bpo-38131: Improve messages when generating AST nodes from objects with wrong field...

diff --git a/Lib/test/test_ast/test_ast.py b/Lib/test/test_ast/test_ast.py
index 0112c9163fd0cdb4ce7d9f8bad80694cb932b9c8..fd3b33bab7f8336ab09ab9587eac15fbe5d2fa2b 100644 (file)
--- a/Lib/test/test_ast/test_ast.py
+++ b/Lib/test/test_ast/test_ast.py
@@ -625,7 +625,7 @@ class AST_Tests(unittest.TestCase):
         ast.fix_missing_locations(m)
         with self.assertRaises(TypeError) as cm:
             compile(m, "<test>", "exec")
-        self.assertIn("identifier must be of type str", str(cm.exception))
+        self.assertIn("expecting a string object", str(cm.exception))
 
     def test_invalid_constant(self):
         for invalid_constant in int, (1, 2, int), frozenset((1, 2, int)):
@@ -1081,6 +1081,30 @@ class AST_Tests(unittest.TestCase):
         for node, attr, source in tests:
             self.assert_none_check(node, attr, source)
 
+    def test_required_field_messages(self):
+        binop = ast.BinOp(
+            left=ast.Constant(value=2),
+            right=ast.Constant(value=2),
+            op=ast.Add(),
+        )
+        expr_without_position = ast.Expression(body=binop)
+        expr_with_wrong_body = ast.Expression(body=[binop])
+
+        with self.assertRaisesRegex(TypeError, "required field") as cm:
+            compile(expr_without_position, "<test>", "eval")
+        with self.assertRaisesRegex(
+            TypeError,
+            "field 'body' was expecting node of type 'expr', got 'list'",
+        ):
+            compile(expr_with_wrong_body, "<test>", "eval")
+
+        constant = ast.parse("u'test'", mode="eval")
+        constant.body.kind = 0xFF
+        with self.assertRaisesRegex(
+            TypeError, "field 'kind' was expecting a string or bytes object"
+        ):
+            compile(constant, "<test>", "eval")
+
     def test_repr(self) -> None:
         snapshots = AST_REPR_DATA_FILE.read_text().split("\n")
         for test, snapshot in zip(ast_repr_get_test_cases(), snapshots, strict=True):

diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2019-12-27-19-20-33.bpo-38131.J5fv54.rst b/Misc/NEWS.d/next/Core_and_Builtins/2019-12-27-19-20-33.bpo-38131.J5fv54.rst
new file mode 100644 (file)
index 0000000..8b606c4
--- /dev/null
+++ b/Misc/NEWS.d/next/Core_and_Builtins/2019-12-27-19-20-33.bpo-38131.J5fv54.rst
@@ -0,0 +1,2 @@
+Produce more meaningful messages when compiling AST objects with wrong field
+values. Patch by Batuhan Taskaya.

diff --git a/Parser/asdl_c.py b/Parser/asdl_c.py
index ed1d2e08df8f40045c1c05775607eca4e69ee3d7..e2a57177d20afb73167427a48934d23d394de6da 100755 (executable)
--- a/Parser/asdl_c.py
+++ b/Parser/asdl_c.py
@@ -487,7 +487,7 @@ class PickleVisitor(EmitVisitor):
 
 class Obj2ModPrototypeVisitor(PickleVisitor):
     def visitProduct(self, prod, name):
-        code = "static int obj2ast_%s(struct ast_state *state, PyObject* obj, %s* out, PyArena* arena);"
+        code = "static int obj2ast_%s(struct ast_state *state, PyObject* obj, %s* out, const char* field, PyArena* arena);"
         self.emit(code % (name, get_c_type(name)), 0)
 
     visitSum = visitProduct
@@ -511,7 +511,7 @@ class Obj2ModVisitor(PickleVisitor):
     def funcHeader(self, name):
         ctype = get_c_type(name)
         self.emit("int", 0)
-        self.emit("obj2ast_%s(struct ast_state *state, PyObject* obj, %s* out, PyArena* arena)" % (name, ctype), 0)
+        self.emit("obj2ast_%s(struct ast_state *state, PyObject* obj, %s* out, const char* field, PyArena* arena)" % (name, ctype), 0)
         self.emit("{", 0)
         self.emit("int isinstance;", 1)
         self.emit("", 0)
@@ -547,6 +547,18 @@ class Obj2ModVisitor(PickleVisitor):
     def buildArgs(self, fields):
         return ", ".join(fields + ["arena"])
 
+    def typeCheck(self, name):
+        self.emit("tp = state->%s_type;" % name, 1)
+        self.emit("isinstance = PyObject_IsInstance(obj, tp);", 1)
+        self.emit("if (isinstance == -1) {", 1)
+        self.emit("return 1;", 2)
+        self.emit("}", 1)
+        self.emit("if (!isinstance && field != NULL) {", 1)
+        error = "field '%%s' was expecting node of type '%s', got '%%s'" % name
+        self.emit("PyErr_Format(PyExc_TypeError, \"%s\", field, _PyType_Name(Py_TYPE(obj)));" % error, 2, reflow=False)
+        self.emit("return 1;", 2)
+        self.emit("}", 1)
+
     def complexSum(self, sum, name):
         self.funcHeader(name)
         self.emit("PyObject *tmp = NULL;", 1)
@@ -559,6 +571,7 @@ class Obj2ModVisitor(PickleVisitor):
         self.emit("*out = NULL;", 2)
         self.emit("return 0;", 2)
         self.emit("}", 1)
+        self.typeCheck(name)
         for a in sum.attributes:
             self.visitField(a, name, sum=sum, depth=1)
         for t in sum.types:
@@ -593,7 +606,7 @@ class Obj2ModVisitor(PickleVisitor):
     def visitProduct(self, prod, name):
         ctype = get_c_type(name)
         self.emit("int", 0)
-        self.emit("obj2ast_%s(struct ast_state *state, PyObject* obj, %s* out, PyArena* arena)" % (name, ctype), 0)
+        self.emit("obj2ast_%s(struct ast_state *state, PyObject* obj, %s* out, const char* field, PyArena* arena)" % (name, ctype), 0)
         self.emit("{", 0)
         self.emit("PyObject* tmp = NULL;", 1)
         for f in prod.fields:
@@ -694,8 +707,8 @@ class Obj2ModVisitor(PickleVisitor):
             self.emit("%s val;" % ctype, depth+2)
             self.emit("PyObject *tmp2 = Py_NewRef(PyList_GET_ITEM(tmp, i));", depth+2)
             with self.recursive_call(name, depth+2):
-                self.emit("res = obj2ast_%s(state, tmp2, &val, arena);" %
-                          field.type, depth+2, reflow=False)
+                self.emit("res = obj2ast_%s(state, tmp2, &val, \"%s\", arena);" %
+                          (field.type, field.name), depth+2, reflow=False)
             self.emit("Py_DECREF(tmp2);", depth+2)
             self.emit("if (res != 0) goto failed;", depth+2)
             self.emit("if (len != PyList_GET_SIZE(tmp)) {", depth+2)
@@ -709,8 +722,8 @@ class Obj2ModVisitor(PickleVisitor):
             self.emit("}", depth+1)
         else:
             with self.recursive_call(name, depth+1):
-                self.emit("res = obj2ast_%s(state, tmp, &%s, arena);" %
-                          (field.type, field.name), depth+1)
+                self.emit("res = obj2ast_%s(state, tmp, &%s, \"%s\", arena);" %
+                          (field.type, field.name, field.name), depth+1)
             self.emit("if (res != 0) goto failed;", depth+1)
 
         self.emit("Py_CLEAR(tmp);", depth+1)
@@ -1701,7 +1714,9 @@ static PyObject* ast2obj_int(struct ast_state *Py_UNUSED(state), long b)
 
 /* Conversion Python -> AST */
 
-static int obj2ast_object(struct ast_state *Py_UNUSED(state), PyObject* obj, PyObject** out, PyArena* arena)
+static int obj2ast_object(struct ast_state *Py_UNUSED(state), PyObject* obj,
+                          PyObject** out,
+                          const char* Py_UNUSED(field), PyArena* arena)
 {
     if (obj == Py_None)
         obj = NULL;
@@ -1718,7 +1733,9 @@ static int obj2ast_object(struct ast_state *Py_UNUSED(state), PyObject* obj, PyO
     return 0;
 }
 
-static int obj2ast_constant(struct ast_state *Py_UNUSED(state), PyObject* obj, PyObject** out, PyArena* arena)
+static int obj2ast_constant(struct ast_state *Py_UNUSED(state), PyObject* obj,
+                            PyObject** out,
+                            const char* Py_UNUSED(field), PyArena* arena)
 {
     if (_PyArena_AddPyObject(arena, obj) < 0) {
         *out = NULL;
@@ -1728,29 +1745,29 @@ static int obj2ast_constant(struct ast_state *Py_UNUSED(state), PyObject* obj, P
     return 0;
 }
 
-static int obj2ast_identifier(struct ast_state *state, PyObject* obj, PyObject** out, PyArena* arena)
+static int obj2ast_identifier(struct ast_state *state, PyObject* obj, PyObject** out, const char* field, PyArena* arena)
 {
     if (!PyUnicode_CheckExact(obj) && obj != Py_None) {
-        PyErr_SetString(PyExc_TypeError, "AST identifier must be of type str");
+        PyErr_Format(PyExc_TypeError, "field '%s' was expecting a string object", field);
         return -1;
     }
-    return obj2ast_object(state, obj, out, arena);
+    return obj2ast_object(state, obj, out, field, arena);
 }
 
-static int obj2ast_string(struct ast_state *state, PyObject* obj, PyObject** out, PyArena* arena)
+static int obj2ast_string(struct ast_state *state, PyObject* obj, PyObject** out, const char* field, PyArena* arena)
 {
     if (!PyUnicode_CheckExact(obj) && !PyBytes_CheckExact(obj)) {
-        PyErr_SetString(PyExc_TypeError, "AST string must be of type str");
+        PyErr_Format(PyExc_TypeError, "field '%s' was expecting a string or bytes object", field);
         return -1;
     }
-    return obj2ast_object(state, obj, out, arena);
+    return obj2ast_object(state, obj, out, field, arena);
 }
 
-static int obj2ast_int(struct ast_state* Py_UNUSED(state), PyObject* obj, int* out, PyArena* arena)
+static int obj2ast_int(struct ast_state* Py_UNUSED(state), PyObject* obj, int* out, const char* field, PyArena* arena)
 {
     int i;
     if (!PyLong_Check(obj)) {
-        PyErr_Format(PyExc_ValueError, "invalid integer value: %R", obj);
+        PyErr_Format(PyExc_ValueError, "field \\"%s\\" got an invalid integer value: %R", field, obj);
         return -1;
     }
 
@@ -2150,7 +2167,7 @@ mod_ty PyAST_obj2mod(PyObject* ast, PyArena* arena, int mode)
     }
 
     mod_ty res = NULL;
-    if (obj2ast_mod(state, ast, &res, arena) != 0)
+    if (obj2ast_mod(state, ast, &res, NULL, arena) != 0)
         return NULL;
     else
         return res;

diff --git a/Python/Python-ast.c b/Python/Python-ast.c
index 5f3d9c4b17410fb9e0508477d9706afaa52a95f4..49b6bf1d12b6fab4e8c9d2d2e07d3e652b83a181 100644 (file)
--- a/Python/Python-ast.c
+++ b/Python/Python-ast.c
@@ -6026,7 +6026,9 @@ static PyObject* ast2obj_int(struct ast_state *Py_UNUSED(state), long b)
 
