bpo-38113: Update the Python-ast.c generator to PEP384 (gh-15957)

Summary: This mostly migrates Python-ast.c to PEP384 and removes all statics from the whole file. This modifies the generator itself that generates the Python-ast.c. It leaves in the usage of _PyObject_LookupAttr even though it's not fully PEP384 compatible (this could always be shimmed in by anyone who needs it).

1 files changed, 187 insertions, 113 deletions

diff --git a/Parser/asdl_c.py b/Parser/asdl_c.py
index 9b18bb4..85d96a3 100755
--- a/Parser/asdl_c.py
+++ b/Parser/asdl_c.py
@@ -78,14 +78,18 @@ class EmitVisitor(asdl.VisitorBase):
     def __init__(self, file):
         self.file = file
         self.identifiers = set()
+        self.singletons = set()
+        self.types = set()
         super(EmitVisitor, self).__init__()
 
     def emit_identifier(self, name):
-        name = str(name)
-        if name in self.identifiers:
-            return
-        self.emit("_Py_IDENTIFIER(%s);" % name, 0)
-        self.identifiers.add(name)
+        self.identifiers.add(str(name))
+
+    def emit_singleton(self, name):
+        self.singletons.add(str(name))
+
+    def emit_type(self, name):
+        self.types.add(str(name))
 
     def emit(self, s, depth, reflow=True):
         # XXX reflow long lines?
@@ -392,7 +396,7 @@ class Obj2ModVisitor(PickleVisitor):
         self.funcHeader(name)
         for t in sum.types:
             line = ("isinstance = PyObject_IsInstance(obj, "
-                    "(PyObject *)%s_type);")
+                    "astmodulestate_global->%s_type);")
             self.emit(line % (t.name,), 1)
             self.emit("if (isinstance == -1) {", 1)
             self.emit("return 1;", 2)
@@ -409,6 +413,7 @@ class Obj2ModVisitor(PickleVisitor):
     def complexSum(self, sum, name):
         self.funcHeader(name)
         self.emit("PyObject *tmp = NULL;", 1)
+        self.emit("PyObject *tp;", 1)
         for a in sum.attributes:
             self.visitAttributeDeclaration(a, name, sum=sum)
         self.emit("", 0)
@@ -420,8 +425,8 @@ class Obj2ModVisitor(PickleVisitor):
         for a in sum.attributes:
             self.visitField(a, name, sum=sum, depth=1)
         for t in sum.types:
-            line = "isinstance = PyObject_IsInstance(obj, (PyObject*)%s_type);"
-            self.emit(line % (t.name,), 1)
+            self.emit("tp = astmodulestate_global->%s_type;" % (t.name,), 1)
+            self.emit("isinstance = PyObject_IsInstance(obj, tp);", 1)
             self.emit("if (isinstance == -1) {", 1)
             self.emit("return 1;", 2)
             self.emit("}", 1)
@@ -497,7 +502,8 @@ class Obj2ModVisitor(PickleVisitor):
 
     def visitField(self, field, name, sum=None, prod=None, depth=0):
         ctype = get_c_type(field.type)
-        self.emit("if (_PyObject_LookupAttrId(obj, &PyId_%s, &tmp) < 0) {" % field.name, depth)
+        line = "if (_PyObject_LookupAttr(obj, astmodulestate_global->%s, &tmp) < 0) {"
+        self.emit(line % field.name, depth)
         self.emit("return 1;", depth+1)
         self.emit("}", depth)
         if not field.opt:
@@ -524,7 +530,7 @@ class Obj2ModVisitor(PickleVisitor):
             self.emit("Py_ssize_t i;", depth+1)
             self.emit("if (!PyList_Check(tmp)) {", depth+1)
             self.emit("PyErr_Format(PyExc_TypeError, \"%s field \\\"%s\\\" must "
-                      "be a list, not a %%.200s\", tmp->ob_type->tp_name);" %
+                      "be a list, not a %%.200s\", _PyType_Name(Py_TYPE(tmp)));" %
                       (name, field.name),
                       depth+2, reflow=False)
             self.emit("goto failed;", depth+2)
@@ -574,7 +580,7 @@ class MarshalPrototypeVisitor(PickleVisitor):
 class PyTypesDeclareVisitor(PickleVisitor):
 
