mirror of https://github.com/python/cpython
gh-92135: Fix _Py_reinterpret_cast() for const (#92138)
Fix C++ compiler warnings on cast macros, like _PyObject_CAST(), when casting a constant expression to a non constant type: use const_cast<> in C++. * In C++, Py_SAFE_DOWNCAST() now uses static_cast<> rather than reinterpret_cast<>. * Add tests to the _testcppext C++ extension. * test_cppext no longer captures stdout in verbose mode.
This commit is contained in:
parent
b11243e85e
commit
031397063e
|
@ -43,8 +43,7 @@ typedef PyObject *(*PyCMethod)(PyObject *, PyTypeObject *, PyObject *const *,
|
|||
// it triggers an undefined behavior when Python calls it with 2 parameters
|
||||
// (bpo-33012).
|
||||
#define _PyCFunction_CAST(func) \
|
||||
_Py_reinterpret_cast(PyCFunction, \
|
||||
_Py_reinterpret_cast(void(*)(void), (func)))
|
||||
_Py_reinterpret_cast(PyCFunction, _Py_reinterpret_cast(void(*)(void), (func)))
|
||||
|
||||
PyAPI_FUNC(PyCFunction) PyCFunction_GetFunction(PyObject *);
|
||||
PyAPI_FUNC(PyObject *) PyCFunction_GetSelf(PyObject *);
|
||||
|
|
|
@ -182,9 +182,9 @@ PyAPI_FUNC(void) PyObject_GC_UnTrack(void *);
|
|||
PyAPI_FUNC(void) PyObject_GC_Del(void *);
|
||||
|
||||
#define PyObject_GC_New(type, typeobj) \
|
||||
_Py_reinterpret_cast(type*, _PyObject_GC_New(typeobj))
|
||||
_Py_reinterpret_cast(type*, _PyObject_GC_New(typeobj))
|
||||
#define PyObject_GC_NewVar(type, typeobj, n) \
|
||||
_Py_reinterpret_cast(type*, _PyObject_GC_NewVar((typeobj), (n)))
|
||||
_Py_reinterpret_cast(type*, _PyObject_GC_NewVar((typeobj), (n)))
|
||||
|
||||
PyAPI_FUNC(int) PyObject_GC_IsTracked(PyObject *);
|
||||
PyAPI_FUNC(int) PyObject_GC_IsFinalized(PyObject *);
|
||||
|
|
|
@ -14,10 +14,20 @@
|
|||
#endif
|
||||
|
||||
|
||||
// Macro to use C++ static_cast<> and reinterpret_cast<> in the Python C API
|
||||
// Macro to use C++ static_cast<>, reinterpret_cast<> and const_cast<>
|
||||
// in the Python C API.
|
||||
//
|
||||
// In C++, _Py_reinterpret_cast(type, expr) converts a constant expression to a
|
||||
// non constant type using const_cast<type>. For example,
|
||||
// _Py_reinterpret_cast(PyObject*, op) can convert a "const PyObject*" to
|
||||
// "PyObject*".
|
||||
//
|
||||
// The type argument must not be constant. For example, in C++,
|
||||
// _Py_reinterpret_cast(const PyObject*, expr) fails with a compiler error.
|
||||
#ifdef __cplusplus
|
||||
# define _Py_static_cast(type, expr) static_cast<type>(expr)
|
||||
# define _Py_reinterpret_cast(type, expr) reinterpret_cast<type>(expr)
|
||||
# define _Py_reinterpret_cast(type, expr) \
|
||||
const_cast<type>(reinterpret_cast<const type>(expr))
|
||||
#else
|
||||
# define _Py_static_cast(type, expr) ((type)(expr))
|
||||
# define _Py_reinterpret_cast(type, expr) ((type)(expr))
|
||||
|
@ -307,10 +317,10 @@ extern "C" {
|
|||
*/
|
||||
#ifdef Py_DEBUG
|
||||
# define Py_SAFE_DOWNCAST(VALUE, WIDE, NARROW) \
|
||||
(assert((WIDE)(NARROW)(VALUE) == (VALUE)), (NARROW)(VALUE))
|
||||
(assert(_Py_static_cast(WIDE, _Py_static_cast(NARROW, (VALUE))) == (VALUE)), \
|
||||
_Py_static_cast(NARROW, (VALUE)))
|
||||
#else
|
||||
# define Py_SAFE_DOWNCAST(VALUE, WIDE, NARROW) \
|
||||
_Py_reinterpret_cast(NARROW, (VALUE))
|
||||
# define Py_SAFE_DOWNCAST(VALUE, WIDE, NARROW) _Py_static_cast(NARROW, (VALUE))
|
||||
#endif
|
||||
|
||||
|
||||
|
|
|
@ -1,6 +1,9 @@
|
|||
// gh-91321: Very basic C++ test extension to check that the Python C API is
|
||||
// compatible with C++ and does not emit C++ compiler warnings.