 /* Conversion Python -> AST */
 
-static int obj2ast_object(struct ast_state *Py_UNUSED(state), PyObject* obj, PyObject** out, PyArena* arena)
+static int obj2ast_object(struct ast_state *Py_UNUSED(state), PyObject* obj,
+                          PyObject** out,
+                          const char* Py_UNUSED(field), PyArena* arena)
 {
     if (obj == Py_None)
         obj = NULL;
@@ -6043,7 +6045,9 @@ static int obj2ast_object(struct ast_state *Py_UNUSED(state), PyObject* obj, PyO
     return 0;
 }
 
-static int obj2ast_constant(struct ast_state *Py_UNUSED(state), PyObject* obj, PyObject** out, PyArena* arena)
+static int obj2ast_constant(struct ast_state *Py_UNUSED(state), PyObject* obj,
+                            PyObject** out,
+                            const char* Py_UNUSED(field), PyArena* arena)
 {
     if (_PyArena_AddPyObject(arena, obj) < 0) {
         *out = NULL;
@@ -6053,29 +6057,29 @@ static int obj2ast_constant(struct ast_state *Py_UNUSED(state), PyObject* obj, P
     return 0;
 }
 
-static int obj2ast_identifier(struct ast_state *state, PyObject* obj, PyObject** out, PyArena* arena)
+static int obj2ast_identifier(struct ast_state *state, PyObject* obj, PyObject** out, const char* field, PyArena* arena)
 {
     if (!PyUnicode_CheckExact(obj) && obj != Py_None) {
-        PyErr_SetString(PyExc_TypeError, "AST identifier must be of type str");
+        PyErr_Format(PyExc_TypeError, "field '%s' was expecting a string object", field);
         return -1;
     }
-    return obj2ast_object(state, obj, out, arena);
+    return obj2ast_object(state, obj, out, field, arena);
 }
 
-static int obj2ast_string(struct ast_state *state, PyObject* obj, PyObject** out, PyArena* arena)
+static int obj2ast_string(struct ast_state *state, PyObject* obj, PyObject** out, const char* field, PyArena* arena)
 {
     if (!PyUnicode_CheckExact(obj) && !PyBytes_CheckExact(obj)) {
-        PyErr_SetString(PyExc_TypeError, "AST string must be of type str");
+        PyErr_Format(PyExc_TypeError, "field '%s' was expecting a string or bytes object", field);
         return -1;
     }
-    return obj2ast_object(state, obj, out, arena);
+    return obj2ast_object(state, obj, out, field, arena);
 }
 
-static int obj2ast_int(struct ast_state* Py_UNUSED(state), PyObject* obj, int* out, PyArena* arena)
+static int obj2ast_int(struct ast_state* Py_UNUSED(state), PyObject* obj, int* out, const char* field, PyArena* arena)
 {
     int i;
     if (!PyLong_Check(obj)) {
-        PyErr_Format(PyExc_ValueError, "invalid integer value: %R", obj);
+        PyErr_Format(PyExc_ValueError, "field \"%s\" got an invalid integer value: %R", field, obj);
         return -1;
     }
 
@@ -6954,43 +6958,52 @@ init_types(void *arg)
 }
 
 static int obj2ast_mod(struct ast_state *state, PyObject* obj, mod_ty* out,
-                       PyArena* arena);
+                       const char* field, PyArena* arena);
 static int obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out,
-                        PyArena* arena);
+                        const char* field, PyArena* arena);
 static int obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out,
-                        PyArena* arena);
+                        const char* field, PyArena* arena);
 static int obj2ast_expr_context(struct ast_state *state, PyObject* obj,
-                                expr_context_ty* out, PyArena* arena);
+                                expr_context_ty* out, const char* field,
+                                PyArena* arena);
 static int obj2ast_boolop(struct ast_state *state, PyObject* obj, boolop_ty*
-                          out, PyArena* arena);
+                          out, const char* field, PyArena* arena);
 static int obj2ast_operator(struct ast_state *state, PyObject* obj,
-                            operator_ty* out, PyArena* arena);
+                            operator_ty* out, const char* field, PyArena*
+                            arena);
 static int obj2ast_unaryop(struct ast_state *state, PyObject* obj, unaryop_ty*
-                           out, PyArena* arena);
+                           out, const char* field, PyArena* arena);
 static int obj2ast_cmpop(struct ast_state *state, PyObject* obj, cmpop_ty* out,
-                         PyArena* arena);
+                         const char* field, PyArena* arena);
 static int obj2ast_comprehension(struct ast_state *state, PyObject* obj,
-                                 comprehension_ty* out, PyArena* arena);
+                                 comprehension_ty* out, const char* field,
+                                 PyArena* arena);
 static int obj2ast_excepthandler(struct ast_state *state, PyObject* obj,
-                                 excepthandler_ty* out, PyArena* arena);
+                                 excepthandler_ty* out, const char* field,
+                                 PyArena* arena);
 static int obj2ast_arguments(struct ast_state *state, PyObject* obj,
-                             arguments_ty* out, PyArena* arena);
+                             arguments_ty* out, const char* field, PyArena*
+                             arena);
 static int obj2ast_arg(struct ast_state *state, PyObject* obj, arg_ty* out,
-                       PyArena* arena);
+                       const char* field, PyArena* arena);
 static int obj2ast_keyword(struct ast_state *state, PyObject* obj, keyword_ty*
-                           out, PyArena* arena);
+                           out, const char* field, PyArena* arena);
 static int obj2ast_alias(struct ast_state *state, PyObject* obj, alias_ty* out,
-                         PyArena* arena);
+                         const char* field, PyArena* arena);
 static int obj2ast_withitem(struct ast_state *state, PyObject* obj,
-                            withitem_ty* out, PyArena* arena);
+                            withitem_ty* out, const char* field, PyArena*
+                            arena);
 static int obj2ast_match_case(struct ast_state *state, PyObject* obj,
-                              match_case_ty* out, PyArena* arena);
+                              match_case_ty* out, const char* field, PyArena*
+                              arena);
 static int obj2ast_pattern(struct ast_state *state, PyObject* obj, pattern_ty*
-                           out, PyArena* arena);
+                           out, const char* field, PyArena* arena);
 static int obj2ast_type_ignore(struct ast_state *state, PyObject* obj,
-                               type_ignore_ty* out, PyArena* arena);
+                               type_ignore_ty* out, const char* field, PyArena*
+                               arena);
 static int obj2ast_type_param(struct ast_state *state, PyObject* obj,
-                              type_param_ty* out, PyArena* arena);
+                              type_param_ty* out, const char* field, PyArena*
+                              arena);
 
 mod_ty
 _PyAST_Module(asdl_stmt_seq * body, asdl_type_ignore_seq * type_ignores,
@@ -10855,7 +10868,8 @@ failed:
 
 
 int
-obj2ast_mod(struct ast_state *state, PyObject* obj, mod_ty* out, PyArena* arena)
+obj2ast_mod(struct ast_state *state, PyObject* obj, mod_ty* out, const char*
+            field, PyArena* arena)
 {
     int isinstance;
 
@@ -10866,6 +10880,15 @@ obj2ast_mod(struct ast_state *state, PyObject* obj, mod_ty* out, PyArena* arena)
         *out = NULL;
         return 0;
     }
+    tp = state->mod_type;
+    isinstance = PyObject_IsInstance(obj, tp);
+    if (isinstance == -1) {
+        return 1;
+    }
+    if (!isinstance && field != NULL) {
+        PyErr_Format(PyExc_TypeError, "field '%s' was expecting node of type 'mod', got '%s'", field, _PyType_Name(Py_TYPE(obj)));
+        return 1;
+    }
     tp = state->Module_type;
     isinstance = PyObject_IsInstance(obj, tp);
     if (isinstance == -1) {
@@ -10901,7 +10924,7 @@ obj2ast_mod(struct ast_state *state, PyObject* obj, mod_ty* out, PyArena* arena)
                 if (_Py_EnterRecursiveCall(" while traversing 'Module' node")) {
                     goto failed;
                 }
-                res = obj2ast_stmt(state, tmp2, &val, arena);
+                res = obj2ast_stmt(state, tmp2, &val, "body", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -10939,7 +10962,7 @@ obj2ast_mod(struct ast_state *state, PyObject* obj, mod_ty* out, PyArena* arena)
                 if (_Py_EnterRecursiveCall(" while traversing 'Module' node")) {
                     goto failed;
                 }
-                res = obj2ast_type_ignore(state, tmp2, &val, arena);
+                res = obj2ast_type_ignore(state, tmp2, &val, "type_ignores", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -10989,7 +11012,7 @@ obj2ast_mod(struct ast_state *state, PyObject* obj, mod_ty* out, PyArena* arena)
                 if (_Py_EnterRecursiveCall(" while traversing 'Interactive' node")) {
                     goto failed;
                 }
-                res = obj2ast_stmt(state, tmp2, &val, arena);
+                res = obj2ast_stmt(state, tmp2, &val, "body", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -11025,7 +11048,7 @@ obj2ast_mod(struct ast_state *state, PyObject* obj, mod_ty* out, PyArena* arena)
             if (_Py_EnterRecursiveCall(" while traversing 'Expression' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &body, arena);
+            res = obj2ast_expr(state, tmp, &body, "body", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -11069,7 +11092,7 @@ obj2ast_mod(struct ast_state *state, PyObject* obj, mod_ty* out, PyArena* arena)
                 if (_Py_EnterRecursiveCall(" while traversing 'FunctionType' node")) {
                     goto failed;
                 }
-                res = obj2ast_expr(state, tmp2, &val, arena);
+                res = obj2ast_expr(state, tmp2, &val, "argtypes", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -11093,7 +11116,7 @@ obj2ast_mod(struct ast_state *state, PyObject* obj, mod_ty* out, PyArena* arena)
             if (_Py_EnterRecursiveCall(" while traversing 'FunctionType' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &returns, arena);
+            res = obj2ast_expr(state, tmp, &returns, "returns", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -11110,8 +11133,8 @@ obj2ast_mod(struct ast_state *state, PyObject* obj, mod_ty* out, PyArena* arena)
 }
 
 int
-obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
-             arena)
+obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, const char*
+             field, PyArena* arena)
 {
     int isinstance;
 