     def visitProduct(self, prod, name):
-        self.emit("static PyTypeObject *%s_type;" % name, 0)
+        self.emit_type("%s_type" % name)
         self.emit("static PyObject* ast2obj_%s(void*);" % name, 0)
         if prod.attributes:
             for a in prod.attributes:
@@ -592,7 +598,7 @@ class PyTypesDeclareVisitor(PickleVisitor):
             self.emit("};", 0)
 
     def visitSum(self, sum, name):
-        self.emit("static PyTypeObject *%s_type;" % name, 0)
+        self.emit_type("%s_type" % name)
         if sum.attributes:
             for a in sum.attributes:
                 self.emit_identifier(a.name)
@@ -603,17 +609,13 @@ class PyTypesDeclareVisitor(PickleVisitor):
         ptype = "void*"
         if is_simple(sum):
             ptype = get_c_type(name)
-            tnames = []
             for t in sum.types:
-                tnames.append(str(t.name)+"_singleton")
-            tnames = ", *".join(tnames)
-            self.emit("static PyObject *%s;" % tnames, 0)
+                self.emit_singleton("%s_singleton" % t.name)
         self.emit("static PyObject* ast2obj_%s(%s);" % (name, ptype), 0)
         for t in sum.types:
             self.visitConstructor(t, name)
 
     def visitConstructor(self, cons, name):
-        self.emit("static PyTypeObject *%s_type;" % cons.name, 0)
         if cons.fields:
             for t in cons.fields:
                 self.emit_identifier(t.name)
@@ -626,8 +628,6 @@ class PyTypesVisitor(PickleVisitor):
 
     def visitModule(self, mod):
         self.emit("""
-_Py_IDENTIFIER(_fields);
-_Py_IDENTIFIER(_attributes);
 
 typedef struct {
     PyObject_HEAD
@@ -663,7 +663,7 @@ ast_type_init(PyObject *self, PyObject *args, PyObject *kw)
     Py_ssize_t i, numfields = 0;
     int res = -1;
     PyObject *key, *value, *fields;
-    if (_PyObject_LookupAttrId((PyObject*)Py_TYPE(self), &PyId__fields, &fields) < 0) {
+    if (_PyObject_LookupAttr((PyObject*)Py_TYPE(self), astmodulestate_global->_fields, &fields) < 0) {
         goto cleanup;
     }
     if (fields) {
@@ -676,7 +676,7 @@ ast_type_init(PyObject *self, PyObject *args, PyObject *kw)
     if (numfields < PyTuple_GET_SIZE(args)) {
         PyErr_Format(PyExc_TypeError, "%.400s constructor takes at most "
                      "%zd positional argument%s",
-                     Py_TYPE(self)->tp_name,
+                     _PyType_Name(Py_TYPE(self)),
                      numfields, numfields == 1 ? "" : "s");
         res = -1;
         goto cleanup;
@@ -710,9 +710,8 @@ ast_type_init(PyObject *self, PyObject *args, PyObject *kw)
 static PyObject *
 ast_type_reduce(PyObject *self, PyObject *unused)
 {
-    _Py_IDENTIFIER(__dict__);
     PyObject *dict;
-    if (_PyObject_LookupAttrId(self, &PyId___dict__, &dict) < 0) {
+    if (_PyObject_LookupAttr(self, astmodulestate_global->__dict__, &dict) < 0) {
         return NULL;
     }
     if (dict) {
@@ -731,54 +730,33 @@ static PyGetSetDef ast_type_getsets[] = {
     {NULL}
 };
 
