bpo-29867: Add asserts in PyTuple_GET_SIZE, PyList_GET_SIZE and PySet_GET_SIZE. (#751)

Include/listobject.h

@@ -71,7 +71,7 @@ PyAPI_FUNC(void) _PyList_DebugMallocStats(FILE *out);
 #ifndef Py_LIMITED_API
 #define PyList_GET_ITEM(op, i) (((PyListObject *)(op))->ob_item[i])
 #define PyList_SET_ITEM(op, i, v) (((PyListObject *)(op))->ob_item[i] = (v))
-#define PyList_GET_SIZE(op)    Py_SIZE(op)
+#define PyList_GET_SIZE(op)    (assert(PyList_Check(op)),Py_SIZE(op))
 #define _PyList_ITEMS(op)      (((PyListObject *)(op))->ob_item)
 #endif
 

Include/setobject.h

@@ -64,7 +64,7 @@ typedef struct {
     PyObject *weakreflist;      /* List of weak references */
 } PySetObject;
 
-#define PySet_GET_SIZE(so) (((PySetObject *)(so))->used)
+#define PySet_GET_SIZE(so) (assert(PyAnySet_Check(so)),(((PySetObject *)(so))->used))
 
 PyAPI_DATA(PyObject *) _PySet_Dummy;
 

Include/tupleobject.h

@@ -56,7 +56,7 @@ PyAPI_FUNC(void) _PyTuple_MaybeUntrack(PyObject *);
 /* Macro, trading safety for speed */
 #ifndef Py_LIMITED_API
 #define PyTuple_GET_ITEM(op, i) (((PyTupleObject *)(op))->ob_item[i])
-#define PyTuple_GET_SIZE(op)    Py_SIZE(op)
+#define PyTuple_GET_SIZE(op)    (assert(PyTuple_Check(op)),Py_SIZE(op))
 
 /* Macro, *only* to be used to fill in brand new tuples */
 #define PyTuple_SET_ITEM(op, i, v) (((PyTupleObject *)(op))->ob_item[i] = v)

Objects/odictobject.c

@@ -1519,7 +1519,7 @@ odict_repr(PyODictObject *self)
             count++;
         }
         if (count < PyList_GET_SIZE(pieces))
-            PyList_GET_SIZE(pieces) = count;
+            Py_SIZE(pieces) = count;
     }
     else {
         PyObject *items = _PyObject_CallMethodIdObjArgs((PyObject *)self,