@@ -11126,6 +11149,15 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
         *out = NULL;
         return 0;
     }
+    tp = state->stmt_type;
+    isinstance = PyObject_IsInstance(obj, tp);
+    if (isinstance == -1) {
+        return 1;
+    }
+    if (!isinstance && field != NULL) {
+        PyErr_Format(PyExc_TypeError, "field '%s' was expecting node of type 'stmt', got '%s'", field, _PyType_Name(Py_TYPE(obj)));
+        return 1;
+    }
     if (PyObject_GetOptionalAttr(obj, state->lineno, &tmp) < 0) {
         return -1;
     }
@@ -11138,7 +11170,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
         if (_Py_EnterRecursiveCall(" while traversing 'stmt' node")) {
             goto failed;
         }
-        res = obj2ast_int(state, tmp, &lineno, arena);
+        res = obj2ast_int(state, tmp, &lineno, "lineno", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -11155,7 +11187,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
         if (_Py_EnterRecursiveCall(" while traversing 'stmt' node")) {
             goto failed;
         }
-        res = obj2ast_int(state, tmp, &col_offset, arena);
+        res = obj2ast_int(state, tmp, &col_offset, "col_offset", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -11172,7 +11204,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
         if (_Py_EnterRecursiveCall(" while traversing 'stmt' node")) {
             goto failed;
         }
-        res = obj2ast_int(state, tmp, &end_lineno, arena);
+        res = obj2ast_int(state, tmp, &end_lineno, "end_lineno", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -11189,7 +11221,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
         if (_Py_EnterRecursiveCall(" while traversing 'stmt' node")) {
             goto failed;
         }
-        res = obj2ast_int(state, tmp, &end_col_offset, arena);
+        res = obj2ast_int(state, tmp, &end_col_offset, "end_col_offset", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -11220,7 +11252,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'FunctionDef' node")) {
                 goto failed;
             }
-            res = obj2ast_identifier(state, tmp, &name, arena);
+            res = obj2ast_identifier(state, tmp, &name, "name", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -11237,7 +11269,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'FunctionDef' node")) {
                 goto failed;
             }
-            res = obj2ast_arguments(state, tmp, &args, arena);
+            res = obj2ast_arguments(state, tmp, &args, "args", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -11268,7 +11300,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'FunctionDef' node")) {
                     goto failed;
                 }
-                res = obj2ast_stmt(state, tmp2, &val, arena);
+                res = obj2ast_stmt(state, tmp2, &val, "body", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -11306,7 +11338,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'FunctionDef' node")) {
                     goto failed;
                 }
-                res = obj2ast_expr(state, tmp2, &val, arena);
+                res = obj2ast_expr(state, tmp2, &val, "decorator_list", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -11330,7 +11362,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'FunctionDef' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &returns, arena);
+            res = obj2ast_expr(state, tmp, &returns, "returns", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -11347,7 +11379,8 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'FunctionDef' node")) {
                 goto failed;
             }
-            res = obj2ast_string(state, tmp, &type_comment, arena);
+            res = obj2ast_string(state, tmp, &type_comment, "type_comment",
+                                 arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -11378,7 +11411,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'FunctionDef' node")) {
                     goto failed;
                 }
-                res = obj2ast_type_param(state, tmp2, &val, arena);
+                res = obj2ast_type_param(state, tmp2, &val, "type_params", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -11423,7 +11456,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'AsyncFunctionDef' node")) {
                 goto failed;
             }
-            res = obj2ast_identifier(state, tmp, &name, arena);
+            res = obj2ast_identifier(state, tmp, &name, "name", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -11440,7 +11473,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'AsyncFunctionDef' node")) {
                 goto failed;
             }
-            res = obj2ast_arguments(state, tmp, &args, arena);
+            res = obj2ast_arguments(state, tmp, &args, "args", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -11471,7 +11504,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'AsyncFunctionDef' node")) {
                     goto failed;
                 }
-                res = obj2ast_stmt(state, tmp2, &val, arena);
+                res = obj2ast_stmt(state, tmp2, &val, "body", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -11509,7 +11542,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'AsyncFunctionDef' node")) {
                     goto failed;
                 }
-                res = obj2ast_expr(state, tmp2, &val, arena);
+                res = obj2ast_expr(state, tmp2, &val, "decorator_list", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -11533,7 +11566,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'AsyncFunctionDef' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &returns, arena);
+            res = obj2ast_expr(state, tmp, &returns, "returns", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -11550,7 +11583,8 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'AsyncFunctionDef' node")) {
                 goto failed;
             }
-            res = obj2ast_string(state, tmp, &type_comment, arena);
+            res = obj2ast_string(state, tmp, &type_comment, "type_comment",
+                                 arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -11581,7 +11615,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'AsyncFunctionDef' node")) {
                     goto failed;
                 }
-                res = obj2ast_type_param(state, tmp2, &val, arena);
+                res = obj2ast_type_param(state, tmp2, &val, "type_params", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -11625,7 +11659,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'ClassDef' node")) {
                 goto failed;
             }
-            res = obj2ast_identifier(state, tmp, &name, arena);
+            res = obj2ast_identifier(state, tmp, &name, "name", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -11656,7 +11690,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'ClassDef' node")) {
                     goto failed;
                 }
-                res = obj2ast_expr(state, tmp2, &val, arena);
+                res = obj2ast_expr(state, tmp2, &val, "bases", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -11694,7 +11728,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'ClassDef' node")) {
                     goto failed;
                 }
-                res = obj2ast_keyword(state, tmp2, &val, arena);
+                res = obj2ast_keyword(state, tmp2, &val, "keywords", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -11732,7 +11766,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'ClassDef' node")) {
                     goto failed;
                 }
-                res = obj2ast_stmt(state, tmp2, &val, arena);
+                res = obj2ast_stmt(state, tmp2, &val, "body", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -11770,7 +11804,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'ClassDef' node")) {
                     goto failed;
                 }
-                res = obj2ast_expr(state, tmp2, &val, arena);
+                res = obj2ast_expr(state, tmp2, &val, "decorator_list", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -11808,7 +11842,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'ClassDef' node")) {
                     goto failed;
                 }
-                res = obj2ast_type_param(state, tmp2, &val, arena);
+                res = obj2ast_type_param(state, tmp2, &val, "type_params", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -11846,7 +11880,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'Return' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &value, arena);
+            res = obj2ast_expr(state, tmp, &value, "value", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -11890,7 +11924,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'Delete' node")) {
                     goto failed;
                 }
-                res = obj2ast_expr(state, tmp2, &val, arena);
+                res = obj2ast_expr(state, tmp2, &val, "targets", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -11943,7 +11977,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'Assign' node")) {
                     goto failed;
                 }
-                res = obj2ast_expr(state, tmp2, &val, arena);
+                res = obj2ast_expr(state, tmp2, &val, "targets", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -11967,7 +12001,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'Assign' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &value, arena);
+            res = obj2ast_expr(state, tmp, &value, "value", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -11984,7 +12018,8 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'Assign' node")) {
                 goto failed;
             }
-            res = obj2ast_string(state, tmp, &type_comment, arena);
+            res = obj2ast_string(state, tmp, &type_comment, "type_comment",
+                                 arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -12016,7 +12051,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'TypeAlias' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &name, arena);
+            res = obj2ast_expr(state, tmp, &name, "name", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -12047,7 +12082,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'TypeAlias' node")) {
                     goto failed;
                 }
-                res = obj2ast_type_param(state, tmp2, &val, arena);
+                res = obj2ast_type_param(state, tmp2, &val, "type_params", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -12071,7 +12106,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'TypeAlias' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &value, arena);
+            res = obj2ast_expr(state, tmp, &value, "value", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -12103,7 +12138,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'AugAssign' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &target, arena);
+            res = obj2ast_expr(state, tmp, &target, "target", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -12120,7 +12155,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'AugAssign' node")) {
                 goto failed;
             }
-            res = obj2ast_operator(state, tmp, &op, arena);
+            res = obj2ast_operator(state, tmp, &op, "op", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -12137,7 +12172,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'AugAssign' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &value, arena);
+            res = obj2ast_expr(state, tmp, &value, "value", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -12170,7 +12205,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'AnnAssign' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &target, arena);
+            res = obj2ast_expr(state, tmp, &target, "target", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -12187,7 +12222,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'AnnAssign' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &annotation, arena);
+            res = obj2ast_expr(state, tmp, &annotation, "annotation", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -12204,7 +12239,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'AnnAssign' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &value, arena);
+            res = obj2ast_expr(state, tmp, &value, "value", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -12221,7 +12256,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'AnnAssign' node")) {
                 goto failed;
             }
-            res = obj2ast_int(state, tmp, &simple, arena);
+            res = obj2ast_int(state, tmp, &simple, "simple", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -12255,7 +12290,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'For' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &target, arena);
+            res = obj2ast_expr(state, tmp, &target, "target", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -12272,7 +12307,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'For' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &iter, arena);
+            res = obj2ast_expr(state, tmp, &iter, "iter", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -12303,7 +12338,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'For' node")) {