-static PyTypeObject AST_type = {
-    PyVarObject_HEAD_INIT(&PyType_Type, 0)
+static PyType_Slot AST_type_slots[] = {
+    {Py_tp_dealloc, ast_dealloc},
+    {Py_tp_getattro, PyObject_GenericGetAttr},
+    {Py_tp_setattro, PyObject_GenericSetAttr},
+    {Py_tp_traverse, ast_traverse},
+    {Py_tp_clear, ast_clear},
+    {Py_tp_methods, ast_type_methods},
+    {Py_tp_getset, ast_type_getsets},
+    {Py_tp_init, ast_type_init},
+    {Py_tp_alloc, PyType_GenericAlloc},
+    {Py_tp_new, PyType_GenericNew},
+    {Py_tp_free, PyType_GenericNew},
+    {Py_tp_free, PyObject_GC_Del},
+    {0, 0},
+};
+
+static PyType_Spec AST_type_spec = {
     "_ast.AST",
     sizeof(AST_object),
     0,
-    (destructor)ast_dealloc, /* tp_dealloc */
-    0,                       /* tp_vectorcall_offset */
-    0,                       /* tp_getattr */
-    0,                       /* tp_setattr */
-    0,                       /* tp_as_async */
-    0,                       /* tp_repr */
-    0,                       /* tp_as_number */
-    0,                       /* tp_as_sequence */
-    0,                       /* tp_as_mapping */
-    0,                       /* tp_hash */
-    0,                       /* tp_call */
-    0,                       /* tp_str */
-    PyObject_GenericGetAttr, /* tp_getattro */
-    PyObject_GenericSetAttr, /* tp_setattro */
-    0,                       /* tp_as_buffer */
-    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HAVE_GC, /* tp_flags */
-    0,                       /* tp_doc */
-    (traverseproc)ast_traverse, /* tp_traverse */
-    (inquiry)ast_clear,      /* tp_clear */
-    0,                       /* tp_richcompare */
-    0,                       /* tp_weaklistoffset */
-    0,                       /* tp_iter */
-    0,                       /* tp_iternext */
-    ast_type_methods,        /* tp_methods */
-    0,                       /* tp_members */
-    ast_type_getsets,        /* tp_getset */
-    0,                       /* tp_base */
-    0,                       /* tp_dict */
-    0,                       /* tp_descr_get */
-    0,                       /* tp_descr_set */
-    offsetof(AST_object, dict),/* tp_dictoffset */
-    (initproc)ast_type_init, /* tp_init */
-    PyType_GenericAlloc,     /* tp_alloc */
-    PyType_GenericNew,       /* tp_new */
-    PyObject_GC_Del,         /* tp_free */
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HAVE_GC,
+    AST_type_slots
 };
 
-
-static PyTypeObject *
-make_type(const char *type, PyTypeObject *base, const char * const *fields, int num_fields)
+static PyObject *
+make_type(const char *type, PyObject* base, const char* const* fields, int num_fields)
 {
-    _Py_IDENTIFIER(__module__);
-    _Py_IDENTIFIER(_ast);
     PyObject *fnames, *result;
     int i;
     fnames = PyTuple_New(num_fields);
@@ -793,15 +771,15 @@ make_type(const char *type, PyTypeObject *base, const char * const *fields, int
     }
     result = PyObject_CallFunction((PyObject*)&PyType_Type, "s(O){OOOO}",
                     type, base,
-                    _PyUnicode_FromId(&PyId__fields), fnames,
-                    _PyUnicode_FromId(&PyId___module__),
-                    _PyUnicode_FromId(&PyId__ast));
+                    astmodulestate_global->_fields, fnames,
+                    astmodulestate_global->__module__,
+                    astmodulestate_global->_ast);
     Py_DECREF(fnames);
-    return (PyTypeObject*)result;
+    return result;
 }
 
 static int
-add_attributes(PyTypeObject *type, const char * const *attrs, int num_fields)
+add_attributes(PyObject *type, const char * const *attrs, int num_fields)
 {
     int i, result;
     PyObject *s, *l = PyTuple_New(num_fields);
@@ -815,7 +793,7 @@ add_attributes(PyTypeObject *type, const char * const *attrs, int num_fields)
         }
         PyTuple_SET_ITEM(l, i, s);
     }
-    result = _PyObject_SetAttrId((PyObject*)type, &PyId__attributes, l) >= 0;
+    result = PyObject_SetAttr(type, astmodulestate_global->_attributes, l) >= 0;
     Py_DECREF(l);
     return result;
 }
@@ -921,14 +899,11 @@ static int obj2ast_int(PyObject* obj, int* out, PyArena* arena)
 
