* Simplify and speed-up list_resize(). Relying on the newly documented
invariants allows the ob_item != NULL check to be replaced with an
assertion.
* Added assertions to list_init() which document and verify that the
tp_new slot establishes the invariants. This may preclude a future
bug if a custom tp_new slot is written.
diff --git a/Objects/listobject.c b/Objects/listobject.c
index 452ffe5..61edd45 100644
--- a/Objects/listobject.c
+++ b/Objects/listobject.c
@@ -19,9 +19,8 @@
current size, then proceed with the realloc() to shrink the list.
*/
- if (self->allocated >= newsize &&
- self->ob_size < newsize + 16 &&
- self->ob_item != NULL) {
+ if (self->allocated >= newsize && self->ob_size < newsize + 16) {
+ assert(self->ob_item != NULL || newsize == 0);
self->ob_size = newsize;
return 0;
}
@@ -2314,6 +2313,11 @@
if (!PyArg_ParseTupleAndKeywords(args, kw, "|O:list", kwlist, &arg))
return -1;
+
+ /* Verify list invariants established by PyType_GenericAlloc() */
+ assert(0 <= self->ob_size && self->ob_size <= self->allocated);
+ assert(self->ob_item != NULL || self->allocated == 0);
+
/* Empty previous contents */
if (self->ob_item != NULL) {
(void)list_clear(self);