Fix check_freezable only checking object types

.gitignore

@@ -178,3 +178,5 @@ CLAUDE.local.md
 #### main branch only stuff below this line, things to backport go above. ####
 # main branch only: ABI files are not checked/maintained.
 Doc/data/python*.abi
+# Ignore the build directory.
+build*

Include/Python.h

@@ -145,6 +145,7 @@
 #include "fileutils.h"
 #include "cpython/pyfpe.h"
 #include "cpython/tracemalloc.h"
+#include "immutability.h"
 
 // Restore warning filter
 #ifdef _MSC_VER

Include/cpython/immutability.h

@@ -0,0 +1,8 @@
+#ifndef Py_CPYTHON_IMMUTABLE_H
+#  error "this header file must not be included directly"
+#endif
+
+PyAPI_DATA(PyTypeObject) _PyNotFreezable_Type;
+
+PyAPI_FUNC(int) _PyImmutability_Freeze(PyObject*);
+PyAPI_FUNC(int) _PyImmutability_RegisterFreezable(PyTypeObject*);

Include/cpython/listobject.h

@@ -44,6 +44,7 @@ PyList_SET_ITEM(PyObject *op, Py_ssize_t index, PyObject *value) {
     PyListObject *list = _PyList_CAST(op);
     assert(0 <= index);
     assert(index < list->allocated);
+    // TODO(Immutable): Add assert to check if the list is immutable
     list->ob_item[index] = value;
 }
 #define PyList_SET_ITEM(op, index, value) \

Include/cpython/object.h

@@ -291,6 +291,7 @@ typedef struct _heaptypeobject {
 PyAPI_FUNC(const char *) _PyType_Name(PyTypeObject *);
 PyAPI_FUNC(PyObject *) _PyType_Lookup(PyTypeObject *, PyObject *);
 PyAPI_FUNC(PyObject *) _PyType_LookupRef(PyTypeObject *, PyObject *);
+PyAPI_FUNC(int) _PyType_HasExtensionSlots(PyTypeObject *);
 PyAPI_FUNC(PyObject *) PyType_GetDict(PyTypeObject *);
 
 PyAPI_FUNC(int) PyObject_Print(PyObject *, FILE *, int);

Include/descrobject.h

@@ -84,6 +84,7 @@ struct PyMemberDef {
 #define Py_AUDIT_READ          2 // Added in 3.10, harmless no-op before that
 #define _Py_WRITE_RESTRICTED   4 // Deprecated, no-op. Do not reuse the value.
 #define Py_RELATIVE_OFFSET     8
+// TODO(Immutable): Could use this to mark members as needing a lock.
 
 PyAPI_FUNC(PyObject *) PyMember_GetOne(const char *, PyMemberDef *);
 PyAPI_FUNC(int) PyMember_SetOne(char *, PyMemberDef *, PyObject *);

Include/dictobject.h

@@ -23,7 +23,8 @@ PyAPI_FUNC(PyObject *) PyDict_GetItem(PyObject *mp, PyObject *key);
 PyAPI_FUNC(PyObject *) PyDict_GetItemWithError(PyObject *mp, PyObject *key);
 PyAPI_FUNC(int) PyDict_SetItem(PyObject *mp, PyObject *key, PyObject *item);
 PyAPI_FUNC(int) PyDict_DelItem(PyObject *mp, PyObject *key);
-PyAPI_FUNC(void) PyDict_Clear(PyObject *mp);
+// Note(Immutable): If dictionary is immutable, then clear can fail. Had to change signature here!
+PyAPI_FUNC(int) PyDict_Clear(PyObject *mp);
 PyAPI_FUNC(int) PyDict_Next(
     PyObject *mp, Py_ssize_t *pos, PyObject **key, PyObject **value);
 PyAPI_FUNC(PyObject *) PyDict_Keys(PyObject *mp);

Include/immutability.h

@@ -0,0 +1,19 @@
+#ifndef Py_IMMUTABILITY_H
+#define Py_IMMUTABILITY_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+
+#ifndef Py_LIMITED_API
+#  define Py_CPYTHON_IMMUTABLE_H
+#  include "cpython/immutability.h"
+#  undef Py_CPYTHON_IMMUTABLE_H
+#endif
+
+
+#ifdef __cplusplus
+}
+#endif
+#endif /* !Py_IMMUTABILITY_H */

Include/internal/pycore_cell.h

@@ -16,21 +16,30 @@ extern "C" {
 // Sets the cell contents to `value` and return previous contents. Steals a
 // reference to `value`.
 static inline PyObject *
-PyCell_SwapTakeRef(PyCellObject *cell, PyObject *value)
+PyCell_SwapTakeRef(PyCellObject *cell, PyObject *value, int* result)
 {
-    PyObject *old_value;
+    PyObject *old_value = NULL;
+    *result = 0;
     Py_BEGIN_CRITICAL_SECTION(cell);
-    old_value = cell->ob_ref;
-    FT_ATOMIC_STORE_PTR_RELEASE(cell->ob_ref, value);
+    if(Py_CHECKWRITE(cell)){
+        old_value = cell->ob_ref;
+        FT_ATOMIC_STORE_PTR_RELEASE(cell->ob_ref, value);
+    }
+    else {
+        *result = -1;
+        Py_XDECREF(value);
+    }
     Py_END_CRITICAL_SECTION();
     return old_value;
 }
 