 static int add_ast_fields(void)
 {
-    PyObject *empty_tuple, *d;
-    if (PyType_Ready(&AST_type) < 0)
-        return -1;
-    d = AST_type.tp_dict;
+    PyObject *empty_tuple;
     empty_tuple = PyTuple_New(0);
     if (!empty_tuple ||
-        _PyDict_SetItemId(d, &PyId__fields, empty_tuple) < 0 ||
-        _PyDict_SetItemId(d, &PyId__attributes, empty_tuple) < 0) {
+        PyObject_SetAttrString(astmodulestate_global->AST_type, "_fields", empty_tuple) < 0 ||
+        PyObject_SetAttrString(astmodulestate_global->AST_type, "_attributes", empty_tuple) < 0) {
         Py_XDECREF(empty_tuple);
         return -1;
     }
@@ -940,12 +915,22 @@ static int add_ast_fields(void)
 
         self.emit("static int init_types(void)",0)
         self.emit("{", 0)
-        self.emit("static int initialized;", 1)
-        self.emit("if (initialized) return 1;", 1)
+        self.emit("PyObject *m;", 1)
+        self.emit("if (PyState_FindModule(&_astmodule) == NULL) {", 1)
+        self.emit("m = PyModule_Create(&_astmodule);", 2)
+        self.emit("if (!m) return 0;", 2)
+        self.emit("PyState_AddModule(m, &_astmodule);", 2)
+        self.emit("}", 1)
+        self.emit("astmodulestate *state = astmodulestate_global;", 1)
+        self.emit("if (state->initialized) return 1;", 1)
+        self.emit("if (init_identifiers() < 0) return 0;", 1)
+        self.emit("state->AST_type = PyType_FromSpec(&AST_type_spec);", 1)
+        self.emit("if (!state->AST_type) return 0;", 1)
+        self.emit("((PyTypeObject*)state->AST_type)->tp_dictoffset = offsetof(AST_object, dict);", 1)
         self.emit("if (add_ast_fields() < 0) return 0;", 1)
         for dfn in mod.dfns:
             self.visit(dfn)
-        self.emit("initialized = 1;", 1)
+        self.emit("state->initialized = 1;", 1)
         self.emit("return 1;", 1);
         self.emit("}", 0)
 
@@ -954,24 +939,27 @@ static int add_ast_fields(void)
             fields = name+"_fields"
         else:
             fields = "NULL"
-        self.emit('%s_type = make_type("%s", &AST_type, %s, %d);' %
+        self.emit('state->%s_type = make_type("%s", state->AST_type, %s, %d);' %
                         (name, name, fields, len(prod.fields)), 1)
-        self.emit("if (!%s_type) return 0;" % name, 1)
+        self.emit("if (!state->%s_type) return 0;" % name, 1)
+        self.emit_type("AST_type")
+        self.emit_type("%s_type" % name)
         if prod.attributes:
-            self.emit("if (!add_attributes(%s_type, %s_attributes, %d)) return 0;" %
+            self.emit("if (!add_attributes(state->%s_type, %s_attributes, %d)) return 0;" %
                             (name, name, len(prod.attributes)), 1)
         else:
-            self.emit("if (!add_attributes(%s_type, NULL, 0)) return 0;" % name, 1)
+            self.emit("if (!add_attributes(state->%s_type, NULL, 0)) return 0;" % name, 1)
 
