python38/bsc1167501-invalid-alignment.patch

From e6f4de57ffd175870e513ffa387fa6e7eaaeaed2 Mon Sep 17 00:00:00 2001
From: Andreas Schneider <asn@cryptomilk.org>
Date: Tue, 24 Mar 2020 07:55:00 +0100
Subject: [PATCH] bpo-40052: Fix alignment issue in PyVectorcall_Function()

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.

Signed-off-by: Andreas Schneider <asn@cryptomilk.org>
---
 Include/cpython/abstract.h                               | 9 ++++++---
 .../next/C API/2020-03-24-09-27-10.bpo-40052.27P2KG.rst  | 1 +
 Objects/call.c                                           | 7 ++++++-
 3 files changed, 13 insertions(+), 4 deletions(-)
 create mode 100644 Misc/NEWS.d/next/C API/2020-03-24-09-27-10.bpo-40052.27P2KG.rst

--- a/Include/cpython/abstract.h
+++ b/Include/cpython/abstract.h
@@ -82,14 +82,17 @@ _PyVectorcall_Function(PyObject *callabl
 {
     PyTypeObject *tp = Py_TYPE(callable);
     Py_ssize_t offset = tp->tp_vectorcall_offset;
-    vectorcallfunc *ptr;
+    union {
+        char *data;
+        vectorcallfunc *ptr;
+    } vc;
     if (!PyType_HasFeature(tp, _Py_TPFLAGS_HAVE_VECTORCALL)) {
         return NULL;
     }
     assert(PyCallable_Check(callable));
     assert(offset > 0);
-    ptr = (vectorcallfunc*)(((char *)callable) + offset);
-    return *ptr;
+    vc.data = (char *)callable + offset;
+    return *vc.ptr;
 }
 
 /* Call the callable object 'callable' with the "vectorcall" calling
--- /dev/null
+++ b/Misc/NEWS.d/next/C API/2020-03-24-09-27-10.bpo-40052.27P2KG.rst
@@ -0,0 +1 @@
+Fix an alignment build warning/error in function ``PyVectorcall_Function()`` publicly exposed by ``abstract.h``.
\ No newline at end of file
--- a/Objects/call.c
+++ b/Objects/call.c
@@ -173,6 +173,11 @@ _PyObject_MakeTpCall(PyObject *callable,
 PyObject *
 PyVectorcall_Call(PyObject *callable, PyObject *tuple, PyObject *kwargs)
 {
+    union {
+        char *data;
+        vectorcallfunc *ptr;
+    } vc;
+
     /* get vectorcallfunc as in _PyVectorcall_Function, but without
      * the _Py_TPFLAGS_HAVE_VECTORCALL check */
     Py_ssize_t offset = Py_TYPE(callable)->tp_vectorcall_offset;
@@ -181,7 +186,8 @@ PyVectorcall_Call(PyObject *callable, Py
                      Py_TYPE(callable)->tp_name);
         return NULL;
     }
-    vectorcallfunc func = *(vectorcallfunc *)(((char *)callable) + offset);
+    vc.data = (char *)callable + offset;
+    vectorcallfunc func = *vc.ptr;
     if (func == NULL) {
         PyErr_Format(PyExc_TypeError, "'%.200s' object does not support vectorcall",
                      Py_TYPE(callable)->tp_name);