cpython/Objects/unionobject.c
Ken Jin 49cd68fb1e
bpo-42195: Disallow isinstance/issubclass for subclasses of genericaliases in Union (GH-24059)
Previously this didn't raise an error. Now it will:
```python
from collections.abc import Callable
isinstance(int, list | Callable[..., str])
```
Also added tests in Union since there were previously none for stuff like ``isinstance(list, list | list[int])`` either.

Backport to 3.9 not required.

Automerge-Triggered-By: GH:gvanrossum
2021-01-02 08:19:15 -08:00

476 lines
13 KiB
C

// types.Union -- used to represent e.g. Union[int, str], int | str
#include "Python.h"
#include "pycore_unionobject.h"
#include "structmember.h"
typedef struct {
PyObject_HEAD
PyObject *args;
} unionobject;
static void
unionobject_dealloc(PyObject *self)
{
unionobject *alias = (unionobject *)self;
Py_XDECREF(alias->args);
Py_TYPE(self)->tp_free(self);
}
static Py_hash_t
union_hash(PyObject *self)
{
unionobject *alias = (unionobject *)self;
Py_hash_t h1 = PyObject_Hash(alias->args);
if (h1 == -1) {
return -1;
}
return h1;
}
static int
is_generic_alias_in_args(PyObject *args) {
Py_ssize_t nargs = PyTuple_GET_SIZE(args);
for (Py_ssize_t iarg = 0; iarg < nargs; iarg++) {
PyObject *arg = PyTuple_GET_ITEM(args, iarg);
if (PyObject_TypeCheck(arg, &Py_GenericAliasType)) {
return 0;
}
}
return 1;
}
static PyObject *
union_instancecheck(PyObject *self, PyObject *instance)
{
unionobject *alias = (unionobject *) self;
Py_ssize_t nargs = PyTuple_GET_SIZE(alias->args);
if (!is_generic_alias_in_args(alias->args)) {
PyErr_SetString(PyExc_TypeError,
"isinstance() argument 2 cannot contain a parameterized generic");
return NULL;
}
for (Py_ssize_t iarg = 0; iarg < nargs; iarg++) {
PyObject *arg = PyTuple_GET_ITEM(alias->args, iarg);
if (arg == Py_None) {
arg = (PyObject *)&_PyNone_Type;
}
if (PyType_Check(arg) && PyObject_IsInstance(instance, arg) != 0) {
Py_RETURN_TRUE;
}
}
Py_RETURN_FALSE;
}
static PyObject *
union_subclasscheck(PyObject *self, PyObject *instance)
{
if (!PyType_Check(instance)) {
PyErr_SetString(PyExc_TypeError, "issubclass() arg 1 must be a class");
return NULL;
}
unionobject *alias = (unionobject *)self;
if (!is_generic_alias_in_args(alias->args)) {
PyErr_SetString(PyExc_TypeError,
"issubclass() argument 2 cannot contain a parameterized generic");
return NULL;
}
Py_ssize_t nargs = PyTuple_GET_SIZE(alias->args);
for (Py_ssize_t iarg = 0; iarg < nargs; iarg++) {
PyObject *arg = PyTuple_GET_ITEM(alias->args, iarg);
if (PyType_Check(arg) && (PyType_IsSubtype((PyTypeObject *)instance, (PyTypeObject *)arg) != 0)) {
Py_RETURN_TRUE;
}
}
Py_RETURN_FALSE;
}
static int
is_typing_module(PyObject *obj) {
PyObject *module = PyObject_GetAttrString(obj, "__module__");
if (module == NULL) {
return -1;
}
int is_typing = PyUnicode_Check(module) && _PyUnicode_EqualToASCIIString(module, "typing");
Py_DECREF(module);
return is_typing;
}
static int
is_typing_name(PyObject *obj, char *name)
{
PyTypeObject *type = Py_TYPE(obj);
if (strcmp(type->tp_name, name) != 0) {
return 0;
}
return is_typing_module(obj);
}
static PyObject *
union_richcompare(PyObject *a, PyObject *b, int op)
{
PyObject *result = NULL;
if (op != Py_EQ && op != Py_NE) {
result = Py_NotImplemented;
Py_INCREF(result);
return result;
}
PyTypeObject *type = Py_TYPE(b);
PyObject* a_set = PySet_New(((unionobject*)a)->args);
if (a_set == NULL) {
return NULL;
}
PyObject* b_set = PySet_New(NULL);
if (b_set == NULL) {
goto exit;
}
// Populate b_set with the data from the right object
int is_typing_union = is_typing_name(b, "_UnionGenericAlias");
if (is_typing_union < 0) {
goto exit;
}
if (is_typing_union) {
PyObject *b_args = PyObject_GetAttrString(b, "__args__");
if (b_args == NULL) {
goto exit;
}
if (!PyTuple_CheckExact(b_args)) {
Py_DECREF(b_args);
PyErr_SetString(PyExc_TypeError, "__args__ argument of typing.Union object is not a tuple");
goto exit;
}
Py_ssize_t b_arg_length = PyTuple_GET_SIZE(b_args);
for (Py_ssize_t i = 0; i < b_arg_length; i++) {
PyObject* arg = PyTuple_GET_ITEM(b_args, i);
if (arg == (PyObject *)&_PyNone_Type) {
arg = Py_None;
}
if (PySet_Add(b_set, arg) == -1) {
Py_DECREF(b_args);