-static inline void
+static inline int
 PyCell_SetTakeRef(PyCellObject *cell, PyObject *value)
 {
-    PyObject *old_value = PyCell_SwapTakeRef(cell, value);
+    int result = 0;
+    PyObject *old_value = PyCell_SwapTakeRef(cell, value, &result);
     Py_XDECREF(old_value);
+    return result;
 }
 
 // Gets the cell contents. Returns a new reference.

Include/internal/pycore_ceval.h

@@ -267,6 +267,7 @@ PyAPI_FUNC(int) _PyEval_ExceptionGroupMatch(_PyInterpreterFrame *, PyObject* exc
 PyAPI_FUNC(void) _PyEval_FormatAwaitableError(PyThreadState *tstate, PyTypeObject *type, int oparg);
 PyAPI_FUNC(void) _PyEval_FormatExcCheckArg(PyThreadState *tstate, PyObject *exc, const char *format_str, PyObject *obj);
 PyAPI_FUNC(void) _PyEval_FormatExcUnbound(PyThreadState *tstate, PyCodeObject *co, int oparg);
+PyAPI_FUNC(void) _PyEval_FormatExcNotWriteable(PyThreadState *tstate, PyCodeObject *co, int oparg);
 PyAPI_FUNC(void) _PyEval_FormatKwargsError(PyThreadState *tstate, PyObject *func, PyObject *kwargs);
 PyAPI_FUNC(PyObject *) _PyEval_ImportFrom(PyThreadState *, PyObject *, PyObject *);
 PyAPI_FUNC(PyObject *) _PyEval_ImportName(PyThreadState *, _PyInterpreterFrame *, PyObject *, PyObject *, PyObject *);

Include/internal/pycore_immutability.h

@@ -0,0 +1,21 @@
+#ifndef Py_INTERNAL_IMMUTABILITY_H
+#define Py_INTERNAL_IMMUTABILITY_H
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifndef Py_BUILD_CORE
+#  error "Py_BUILD_CORE must be defined to include this header"
+#endif
+
+struct _Py_immutability_state {
+    PyObject *module_locks;
+    PyObject *blocking_on;
+    PyObject *freezable_types;
+    PyObject *destroy_cb;
+};
+
+#ifdef __cplusplus
+}
+#endif
+#endif /* !Py_INTERNAL_IMMUTABILITY_H */

Include/internal/pycore_interp_structs.h

@@ -8,6 +8,7 @@ extern "C" {
 #endif
 
 #include "pycore_ast_state.h"     // struct ast_state
+#include "pycore_immutability.h"  // struct _immutability_runtime_state
 #include "pycore_llist.h"         // struct llist_node
 #include "pycore_opcode_utils.h"  // NUM_COMMON_CONSTANTS
 #include "pycore_pymath.h"        // _PY_SHORT_FLOAT_REPR
@@ -934,6 +935,7 @@ struct _is {
 
     struct _Py_dict_state dict_state;
     struct _Py_exc_state exc_state;
+    struct _Py_immutability_state immutability;
     struct _Py_mem_interp_free_queue mem_free_queue;
 
     struct ast_state ast;

Include/internal/pycore_object.h

@@ -205,11 +205,17 @@ static inline void _Py_SetMortal(PyObject *op, short refcnt)
     if (op) {
         assert(_Py_IsImmortal(op));
 #ifdef Py_GIL_DISABLED
+        // TODO(Immutable): Do we need to do something here?
         op->ob_tid = _Py_UNOWNED_TID;
         op->ob_ref_local = 0;
         op->ob_ref_shared = _Py_REF_SHARED(refcnt, _Py_REF_MERGED);
 #else
+        // TODO(Immutable): Need to clear flag in other cases?
+        // note this also clears the _Py_IMMUTABLE_FLAG, if set in 32bit
         op->ob_refcnt = refcnt;
+#if SIZEOF_VOID_P > 4
+        op->ob_flags &= ~_Py_IMMORTAL_FLAGS;
+#endif
 #endif
     }
 }
@@ -229,18 +235,38 @@ static inline void _Py_ClearImmortal(PyObject *op)
     } while (0)
 
