https://github.com/python/cpython/commit/003e6d2b9776c07147a9c628eb028fd2ac3f0008
commit: 003e6d2b9776c07147a9c628eb028fd2ac3f0008
branch: main
author: Petr Viktorin <encu...@gmail.com>
committer: encukou <encu...@gmail.com>
date: 2025-02-28T16:03:02+01:00
summary:
gh-129666: Add C11/C++11 to docs and `-pedantic-errors` to GCC/clang
test_c[pp]ext tests (GH-130686)
files:
M Doc/c-api/intro.rst
M Lib/test/test_cext/__init__.py
M Lib/test/test_cext/extension.c
M Lib/test/test_cext/setup.py
M Lib/test/test_cppext/__init__.py
M Lib/test/test_cppext/extension.cpp
M Lib/test/test_cppext/setup.py
diff --git a/Doc/c-api/intro.rst b/Doc/c-api/intro.rst
index 8ef463e3f88ca8..76d7d5793428f8 100644
--- a/Doc/c-api/intro.rst
+++ b/Doc/c-api/intro.rst
@@ -30,6 +30,16 @@ familiar with writing an extension before attempting to
embed Python in a real
application.
+Language version compatibility
+==============================
+
+Python's C API is compatible with C11 and C++11 versions of C and C++.
+
+This is a lower limit: the C API does not require features from later
+C/C++ versions.
+You do *not* need to enable your compiler's "c11 mode".
+
+
Coding standards
================
diff --git a/Lib/test/test_cext/__init__.py b/Lib/test/test_cext/__init__.py
index 54859f9ff7622d..402a2d04fa875e 100644
--- a/Lib/test/test_cext/__init__.py
+++ b/Lib/test/test_cext/__init__.py
@@ -38,6 +38,9 @@ def test_build_c11(self):
@unittest.skipIf(support.MS_WINDOWS, "MSVC doesn't support /std:c99")
def test_build_c99(self):
+ # In public docs, we say C API is compatible with C11. However,
+ # in practice we do maintain C99 compatibility in public headers.
+ # Please ask the C API WG before adding a new C11-only feature.
self.check_build('_test_c99_cext', std='c99')
@support.requires_gil_enabled('incompatible with Free Threading')
diff --git a/Lib/test/test_cext/extension.c b/Lib/test/test_cext/extension.c
index b76abe1d74c628..64629c5a6da8cd 100644
--- a/Lib/test/test_cext/extension.c
+++ b/Lib/test/test_cext/extension.c
@@ -58,11 +58,24 @@ _testcext_exec(
return 0;
}
+// Converting from function pointer to void* has undefined behavior, but
+// works on all known platforms, and CPython's module and type slots currently
+// need it.
+// (GCC doesn't have a narrower category for this than -Wpedantic.)
+_Py_COMP_DIAG_PUSH
+#if defined(__GNUC__)
+#pragma GCC diagnostic ignored "-Wpedantic"
+#elif defined(__clang__)
+#pragma clang diagnostic ignored "-Wpedantic"
+#endif
+
static PyModuleDef_Slot _testcext_slots[] = {
{Py_mod_exec, (void*)_testcext_exec},
{0, NULL}
};
+_Py_COMP_DIAG_POP
+
PyDoc_STRVAR(_testcext_doc, "C test extension.");
diff --git a/Lib/test/test_cext/setup.py b/Lib/test/test_cext/setup.py
index e97749b45ea6f3..1275282983f7ff 100644
--- a/Lib/test/test_cext/setup.py
+++ b/Lib/test/test_cext/setup.py
@@ -21,6 +21,9 @@
# gh-120593: Check the 'const' qualifier
'-Wcast-qual',
+
+ # Ask for strict(er) compliance with the standard
+ '-pedantic-errors',
]
if not support.Py_GIL_DISABLED:
CFLAGS.append(
diff --git a/Lib/test/test_cppext/__init__.py b/Lib/test/test_cppext/__init__.py
index d5195227308fec..7d56cb8b68620a 100644
--- a/Lib/test/test_cppext/__init__.py
+++ b/Lib/test/test_cppext/__init__.py
@@ -29,6 +29,9 @@ def test_build(self):
self.check_build('_testcppext')
def test_build_cpp03(self):
+ # In public docs, we say C API is compatible with C++11. However,
+ # in practice we do maintain C++03 compatibility in public headers.
+ # Please ask the C API WG before adding a new C++11-only feature.
self.check_build('_testcpp03ext', std='c++03')
@unittest.skipIf(support.MS_WINDOWS, "MSVC doesn't support /std:c++11")
diff --git a/Lib/test/test_cppext/extension.cpp
b/Lib/test/test_cppext/extension.cpp
index 500d5918145c00..5b3571b295bec3 100644
--- a/Lib/test/test_cppext/extension.cpp
+++ b/Lib/test/test_cppext/extension.cpp
@@ -161,11 +161,24 @@ class VirtualPyObject : public PyObject {
int VirtualPyObject::instance_count = 0;
+// Converting from function pointer to void* has undefined behavior, but
+// works on all known platforms, and CPython's module and type slots currently
+// need it.
+// (GCC doesn't have a narrower category for this than -Wpedantic.)
+_Py_COMP_DIAG_PUSH
+#if defined(__GNUC__)
+#pragma GCC diagnostic ignored "-Wpedantic"
+#elif defined(__clang__)
+#pragma clang diagnostic ignored "-Wpedantic"
+#endif
+
PyType_Slot VirtualPyObject_Slots[] = {
{Py_tp_free, (void*)VirtualPyObject::dealloc},
{0, _Py_NULL},
};
+_Py_COMP_DIAG_POP
+
PyType_Spec VirtualPyObject_Spec = {
/* .name */ STR(MODULE_NAME) ".VirtualPyObject",
/* .basicsize */ sizeof(VirtualPyObject),
@@ -241,11 +254,20 @@ _testcppext_exec(PyObject *module)
return 0;
}
+// Need to ignore "-Wpedantic" warnings; see VirtualPyObject_Slots above
+_Py_COMP_DIAG_PUSH
+#if defined(__GNUC__)
+#pragma GCC diagnostic ignored "-Wpedantic"
+#elif defined(__clang__)
+#pragma clang diagnostic ignored "-Wpedantic"
+#endif
+
static PyModuleDef_Slot _testcppext_slots[] = {
{Py_mod_exec, reinterpret_cast<void*>(_testcppext_exec)},
{0, _Py_NULL}
};
+_Py_COMP_DIAG_POP
PyDoc_STRVAR(_testcppext_doc, "C++ test extension.");
diff --git a/Lib/test/test_cppext/setup.py b/Lib/test/test_cppext/setup.py
index 019ff18446a2eb..aa09c7bc8cb170 100644
--- a/Lib/test/test_cppext/setup.py
+++ b/Lib/test/test_cppext/setup.py
@@ -18,6 +18,14 @@
# a C++ extension using the Python C API does not emit C++ compiler
# warnings
'-Werror',
+
+ # Ask for strict(er) compliance with the standard.
+ '-pedantic-errors',
+
+ # But allow C++11 features for -std=C++03. We use:
+ # - `long long` (-Wno-c++11-long-long)
+ # - comma at end of `enum` lists (no narrower GCC option exists)
+ '-Wno-c++11-extensions',
]
else:
# MSVC compiler flags
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