[Python-checkins] gh-91321: Fix compatibility with C++ older than C++11 (#93784)
vstinner
webhook-mailer at python.org
Tue Jun 14 05:43:12 EDT 2022
https://github.com/python/cpython/commit/4caf5c2753f1aa28d6f4bc1aa377975fd2a62331
commit: 4caf5c2753f1aa28d6f4bc1aa377975fd2a62331
branch: main
author: Victor Stinner <vstinner at python.org>
committer: vstinner <vstinner at python.org>
date: 2022-06-14T11:43:08+02:00
summary:
gh-91321: Fix compatibility with C++ older than C++11 (#93784)
Fix the compatibility of the Python C API with C++ older than C++11.
_Py_NULL is only defined as nullptr on C++11 and newer.
files:
A Misc/NEWS.d/next/C API/2022-06-13-21-37-31.gh-issue-91321.DgJFvS.rst
M Include/pyport.h
M Lib/test/_testcppext.cpp
M Lib/test/setup_testcppext.py
M Lib/test/test_cppext.py
diff --git a/Include/pyport.h b/Include/pyport.h
index faaeb83291811..313bc8d21c83f 100644
--- a/Include/pyport.h
+++ b/Include/pyport.h
@@ -36,10 +36,12 @@ extern "C++" {
inline type _Py_CAST_impl(int ptr) {
return reinterpret_cast<type>(ptr);
}
+#if __cplusplus >= 201103
template <typename type>
inline type _Py_CAST_impl(std::nullptr_t) {
return static_cast<type>(nullptr);
}
+#endif
template <typename type, typename expr_type>
inline type _Py_CAST_impl(expr_type *expr) {
@@ -70,8 +72,9 @@ extern "C++" {
#endif
// Static inline functions should use _Py_NULL rather than using directly NULL
-// to prevent C++ compiler warnings. In C++, _Py_NULL uses nullptr.
-#ifdef __cplusplus
+// to prevent C++ compiler warnings. On C++11 and newer, _Py_NULL is defined as
+// nullptr.
+#if defined(__cplusplus) && __cplusplus >= 201103
# define _Py_NULL nullptr
#else
# define _Py_NULL NULL
diff --git a/Lib/test/_testcppext.cpp b/Lib/test/_testcppext.cpp
index 5e3d76b7b2072..b6d35407a61ed 100644
--- a/Lib/test/_testcppext.cpp
+++ b/Lib/test/_testcppext.cpp
@@ -6,6 +6,12 @@
#include "Python.h"
+#if __cplusplus >= 201103
+# define NAME _testcpp11ext
+#else
+# define NAME _testcpp03ext
+#endif
+
PyDoc_STRVAR(_testcppext_add_doc,
"add(x, y)\n"
"\n"
@@ -16,7 +22,7 @@ _testcppext_add(PyObject *Py_UNUSED(module), PyObject *args)
{
long i, j;
if (!PyArg_ParseTuple(args, "ll:foo", &i, &j)) {
- return nullptr;
+ return _Py_NULL;
}
long res = i + j;
return PyLong_FromLong(res);
@@ -47,8 +53,8 @@ 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;
+ if (obj == _Py_NULL) {
+ return _Py_NULL;
}
Py_ssize_t refcnt = Py_REFCNT(obj);
assert(refcnt >= 1);
@@ -77,9 +83,11 @@ test_api_casts(PyObject *Py_UNUSED(module), PyObject *Py_UNUSED(args))
// gh-93442: Pass 0 as NULL for PyObject*
Py_XINCREF(0);
Py_XDECREF(0);
- // ensure that nullptr works too
+#if _cplusplus >= 201103
+ // Test nullptr passed as PyObject*
Py_XINCREF(nullptr);
Py_XDECREF(nullptr);
+#endif
Py_DECREF(obj);
Py_RETURN_NONE;
@@ -90,8 +98,8 @@ static PyObject *
test_unicode(PyObject *Py_UNUSED(module), PyObject *Py_UNUSED(args))
{
PyObject *str = PyUnicode_FromString("abc");
- if (str == nullptr) {
- return nullptr;
+ if (str == _Py_NULL) {
+ return _Py_NULL;
}
assert(PyUnicode_Check(str));
@@ -99,7 +107,7 @@ test_unicode(PyObject *Py_UNUSED(module), PyObject *Py_UNUSED(args))
// gh-92800: test PyUnicode_READ()
const void* data = PyUnicode_DATA(str);
- assert(data != nullptr);
+ assert(data != _Py_NULL);
int kind = PyUnicode_KIND(str);
assert(kind == PyUnicode_1BYTE_KIND);
assert(PyUnicode_READ(kind, data, 0) == 'a');
@@ -118,9 +126,9 @@ test_unicode(PyObject *Py_UNUSED(module), PyObject *Py_UNUSED(args))
static PyMethodDef _testcppext_methods[] = {
{"add", _testcppext_add, METH_VARARGS, _testcppext_add_doc},
- {"test_api_casts", test_api_casts, METH_NOARGS, nullptr},
- {"test_unicode", test_unicode, METH_NOARGS, nullptr},
- {nullptr, nullptr, 0, nullptr} /* sentinel */
+ {"test_api_casts", test_api_casts, METH_NOARGS, _Py_NULL},
+ {"test_unicode", test_unicode, METH_NOARGS, _Py_NULL},
+ {_Py_NULL, _Py_NULL, 0, _Py_NULL} /* sentinel */
};
@@ -135,26 +143,32 @@ _testcppext_exec(PyObject *module)
static PyModuleDef_Slot _testcppext_slots[] = {
{Py_mod_exec, reinterpret_cast<void*>(_testcppext_exec)},
- {0, nullptr}
+ {0, _Py_NULL}
};
PyDoc_STRVAR(_testcppext_doc, "C++ test extension.");
