diff --git a/Lib/test/test_ast.py b/Lib/test/test_ast.py
index 64fcb02309de77..0afc095cac2379 100644
--- a/Lib/test/test_ast.py
+++ b/Lib/test/test_ast.py
@@ -956,7 +956,7 @@ def test_invalid_identifier(self):
         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)):
@@ -1178,6 +1178,31 @@ def test_none_checks(self) -> None:
         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")
+
+
 class ASTHelpers_Test(unittest.TestCase):
     maxDiff = None
 
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
index 00000000000000..8b606c4335e033
--- /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 4bb337349748cf..8a348dcd7c66d4 100755
--- a/Parser/asdl_c.py
+++ b/Parser/asdl_c.py
@@ -480,7 +480,7 @@ def visitField(self, sum):
 
 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
@@ -504,7 +504,7 @@ def recursive_call(self, node, level):
     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)
@@ -540,6 +540,18 @@ def simpleSum(self, sum, name):
     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)
@@ -552,6 +564,7 @@ def complexSum(self, sum, name):
         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:
@@ -586,7 +599,7 @@ def visitSum(self, sum, name):
     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:
@@ -687,8 +700,8 @@ def visitField(self, field, name, sum=None, prod=None, depth=0):
             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)
@@ -702,8 +715,8 @@ def visitField(self, field, name, sum=None, prod=None, depth=0):
             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)
@@ -1022,7 +1035,9 @@ def visitModule(self, mod):
 
 /* 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;
@@ -1039,7 +1054,9 @@ def visitModule(self, mod):
     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;
@@ -1049,29 +1066,29 @@ def visitModule(self, mod):
     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;
     }
 
@@ -1443,7 +1460,7 @@ class PartingShots(StaticVisitor):
     }
 
     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 699e1c157c591c..0d31e059c03726 100644
--- a/Python/Python-ast.c
+++ b/Python/Python-ast.c
@@ -1070,7 +1070,9 @@ static PyObject* ast2obj_int(struct ast_state *Py_UNUSED(state), struct validato
 
 /* 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;
@@ -1087,7 +1089,9 @@ 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;
@@ -1097,29 +1101,29 @@ 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;
     }
 
@@ -1943,43 +1947,52 @@ init_types(struct ast_state *state)
 }
 
 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,
@@ -5802,7 +5815,8 @@ ast2obj_type_param(struct ast_state *state, struct validator *vstate, void* _o)
 
 
 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;
 
@@ -5813,6 +5827,15 @@ 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) {
@@ -5848,7 +5871,7 @@ 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;
@@ -5886,7 +5909,7 @@ 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;
@@ -5936,7 +5959,7 @@ 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;
@@ -5972,7 +5995,7 @@ 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);
@@ -6016,7 +6039,7 @@ 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;
@@ -6040,7 +6063,7 @@ 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);
@@ -6057,8 +6080,8 @@ 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;
 
