test_cext: Define PyInit_* function which asserts that it wasn't called

Author: encukou

Lib/test/test_cext/extension.c

@@ -111,3 +111,17 @@ FUNC_NAME(MODULE_NAME)(void)
 {
     return _testcext_slots;
 }
+
+// Also define the soft-deprecated entrypoint to ensure it isn't called
+
+#define _INITFUNC_NAME(NAME) PyInit_ ## NAME
+#define INITFUNC_NAME(NAME) _INITFUNC_NAME(NAME)
+
+PyMODINIT_FUNC
+INITFUNC_NAME(MODULE_NAME)(void)
+{
+    PyErr_SetString(
+        PyExc_AssertionError,
+        "PyInit_* function called while a PyModExport_* one is available");
+    return NULL;
+}