bpo-42000: Cleanup the AST related C-code (GH-22641)

- Use the proper asdl sequence when creating empty arguments
- Remove reduntant casts (thanks to new typed asdl_sequences)
- Remove MarshalPrototypeVisitor and some utilities from asdl generator
- Fix the header of `Python/ast.c` (kept from pgen times)

Automerge-Triggered-By: @pablogsal

1 files changed, 1 insertions, 1 deletions

diff --git a/Parser/pegen.c b/Parser/pegen.c
index 1de495e..efa5ed9 100644
--- a/Parser/pegen.c
+++ b/Parser/pegen.c
@@ -1897,7 +1897,7 @@ _PyPegen_empty_arguments(Parser *p)
         return NULL;
     }
 
-    return _Py_arguments(posonlyargs, posargs, NULL, kwonlyargs, kwdefaults, NULL, kwdefaults,
+    return _Py_arguments(posonlyargs, posargs, NULL, kwonlyargs, kwdefaults, NULL, posdefaults,
                          p->arena);
 }