@@ -6073,6 +6096,15 @@ 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;
     }
@@ -6085,7 +6117,7 @@ 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);
@@ -6102,7 +6134,7 @@ 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);
@@ -6119,7 +6151,7 @@ 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);
@@ -6136,7 +6168,7 @@ 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);
@@ -6167,7 +6199,7 @@ 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);
@@ -6184,7 +6216,7 @@ 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);
@@ -6215,7 +6247,7 @@ 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;
@@ -6253,7 +6285,7 @@ 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;
@@ -6277,7 +6309,7 @@ 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);
@@ -6294,7 +6326,8 @@ 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);
@@ -6325,7 +6358,7 @@ 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;
@@ -6370,7 +6403,7 @@ 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);
@@ -6387,7 +6420,7 @@ 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);
@@ -6418,7 +6451,7 @@ 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;
@@ -6456,7 +6489,7 @@ 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;
@@ -6480,7 +6513,7 @@ 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);
@@ -6497,7 +6530,8 @@ 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);
@@ -6528,7 +6562,7 @@ 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;
@@ -6572,7 +6606,7 @@ 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);
@@ -6603,7 +6637,7 @@ 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;
@@ -6641,7 +6675,7 @@ 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;
@@ -6679,7 +6713,7 @@ 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;
@@ -6717,7 +6751,7 @@ 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;
@@ -6755,7 +6789,7 @@ 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;
@@ -6793,7 +6827,7 @@ 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);
@@ -6837,7 +6871,7 @@ 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;
@@ -6890,7 +6924,7 @@ 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;
@@ -6914,7 +6948,7 @@ 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);
@@ -6931,7 +6965,8 @@ 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);
@@ -6963,7 +6998,7 @@ 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);
@@ -6994,7 +7029,7 @@ 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;
@@ -7018,7 +7053,7 @@ 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);
@@ -7050,7 +7085,7 @@ 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);
@@ -7067,7 +7102,7 @@ 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);
@@ -7084,7 +7119,7 @@ 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);
@@ -7117,7 +7152,7 @@ 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);
@@ -7134,7 +7169,7 @@ 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);
@@ -7151,7 +7186,7 @@ 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);
@@ -7168,7 +7203,7 @@ 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);
@@ -7202,7 +7237,7 @@ 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);
@@ -7219,7 +7254,7 @@ 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);
@@ -7250,7 +7285,7 @@ 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;
@@ -7288,7 +7323,7 @@ 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;
@@ -7312,7 +7347,8 @@ 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);
@@ -7346,7 +7382,7 @@ 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);
@@ -7363,7 +7399,7 @@ 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);
@@ -7394,7 +7430,7 @@ 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;
@@ -7432,7 +7468,7 @@ 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;
@@ -7456,7 +7492,8 @@ 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);
@@ -7489,7 +7526,7 @@ 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);
@@ -7520,7 +7557,7 @@ 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;
@@ -7558,7 +7595,7 @@ 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;
@@ -7597,7 +7634,7 @@ 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);
@@ -7628,7 +7665,7 @@ 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;
@@ -7666,7 +7703,7 @@ 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;
@@ -7719,7 +7756,7 @@ 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;
@@ -7757,7 +7794,7 @@ 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;
@@ -7781,7 +7818,8 @@ 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);
@@ -7827,7 +7865,7 @@ 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;
@@ -7865,7 +7903,7 @@ 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;
@@ -7889,7 +7927,8 @@ 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);
@@ -7920,7 +7959,7 @@ 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);
@@ -7951,7 +7990,7 @@ 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;
@@ -7989,7 +8028,7 @@ 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);
@@ -8006,7 +8045,7 @@ 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);
@@ -8053,7 +8092,7 @@ 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;
@@ -8091,7 +8130,7 @@ 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;
@@ -8129,7 +8168,7 @@ 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;
@@ -8167,7 +8206,7 @@ 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;
@@ -8221,7 +8260,7 @@ 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;
@@ -8259,7 +8298,7 @@ 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;
@@ -8297,7 +8336,7 @@ 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;
@@ -8335,7 +8374,7 @@ 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;
@@ -8373,7 +8412,7 @@ 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);
@@ -8390,7 +8429,7 @@ 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);
@@ -8434,7 +8473,7 @@ 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;
@@ -8473,7 +8512,7 @@ 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);
@@ -8504,7 +8543,7 @@ 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;
@@ -8528,7 +8567,7 @@ 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);
@@ -8572,7 +8611,7 @@ 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;
@@ -8623,7 +8662,7 @@ 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;
@@ -8660,7 +8699,7 @@ 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);
@@ -8714,8 +8753,8 @@ 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;
 
