gh-129666: Add C11/C++11 to docs and `-pedantic-errors` to GCC/clang test_c[pp]ext...

diff --git a/Doc/c-api/intro.rst b/Doc/c-api/intro.rst
index 8ef463e3f88ca8fb4a3cd13977d20ad744d49bec..76d7d5793428f8db173b8ce4d8370d159197efe8 100644 (file)
--- 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 54859f9ff7622d13986d3cd86ede568a2b55b3fe..402a2d04fa875e10f4cb5f94e5ac8d2dbe66647c 100644 (file)
--- a/Lib/test/test_cext/__init__.py
+++ b/Lib/test/test_cext/__init__.py
@@ -38,6 +38,9 @@ class TestExt(unittest.TestCase):
 
     @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 b76abe1d74c628584a827f1a1c113b6527d7b773..64629c5a6da8cd26d2208170ac1befd87920464a 100644 (file)
--- 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 e97749b45ea6f31d20ec3eec10a112b61eb99d04..1275282983f7ffd700f7cbbf423f9e172eb81f5d 100644 (file)
--- a/Lib/test/test_cext/setup.py
+++ b/Lib/test/test_cext/setup.py
@@ -21,6 +21,9 @@ if not support.MS_WINDOWS:
 
         # 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 d5195227308fecd90f384205971bb4b3339d7149..7d56cb8b68620ad213963c03d54f1065a1edbf77 100644 (file)
--- a/Lib/test/test_cppext/__init__.py
+++ b/Lib/test/test_cppext/__init__.py
@@ -29,6 +29,9 @@ class TestCPPExt(unittest.TestCase):
         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 500d5918145c00ab00dfca4d965fbb8f7b060d39..5b3571b295bec3bf897938975d479cf8c3092be3 100644 (file)
--- a/Lib/test/test_cppext/extension.cpp
+++ b/Lib/test/test_cppext/extension.cpp
@@ -161,11 +161,24 @@ private:
 
 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 019ff18446a2ebc4036afbad89899ef3ee904744..aa09c7bc8cb170c18142f19fe0170c5112d9cd39 100644 (file)
--- a/Lib/test/test_cppext/setup.py
+++ b/Lib/test/test_cppext/setup.py
@@ -18,6 +18,14 @@ if not support.MS_WINDOWS:
         # 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