                     goto failed;
                 }
-                res = obj2ast_stmt(state, tmp2, &val, arena);
+                res = obj2ast_stmt(state, tmp2, &val, "body", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -12341,7 +12376,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'For' node")) {
                     goto failed;
                 }
-                res = obj2ast_stmt(state, tmp2, &val, arena);
+                res = obj2ast_stmt(state, tmp2, &val, "orelse", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -12365,7 +12400,8 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'For' node")) {
                 goto failed;
             }
-            res = obj2ast_string(state, tmp, &type_comment, arena);
+            res = obj2ast_string(state, tmp, &type_comment, "type_comment",
+                                 arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -12399,7 +12435,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'AsyncFor' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &target, arena);
+            res = obj2ast_expr(state, tmp, &target, "target", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -12416,7 +12452,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'AsyncFor' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &iter, arena);
+            res = obj2ast_expr(state, tmp, &iter, "iter", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -12447,7 +12483,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'AsyncFor' node")) {
                     goto failed;
                 }
-                res = obj2ast_stmt(state, tmp2, &val, arena);
+                res = obj2ast_stmt(state, tmp2, &val, "body", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -12485,7 +12521,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'AsyncFor' node")) {
                     goto failed;
                 }
-                res = obj2ast_stmt(state, tmp2, &val, arena);
+                res = obj2ast_stmt(state, tmp2, &val, "orelse", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -12509,7 +12545,8 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'AsyncFor' node")) {
                 goto failed;
             }
-            res = obj2ast_string(state, tmp, &type_comment, arena);
+            res = obj2ast_string(state, tmp, &type_comment, "type_comment",
+                                 arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -12542,7 +12579,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'While' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &test, arena);
+            res = obj2ast_expr(state, tmp, &test, "test", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -12573,7 +12610,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'While' node")) {
                     goto failed;
                 }
-                res = obj2ast_stmt(state, tmp2, &val, arena);
+                res = obj2ast_stmt(state, tmp2, &val, "body", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -12611,7 +12648,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'While' node")) {
                     goto failed;
                 }
-                res = obj2ast_stmt(state, tmp2, &val, arena);
+                res = obj2ast_stmt(state, tmp2, &val, "orelse", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -12650,7 +12687,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'If' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &test, arena);
+            res = obj2ast_expr(state, tmp, &test, "test", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -12681,7 +12718,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'If' node")) {
                     goto failed;
                 }
-                res = obj2ast_stmt(state, tmp2, &val, arena);
+                res = obj2ast_stmt(state, tmp2, &val, "body", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -12719,7 +12756,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'If' node")) {
                     goto failed;
                 }
-                res = obj2ast_stmt(state, tmp2, &val, arena);
+                res = obj2ast_stmt(state, tmp2, &val, "orelse", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -12772,7 +12809,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'With' node")) {
                     goto failed;
                 }
-                res = obj2ast_withitem(state, tmp2, &val, arena);
+                res = obj2ast_withitem(state, tmp2, &val, "items", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -12810,7 +12847,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'With' node")) {
                     goto failed;
                 }
-                res = obj2ast_stmt(state, tmp2, &val, arena);
+                res = obj2ast_stmt(state, tmp2, &val, "body", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -12834,7 +12871,8 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'With' node")) {
                 goto failed;
             }
-            res = obj2ast_string(state, tmp, &type_comment, arena);
+            res = obj2ast_string(state, tmp, &type_comment, "type_comment",
+                                 arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -12880,7 +12918,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'AsyncWith' node")) {
                     goto failed;
                 }
-                res = obj2ast_withitem(state, tmp2, &val, arena);
+                res = obj2ast_withitem(state, tmp2, &val, "items", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -12918,7 +12956,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'AsyncWith' node")) {
                     goto failed;
                 }
-                res = obj2ast_stmt(state, tmp2, &val, arena);
+                res = obj2ast_stmt(state, tmp2, &val, "body", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -12942,7 +12980,8 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'AsyncWith' node")) {
                 goto failed;
             }
-            res = obj2ast_string(state, tmp, &type_comment, arena);
+            res = obj2ast_string(state, tmp, &type_comment, "type_comment",
+                                 arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -12973,7 +13012,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'Match' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &subject, arena);
+            res = obj2ast_expr(state, tmp, &subject, "subject", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -13004,7 +13043,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'Match' node")) {
                     goto failed;
                 }
-                res = obj2ast_match_case(state, tmp2, &val, arena);
+                res = obj2ast_match_case(state, tmp2, &val, "cases", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -13042,7 +13081,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'Raise' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &exc, arena);
+            res = obj2ast_expr(state, tmp, &exc, "exc", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -13059,7 +13098,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'Raise' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &cause, arena);
+            res = obj2ast_expr(state, tmp, &cause, "cause", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -13106,7 +13145,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'Try' node")) {
                     goto failed;
                 }
-                res = obj2ast_stmt(state, tmp2, &val, arena);
+                res = obj2ast_stmt(state, tmp2, &val, "body", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -13144,7 +13183,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'Try' node")) {
                     goto failed;
                 }
-                res = obj2ast_excepthandler(state, tmp2, &val, arena);
+                res = obj2ast_excepthandler(state, tmp2, &val, "handlers", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -13182,7 +13221,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'Try' node")) {
                     goto failed;
                 }
-                res = obj2ast_stmt(state, tmp2, &val, arena);
+                res = obj2ast_stmt(state, tmp2, &val, "orelse", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -13220,7 +13259,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'Try' node")) {
                     goto failed;
                 }
-                res = obj2ast_stmt(state, tmp2, &val, arena);
+                res = obj2ast_stmt(state, tmp2, &val, "finalbody", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -13274,7 +13313,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'TryStar' node")) {
                     goto failed;
                 }
-                res = obj2ast_stmt(state, tmp2, &val, arena);
+                res = obj2ast_stmt(state, tmp2, &val, "body", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -13312,7 +13351,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'TryStar' node")) {
                     goto failed;
                 }
-                res = obj2ast_excepthandler(state, tmp2, &val, arena);
+                res = obj2ast_excepthandler(state, tmp2, &val, "handlers", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -13350,7 +13389,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'TryStar' node")) {
                     goto failed;
                 }
-                res = obj2ast_stmt(state, tmp2, &val, arena);
+                res = obj2ast_stmt(state, tmp2, &val, "orelse", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -13388,7 +13427,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'TryStar' node")) {
                     goto failed;
                 }
-                res = obj2ast_stmt(state, tmp2, &val, arena);
+                res = obj2ast_stmt(state, tmp2, &val, "finalbody", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -13426,7 +13465,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'Assert' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &test, arena);
+            res = obj2ast_expr(state, tmp, &test, "test", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -13443,7 +13482,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'Assert' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &msg, arena);
+            res = obj2ast_expr(state, tmp, &msg, "msg", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -13488,7 +13527,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'Import' node")) {
                     goto failed;
                 }
-                res = obj2ast_alias(state, tmp2, &val, arena);
+                res = obj2ast_alias(state, tmp2, &val, "names", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -13512,7 +13551,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'Import' node")) {
                 goto failed;
             }
-            res = obj2ast_int(state, tmp, &is_lazy, arena);
+            res = obj2ast_int(state, tmp, &is_lazy, "is_lazy", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -13545,7 +13584,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'ImportFrom' node")) {
                 goto failed;
             }
-            res = obj2ast_identifier(state, tmp, &module, arena);
+            res = obj2ast_identifier(state, tmp, &module, "module", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -13576,7 +13615,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'ImportFrom' node")) {
                     goto failed;
                 }
-                res = obj2ast_alias(state, tmp2, &val, arena);
+                res = obj2ast_alias(state, tmp2, &val, "names", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -13600,7 +13639,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'ImportFrom' node")) {
                 goto failed;
             }
-            res = obj2ast_int(state, tmp, &level, arena);
+            res = obj2ast_int(state, tmp, &level, "level", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -13617,7 +13656,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'ImportFrom' node")) {
                 goto failed;
             }
-            res = obj2ast_int(state, tmp, &is_lazy, arena);
+            res = obj2ast_int(state, tmp, &is_lazy, "is_lazy", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -13661,7 +13700,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'Global' node")) {
                     goto failed;
                 }
-                res = obj2ast_identifier(state, tmp2, &val, arena);
+                res = obj2ast_identifier(state, tmp2, &val, "names", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -13712,7 +13751,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'Nonlocal' node")) {
                     goto failed;
                 }
-                res = obj2ast_identifier(state, tmp2, &val, arena);
+                res = obj2ast_identifier(state, tmp2, &val, "names", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -13749,7 +13788,7 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'Expr' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &value, arena);
+            res = obj2ast_expr(state, tmp, &value, "value", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -13803,8 +13842,8 @@ obj2ast_stmt(struct ast_state *state, PyObject* obj, stmt_ty* out, PyArena*
 }
 