@@ -8730,6 +8769,15 @@ 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;
     }
@@ -8742,7 +8790,7 @@ 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);
@@ -8759,7 +8807,7 @@ 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);
@@ -8776,7 +8824,7 @@ 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);
@@ -8793,7 +8841,7 @@ 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);
@@ -8819,7 +8867,7 @@ 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);
@@ -8850,7 +8898,7 @@ 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;
@@ -8888,7 +8936,7 @@ 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);
@@ -8905,7 +8953,7 @@ 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);
@@ -8937,7 +8985,7 @@ 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);
@@ -8954,7 +9002,7 @@ 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);
@@ -8971,7 +9019,7 @@ 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);
@@ -9002,7 +9050,7 @@ 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);
@@ -9019,7 +9067,7 @@ 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);
@@ -9050,7 +9098,7 @@ 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);
@@ -9067,7 +9115,7 @@ 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);
@@ -9099,7 +9147,7 @@ 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);
@@ -9116,7 +9164,7 @@ 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);
@@ -9133,7 +9181,7 @@ 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);
@@ -9178,7 +9226,7 @@ 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;
@@ -9216,7 +9264,7 @@ 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;
@@ -9267,7 +9315,7 @@ 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;
@@ -9305,7 +9353,7 @@ 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);
@@ -9336,7 +9384,7 @@ 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;
@@ -9374,7 +9422,7 @@ 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);
@@ -9405,7 +9453,7 @@ 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;
@@ -9444,7 +9492,7 @@ 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);
@@ -9461,7 +9509,7 @@ 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);
@@ -9492,7 +9540,7 @@ 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;
@@ -9530,7 +9578,7 @@ 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);
@@ -9561,7 +9609,7 @@ 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;
@@ -9598,7 +9646,7 @@ 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);
@@ -9628,7 +9676,7 @@ 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);
@@ -9658,7 +9706,7 @@ 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);
@@ -9690,7 +9738,7 @@ 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);
@@ -9721,7 +9769,7 @@ 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;
@@ -9759,7 +9807,7 @@ 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;
@@ -9798,7 +9846,7 @@ 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);
@@ -9829,7 +9877,7 @@ 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;
@@ -9867,7 +9915,7 @@ 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;
@@ -9906,7 +9954,7 @@ 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);
@@ -9923,7 +9971,7 @@ 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);
@@ -9940,7 +9988,7 @@ 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);
@@ -9985,7 +10033,7 @@ 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;
@@ -10023,7 +10071,7 @@ 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);
@@ -10040,7 +10088,7 @@ 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);
@@ -10072,7 +10120,7 @@ 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);
@@ -10089,7 +10137,7 @@ 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);
@@ -10106,7 +10154,7 @@ 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);
@@ -10138,7 +10186,7 @@ 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);
@@ -10155,7 +10203,7 @@ 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);
@@ -10172,7 +10220,7 @@ 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);
@@ -10203,7 +10251,7 @@ 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);
@@ -10220,7 +10268,7 @@ 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);
@@ -10251,7 +10299,7 @@ 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);
@@ -10268,7 +10316,7 @@ 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);
@@ -10313,7 +10361,7 @@ 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;
@@ -10337,7 +10385,7 @@ 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);
@@ -10382,7 +10430,7 @@ 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;
@@ -10406,7 +10454,7 @@ 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);
@@ -10438,7 +10486,7 @@ 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);
@@ -10455,7 +10503,7 @@ 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);
@@ -10472,7 +10520,7 @@ 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);
@@ -10491,7 +10539,7 @@ 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;
 
@@ -10525,8 +10573,8 @@ 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;
 
@@ -10553,7 +10601,7 @@ 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;
 
@@ -10667,8 +10715,8 @@ 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;
 
@@ -10710,8 +10758,8 @@ 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;
 
@@ -10802,7 +10850,7 @@ 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;
@@ -10822,7 +10870,7 @@ 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);
@@ -10839,7 +10887,7 @@ 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);
@@ -10870,7 +10918,7 @@ 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;
@@ -10894,7 +10942,7 @@ 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);
@@ -10909,7 +10957,7 @@ obj2ast_comprehension(struct ast_state *state, PyObject* obj, comprehension_ty*
 
 int
 obj2ast_excepthandler(struct ast_state *state, PyObject* obj, excepthandler_ty*
-                      out, PyArena* arena)
+                      out, const char* field, PyArena* arena)
 {
     int isinstance;
 
@@ -10924,6 +10972,15 @@ 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;
     }
@@ -10936,7 +10993,7 @@ 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);
@@ -10953,7 +11010,7 @@ 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);
@@ -10970,7 +11027,7 @@ 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);
@@ -10987,7 +11044,7 @@ 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);
@@ -11014,7 +11071,7 @@ 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);
@@ -11031,7 +11088,7 @@ 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);
@@ -11062,7 +11119,7 @@ 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;
@@ -11088,7 +11145,7 @@ 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;
@@ -11125,7 +11182,7 @@ 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;
@@ -11163,7 +11220,7 @@ 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;
@@ -11187,7 +11244,7 @@ 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);
@@ -11218,7 +11275,7 @@ 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;
@@ -11256,7 +11313,7 @@ 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;
@@ -11280,7 +11337,7 @@ 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);
@@ -11311,7 +11368,7 @@ 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;
@@ -11333,7 +11390,8 @@ obj2ast_arguments(struct ast_state *state, PyObject* obj, arguments_ty* out,
 }
 
