pythongh-116946: fully implement GC protocol for bz2 objects (python#138266)

Author: picnixz

Modules/_bz2module.c

@@ -381,13 +381,14 @@ _bz2_BZ2Compressor_impl(PyTypeObject *type, int compresslevel)
 static void
 BZ2Compressor_dealloc(PyObject *op)
 {
+    PyTypeObject *tp = Py_TYPE(op);
+    PyObject_GC_UnTrack(op);
     BZ2Compressor *self = _BZ2Compressor_CAST(op);
     BZ2_bzCompressEnd(&self->bzs);
     if (self->lock != NULL) {
         PyThread_free_lock(self->lock);
     }
-    PyTypeObject *tp = Py_TYPE(self);
-    tp->tp_free((PyObject *)self);
+    tp->tp_free(self);
     Py_DECREF(tp);
 }
 
@@ -420,7 +421,7 @@ static PyType_Spec bz2_compressor_type_spec = {
     // bz2_compressor_type_spec does not have Py_TPFLAGS_BASETYPE flag
     // which prevents to create a subclass.
     // So calling PyType_GetModuleState() in this file is always safe.
-    .flags = (Py_TPFLAGS_DEFAULT | Py_TPFLAGS_IMMUTABLETYPE),
+    .flags = (Py_TPFLAGS_DEFAULT | Py_TPFLAGS_IMMUTABLETYPE | Py_TPFLAGS_HAVE_GC),
     .slots = bz2_compressor_type_slots,
 };
 
@@ -687,19 +688,19 @@ _bz2_BZ2Decompressor_impl(PyTypeObject *type)
 static void
 BZ2Decompressor_dealloc(PyObject *op)
 {
+    PyTypeObject *tp = Py_TYPE(op);
+    PyObject_GC_UnTrack(op);
     BZ2Decompressor *self = _BZ2Decompressor_CAST(op);
 
-    if(self->input_buffer != NULL) {
+    if (self->input_buffer != NULL) {
         PyMem_Free(self->input_buffer);
     }
     BZ2_bzDecompressEnd(&self->bzs);
     Py_CLEAR(self->unused_data);
     if (self->lock != NULL) {
         PyThread_free_lock(self->lock);
     }
-
-    PyTypeObject *tp = Py_TYPE(self);
-    tp->tp_free((PyObject *)self);
+    tp->tp_free(self);
     Py_DECREF(tp);
 }
 
@@ -751,7 +752,7 @@ static PyType_Spec bz2_decompressor_type_spec = {
     // bz2_decompressor_type_spec does not have Py_TPFLAGS_BASETYPE flag
     // which prevents to create a subclass.
     // So calling PyType_GetModuleState() in this file is always safe.
-    .flags = (Py_TPFLAGS_DEFAULT | Py_TPFLAGS_IMMUTABLETYPE),
+    .flags = (Py_TPFLAGS_DEFAULT | Py_TPFLAGS_IMMUTABLETYPE | Py_TPFLAGS_HAVE_GC),
     .slots = bz2_decompressor_type_slots,
 };