bpo-40052: Fix alignment issue in PyVectorcall_Function() (GH-23999)
```
In file included from /usr/include/python3.8/Python.h:147:
In file included from /usr/include/python3.8/abstract.h:837:
/usr/include/python3.8/cpython/abstract.h:91:11: error: cast from 'char *' to 'vectorcallfunc *'
(aka 'struct _object *(**)(struct _object *, struct _object *const *, unsigned long, struct _object *)')
increases required alignment from 1 to 8 [-Werror,-Wcast-align]
ptr = (vectorcallfunc*)(((char *)callable) + offset);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 error generated.
```
Co-Authored-By: Andreas Schneider <asn@cryptomilk.org>
Co-Authored-By: Antoine Pitrou <antoine@python.org>diff --git a/Include/cpython/abstract.h b/Include/cpython/abstract.h
index b5b6e48..1083942 100644
--- a/Include/cpython/abstract.h
+++ b/Include/cpython/abstract.h
@@ -63,7 +63,7 @@ PyVectorcall_Function(PyObject *callable)
{
PyTypeObject *tp;
Py_ssize_t offset;
- vectorcallfunc *ptr;
+ vectorcallfunc ptr;
assert(callable != NULL);
tp = Py_TYPE(callable);
@@ -73,8 +73,8 @@ PyVectorcall_Function(PyObject *callable)
assert(PyCallable_Check(callable));
offset = tp->tp_vectorcall_offset;
assert(offset > 0);
- ptr = (vectorcallfunc *)(((char *)callable) + offset);
- return *ptr;
+ memcpy(&ptr, (char *) callable + offset, sizeof(ptr));
+ return ptr;
}
/* Call the callable object 'callable' with the "vectorcall" calling
diff --git a/Misc/NEWS.d/next/C API/2020-03-24-09-27-10.bpo-40052.27P2KG.rst b/Misc/NEWS.d/next/C API/2020-03-24-09-27-10.bpo-40052.27P2KG.rst
new file mode 100644
index 0000000..538488e
--- /dev/null
+++ b/Misc/NEWS.d/next/C API/2020-03-24-09-27-10.bpo-40052.27P2KG.rst
@@ -0,0 +1,2 @@
+Fix an alignment build warning/error in function ``PyVectorcall_Function()``.
+Patch by Andreas Schneider, Antoine Pitrou and Petr Viktorin.
diff --git a/Objects/call.c b/Objects/call.c
index 30fa14c..35b06a9 100644
--- a/Objects/call.c
+++ b/Objects/call.c
@@ -205,6 +205,7 @@ PyObject *
PyVectorcall_Call(PyObject *callable, PyObject *tuple, PyObject *kwargs)
{
PyThreadState *tstate = _PyThreadState_GET();
+ vectorcallfunc func;
/* get vectorcallfunc as in PyVectorcall_Function, but without
* the Py_TPFLAGS_HAVE_VECTORCALL check */
@@ -215,7 +216,7 @@ PyVectorcall_Call(PyObject *callable, PyObject *tuple, PyObject *kwargs)
Py_TYPE(callable)->tp_name);
return NULL;
}
- vectorcallfunc func = *(vectorcallfunc *)(((char *)callable) + offset);
+ memcpy(&func, (char *) callable + offset, sizeof(func));
if (func == NULL) {
_PyErr_Format(tstate, PyExc_TypeError,
"'%.200s' object does not support vectorcall",