 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;
@@ -11356,7 +11414,7 @@ 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);
@@ -11373,7 +11431,7 @@ 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);
@@ -11390,7 +11448,7 @@ 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);
@@ -11407,7 +11465,7 @@ 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);
@@ -11424,7 +11482,7 @@ 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);
@@ -11441,7 +11499,7 @@ 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);
@@ -11458,7 +11516,7 @@ 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);
@@ -11473,8 +11531,8 @@ obj2ast_arg(struct ast_state *state, PyObject* obj, arg_ty* out, PyArena* arena)
 }
 
 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;
@@ -11496,7 +11554,7 @@ 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);
@@ -11513,7 +11571,7 @@ 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);
@@ -11530,7 +11588,7 @@ 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);
@@ -11547,7 +11605,7 @@ 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);
@@ -11564,7 +11622,7 @@ 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);
@@ -11581,7 +11639,7 @@ 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);
@@ -11596,8 +11654,8 @@ obj2ast_keyword(struct ast_state *state, PyObject* obj, keyword_ty* out,
 }
 
 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;
@@ -11619,7 +11677,7 @@ 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);
@@ -11636,7 +11694,7 @@ 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);
@@ -11653,7 +11711,7 @@ 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);
@@ -11670,7 +11728,7 @@ 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);
@@ -11687,7 +11745,7 @@ 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);
@@ -11704,7 +11762,7 @@ 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);
@@ -11720,7 +11778,7 @@ obj2ast_alias(struct ast_state *state, PyObject* obj, alias_ty* out, PyArena*
 
 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;
@@ -11738,7 +11796,7 @@ 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);
@@ -11755,7 +11813,7 @@ 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);
@@ -11770,7 +11828,7 @@ obj2ast_withitem(struct ast_state *state, PyObject* obj, withitem_ty* out,
 
 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;
@@ -11789,7 +11847,7 @@ 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);
@@ -11806,7 +11864,7 @@ 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);
@@ -11837,7 +11895,7 @@ 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;
@@ -11858,8 +11916,8 @@ obj2ast_match_case(struct ast_state *state, PyObject* obj, match_case_ty* out,
 }
 
 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;
 
@@ -11874,6 +11932,15 @@ 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;
     }
@@ -11886,7 +11953,7 @@ 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);
@@ -11903,7 +11970,7 @@ 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);
@@ -11920,7 +11987,7 @@ 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);
@@ -11937,7 +12004,7 @@ 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);
@@ -11962,7 +12029,7 @@ 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);
@@ -11992,7 +12059,7 @@ 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);
@@ -12036,7 +12103,7 @@ 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;
@@ -12089,7 +12156,7 @@ 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;
@@ -12127,7 +12194,7 @@ 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;
@@ -12151,7 +12218,7 @@ 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);
@@ -12184,7 +12251,7 @@ 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);
@@ -12215,7 +12282,7 @@ 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;
@@ -12253,7 +12320,7 @@ 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;
@@ -12291,7 +12358,7 @@ 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;
@@ -12329,7 +12396,7 @@ 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);
@@ -12360,7 +12427,7 @@ 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);
@@ -12377,7 +12444,7 @@ 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);
@@ -12421,7 +12488,7 @@ 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;
@@ -12447,7 +12514,7 @@ 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;
 
@@ -12458,6 +12525,15 @@ 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) {
@@ -12479,7 +12555,7 @@ 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);
@@ -12496,7 +12572,7 @@ 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);
@@ -12514,7 +12590,7 @@ 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;
 
@@ -12529,6 +12605,15 @@ 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;
     }
@@ -12541,7 +12626,7 @@ 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);
@@ -12558,7 +12643,7 @@ 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);
@@ -12575,7 +12660,7 @@ 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);
@@ -12592,7 +12677,7 @@ 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);
@@ -12618,7 +12703,7 @@ 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);
@@ -12635,7 +12720,7 @@ 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);
@@ -12665,7 +12750,7 @@ 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);
@@ -12695,7 +12780,7 @@ 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);
@@ -13204,7 +13289,7 @@ 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;