c
index 47d308b..4b1b24f 100644
--- a/Objects/floatobject.c
+++ b/Objects/floatobject.c
@@ -1992,7 +1992,8 @@ _PyFloat_InitTypes(PyInterpreterState *interp)
 
     /* Init float info */
     if (FloatInfoType.tp_name == NULL) {
-        if (PyStructSequence_InitType2(&FloatInfoType, &floatinfo_desc) < 0) {
+        if (_PyStructSequence_InitBuiltin(&FloatInfoType,
+                                          &floatinfo_desc) < 0) {
             return _PyStatus_ERR("can't init float info type");
         }
     }
diff --git a/Objects/longobject.c b/Objects/longobject.c
index 4a1e5ca..90ed02b 100644
--- a/Objects/longobject.c
+++ b/Objects/longobject.c
@@ -6135,7 +6135,7 @@ _PyLong_InitTypes(PyInterpreterState *interp)
 
     /* initialize int_info */
     if (Int_InfoType.tp_name == NULL) {
-        if (PyStructSequence_InitType2(&Int_InfoType, &int_info_desc) < 0) {
+        if (_PyStructSequence_InitBuiltin(&Int_InfoType, &int_info_desc) < 0) {
             return _PyStatus_ERR("can't init int info type");
         }
     }
diff --git a/Objects/object.c b/Objects/object.c
index 75aee90..758b79e 100644
--- a/Objects/object.c
+++ b/Objects/object.c
@@ -1975,8 +1975,8 @@ _PyTypes_InitTypes(PyInterpreterState *interp)
     // All other static types (unless initialized elsewhere)
     for (size_t i=0; i < Py_ARRAY_LENGTH(static_types); i++) {
         PyTypeObject *type = static_types[i];
-        if (PyType_Ready(type) < 0) {
-            return _PyStatus_ERR("Can't initialize types");
+        if (_PyStaticType_InitBuiltin(type) < 0) {
+            return _PyStatus_ERR("Can't initialize builtin type");
         }
         if (type == &PyType_Type) {
             // Sanitify checks of the two most important types
diff --git a/Objects/structseq.c b/Objects/structseq.c
index 229e3d8..24cd0e7 100644
--- a/Objects/structseq.c
+++ b/Objects/structseq.c
@@ -432,11 +432,21 @@ error:
     return -1;
 }
 
-static void
-initialize_members(PyStructSequence_Desc *desc, PyMemberDef* members,
-                   Py_ssize_t n_members) {
-    Py_ssize_t i, k;
+static PyMemberDef *
+initialize_members(PyStructSequence_Desc *desc,
+                   Py_ssize_t *pn_members, Py_ssize_t *pn_unnamed_members)
+{
+    PyMemberDef *members;
+    Py_ssize_t n_members, n_unnamed_members;
+
+    n_members = count_members(desc, &n_unnamed_members);
+    members = PyMem_NEW(PyMemberDef, n_members - n_unnamed_members + 1);
+    if (members == NULL) {
+        PyErr_NoMemory();
+        return NULL;
+    }
 
+    Py_ssize_t i, k;
     for (i = k = 0; i < n_members; ++i) {
         if (desc->fields[i].name == PyStructSequence_UnnamedField) {
             continue;
@@ -453,30 +463,17 @@ initialize_members(PyStructSequence_Desc *desc, PyMemberDef* members,
         k++;
     }
     members[k].name = NULL;
+
+    *pn_members = n_members;
+    *pn_unnamed_members = n_unnamed_members;
+    return members;
 }
 
 
-int
-_PyStructSequence_InitType(PyTypeObject *type, PyStructSequence_Desc *desc,
-                           unsigned long tp_flags)
+static void
+initialize_static_fields(PyTypeObject *type, PyStructSequence_Desc *desc,
+                         PyMemberDef *tp_members, unsigned long tp_flags)
 {
-    PyMemberDef *members;
-    Py_ssize_t n_members, n_unnamed_members;
-
-#ifdef Py_TRACE_REFS
-    /* if the type object was chained, unchain it first
-       before overwriting its storage */
-    if (type->ob_base.ob_base._ob_next) {
-        _Py_ForgetReference((PyObject *)type);
-    }
-#endif
-
-    /* PyTypeObject has already been initialized */
-    if (Py_REFCNT(type) != 0) {
-        PyErr_BadInternalCall();
-        return -1;
-    }
-
     type->tp_name = desc->name;
     type->tp_basicsize = sizeof(PyStructSequence) - sizeof(PyObject *);
     type->tp_itemsize = sizeof(PyObject *);
@@ -488,25 +485,20 @@ _PyStructSequence_InitType(PyTypeObject *type, PyStructSequence_Desc *desc,
     type->tp_new = structseq_new;
     type->tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC | tp_flags;
     type->tp_traverse = (traverseproc) structseq_traverse;
+    type->tp_members = tp_members;
+}
 