     def visitSum(self, sum, name):
-        self.emit('%s_type = make_type("%s", &AST_type, NULL, 0);' %
+        self.emit('state->%s_type = make_type("%s", state->AST_type, NULL, 0);' %
                   (name, name), 1)
-        self.emit("if (!%s_type) return 0;" % name, 1)
+        self.emit_type("%s_type" % name)
+        self.emit("if (!state->%s_type) return 0;" % name, 1)
         if sum.attributes:
-            self.emit("if (!add_attributes(%s_type, %s_attributes, %d)) return 0;" %
+            self.emit("if (!add_attributes(state->%s_type, %s_attributes, %d)) return 0;" %
                             (name, name, len(sum.attributes)), 1)
         else:
-            self.emit("if (!add_attributes(%s_type, NULL, 0)) return 0;" % name, 1)
+            self.emit("if (!add_attributes(state->%s_type, NULL, 0)) return 0;" % name, 1)
         simple = is_simple(sum)
         for t in sum.types:
             self.visitConstructor(t, name, simple)
@@ -981,30 +969,29 @@ static int add_ast_fields(void)
             fields = cons.name+"_fields"
         else:
             fields = "NULL"
-        self.emit('%s_type = make_type("%s", %s_type, %s, %d);' %
+        self.emit('state->%s_type = make_type("%s", state->%s_type, %s, %d);' %
                             (cons.name, cons.name, name, fields, len(cons.fields)), 1)
-        self.emit("if (!%s_type) return 0;" % cons.name, 1)
+        self.emit("if (!state->%s_type) return 0;" % cons.name, 1)
+        self.emit_type("%s_type" % cons.name)
         if simple:
-            self.emit("%s_singleton = PyType_GenericNew(%s_type, NULL, NULL);" %
+            self.emit("state->%s_singleton = PyType_GenericNew((PyTypeObject *)"
+                      "state->%s_type, NULL, NULL);" %
                              (cons.name, cons.name), 1)
-            self.emit("if (!%s_singleton) return 0;" % cons.name, 1)
+            self.emit("if (!state->%s_singleton) return 0;" % cons.name, 1)
 
 
 class ASTModuleVisitor(PickleVisitor):
 
     def visitModule(self, mod):
-        self.emit("static struct PyModuleDef _astmodule = {", 0)
-        self.emit('  PyModuleDef_HEAD_INIT, "_ast"', 0)
-        self.emit("};", 0)
         self.emit("PyMODINIT_FUNC", 0)
         self.emit("PyInit__ast(void)", 0)
         self.emit("{", 0)
-        self.emit("PyObject *m, *d;", 1)
+        self.emit("PyObject *m;", 1)
         self.emit("if (!init_types()) return NULL;", 1)
-        self.emit('m = PyModule_Create(&_astmodule);', 1)
+        self.emit('m = PyState_FindModule(&_astmodule);', 1)
         self.emit("if (!m) return NULL;", 1)
-        self.emit("d = PyModule_GetDict(m);", 1)
-        self.emit('if (PyDict_SetItemString(d, "AST", (PyObject*)&AST_type) < 0) return NULL;', 1)
+        self.emit('Py_INCREF(astmodulestate(m)->AST_type);', 1)
+        self.emit('if (PyModule_AddObject(m, "AST", astmodulestate_global->AST_type) < 0) return NULL;', 1)
         self.emit('if (PyModule_AddIntMacro(m, PyCF_ALLOW_TOP_LEVEL_AWAIT) < 0)', 1)
         self.emit("return NULL;", 2)
         self.emit('if (PyModule_AddIntMacro(m, PyCF_ONLY_AST) < 0)', 1)
@@ -1028,7 +1015,9 @@ class ASTModuleVisitor(PickleVisitor):
         self.addObj(cons.name)
 
     def addObj(self, name):
-        self.emit('if (PyDict_SetItemString(d, "%s", (PyObject*)%s_type) < 0) return NULL;' % (name, name), 1)
+        self.emit("if (PyModule_AddObject(m, \"%s\", "
+                  "astmodulestate_global->%s_type) < 0) return NULL;" % (name, name), 1)
+        self.emit("Py_INCREF(astmodulestate(m)->%s_type);" % name, 1)
 