 int
-obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
-             arena)
+obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, const char*
+             field, PyArena* arena)
 {
     int isinstance;
 
@@ -13819,6 +13858,15 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
         *out = NULL;
         return 0;
     }
+    tp = state->expr_type;
+    isinstance = PyObject_IsInstance(obj, tp);
+    if (isinstance == -1) {
+        return 1;
+    }
+    if (!isinstance && field != NULL) {
+        PyErr_Format(PyExc_TypeError, "field '%s' was expecting node of type 'expr', got '%s'", field, _PyType_Name(Py_TYPE(obj)));
+        return 1;
+    }
     if (PyObject_GetOptionalAttr(obj, state->lineno, &tmp) < 0) {
         return -1;
     }
@@ -13831,7 +13879,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
         if (_Py_EnterRecursiveCall(" while traversing 'expr' node")) {
             goto failed;
         }
-        res = obj2ast_int(state, tmp, &lineno, arena);
+        res = obj2ast_int(state, tmp, &lineno, "lineno", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -13848,7 +13896,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
         if (_Py_EnterRecursiveCall(" while traversing 'expr' node")) {
             goto failed;
         }
-        res = obj2ast_int(state, tmp, &col_offset, arena);
+        res = obj2ast_int(state, tmp, &col_offset, "col_offset", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -13865,7 +13913,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
         if (_Py_EnterRecursiveCall(" while traversing 'expr' node")) {
             goto failed;
         }
-        res = obj2ast_int(state, tmp, &end_lineno, arena);
+        res = obj2ast_int(state, tmp, &end_lineno, "end_lineno", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -13882,7 +13930,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
         if (_Py_EnterRecursiveCall(" while traversing 'expr' node")) {
             goto failed;
         }
-        res = obj2ast_int(state, tmp, &end_col_offset, arena);
+        res = obj2ast_int(state, tmp, &end_col_offset, "end_col_offset", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -13908,7 +13956,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'BoolOp' node")) {
                 goto failed;
             }
-            res = obj2ast_boolop(state, tmp, &op, arena);
+            res = obj2ast_boolop(state, tmp, &op, "op", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -13939,7 +13987,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'BoolOp' node")) {
                     goto failed;
                 }
-                res = obj2ast_expr(state, tmp2, &val, arena);
+                res = obj2ast_expr(state, tmp2, &val, "values", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -13977,7 +14025,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'NamedExpr' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &target, arena);
+            res = obj2ast_expr(state, tmp, &target, "target", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -13994,7 +14042,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'NamedExpr' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &value, arena);
+            res = obj2ast_expr(state, tmp, &value, "value", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -14026,7 +14074,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'BinOp' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &left, arena);
+            res = obj2ast_expr(state, tmp, &left, "left", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -14043,7 +14091,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'BinOp' node")) {
                 goto failed;
             }
-            res = obj2ast_operator(state, tmp, &op, arena);
+            res = obj2ast_operator(state, tmp, &op, "op", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -14060,7 +14108,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'BinOp' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &right, arena);
+            res = obj2ast_expr(state, tmp, &right, "right", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -14091,7 +14139,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'UnaryOp' node")) {
                 goto failed;
             }
-            res = obj2ast_unaryop(state, tmp, &op, arena);
+            res = obj2ast_unaryop(state, tmp, &op, "op", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -14108,7 +14156,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'UnaryOp' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &operand, arena);
+            res = obj2ast_expr(state, tmp, &operand, "operand", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -14139,7 +14187,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'Lambda' node")) {
                 goto failed;
             }
-            res = obj2ast_arguments(state, tmp, &args, arena);
+            res = obj2ast_arguments(state, tmp, &args, "args", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -14156,7 +14204,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'Lambda' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &body, arena);
+            res = obj2ast_expr(state, tmp, &body, "body", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -14188,7 +14236,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'IfExp' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &test, arena);
+            res = obj2ast_expr(state, tmp, &test, "test", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -14205,7 +14253,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'IfExp' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &body, arena);
+            res = obj2ast_expr(state, tmp, &body, "body", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -14222,7 +14270,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'IfExp' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &orelse, arena);
+            res = obj2ast_expr(state, tmp, &orelse, "orelse", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -14267,7 +14315,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'Dict' node")) {
                     goto failed;
                 }
-                res = obj2ast_expr(state, tmp2, &val, arena);
+                res = obj2ast_expr(state, tmp2, &val, "keys", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -14305,7 +14353,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'Dict' node")) {
                     goto failed;
                 }
-                res = obj2ast_expr(state, tmp2, &val, arena);
+                res = obj2ast_expr(state, tmp2, &val, "values", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -14356,7 +14404,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'Set' node")) {
                     goto failed;
                 }
-                res = obj2ast_expr(state, tmp2, &val, arena);
+                res = obj2ast_expr(state, tmp2, &val, "elts", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -14394,7 +14442,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'ListComp' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &elt, arena);
+            res = obj2ast_expr(state, tmp, &elt, "elt", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -14425,7 +14473,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'ListComp' node")) {
                     goto failed;
                 }
-                res = obj2ast_comprehension(state, tmp2, &val, arena);
+                res = obj2ast_comprehension(state, tmp2, &val, "generators", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -14463,7 +14511,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'SetComp' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &elt, arena);
+            res = obj2ast_expr(state, tmp, &elt, "elt", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -14494,7 +14542,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'SetComp' node")) {
                     goto failed;
                 }
-                res = obj2ast_comprehension(state, tmp2, &val, arena);
+                res = obj2ast_comprehension(state, tmp2, &val, "generators", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -14533,7 +14581,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'DictComp' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &key, arena);
+            res = obj2ast_expr(state, tmp, &key, "key", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -14550,7 +14598,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'DictComp' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &value, arena);
+            res = obj2ast_expr(state, tmp, &value, "value", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -14581,7 +14629,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'DictComp' node")) {
                     goto failed;
                 }
-                res = obj2ast_comprehension(state, tmp2, &val, arena);
+                res = obj2ast_comprehension(state, tmp2, &val, "generators", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -14619,7 +14667,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'GeneratorExp' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &elt, arena);
+            res = obj2ast_expr(state, tmp, &elt, "elt", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -14650,7 +14698,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'GeneratorExp' node")) {
                     goto failed;
                 }
-                res = obj2ast_comprehension(state, tmp2, &val, arena);
+                res = obj2ast_comprehension(state, tmp2, &val, "generators", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -14687,7 +14735,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'Await' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &value, arena);
+            res = obj2ast_expr(state, tmp, &value, "value", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -14717,7 +14765,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'Yield' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &value, arena);
+            res = obj2ast_expr(state, tmp, &value, "value", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -14747,7 +14795,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'YieldFrom' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &value, arena);
+            res = obj2ast_expr(state, tmp, &value, "value", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -14779,7 +14827,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'Compare' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &left, arena);
+            res = obj2ast_expr(state, tmp, &left, "left", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -14810,7 +14858,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'Compare' node")) {
                     goto failed;
                 }
-                res = obj2ast_cmpop(state, tmp2, &val, arena);
+                res = obj2ast_cmpop(state, tmp2, &val, "ops", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -14848,7 +14896,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'Compare' node")) {
                     goto failed;
                 }
-                res = obj2ast_expr(state, tmp2, &val, arena);
+                res = obj2ast_expr(state, tmp2, &val, "comparators", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -14887,7 +14935,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'Call' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &func, arena);
+            res = obj2ast_expr(state, tmp, &func, "func", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -14918,7 +14966,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'Call' node")) {
                     goto failed;
                 }
-                res = obj2ast_expr(state, tmp2, &val, arena);
+                res = obj2ast_expr(state, tmp2, &val, "args", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -14956,7 +15004,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'Call' node")) {
                     goto failed;
                 }
-                res = obj2ast_keyword(state, tmp2, &val, arena);
+                res = obj2ast_keyword(state, tmp2, &val, "keywords", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -14995,7 +15043,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'FormattedValue' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &value, arena);
+            res = obj2ast_expr(state, tmp, &value, "value", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -15012,7 +15060,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'FormattedValue' node")) {
                 goto failed;
             }
-            res = obj2ast_int(state, tmp, &conversion, arena);
+            res = obj2ast_int(state, tmp, &conversion, "conversion", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -15029,7 +15077,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'FormattedValue' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &format_spec, arena);
+            res = obj2ast_expr(state, tmp, &format_spec, "format_spec", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -15063,7 +15111,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'Interpolation' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &value, arena);
+            res = obj2ast_expr(state, tmp, &value, "value", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -15080,7 +15128,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'Interpolation' node")) {
                 goto failed;
             }
-            res = obj2ast_constant(state, tmp, &str, arena);
+            res = obj2ast_constant(state, tmp, &str, "str", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -15097,7 +15145,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'Interpolation' node")) {
                 goto failed;
             }
-            res = obj2ast_int(state, tmp, &conversion, arena);
+            res = obj2ast_int(state, tmp, &conversion, "conversion", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -15114,7 +15162,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'Interpolation' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &format_spec, arena);
+            res = obj2ast_expr(state, tmp, &format_spec, "format_spec", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -15159,7 +15207,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'JoinedStr' node")) {
                     goto failed;
                 }
-                res = obj2ast_expr(state, tmp2, &val, arena);
+                res = obj2ast_expr(state, tmp2, &val, "values", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -15210,7 +15258,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'TemplateStr' node")) {
                     goto failed;
                 }
-                res = obj2ast_expr(state, tmp2, &val, arena);
+                res = obj2ast_expr(state, tmp2, &val, "values", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -15248,7 +15296,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'Constant' node")) {
                 goto failed;
             }
-            res = obj2ast_constant(state, tmp, &value, arena);
+            res = obj2ast_constant(state, tmp, &value, "value", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -15265,7 +15313,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'Constant' node")) {
                 goto failed;
             }
-            res = obj2ast_string(state, tmp, &kind, arena);
+            res = obj2ast_string(state, tmp, &kind, "kind", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -15297,7 +15345,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'Attribute' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &value, arena);
+            res = obj2ast_expr(state, tmp, &value, "value", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -15314,7 +15362,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'Attribute' node")) {
                 goto failed;
             }
-            res = obj2ast_identifier(state, tmp, &attr, arena);
+            res = obj2ast_identifier(state, tmp, &attr, "attr", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -15331,7 +15379,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'Attribute' node")) {
                 goto failed;
             }
-            res = obj2ast_expr_context(state, tmp, &ctx, arena);
+            res = obj2ast_expr_context(state, tmp, &ctx, "ctx", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -15363,7 +15411,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'Subscript' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &value, arena);
+            res = obj2ast_expr(state, tmp, &value, "value", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -15380,7 +15428,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'Subscript' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &slice, arena);
+            res = obj2ast_expr(state, tmp, &slice, "slice", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -15397,7 +15445,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'Subscript' node")) {
                 goto failed;
             }
-            res = obj2ast_expr_context(state, tmp, &ctx, arena);
+            res = obj2ast_expr_context(state, tmp, &ctx, "ctx", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -15428,7 +15476,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'Starred' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &value, arena);
+            res = obj2ast_expr(state, tmp, &value, "value", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -15445,7 +15493,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'Starred' node")) {
                 goto failed;
             }
-            res = obj2ast_expr_context(state, tmp, &ctx, arena);
+            res = obj2ast_expr_context(state, tmp, &ctx, "ctx", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -15476,7 +15524,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'Name' node")) {
                 goto failed;
             }
-            res = obj2ast_identifier(state, tmp, &id, arena);
+            res = obj2ast_identifier(state, tmp, &id, "id", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -15493,7 +15541,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'Name' node")) {
                 goto failed;
             }
-            res = obj2ast_expr_context(state, tmp, &ctx, arena);
+            res = obj2ast_expr_context(state, tmp, &ctx, "ctx", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -15538,7 +15586,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'List' node")) {
                     goto failed;
                 }
-                res = obj2ast_expr(state, tmp2, &val, arena);
+                res = obj2ast_expr(state, tmp2, &val, "elts", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -15562,7 +15610,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'List' node")) {
                 goto failed;
             }
-            res = obj2ast_expr_context(state, tmp, &ctx, arena);
+            res = obj2ast_expr_context(state, tmp, &ctx, "ctx", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -15607,7 +15655,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
                 if (_Py_EnterRecursiveCall(" while traversing 'Tuple' node")) {
                     goto failed;
                 }
-                res = obj2ast_expr(state, tmp2, &val, arena);
+                res = obj2ast_expr(state, tmp2, &val, "elts", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -15631,7 +15679,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'Tuple' node")) {
                 goto failed;
             }
-            res = obj2ast_expr_context(state, tmp, &ctx, arena);
+            res = obj2ast_expr_context(state, tmp, &ctx, "ctx", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -15663,7 +15711,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'Slice' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &lower, arena);
+            res = obj2ast_expr(state, tmp, &lower, "lower", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -15680,7 +15728,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'Slice' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &upper, arena);
+            res = obj2ast_expr(state, tmp, &upper, "upper", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -15697,7 +15745,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
             if (_Py_EnterRecursiveCall(" while traversing 'Slice' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &step, arena);
+            res = obj2ast_expr(state, tmp, &step, "step", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -15716,7 +15764,7 @@ obj2ast_expr(struct ast_state *state, PyObject* obj, expr_ty* out, PyArena*
 
 int
 obj2ast_expr_context(struct ast_state *state, PyObject* obj, expr_context_ty*
-                     out, PyArena* arena)
+                     out, const char* field, PyArena* arena)
 {
     int isinstance;
 
@@ -15750,8 +15798,8 @@ obj2ast_expr_context(struct ast_state *state, PyObject* obj, expr_context_ty*
 }
 
 int
-obj2ast_boolop(struct ast_state *state, PyObject* obj, boolop_ty* out, PyArena*
-               arena)
+obj2ast_boolop(struct ast_state *state, PyObject* obj, boolop_ty* out, const
+               char* field, PyArena* arena)
 {
     int isinstance;
 
@@ -15778,7 +15826,7 @@ obj2ast_boolop(struct ast_state *state, PyObject* obj, boolop_ty* out, PyArena*
 
 int
 obj2ast_operator(struct ast_state *state, PyObject* obj, operator_ty* out,
-                 PyArena* arena)
+                 const char* field, PyArena* arena)
 {
     int isinstance;
 
@@ -15892,8 +15940,8 @@ obj2ast_operator(struct ast_state *state, PyObject* obj, operator_ty* out,
 }
 
 int
-obj2ast_unaryop(struct ast_state *state, PyObject* obj, unaryop_ty* out,
-                PyArena* arena)
+obj2ast_unaryop(struct ast_state *state, PyObject* obj, unaryop_ty* out, const
+                char* field, PyArena* arena)
 {
     int isinstance;
 
@@ -15935,8 +15983,8 @@ obj2ast_unaryop(struct ast_state *state, PyObject* obj, unaryop_ty* out,
 }
 
 int
-obj2ast_cmpop(struct ast_state *state, PyObject* obj, cmpop_ty* out, PyArena*
-              arena)
+obj2ast_cmpop(struct ast_state *state, PyObject* obj, cmpop_ty* out, const
+              char* field, PyArena* arena)
 {
     int isinstance;
 
@@ -16027,7 +16075,7 @@ obj2ast_cmpop(struct ast_state *state, PyObject* obj, cmpop_ty* out, PyArena*
 
 int
 obj2ast_comprehension(struct ast_state *state, PyObject* obj, comprehension_ty*
-                      out, PyArena* arena)
+                      out, const char* field, PyArena* arena)
 {
     PyObject* tmp = NULL;
     expr_ty target;
@@ -16047,7 +16095,7 @@ obj2ast_comprehension(struct ast_state *state, PyObject* obj, comprehension_ty*
         if (_Py_EnterRecursiveCall(" while traversing 'comprehension' node")) {
             goto failed;
         }
-        res = obj2ast_expr(state, tmp, &target, arena);
+        res = obj2ast_expr(state, tmp, &target, "target", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -16064,7 +16112,7 @@ obj2ast_comprehension(struct ast_state *state, PyObject* obj, comprehension_ty*
         if (_Py_EnterRecursiveCall(" while traversing 'comprehension' node")) {
             goto failed;
         }
-        res = obj2ast_expr(state, tmp, &iter, arena);
+        res = obj2ast_expr(state, tmp, &iter, "iter", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -16095,7 +16143,7 @@ obj2ast_comprehension(struct ast_state *state, PyObject* obj, comprehension_ty*
             if (_Py_EnterRecursiveCall(" while traversing 'comprehension' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp2, &val, arena);
+            res = obj2ast_expr(state, tmp2, &val, "ifs", arena);
             _Py_LeaveRecursiveCall();
             Py_DECREF(tmp2);
             if (res != 0) goto failed;
@@ -16119,7 +16167,7 @@ obj2ast_comprehension(struct ast_state *state, PyObject* obj, comprehension_ty*
         if (_Py_EnterRecursiveCall(" while traversing 'comprehension' node")) {
             goto failed;
         }
-        res = obj2ast_int(state, tmp, &is_async, arena);
+        res = obj2ast_int(state, tmp, &is_async, "is_async", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -16134,7 +16182,7 @@ failed:
 
 int
 obj2ast_excepthandler(struct ast_state *state, PyObject* obj, excepthandler_ty*
-                      out, PyArena* arena)
+                      out, const char* field, PyArena* arena)
 {
     int isinstance;
 