 #if !defined(Py_GIL_DISABLED)
+static inline void _Py_SetImmutable(PyObject *op)
+{
+if(op) {
+#if SIZEOF_VOID_P > 4
+        op->ob_flags |= _Py_IMMUTABLE_FLAG;
+#else
+        op->ob_refcnt |= _Py_IMMUTABLE_FLAG;
+#endif
+    }
+}
+#define _Py_SetImmutable(op) _Py_SetImmutable(_PyObject_CAST(op))
+
 static inline void
 _Py_DECREF_SPECIALIZED(PyObject *op, const destructor destruct)
 {
-    if (_Py_IsImmortal(op)) {
-        _Py_DECREF_IMMORTAL_STAT_INC();
+    if (_Py_IsImmortalOrImmutable(op)) {
+        if (_Py_IsImmortal(op)) {
+            _Py_DECREF_IMMORTAL_STAT_INC();
+            return;
+        }
+        assert(_Py_IsImmutable(op));
+        if (_Py_DecRef_Immutable(op)) {
+            destruct(op);
+        }
         return;
     }
     _Py_DECREF_STAT_INC();
 #ifdef Py_REF_DEBUG
     _Py_DEC_REFTOTAL(PyInterpreterState_Get());
 #endif
-    if (--op->ob_refcnt != 0) {
+    op->ob_refcnt -= 1;
+    if (_Py_IMMUTABLE_FLAG_CLEAR(op->ob_refcnt) != 0) {
         assert(op->ob_refcnt > 0);
     }
     else {
@@ -255,8 +281,12 @@ _Py_DECREF_SPECIALIZED(PyObject *op, const destructor destruct)
 static inline void
 _Py_DECREF_NO_DEALLOC(PyObject *op)
 {
-    if (_Py_IsImmortal(op)) {
-        _Py_DECREF_IMMORTAL_STAT_INC();
+    if (_Py_IsImmortalOrImmutable(op)) {
+        if (_Py_IsImmortal(op)) {
+            _Py_DECREF_IMMORTAL_STAT_INC();
+            return;
+        }
+        _Py_DecRef_Immutable(op);
         return;
     }
     _Py_DECREF_STAT_INC();
@@ -272,6 +302,7 @@ _Py_DECREF_NO_DEALLOC(PyObject *op)
 }
 
 #else
+// TODO(Immutable): We need to do stuff in the NoGIL build
 // TODO: implement Py_DECREF specializations for Py_GIL_DISABLED build
 static inline void
 _Py_DECREF_SPECIALIZED(PyObject *op, const destructor destruct)
@@ -476,6 +507,7 @@ static inline void _Py_DECREF_MORTAL_SPECIALIZED(const char *filename, int linen
 
 static inline void Py_DECREF_MORTAL(PyObject *op)
 {
+    // TODO(Immutable): Need to catch immutable things here
     assert(!_Py_IsStaticImmortal(op));
     _Py_DECREF_STAT_INC();
     if (--op->ob_refcnt == 0) {
@@ -486,6 +518,7 @@ static inline void Py_DECREF_MORTAL(PyObject *op)
 
 static inline void Py_DECREF_MORTAL_SPECIALIZED(PyObject *op, destructor destruct)
 {
+    // TODO(Immutable): Need to catch immutable things here
     assert(!_Py_IsStaticImmortal(op));
     _Py_DECREF_STAT_INC();
     if (--op->ob_refcnt == 0) {

Include/object.h

@@ -296,7 +296,6 @@ static inline int Py_IS_TYPE(PyObject *ob, PyTypeObject *type) {
 #  define Py_IS_TYPE(ob, type) Py_IS_TYPE(_PyObject_CAST(ob), (type))
 #endif
 
-
 static inline void Py_SET_TYPE(PyObject *ob, PyTypeObject *type) {
     ob->ob_type = type;
 }

Include/pyerrors.h

@@ -166,6 +166,8 @@ PyAPI_DATA(PyObject *) PyExc_ResourceWarning;
 PyAPI_FUNC(int) PyErr_BadArgument(void);
 PyAPI_FUNC(PyObject *) PyErr_NoMemory(void);
 PyAPI_FUNC(PyObject *) PyErr_SetFromErrno(PyObject *);
+PyAPI_FUNC(PyObject *) _PyErr_WriteToImmutable(PyObject *);
+#define PyErr_WriteToImmutable(op) _PyErr_WriteToImmutable(_PyObject_CAST(op))
 PyAPI_FUNC(PyObject *) PyErr_SetFromErrnoWithFilenameObject(
     PyObject *, PyObject *);
 #if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x03040000

Include/pylifecycle.h

@@ -16,6 +16,7 @@ PyAPI_FUNC(void) Py_Finalize(void);
 PyAPI_FUNC(int) Py_FinalizeEx(void);
 #endif
 PyAPI_FUNC(int) Py_IsInitialized(void);
+PyAPI_FUNC(int) Py_IsFinalizing(void);
 
 /* Subinterpreter support */
 PyAPI_FUNC(PyThreadState *) Py_NewInterpreter(void);