 
 _SPECIALIZED_SEQUENCES = ('stmt', 'expr')
@@ -1066,6 +1055,7 @@ class ObjVisitor(PickleVisitor):
         self.emit("{", 0)
         self.emit("%s o = (%s)_o;" % (ctype, ctype), 1)
         self.emit("PyObject *result = NULL, *value = NULL;", 1)
+        self.emit("PyTypeObject *tp;", 1)
         self.emit('if (!o) {', 1)
         self.emit("Py_RETURN_NONE;", 2)
         self.emit("}", 1)
@@ -1093,7 +1083,7 @@ class ObjVisitor(PickleVisitor):
         for a in sum.attributes:
             self.emit("value = ast2obj_%s(o->%s);" % (a.type, a.name), 1)
             self.emit("if (!value) goto failed;", 1)
-            self.emit('if (_PyObject_SetAttrId(result, &PyId_%s, value) < 0)' % a.name, 1)
+            self.emit('if (PyObject_SetAttr(result, astmodulestate_global->%s, value) < 0)' % a.name, 1)
             self.emit('goto failed;', 2)
             self.emit('Py_DECREF(value);', 1)
         self.func_end()
@@ -1104,8 +1094,8 @@ class ObjVisitor(PickleVisitor):
         self.emit("switch(o) {", 1)
         for t in sum.types:
             self.emit("case %s:" % t.name, 2)
-            self.emit("Py_INCREF(%s_singleton);" % t.name, 3)
-            self.emit("return %s_singleton;" % t.name, 3)
+            self.emit("Py_INCREF(astmodulestate_global->%s_singleton);" % t.name, 3)
+            self.emit("return astmodulestate_global->%s_singleton;" % t.name, 3)
         self.emit("default:", 2)
         self.emit('/* should never happen, but just in case ... */', 3)
         code = "PyErr_Format(PyExc_SystemError, \"unknown %s found\");" % name
@@ -1116,21 +1106,23 @@ class ObjVisitor(PickleVisitor):
 
     def visitProduct(self, prod, name):
         self.func_begin(name)
-        self.emit("result = PyType_GenericNew(%s_type, NULL, NULL);" % name, 1);
+        self.emit("tp = (PyTypeObject *)astmodulestate_global->%s_type;" % name, 1)
+        self.emit("result = PyType_GenericNew(tp, NULL, NULL);", 1);
         self.emit("if (!result) return NULL;", 1)
         for field in prod.fields:
             self.visitField(field, name, 1, True)
         for a in prod.attributes:
             self.emit("value = ast2obj_%s(o->%s);" % (a.type, a.name), 1)
             self.emit("if (!value) goto failed;", 1)
-            self.emit('if (_PyObject_SetAttrId(result, &PyId_%s, value) < 0)' % a.name, 1)
+            self.emit("if (PyObject_SetAttr(result, astmodulestate_global->%s, value) < 0)" % a.name, 1)
             self.emit('goto failed;', 2)
             self.emit('Py_DECREF(value);', 1)
         self.func_end()
 
     def visitConstructor(self, cons, enum, name):
         self.emit("case %s_kind:" % cons.name, 1)
-        self.emit("result = PyType_GenericNew(%s_type, NULL, NULL);" % cons.name, 2);
+        self.emit("tp = (PyTypeObject *)astmodulestate_global->%s_type;" % cons.name, 2)
+        self.emit("result = PyType_GenericNew(tp, NULL, NULL);", 2);
         self.emit("if (!result) goto failed;", 2)
         for f in cons.fields:
             self.visitField(f, cons.name, 2, False)
@@ -1145,7 +1137,7 @@ class ObjVisitor(PickleVisitor):
             value = "o->v.%s.%s" % (name, field.name)
         self.set(field, value, depth)
         emit("if (!value) goto failed;", 0)
-        emit('if (_PyObject_SetAttrId(result, &PyId_%s, value) == -1)' % field.name, 0)
+        emit("if (PyObject_SetAttr(result, astmodulestate_global->%s, value) == -1)" % field.name, 0)
         emit("goto failed;", 1)
         emit("Py_DECREF(value);", 0)
 
@@ -1205,9 +1197,9 @@ mod_ty PyAST_obj2mod(PyObject* ast, PyArena* arena, int mode)
         return NULL;
     }
 
-    req_type[0] = (PyObject*)Module_type;
-    req_type[1] = (PyObject*)Expression_type;
-    req_type[2] = (PyObject*)Interactive_type;
+    req_type[0] = astmodulestate_global->Module_type;
+    req_type[1] = astmodulestate_global->Expression_type;
+    req_type[2] = astmodulestate_global->Interactive_type;
 
     assert(0 <= mode && mode <= 2);
 