@@ -16149,6 +16197,15 @@ obj2ast_excepthandler(struct ast_state *state, PyObject* obj, excepthandler_ty*
         *out = NULL;
         return 0;
     }
+    tp = state->excepthandler_type;
+    isinstance = PyObject_IsInstance(obj, tp);
+    if (isinstance == -1) {
+        return 1;
+    }
+    if (!isinstance && field != NULL) {
+        PyErr_Format(PyExc_TypeError, "field '%s' was expecting node of type 'excepthandler', got '%s'", field, _PyType_Name(Py_TYPE(obj)));
+        return 1;
+    }
     if (PyObject_GetOptionalAttr(obj, state->lineno, &tmp) < 0) {
         return -1;
     }
@@ -16161,7 +16218,7 @@ obj2ast_excepthandler(struct ast_state *state, PyObject* obj, excepthandler_ty*
         if (_Py_EnterRecursiveCall(" while traversing 'excepthandler' node")) {
             goto failed;
         }
-        res = obj2ast_int(state, tmp, &lineno, arena);
+        res = obj2ast_int(state, tmp, &lineno, "lineno", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -16178,7 +16235,7 @@ obj2ast_excepthandler(struct ast_state *state, PyObject* obj, excepthandler_ty*
         if (_Py_EnterRecursiveCall(" while traversing 'excepthandler' node")) {
             goto failed;
         }
-        res = obj2ast_int(state, tmp, &col_offset, arena);
+        res = obj2ast_int(state, tmp, &col_offset, "col_offset", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -16195,7 +16252,7 @@ obj2ast_excepthandler(struct ast_state *state, PyObject* obj, excepthandler_ty*
         if (_Py_EnterRecursiveCall(" while traversing 'excepthandler' node")) {
             goto failed;
         }
-        res = obj2ast_int(state, tmp, &end_lineno, arena);
+        res = obj2ast_int(state, tmp, &end_lineno, "end_lineno", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -16212,7 +16269,7 @@ obj2ast_excepthandler(struct ast_state *state, PyObject* obj, excepthandler_ty*
         if (_Py_EnterRecursiveCall(" while traversing 'excepthandler' node")) {
             goto failed;
         }
-        res = obj2ast_int(state, tmp, &end_col_offset, arena);
+        res = obj2ast_int(state, tmp, &end_col_offset, "end_col_offset", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -16239,7 +16296,7 @@ obj2ast_excepthandler(struct ast_state *state, PyObject* obj, excepthandler_ty*
             if (_Py_EnterRecursiveCall(" while traversing 'ExceptHandler' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &type, arena);
+            res = obj2ast_expr(state, tmp, &type, "type", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -16256,7 +16313,7 @@ obj2ast_excepthandler(struct ast_state *state, PyObject* obj, excepthandler_ty*
             if (_Py_EnterRecursiveCall(" while traversing 'ExceptHandler' node")) {
                 goto failed;
             }
-            res = obj2ast_identifier(state, tmp, &name, arena);
+            res = obj2ast_identifier(state, tmp, &name, "name", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -16287,7 +16344,7 @@ obj2ast_excepthandler(struct ast_state *state, PyObject* obj, excepthandler_ty*
                 if (_Py_EnterRecursiveCall(" while traversing 'ExceptHandler' node")) {
                     goto failed;
                 }
-                res = obj2ast_stmt(state, tmp2, &val, arena);
+                res = obj2ast_stmt(state, tmp2, &val, "body", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -16313,7 +16370,7 @@ obj2ast_excepthandler(struct ast_state *state, PyObject* obj, excepthandler_ty*
 
 int
 obj2ast_arguments(struct ast_state *state, PyObject* obj, arguments_ty* out,
-                  PyArena* arena)
+                  const char* field, PyArena* arena)
 {
     PyObject* tmp = NULL;
     asdl_arg_seq* posonlyargs;
@@ -16350,7 +16407,7 @@ obj2ast_arguments(struct ast_state *state, PyObject* obj, arguments_ty* out,
             if (_Py_EnterRecursiveCall(" while traversing 'arguments' node")) {
                 goto failed;
             }
-            res = obj2ast_arg(state, tmp2, &val, arena);
+            res = obj2ast_arg(state, tmp2, &val, "posonlyargs", arena);
             _Py_LeaveRecursiveCall();
             Py_DECREF(tmp2);
             if (res != 0) goto failed;
@@ -16388,7 +16445,7 @@ obj2ast_arguments(struct ast_state *state, PyObject* obj, arguments_ty* out,
             if (_Py_EnterRecursiveCall(" while traversing 'arguments' node")) {
                 goto failed;
             }
-            res = obj2ast_arg(state, tmp2, &val, arena);
+            res = obj2ast_arg(state, tmp2, &val, "args", arena);
             _Py_LeaveRecursiveCall();
             Py_DECREF(tmp2);
             if (res != 0) goto failed;
@@ -16412,7 +16469,7 @@ obj2ast_arguments(struct ast_state *state, PyObject* obj, arguments_ty* out,
         if (_Py_EnterRecursiveCall(" while traversing 'arguments' node")) {
             goto failed;
         }
-        res = obj2ast_arg(state, tmp, &vararg, arena);
+        res = obj2ast_arg(state, tmp, &vararg, "vararg", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -16443,7 +16500,7 @@ obj2ast_arguments(struct ast_state *state, PyObject* obj, arguments_ty* out,
             if (_Py_EnterRecursiveCall(" while traversing 'arguments' node")) {
                 goto failed;
             }
-            res = obj2ast_arg(state, tmp2, &val, arena);
+            res = obj2ast_arg(state, tmp2, &val, "kwonlyargs", arena);
             _Py_LeaveRecursiveCall();
             Py_DECREF(tmp2);
             if (res != 0) goto failed;
@@ -16481,7 +16538,7 @@ obj2ast_arguments(struct ast_state *state, PyObject* obj, arguments_ty* out,
             if (_Py_EnterRecursiveCall(" while traversing 'arguments' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp2, &val, arena);
+            res = obj2ast_expr(state, tmp2, &val, "kw_defaults", arena);
             _Py_LeaveRecursiveCall();
             Py_DECREF(tmp2);
             if (res != 0) goto failed;
@@ -16505,7 +16562,7 @@ obj2ast_arguments(struct ast_state *state, PyObject* obj, arguments_ty* out,
         if (_Py_EnterRecursiveCall(" while traversing 'arguments' node")) {
             goto failed;
         }
-        res = obj2ast_arg(state, tmp, &kwarg, arena);
+        res = obj2ast_arg(state, tmp, &kwarg, "kwarg", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -16536,7 +16593,7 @@ obj2ast_arguments(struct ast_state *state, PyObject* obj, arguments_ty* out,
             if (_Py_EnterRecursiveCall(" while traversing 'arguments' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp2, &val, arena);
+            res = obj2ast_expr(state, tmp2, &val, "defaults", arena);
             _Py_LeaveRecursiveCall();
             Py_DECREF(tmp2);
             if (res != 0) goto failed;
@@ -16558,7 +16615,8 @@ failed:
 }
 
 int
-obj2ast_arg(struct ast_state *state, PyObject* obj, arg_ty* out, PyArena* arena)
+obj2ast_arg(struct ast_state *state, PyObject* obj, arg_ty* out, const char*
+            field, PyArena* arena)
 {
     PyObject* tmp = NULL;
     identifier arg;
@@ -16581,7 +16639,7 @@ obj2ast_arg(struct ast_state *state, PyObject* obj, arg_ty* out, PyArena* arena)
         if (_Py_EnterRecursiveCall(" while traversing 'arg' node")) {
             goto failed;
         }
-        res = obj2ast_identifier(state, tmp, &arg, arena);
+        res = obj2ast_identifier(state, tmp, &arg, "arg", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -16598,7 +16656,7 @@ obj2ast_arg(struct ast_state *state, PyObject* obj, arg_ty* out, PyArena* arena)
         if (_Py_EnterRecursiveCall(" while traversing 'arg' node")) {
             goto failed;
         }
-        res = obj2ast_expr(state, tmp, &annotation, arena);
+        res = obj2ast_expr(state, tmp, &annotation, "annotation", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -16615,7 +16673,7 @@ obj2ast_arg(struct ast_state *state, PyObject* obj, arg_ty* out, PyArena* arena)
         if (_Py_EnterRecursiveCall(" while traversing 'arg' node")) {
             goto failed;
         }
-        res = obj2ast_string(state, tmp, &type_comment, arena);
+        res = obj2ast_string(state, tmp, &type_comment, "type_comment", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -16632,7 +16690,7 @@ obj2ast_arg(struct ast_state *state, PyObject* obj, arg_ty* out, PyArena* arena)
         if (_Py_EnterRecursiveCall(" while traversing 'arg' node")) {
             goto failed;
         }
-        res = obj2ast_int(state, tmp, &lineno, arena);
+        res = obj2ast_int(state, tmp, &lineno, "lineno", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -16649,7 +16707,7 @@ obj2ast_arg(struct ast_state *state, PyObject* obj, arg_ty* out, PyArena* arena)
         if (_Py_EnterRecursiveCall(" while traversing 'arg' node")) {
             goto failed;
         }
-        res = obj2ast_int(state, tmp, &col_offset, arena);
+        res = obj2ast_int(state, tmp, &col_offset, "col_offset", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -16666,7 +16724,7 @@ obj2ast_arg(struct ast_state *state, PyObject* obj, arg_ty* out, PyArena* arena)
         if (_Py_EnterRecursiveCall(" while traversing 'arg' node")) {
             goto failed;
         }
-        res = obj2ast_int(state, tmp, &end_lineno, arena);
+        res = obj2ast_int(state, tmp, &end_lineno, "end_lineno", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -16683,7 +16741,7 @@ obj2ast_arg(struct ast_state *state, PyObject* obj, arg_ty* out, PyArena* arena)
         if (_Py_EnterRecursiveCall(" while traversing 'arg' node")) {
             goto failed;
         }
-        res = obj2ast_int(state, tmp, &end_col_offset, arena);
+        res = obj2ast_int(state, tmp, &end_col_offset, "end_col_offset", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -16698,8 +16756,8 @@ failed:
 }
 
