test_cppext: Enable -pedantic-errors under GCC & clang

Author: encukou

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.");
 

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