-    n_members = count_members(desc, &n_unnamed_members);
-    members = PyMem_NEW(PyMemberDef, n_members - n_unnamed_members + 1);
-    if (members == NULL) {
-        PyErr_NoMemory();
-        return -1;
-    }
-    initialize_members(desc, members, n_members);
-    type->tp_members = members;
-
+static int
+initialize_static_type(PyTypeObject *type, PyStructSequence_Desc *desc,
+                       Py_ssize_t n_members, Py_ssize_t n_unnamed_members) {
+    /* initialize_static_fields() should have been called already. */
     if (PyType_Ready(type) < 0) {
-        PyMem_Free(members);
         return -1;
     }
     Py_INCREF(type);
 
     if (initialize_structseq_dict(
             desc, type->tp_dict, n_members, n_unnamed_members) < 0) {
-        PyMem_Free(members);
         Py_DECREF(type);
         return -1;
     }
@@ -515,9 +507,62 @@ _PyStructSequence_InitType(PyTypeObject *type, PyStructSequence_Desc *desc,
 }
 
 int
+_PyStructSequence_InitBuiltinWithFlags(PyTypeObject *type,
+                                       PyStructSequence_Desc *desc,
+                                       unsigned long tp_flags)
+{
+    PyMemberDef *members;
+    Py_ssize_t n_members, n_unnamed_members;
+
+    members = initialize_members(desc, &n_members, &n_unnamed_members);
+    if (members == NULL) {
+        return -1;
+    }
+    initialize_static_fields(type, desc, members, tp_flags);
+    if (_PyStaticType_InitBuiltin(type) < 0) {
+        PyMem_Free(members);
+        PyErr_Format(PyExc_RuntimeError,
+                     "Can't initialize builtin type %s",
+                     desc->name);
+        return -1;
+    }
+    if (initialize_static_type(type, desc, n_members, n_unnamed_members) < 0) {
+        PyMem_Free(members);
+        return -1;
+    }
+    return 0;
+}
+
+int
 PyStructSequence_InitType2(PyTypeObject *type, PyStructSequence_Desc *desc)
 {
-    return _PyStructSequence_InitType(type, desc, 0);
+    PyMemberDef *members;
+    Py_ssize_t n_members, n_unnamed_members;
+
+#ifdef Py_TRACE_REFS
+    /* if the type object was chained, unchain it first
+       before overwriting its storage */
+    if (type->ob_base.ob_base._ob_next) {
+        _Py_ForgetReference((PyObject *)type);
+    }
+#endif
+
+    /* PyTypeObject has already been initialized */
+    if (Py_REFCNT(type) != 0) {
+        PyErr_BadInternalCall();
+        return -1;
+    }
+
+    members = initialize_members(desc, &n_members, &n_unnamed_members);
+    if (members == NULL) {
+        return -1;
+    }
+    initialize_static_fields(type, desc, members, 0);
+    if (initialize_static_type(type, desc, n_members, n_unnamed_members) < 0) {
+        PyMem_Free(members);
+        return -1;
+    }
+    return 0;
 }
 
 void
@@ -569,13 +614,10 @@ _PyStructSequence_NewType(PyStructSequence_Desc *desc, unsigned long tp_flags)
     Py_ssize_t n_members, n_unnamed_members;
 
     /* Initialize MemberDefs */
-    n_members = count_members(desc, &n_unnamed_members);
-    members = PyMem_NEW(PyMemberDef, n_members - n_unnamed_members + 1);
+    members = initialize_members(desc, &n_members, &n_unnamed_members);
     if (members == NULL) {
-        PyErr_NoMemory();
         return NULL;
     }
-    initialize_members(desc, members, n_members);
 
     /* Initialize Slots */
     slots[0] = (PyType_Slot){Py_tp_dealloc, (destructor)structseq_dealloc};
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index 5ebff60..8510196 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -6650,6 +6650,14 @@ PyType_Ready(PyTypeObject *type)
     return 0;
 }
 
+int
+_PyStaticType_InitBuiltin(PyTypeObject *self)
+{
+    self->tp_flags = self->tp_flags | _Py_TPFLAGS_STATIC_BUILTIN;
+
+    return PyType_Ready(self);
+}
+
 
 static int
 add_subclass(PyTypeObject *base, PyTypeObject *type)
diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index 669ffe7..7e3caf1 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -14604,13 +14604,13 @@ _PyUnicode_InitTypes(PyInterpreterState *interp)
         return _PyStatus_OK();
     }
 
-    if (PyType_Ready(&EncodingMapType) < 0) {
+    if (_PyStaticType_InitBuiltin(&EncodingMapType) < 0) {
         goto error;
     }
-    if (PyType_Ready(&PyFieldNameIter_Type) < 0) {
+    if (_PyStaticType_InitBuiltin(&PyFieldNameIter_Type) < 0) {
         goto error;
     }
-    if (PyType_Ready(&PyFormatterIter_Type) < 0) {
+    if (_PyStaticType_InitBuiltin(&PyFormatterIter_Type) < 0) {
         goto error;
     }
     return _PyStatus_OK();