|
||||
|
||||
// Always enable assertions
|
||||
#undef NDEBUG
|
||||
|
||||
#include "Python.h"
|
||||
|
||||
PyDoc_STRVAR(_testcppext_add_doc,
|
||||
|
@ -20,8 +23,36 @@ _testcppext_add(PyObject *Py_UNUSED(module), PyObject *args)
|
|||
}
|
||||
|
||||
|
||||
static PyObject *
|
||||
test_api_casts(PyObject *Py_UNUSED(module), PyObject *Py_UNUSED(args))
|
||||
{
|
||||
PyObject *obj = Py_BuildValue("(ii)", 1, 2);
|
||||
if (obj == nullptr) {
|
||||
return nullptr;
|
||||
}
|
||||
|
||||
// gh-92138: For backward compatibility, functions of Python C API accepts
|
||||
// "const PyObject*". Check that using it does not emit C++ compiler
|
||||
// warnings.
|
||||
const PyObject *const_obj = obj;
|
||||
Py_INCREF(const_obj);
|
||||
Py_DECREF(const_obj);
|
||||
PyTypeObject *type = Py_TYPE(const_obj);
|
||||
assert(Py_REFCNT(const_obj) >= 1);
|
||||
|
||||
assert(type == &PyTuple_Type);
|
||||
assert(PyTuple_GET_SIZE(const_obj) == 2);
|
||||
PyObject *one = PyTuple_GET_ITEM(const_obj, 0);
|
||||
assert(PyLong_AsLong(one) == 1);
|
||||
|
||||
Py_DECREF(obj);
|
||||
Py_RETURN_NONE;
|
||||
}
|
||||
|
||||
|
||||
static PyMethodDef _testcppext_methods[] = {
|
||||
{"add", _testcppext_add, METH_VARARGS, _testcppext_add_doc},
|
||||
{"test_api_casts", test_api_casts, METH_NOARGS, NULL},
|
||||
{nullptr, nullptr, 0, nullptr} /* sentinel */
|
||||
};
|
||||
|
||||
|
|
|
@ -1,5 +1,6 @@
|
|||
# gh-91321: Build a basic C++ test extension to check that the Python C API is
|
||||
# compatible with C++ and does not emit C++ compiler warnings.
|
||||
import contextlib
|
||||
import os
|
||||
import sys
|
||||
import unittest
|
||||
|
@ -39,17 +40,24 @@ class TestCPPExt(unittest.TestCase):
|
|||
sources=[SOURCE],
|
||||
language='c++',
|
||||
extra_compile_args=CPPFLAGS)
|
||||
capture_stdout = (not support.verbose)
|
||||
|
||||
try:
|
||||
try:
|
||||
with (support.captured_stdout() as stdout,
|
||||
support.swap_attr(sys, 'argv', ['setup.py', 'build_ext'])):
|
||||
if capture_stdout:
|
||||
stdout = support.captured_stdout()
|
||||
else:
|
||||
print()
|
||||
stdout = contextlib.nullcontext()
|
||||
with (stdout,
|
||||
support.swap_attr(sys, 'argv', ['setup.py', 'build_ext', '--verbose'])):
|
||||
setup(name="_testcppext", ext_modules=[cpp_ext])
|
||||
return
|
||||
except:
|
||||
# Show output on error
|
||||
print()
|
||||
print(stdout.getvalue())
|
||||
if capture_stdout:
|
||||
# Show output on error
|
||||
print()
|
||||
print(stdout.getvalue())
|
||||
raise
|
||||
except SystemExit:
|
||||
self.fail("Build failed")
|
||||
|
|
Loading…
Reference in New Issue