+#define _STR(NAME) #NAME
+#define STR(NAME) _STR(NAME)
+
static struct PyModuleDef _testcppext_module = {
PyModuleDef_HEAD_INIT, // m_base
- "_testcppext", // m_name
+ STR(NAME), // m_name
_testcppext_doc, // m_doc
0, // m_size
_testcppext_methods, // m_methods
_testcppext_slots, // m_slots
- nullptr, // m_traverse
- nullptr, // m_clear
- nullptr, // m_free
+ _Py_NULL, // m_traverse
+ _Py_NULL, // m_clear
+ _Py_NULL, // m_free
};
+#define _FUNC_NAME(NAME) PyInit_ ## NAME
+#define FUNC_NAME(NAME) _FUNC_NAME(NAME)
+
PyMODINIT_FUNC
-PyInit__testcppext(void)
+FUNC_NAME(NAME)(void)
{
return PyModuleDef_Init(&_testcppext_module);
}
diff --git a/Lib/test/setup_testcppext.py b/Lib/test/setup_testcppext.py
index 780cb7b24a78c..a288dbdc57bde 100644
--- a/Lib/test/setup_testcppext.py
+++ b/Lib/test/setup_testcppext.py
@@ -13,8 +13,6 @@
if not MS_WINDOWS:
# C++ compiler flags for GCC and clang
CPPFLAGS = [
- # Python currently targets C++11
- '-std=c++11',
# gh-91321: The purpose of _testcppext extension is to check that building
# a C++ extension using the Python C API does not emit C++ compiler
# warnings
@@ -30,12 +28,23 @@
def main():
+ cppflags = list(CPPFLAGS)
+ if '-std=c++03' in sys.argv:
+ sys.argv.remove('-std=c++03')
+ std = 'c++03'
+ name = '_testcpp03ext'
+ else:
+ # Python currently targets C++11
+ std = 'c++11'
+ name = '_testcpp11ext'
+
+ cppflags = [*CPPFLAGS, f'-std={std}']
cpp_ext = Extension(
- '_testcppext',
+ name,
sources=[SOURCE],
language='c++',
- extra_compile_args=CPPFLAGS)
- setup(name="_testcppext", ext_modules=[cpp_ext])
+ extra_compile_args=cppflags)
+ setup(name=name, ext_modules=[cpp_ext])
if __name__ == "__main__":
diff --git a/Lib/test/test_cppext.py b/Lib/test/test_cppext.py
index 9ed90616b0eab..8673911ecfae5 100644
--- a/Lib/test/test_cppext.py
+++ b/Lib/test/test_cppext.py
@@ -16,22 +16,29 @@
@support.requires_subprocess()
class TestCPPExt(unittest.TestCase):
+ def test_build_cpp11(self):
+ self.check_build(False)
+
+ def test_build_cpp03(self):
+ self.check_build(True)
+
# With MSVC, the linker fails with: cannot open file 'python311.lib'
# https://github.com/python/cpython/pull/32175#issuecomment-1111175897
@unittest.skipIf(MS_WINDOWS, 'test fails on Windows')
# the test uses venv+pip: skip if it's not available
@support.requires_venv_with_pip()
- def test_build(self):
+ def check_build(self, std_cpp03):
# Build in a temporary directory
with os_helper.temp_cwd():
- self._test_build()
+ self._check_build(std_cpp03)
- def _test_build(self):
+ def _check_build(self, std_cpp03):
venv_dir = 'env'
+ verbose = support.verbose
# Create virtual environment to get setuptools
cmd = [sys.executable, '-X', 'dev', '-m', 'venv', venv_dir]
- if support.verbose:
+ if verbose:
print()
print('Run:', ' '.join(cmd))
subprocess.run(cmd, check=True)
@@ -46,16 +53,21 @@ def _test_build(self):
python = os.path.join(venv_dir, 'bin', python_exe)
# Build the C++ extension
- cmd = [python, '-X', 'dev', SETUP_TESTCPPEXT, 'build_ext', '--verbose']
- if support.verbose:
+ cmd = [python, '-X', 'dev',
+ SETUP_TESTCPPEXT, 'build_ext', '--verbose']
+ if std_cpp03:
+ cmd.append('-std=c++03')
+ if verbose:
print('Run:', ' '.join(cmd))
- proc = subprocess.run(cmd,
- stdout=subprocess.PIPE,
- stderr=subprocess.STDOUT,
- text=True)
- if proc.returncode:
- print(proc.stdout, end='')
- self.fail(f"Build failed with exit code {proc.returncode}")
+ subprocess.run(cmd, check=True)
+ else:
+ proc = subprocess.run(cmd,
+ stdout=subprocess.PIPE,
+ stderr=subprocess.STDOUT,
+ text=True)
+ if proc.returncode:
+ print(proc.stdout, end='')
+ self.fail(f"Build failed with exit code {proc.returncode}")
if __name__ == "__main__":
diff --git a/Misc/NEWS.d/next/C API/2022-06-13-21-37-31.gh-issue-91321.DgJFvS.rst b/Misc/NEWS.d/next/C API/2022-06-13-21-37-31.gh-issue-91321.DgJFvS.rst
new file mode 100644
index 0000000000000..57c39bc8d83c8
--- /dev/null
+++ b/Misc/NEWS.d/next/C API/2022-06-13-21-37-31.gh-issue-91321.DgJFvS.rst
@@ -0,0 +1,2 @@
+Fix the compatibility of the Python C API with C++ older than C++11. Patch by
+Victor Stinner.
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