python · vstinner · Nov 22, 2018
diff --git a/Include/object.h b/Include/object.h
@@ -112,16 +112,37 @@ typedef struct _object {
    struct _typeobject *ob_type;
 } PyObject;

-/* Cast argument to PyObject* type. */
-#define _PyObject_CAST(op) ((PyObject*)(op))
-
 typedef struct {
    PyObject ob_base;
    Py_ssize_t ob_size; /* Number of items in variable part */
 } PyVarObject;

-/* Cast argument to PyVarObject* type. */
-#define _PyVarObject_CAST(op) ((PyVarObject*)(op))
+/* sizeof(*op) doesn't work on Visual Studio with void*:
+   sizeof(void) raises a compilation error.
+
+   sizeof(*op) is incompatible with Py_LIMITED_API which doesn't define
+   structures. */
+#if !defined(_MSC_VER) && !defined(Py_LIMITED_API)
+/* _PyObject_CAST(op): Cast argument to PyObject* type.
+
+   Raise a compilation error if the argument type is PyObject or PyObject**.
+
+   Detect for example the bug "&item" instead of "item" in:
+
+   const char *func(PyObject *item) { return Py_TYPE(&item)->tp_name; }
+
+   Note: sizeof(op) doesn't evaluate 'op', so sizeof(op) has no side effect. */
+#  define _PyObject_CAST(op) \
+    ((PyObject*)(op) + Py_BUILD_ASSERT_EXPR(sizeof(*(op)) != sizeof(op)))
+
+/* _PyVarObject_CAST(op): Cast argument to PyVarObject* type.
+   Similar to _PyObject_CAST(). */
+#  define _PyVarObject_CAST(op) \
+    ((PyVarObject*)(op) + Py_BUILD_ASSERT_EXPR(sizeof(*(op)) != sizeof(op)))
+#else
+#  define _PyObject_CAST(op) ((PyObject*)(op))
+#  define _PyVarObject_CAST(op) ((PyVarObject*)(op))
+#endif   /* defined(_MSC_VER) */

 #define Py_REFCNT(ob)           (_PyObject_CAST(ob)->ob_refcnt)
 #define Py_TYPE(ob)             (_PyObject_CAST(ob)->ob_type)

diff --git a/Modules/_ssl.c b/Modules/_ssl.c
@@ -5983,12 +5983,9 @@ PyInit__ssl(void)
    PyModule_AddIntConstant(m, "PROTO_TLSv1_2", PY_PROTO_TLSv1_2);
    PyModule_AddIntConstant(m, "PROTO_TLSv1_3", PY_PROTO_TLSv1_3);

-#define addbool(m, key, value) \
-    do { \
-        PyObject *bool_obj = (value) ? Py_True : Py_False; \
-        Py_INCREF(bool_obj); \
-        PyModule_AddObject((m), (key), bool_obj); \
-    } while (0)
+#define addbool(m, v, b) \
+    Py_INCREF((b) ? Py_True : Py_False); \
+    PyModule_AddObject((m), (v), (b) ? Py_True : Py_False);

 #if HAVE_SNI
    addbool(m, "HAS_SNI", 1);

diff --git a/Objects/weakrefobject.c b/Objects/weakrefobject.c
@@ -833,8 +833,7 @@ PyWeakref_NewProxy(PyObject *ob, PyObject *callback)
                       to avoid violating the invariants of the list
                       of weakrefs for ob. */
                    Py_DECREF(result);
-                    result = proxy;
-                    Py_INCREF(result);
+                    Py_INCREF(result = proxy);
                    goto skip_insert;
                }
                prev = ref;

diff --git a/Python/pystate.c b/Python/pystate.c
@@ -2,6 +2,7 @@
 /* Thread and interpreter state structures and their interfaces */

 #include "Python.h"
+#include "frameobject.h"
 #include "pycore_pymem.h"
 #include "pycore_pystate.h"