@@ -1219,7 +1211,7 @@ mod_ty PyAST_obj2mod(PyObject* ast, PyArena* arena, int mode)
         return NULL;
     if (!isinstance) {
         PyErr_Format(PyExc_TypeError, "expected %s node, got %.400s",
-                     req_name[mode], Py_TYPE(ast)->tp_name);
+                     req_name[mode], _PyType_Name(Py_TYPE(ast)));
         return NULL;
     }
     if (obj2ast_mod(ast, &res, arena) != 0)
@@ -1232,7 +1224,7 @@ int PyAST_Check(PyObject* obj)
 {
     if (!init_types())
         return -1;
-    return PyObject_IsInstance(obj, (PyObject*)&AST_type);
+    return PyObject_IsInstance(obj, astmodulestate_global->AST_type);
 }
 """
 
@@ -1245,6 +1237,86 @@ class ChainOfVisitors:
             v.visit(object)
             v.emit("", 0)
 
+
+def generate_module_def(f, mod):
+    # Gather all the data needed for ModuleSpec
+    visitor_list = set()
+    with open(os.devnull, "w") as devnull:
+        visitor = PyTypesDeclareVisitor(devnull)
+        visitor.visit(mod)
+        visitor_list.add(visitor)
+        visitor = PyTypesVisitor(devnull)
+        visitor.visit(mod)
+        visitor_list.add(visitor)
+
+    state_strings = set(["__dict__", "_attributes", "_fields", "__module__", "_ast"])
+    module_state = set(["__dict__", "_attributes", "_fields", "__module__", "_ast"])
+    for visitor in visitor_list:
+        for identifier in visitor.identifiers:
+            module_state.add(identifier)
+            state_strings.add(identifier)
+        for singleton in visitor.singletons:
+            module_state.add(singleton)
+        for tp in visitor.types:
+            module_state.add(tp)
+    state_strings = sorted(state_strings)
+    module_state = sorted(module_state)
+    f.write('typedef struct {\n')
+    f.write('    int initialized;\n')
+    for s in module_state:
+        f.write('    PyObject *' + s + ';\n')
+    f.write('} astmodulestate;\n\n')
+    f.write("""
+#define astmodulestate(o) ((astmodulestate *)PyModule_GetState(o))
+
+static int astmodule_clear(PyObject *module)
+{
+""")
+    for s in module_state:
+        f.write("    Py_CLEAR(astmodulestate(module)->" + s + ');\n')
+    f.write("""
+    return 0;
+}
+
+static int astmodule_traverse(PyObject *module, visitproc visit, void* arg)
+{
+""")
+    for s in module_state:
+        f.write("    Py_VISIT(astmodulestate(module)->" + s + ');\n')
+    f.write("""
+    return 0;
+}
+
+static void astmodule_free(void* module) {
+    astmodule_clear((PyObject*)module);
+}
+
+static struct PyModuleDef _astmodule = {
+    PyModuleDef_HEAD_INIT,
+    "_ast",
+    NULL,
+    sizeof(astmodulestate),
+    NULL,
+    NULL,
+    astmodule_traverse,
+    astmodule_clear,
+    astmodule_free,
+};
+
+#define astmodulestate_global ((astmodulestate *)PyModule_GetState(PyState_FindModule(&_astmodule)))
+
+""")
+    f.write('static int init_identifiers(void)\n')
+    f.write('{\n')
+    f.write('    astmodulestate *state = astmodulestate_global;\n')
+    for identifier in state_strings:
+        f.write('    if ((state->' + identifier)
+        f.write(' = PyUnicode_InternFromString("')
+        f.write(identifier + '")) == NULL) return 0;\n')
+    f.write('    return 1;\n')
+    f.write('};\n\n')
+
+
 common_msg = "/* File automatically generated by %s. */\n\n"
 
 def main(srcfile, dump_module=False):
@@ -1295,7 +1367,9 @@ def main(srcfile, dump_module=False):
             f.write('#include "Python.h"\n')
             f.write('#include "%s-ast.h"\n' % mod.name)
             f.write('\n')
-            f.write("static PyTypeObject AST_type;\n")
+
+            generate_module_def(f, mod)
+
             v = ChainOfVisitors(
                 PyTypesDeclareVisitor(f),
                 PyTypesVisitor(f),