Here is a shell script that uses the C preprocessor and other Unix tools to generate PC/python3.def. It doesn't add PyAST_* and PyNode_* functions and doesn't remove PyArg_VaParse* functions. But it still removes some names that are no longer used in public interface, but should be kept in the stable ABI for compatibility. E.g. PyCFunction_New (now it is a macro expanded to PyCFunction_NewEx) or _PyTrash_deposit_object (invoked by the macros before 3.2.4). It seems to me that this is unavoidable, and the resulting file must be manually edited.