 int
-obj2ast_keyword(struct ast_state *state, PyObject* obj, keyword_ty* out,
-                PyArena* arena)
+obj2ast_keyword(struct ast_state *state, PyObject* obj, keyword_ty* out, const
+                char* field, PyArena* arena)
 {
     PyObject* tmp = NULL;
     identifier arg;
@@ -16721,7 +16779,7 @@ obj2ast_keyword(struct ast_state *state, PyObject* obj, keyword_ty* out,
         if (_Py_EnterRecursiveCall(" while traversing 'keyword' node")) {
             goto failed;
         }
-        res = obj2ast_identifier(state, tmp, &arg, arena);
+        res = obj2ast_identifier(state, tmp, &arg, "arg", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -16738,7 +16796,7 @@ obj2ast_keyword(struct ast_state *state, PyObject* obj, keyword_ty* out,
         if (_Py_EnterRecursiveCall(" while traversing 'keyword' node")) {
             goto failed;
         }
-        res = obj2ast_expr(state, tmp, &value, arena);
+        res = obj2ast_expr(state, tmp, &value, "value", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -16755,7 +16813,7 @@ obj2ast_keyword(struct ast_state *state, PyObject* obj, keyword_ty* out,
         if (_Py_EnterRecursiveCall(" while traversing 'keyword' node")) {
             goto failed;
         }
-        res = obj2ast_int(state, tmp, &lineno, arena);
+        res = obj2ast_int(state, tmp, &lineno, "lineno", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -16772,7 +16830,7 @@ obj2ast_keyword(struct ast_state *state, PyObject* obj, keyword_ty* out,
         if (_Py_EnterRecursiveCall(" while traversing 'keyword' node")) {
             goto failed;
         }
-        res = obj2ast_int(state, tmp, &col_offset, arena);
+        res = obj2ast_int(state, tmp, &col_offset, "col_offset", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -16789,7 +16847,7 @@ obj2ast_keyword(struct ast_state *state, PyObject* obj, keyword_ty* out,
         if (_Py_EnterRecursiveCall(" while traversing 'keyword' node")) {
             goto failed;
         }
-        res = obj2ast_int(state, tmp, &end_lineno, arena);
+        res = obj2ast_int(state, tmp, &end_lineno, "end_lineno", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -16806,7 +16864,7 @@ obj2ast_keyword(struct ast_state *state, PyObject* obj, keyword_ty* out,
         if (_Py_EnterRecursiveCall(" while traversing 'keyword' node")) {
             goto failed;
         }
-        res = obj2ast_int(state, tmp, &end_col_offset, arena);
+        res = obj2ast_int(state, tmp, &end_col_offset, "end_col_offset", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -16821,8 +16879,8 @@ failed:
 }
 
 int
-obj2ast_alias(struct ast_state *state, PyObject* obj, alias_ty* out, PyArena*
-              arena)
+obj2ast_alias(struct ast_state *state, PyObject* obj, alias_ty* out, const
+              char* field, PyArena* arena)
 {
     PyObject* tmp = NULL;
     identifier name;
@@ -16844,7 +16902,7 @@ obj2ast_alias(struct ast_state *state, PyObject* obj, alias_ty* out, PyArena*
         if (_Py_EnterRecursiveCall(" while traversing 'alias' node")) {
             goto failed;
         }
-        res = obj2ast_identifier(state, tmp, &name, arena);
+        res = obj2ast_identifier(state, tmp, &name, "name", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -16861,7 +16919,7 @@ obj2ast_alias(struct ast_state *state, PyObject* obj, alias_ty* out, PyArena*
         if (_Py_EnterRecursiveCall(" while traversing 'alias' node")) {
             goto failed;
         }
-        res = obj2ast_identifier(state, tmp, &asname, arena);
+        res = obj2ast_identifier(state, tmp, &asname, "asname", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -16878,7 +16936,7 @@ obj2ast_alias(struct ast_state *state, PyObject* obj, alias_ty* out, PyArena*
         if (_Py_EnterRecursiveCall(" while traversing 'alias' node")) {
             goto failed;
         }
-        res = obj2ast_int(state, tmp, &lineno, arena);
+        res = obj2ast_int(state, tmp, &lineno, "lineno", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -16895,7 +16953,7 @@ obj2ast_alias(struct ast_state *state, PyObject* obj, alias_ty* out, PyArena*
         if (_Py_EnterRecursiveCall(" while traversing 'alias' node")) {
             goto failed;
         }
-        res = obj2ast_int(state, tmp, &col_offset, arena);
+        res = obj2ast_int(state, tmp, &col_offset, "col_offset", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -16912,7 +16970,7 @@ obj2ast_alias(struct ast_state *state, PyObject* obj, alias_ty* out, PyArena*
         if (_Py_EnterRecursiveCall(" while traversing 'alias' node")) {
             goto failed;
         }
-        res = obj2ast_int(state, tmp, &end_lineno, arena);
+        res = obj2ast_int(state, tmp, &end_lineno, "end_lineno", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -16929,7 +16987,7 @@ obj2ast_alias(struct ast_state *state, PyObject* obj, alias_ty* out, PyArena*
         if (_Py_EnterRecursiveCall(" while traversing 'alias' node")) {
             goto failed;
         }
-        res = obj2ast_int(state, tmp, &end_col_offset, arena);
+        res = obj2ast_int(state, tmp, &end_col_offset, "end_col_offset", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -16945,7 +17003,7 @@ failed:
 
 int
 obj2ast_withitem(struct ast_state *state, PyObject* obj, withitem_ty* out,
-                 PyArena* arena)
+                 const char* field, PyArena* arena)
 {
     PyObject* tmp = NULL;
     expr_ty context_expr;
@@ -16963,7 +17021,7 @@ obj2ast_withitem(struct ast_state *state, PyObject* obj, withitem_ty* out,
         if (_Py_EnterRecursiveCall(" while traversing 'withitem' node")) {
             goto failed;
         }
-        res = obj2ast_expr(state, tmp, &context_expr, arena);
+        res = obj2ast_expr(state, tmp, &context_expr, "context_expr", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -16980,7 +17038,7 @@ obj2ast_withitem(struct ast_state *state, PyObject* obj, withitem_ty* out,
         if (_Py_EnterRecursiveCall(" while traversing 'withitem' node")) {
             goto failed;
         }
-        res = obj2ast_expr(state, tmp, &optional_vars, arena);
+        res = obj2ast_expr(state, tmp, &optional_vars, "optional_vars", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -16995,7 +17053,7 @@ failed:
 
 int
 obj2ast_match_case(struct ast_state *state, PyObject* obj, match_case_ty* out,
-                   PyArena* arena)
+                   const char* field, PyArena* arena)
 {
     PyObject* tmp = NULL;
     pattern_ty pattern;
@@ -17014,7 +17072,7 @@ obj2ast_match_case(struct ast_state *state, PyObject* obj, match_case_ty* out,
         if (_Py_EnterRecursiveCall(" while traversing 'match_case' node")) {
             goto failed;
         }
-        res = obj2ast_pattern(state, tmp, &pattern, arena);
+        res = obj2ast_pattern(state, tmp, &pattern, "pattern", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -17031,7 +17089,7 @@ obj2ast_match_case(struct ast_state *state, PyObject* obj, match_case_ty* out,
         if (_Py_EnterRecursiveCall(" while traversing 'match_case' node")) {
             goto failed;
         }
-        res = obj2ast_expr(state, tmp, &guard, arena);
+        res = obj2ast_expr(state, tmp, &guard, "guard", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -17062,7 +17120,7 @@ obj2ast_match_case(struct ast_state *state, PyObject* obj, match_case_ty* out,
             if (_Py_EnterRecursiveCall(" while traversing 'match_case' node")) {
                 goto failed;
             }
-            res = obj2ast_stmt(state, tmp2, &val, arena);
+            res = obj2ast_stmt(state, tmp2, &val, "body", arena);
             _Py_LeaveRecursiveCall();
             Py_DECREF(tmp2);
             if (res != 0) goto failed;
@@ -17083,8 +17141,8 @@ failed:
 }
 
 int
-obj2ast_pattern(struct ast_state *state, PyObject* obj, pattern_ty* out,
-                PyArena* arena)
+obj2ast_pattern(struct ast_state *state, PyObject* obj, pattern_ty* out, const
+                char* field, PyArena* arena)
 {
     int isinstance;
 
