From 056c08211b402b4dbc1530a9de9d00ad5309909f Mon Sep 17 00:00:00 2001 From: Petr Viktorin Date: Wed, 30 Dec 2020 00:32:07 +0100 Subject: [PATCH] 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 Co-Authored-By: Antoine Pitrou --- Include/cpython/abstract.h | 6 +++--- .../next/C API/2020-03-24-09-27-10.bpo-40052.27P2KG.rst | 2 ++ Objects/call.c | 3 ++- 3 files changed, 7 insertions(+), 4 deletions(-) create mode 100644 Misc/NEWS.d/next/C API/2020-03-24-09-27-10.bpo-40052.27P2KG.rst diff --git a/Include/cpython/abstract.h b/Include/cpython/abstract.h index b5b6e481978..1083942c149 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 00000000000..538488e2fba --- /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 30fa14ccfd7..35b06a9b9c4 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",