@@ -17099,6 +17157,15 @@ obj2ast_pattern(struct ast_state *state, PyObject* obj, pattern_ty* out,
         *out = NULL;
         return 0;
     }
+    tp = state->pattern_type;
+    isinstance = PyObject_IsInstance(obj, tp);
+    if (isinstance == -1) {
+        return 1;
+    }
+    if (!isinstance && field != NULL) {
+        PyErr_Format(PyExc_TypeError, "field '%s' was expecting node of type 'pattern', got '%s'", field, _PyType_Name(Py_TYPE(obj)));
+        return 1;
+    }
     if (PyObject_GetOptionalAttr(obj, state->lineno, &tmp) < 0) {
         return -1;
     }
@@ -17111,7 +17178,7 @@ obj2ast_pattern(struct ast_state *state, PyObject* obj, pattern_ty* out,
         if (_Py_EnterRecursiveCall(" while traversing 'pattern' node")) {
             goto failed;
         }
-        res = obj2ast_int(state, tmp, &lineno, arena);
+        res = obj2ast_int(state, tmp, &lineno, "lineno", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -17128,7 +17195,7 @@ obj2ast_pattern(struct ast_state *state, PyObject* obj, pattern_ty* out,
         if (_Py_EnterRecursiveCall(" while traversing 'pattern' node")) {
             goto failed;
         }
-        res = obj2ast_int(state, tmp, &col_offset, arena);
+        res = obj2ast_int(state, tmp, &col_offset, "col_offset", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -17145,7 +17212,7 @@ obj2ast_pattern(struct ast_state *state, PyObject* obj, pattern_ty* out,
         if (_Py_EnterRecursiveCall(" while traversing 'pattern' node")) {
             goto failed;
         }
-        res = obj2ast_int(state, tmp, &end_lineno, arena);
+        res = obj2ast_int(state, tmp, &end_lineno, "end_lineno", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -17162,7 +17229,7 @@ obj2ast_pattern(struct ast_state *state, PyObject* obj, pattern_ty* out,
         if (_Py_EnterRecursiveCall(" while traversing 'pattern' node")) {
             goto failed;
         }
-        res = obj2ast_int(state, tmp, &end_col_offset, arena);
+        res = obj2ast_int(state, tmp, &end_col_offset, "end_col_offset", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -17187,7 +17254,7 @@ obj2ast_pattern(struct ast_state *state, PyObject* obj, pattern_ty* out,
             if (_Py_EnterRecursiveCall(" while traversing 'MatchValue' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &value, arena);
+            res = obj2ast_expr(state, tmp, &value, "value", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -17217,7 +17284,7 @@ obj2ast_pattern(struct ast_state *state, PyObject* obj, pattern_ty* out,
             if (_Py_EnterRecursiveCall(" while traversing 'MatchSingleton' node")) {
                 goto failed;
             }
-            res = obj2ast_constant(state, tmp, &value, arena);
+            res = obj2ast_constant(state, tmp, &value, "value", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -17261,7 +17328,7 @@ obj2ast_pattern(struct ast_state *state, PyObject* obj, pattern_ty* out,
                 if (_Py_EnterRecursiveCall(" while traversing 'MatchSequence' node")) {
                     goto failed;
                 }
-                res = obj2ast_pattern(state, tmp2, &val, arena);
+                res = obj2ast_pattern(state, tmp2, &val, "patterns", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -17314,7 +17381,7 @@ obj2ast_pattern(struct ast_state *state, PyObject* obj, pattern_ty* out,
                 if (_Py_EnterRecursiveCall(" while traversing 'MatchMapping' node")) {
                     goto failed;
                 }
-                res = obj2ast_expr(state, tmp2, &val, arena);
+                res = obj2ast_expr(state, tmp2, &val, "keys", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -17352,7 +17419,7 @@ obj2ast_pattern(struct ast_state *state, PyObject* obj, pattern_ty* out,
                 if (_Py_EnterRecursiveCall(" while traversing 'MatchMapping' node")) {
                     goto failed;
                 }
-                res = obj2ast_pattern(state, tmp2, &val, arena);
+                res = obj2ast_pattern(state, tmp2, &val, "patterns", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -17376,7 +17443,7 @@ obj2ast_pattern(struct ast_state *state, PyObject* obj, pattern_ty* out,
             if (_Py_EnterRecursiveCall(" while traversing 'MatchMapping' node")) {
                 goto failed;
             }
-            res = obj2ast_identifier(state, tmp, &rest, arena);
+            res = obj2ast_identifier(state, tmp, &rest, "rest", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -17409,7 +17476,7 @@ obj2ast_pattern(struct ast_state *state, PyObject* obj, pattern_ty* out,
             if (_Py_EnterRecursiveCall(" while traversing 'MatchClass' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &cls, arena);
+            res = obj2ast_expr(state, tmp, &cls, "cls", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -17440,7 +17507,7 @@ obj2ast_pattern(struct ast_state *state, PyObject* obj, pattern_ty* out,
                 if (_Py_EnterRecursiveCall(" while traversing 'MatchClass' node")) {
                     goto failed;
                 }
-                res = obj2ast_pattern(state, tmp2, &val, arena);
+                res = obj2ast_pattern(state, tmp2, &val, "patterns", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -17478,7 +17545,7 @@ obj2ast_pattern(struct ast_state *state, PyObject* obj, pattern_ty* out,
                 if (_Py_EnterRecursiveCall(" while traversing 'MatchClass' node")) {
                     goto failed;
                 }
-                res = obj2ast_identifier(state, tmp2, &val, arena);
+                res = obj2ast_identifier(state, tmp2, &val, "kwd_attrs", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -17516,7 +17583,7 @@ obj2ast_pattern(struct ast_state *state, PyObject* obj, pattern_ty* out,
                 if (_Py_EnterRecursiveCall(" while traversing 'MatchClass' node")) {
                     goto failed;
                 }
-                res = obj2ast_pattern(state, tmp2, &val, arena);
+                res = obj2ast_pattern(state, tmp2, &val, "kwd_patterns", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -17554,7 +17621,7 @@ obj2ast_pattern(struct ast_state *state, PyObject* obj, pattern_ty* out,
             if (_Py_EnterRecursiveCall(" while traversing 'MatchStar' node")) {
                 goto failed;
             }
-            res = obj2ast_identifier(state, tmp, &name, arena);
+            res = obj2ast_identifier(state, tmp, &name, "name", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -17585,7 +17652,7 @@ obj2ast_pattern(struct ast_state *state, PyObject* obj, pattern_ty* out,
             if (_Py_EnterRecursiveCall(" while traversing 'MatchAs' node")) {
                 goto failed;
             }
-            res = obj2ast_pattern(state, tmp, &pattern, arena);
+            res = obj2ast_pattern(state, tmp, &pattern, "pattern", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -17602,7 +17669,7 @@ obj2ast_pattern(struct ast_state *state, PyObject* obj, pattern_ty* out,
             if (_Py_EnterRecursiveCall(" while traversing 'MatchAs' node")) {
                 goto failed;
             }
-            res = obj2ast_identifier(state, tmp, &name, arena);
+            res = obj2ast_identifier(state, tmp, &name, "name", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -17646,7 +17713,7 @@ obj2ast_pattern(struct ast_state *state, PyObject* obj, pattern_ty* out,
                 if (_Py_EnterRecursiveCall(" while traversing 'MatchOr' node")) {
                     goto failed;
                 }
-                res = obj2ast_pattern(state, tmp2, &val, arena);
+                res = obj2ast_pattern(state, tmp2, &val, "patterns", arena);
                 _Py_LeaveRecursiveCall();
                 Py_DECREF(tmp2);
                 if (res != 0) goto failed;
@@ -17672,7 +17739,7 @@ obj2ast_pattern(struct ast_state *state, PyObject* obj, pattern_ty* out,
 
 int
 obj2ast_type_ignore(struct ast_state *state, PyObject* obj, type_ignore_ty*
-                    out, PyArena* arena)
+                    out, const char* field, PyArena* arena)
 {
     int isinstance;
 
@@ -17683,6 +17750,15 @@ obj2ast_type_ignore(struct ast_state *state, PyObject* obj, type_ignore_ty*
         *out = NULL;
         return 0;
     }
+    tp = state->type_ignore_type;
+    isinstance = PyObject_IsInstance(obj, tp);
+    if (isinstance == -1) {
+        return 1;
+    }
+    if (!isinstance && field != NULL) {
+        PyErr_Format(PyExc_TypeError, "field '%s' was expecting node of type 'type_ignore', got '%s'", field, _PyType_Name(Py_TYPE(obj)));
+        return 1;
+    }
     tp = state->TypeIgnore_type;
     isinstance = PyObject_IsInstance(obj, tp);
     if (isinstance == -1) {
@@ -17704,7 +17780,7 @@ obj2ast_type_ignore(struct ast_state *state, PyObject* obj, type_ignore_ty*
             if (_Py_EnterRecursiveCall(" while traversing 'TypeIgnore' node")) {
                 goto failed;
             }
-            res = obj2ast_int(state, tmp, &lineno, arena);
+            res = obj2ast_int(state, tmp, &lineno, "lineno", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -17721,7 +17797,7 @@ obj2ast_type_ignore(struct ast_state *state, PyObject* obj, type_ignore_ty*
             if (_Py_EnterRecursiveCall(" while traversing 'TypeIgnore' node")) {
                 goto failed;
             }
-            res = obj2ast_string(state, tmp, &tag, arena);
+            res = obj2ast_string(state, tmp, &tag, "tag", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -17739,7 +17815,7 @@ obj2ast_type_ignore(struct ast_state *state, PyObject* obj, type_ignore_ty*
 
 int
 obj2ast_type_param(struct ast_state *state, PyObject* obj, type_param_ty* out,
-                   PyArena* arena)
+                   const char* field, PyArena* arena)
 {
     int isinstance;
 
@@ -17754,6 +17830,15 @@ obj2ast_type_param(struct ast_state *state, PyObject* obj, type_param_ty* out,
         *out = NULL;
         return 0;
     }
+    tp = state->type_param_type;
+    isinstance = PyObject_IsInstance(obj, tp);
+    if (isinstance == -1) {
+        return 1;
+    }
+    if (!isinstance && field != NULL) {
+        PyErr_Format(PyExc_TypeError, "field '%s' was expecting node of type 'type_param', got '%s'", field, _PyType_Name(Py_TYPE(obj)));
+        return 1;
+    }
     if (PyObject_GetOptionalAttr(obj, state->lineno, &tmp) < 0) {
         return -1;
     }
@@ -17766,7 +17851,7 @@ obj2ast_type_param(struct ast_state *state, PyObject* obj, type_param_ty* out,
         if (_Py_EnterRecursiveCall(" while traversing 'type_param' node")) {
             goto failed;
         }
-        res = obj2ast_int(state, tmp, &lineno, arena);
+        res = obj2ast_int(state, tmp, &lineno, "lineno", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -17783,7 +17868,7 @@ obj2ast_type_param(struct ast_state *state, PyObject* obj, type_param_ty* out,
         if (_Py_EnterRecursiveCall(" while traversing 'type_param' node")) {
             goto failed;
         }
-        res = obj2ast_int(state, tmp, &col_offset, arena);
+        res = obj2ast_int(state, tmp, &col_offset, "col_offset", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -17800,7 +17885,7 @@ obj2ast_type_param(struct ast_state *state, PyObject* obj, type_param_ty* out,
         if (_Py_EnterRecursiveCall(" while traversing 'type_param' node")) {
             goto failed;
         }
-        res = obj2ast_int(state, tmp, &end_lineno, arena);
+        res = obj2ast_int(state, tmp, &end_lineno, "end_lineno", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -17817,7 +17902,7 @@ obj2ast_type_param(struct ast_state *state, PyObject* obj, type_param_ty* out,
         if (_Py_EnterRecursiveCall(" while traversing 'type_param' node")) {
             goto failed;
         }
-        res = obj2ast_int(state, tmp, &end_col_offset, arena);
+        res = obj2ast_int(state, tmp, &end_col_offset, "end_col_offset", arena);
         _Py_LeaveRecursiveCall();
         if (res != 0) goto failed;
         Py_CLEAR(tmp);
@@ -17844,7 +17929,7 @@ obj2ast_type_param(struct ast_state *state, PyObject* obj, type_param_ty* out,
             if (_Py_EnterRecursiveCall(" while traversing 'TypeVar' node")) {
                 goto failed;
             }
-            res = obj2ast_identifier(state, tmp, &name, arena);
+            res = obj2ast_identifier(state, tmp, &name, "name", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -17861,7 +17946,7 @@ obj2ast_type_param(struct ast_state *state, PyObject* obj, type_param_ty* out,
             if (_Py_EnterRecursiveCall(" while traversing 'TypeVar' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &bound, arena);
+            res = obj2ast_expr(state, tmp, &bound, "bound", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -17878,7 +17963,8 @@ obj2ast_type_param(struct ast_state *state, PyObject* obj, type_param_ty* out,
             if (_Py_EnterRecursiveCall(" while traversing 'TypeVar' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &default_value, arena);
+            res = obj2ast_expr(state, tmp, &default_value, "default_value",
+                               arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -17909,7 +17995,7 @@ obj2ast_type_param(struct ast_state *state, PyObject* obj, type_param_ty* out,
             if (_Py_EnterRecursiveCall(" while traversing 'ParamSpec' node")) {
                 goto failed;
             }
-            res = obj2ast_identifier(state, tmp, &name, arena);
+            res = obj2ast_identifier(state, tmp, &name, "name", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -17926,7 +18012,8 @@ obj2ast_type_param(struct ast_state *state, PyObject* obj, type_param_ty* out,
             if (_Py_EnterRecursiveCall(" while traversing 'ParamSpec' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &default_value, arena);
+            res = obj2ast_expr(state, tmp, &default_value, "default_value",
+                               arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -17957,7 +18044,7 @@ obj2ast_type_param(struct ast_state *state, PyObject* obj, type_param_ty* out,
             if (_Py_EnterRecursiveCall(" while traversing 'TypeVarTuple' node")) {
                 goto failed;
             }
-            res = obj2ast_identifier(state, tmp, &name, arena);
+            res = obj2ast_identifier(state, tmp, &name, "name", arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -17974,7 +18061,8 @@ obj2ast_type_param(struct ast_state *state, PyObject* obj, type_param_ty* out,
             if (_Py_EnterRecursiveCall(" while traversing 'TypeVarTuple' node")) {
                 goto failed;
             }
-            res = obj2ast_expr(state, tmp, &default_value, arena);
+            res = obj2ast_expr(state, tmp, &default_value, "default_value",
+                               arena);
             _Py_LeaveRecursiveCall();
             if (res != 0) goto failed;
             Py_CLEAR(tmp);
@@ -18506,7 +18594,7 @@ mod_ty PyAST_obj2mod(PyObject* ast, PyArena* arena, int mode)
     }
 
     mod_ty res = NULL;
-    if (obj2ast_mod(state, ast, &res, arena) != 0)
+    if (obj2ast_mod(state, ast, &res, NULL, arena) != 0)
         return NULL;
     else
         return res;