goto exit;
}
}
Py_DECREF(b_args);
} else if (type == &_Py_UnionType) {
PyObject* args = ((unionobject*) b)->args;
Py_ssize_t arg_length = PyTuple_GET_SIZE(args);
for (Py_ssize_t i = 0; i < arg_length; i++) {
PyObject* arg = PyTuple_GET_ITEM(args, i);
if (PySet_Add(b_set, arg) == -1) {
goto exit;
}
}
} else {
if (PySet_Add(b_set, b) == -1) {
goto exit;
}
}
result = PyObject_RichCompare(a_set, b_set, op);
exit:
Py_XDECREF(a_set);
Py_XDECREF(b_set);
return result;
}
static PyObject*
flatten_args(PyObject* args)
{
Py_ssize_t arg_length = PyTuple_GET_SIZE(args);
Py_ssize_t total_args = 0;
// Get number of total args once it's flattened.
for (Py_ssize_t i = 0; i < arg_length; i++) {
PyObject *arg = PyTuple_GET_ITEM(args, i);
PyTypeObject* arg_type = Py_TYPE(arg);
if (arg_type == &_Py_UnionType) {
total_args += PyTuple_GET_SIZE(((unionobject*) arg)->args);
} else {
total_args++;
}
}
// Create new tuple of flattened args.
PyObject *flattened_args = PyTuple_New(total_args);
if (flattened_args == NULL) {
return NULL;
}
Py_ssize_t pos = 0;
for (Py_ssize_t i = 0; i < arg_length; i++) {
PyObject *arg = PyTuple_GET_ITEM(args, i);
PyTypeObject* arg_type = Py_TYPE(arg);
if (arg_type == &_Py_UnionType) {
PyObject* nested_args = ((unionobject*)arg)->args;
Py_ssize_t nested_arg_length = PyTuple_GET_SIZE(nested_args);
for (Py_ssize_t j = 0; j < nested_arg_length; j++) {
PyObject* nested_arg = PyTuple_GET_ITEM(nested_args, j);
Py_INCREF(nested_arg);
PyTuple_SET_ITEM(flattened_args, pos, nested_arg);
pos++;
}
} else {
Py_INCREF(arg);
PyTuple_SET_ITEM(flattened_args, pos, arg);
pos++;
}
}
return flattened_args;
}
static PyObject*
dedup_and_flatten_args(PyObject* args)
{
args = flatten_args(args);
if (args == NULL) {
return NULL;
}
Py_ssize_t arg_length = PyTuple_GET_SIZE(args);
PyObject *new_args = PyTuple_New(arg_length);
if (new_args == NULL) {
return NULL;
}
// Add unique elements to an array.
Py_ssize_t added_items = 0;
for (Py_ssize_t i = 0; i < arg_length; i++) {
int is_duplicate = 0;
PyObject* i_element = PyTuple_GET_ITEM(args, i);
for (Py_ssize_t j = i + 1; j < arg_length; j++) {
PyObject* j_element = PyTuple_GET_ITEM(args, j);
int is_ga = PyObject_TypeCheck(i_element, &Py_GenericAliasType) &&
PyObject_TypeCheck(j_element, &Py_GenericAliasType);
// RichCompare to also deduplicate GenericAlias types (slower)
is_duplicate = is_ga ? PyObject_RichCompareBool(i_element, j_element, Py_EQ)
: i_element == j_element;
// Should only happen if RichCompare fails
if (is_duplicate < 0) {
Py_DECREF(args);
Py_DECREF(new_args);
return NULL;
}
if (is_duplicate)
break;
}
if (!is_duplicate) {
Py_INCREF(i_element);
PyTuple_SET_ITEM(new_args, added_items, i_element);
added_items++;
}
}
Py_DECREF(args);
_PyTuple_Resize(&new_args, added_items);
return new_args;
}
static int
is_typevar(PyObject *obj)
{
return is_typing_name(obj, "TypeVar");
}
static int
is_special_form(PyObject *obj)
{
return is_typing_name(obj, "_SpecialForm");
}
static int
is_new_type(PyObject *obj)
{
PyTypeObject *type = Py_TYPE(obj);
if (type != &PyFunction_Type) {
return 0;
}
return is_typing_module(obj);
}
static int
is_unionable(PyObject *obj)
{
if (obj == Py_None) {
return 1;
}
PyTypeObject *type = Py_TYPE(obj);
return (
is_typevar(obj) ||
is_new_type(obj) ||
is_special_form(obj) ||
PyType_Check(obj) ||
PyObject_TypeCheck(obj, &Py_GenericAliasType) ||
type == &_Py_UnionType);
}
PyObject *
_Py_union_type_or(PyObject* self, PyObject* param)
{
PyObject *tuple = PyTuple_Pack(2, self, param);
if (tuple == NULL) {
return NULL;
}
PyObject *new_union = _Py_Union(tuple);
Py_DECREF(tuple);
return new_union;
}
static int
union_repr_item(_PyUnicodeWriter *writer, PyObject *p)
{
_Py_IDENTIFIER(__module__);
_Py_IDENTIFIER(__qualname__);
_Py_IDENTIFIER(__origin__);
_Py_IDENTIFIER(__args__);
PyObject *qualname = NULL;
PyObject *module = NULL;
PyObject *tmp;
PyObject *r = NULL;
int err;
if (_PyObject_LookupAttrId(p, &PyId___origin__, &tmp) < 0) {
goto exit;
}
if (tmp) {
Py_DECREF(tmp);
if (_PyObject_LookupAttrId(p, &PyId___args__, &tmp) < 0) {
goto exit;
}
if (tmp) {
// It looks like a GenericAlias
Py_DECREF(tmp);
goto use_repr;
}
}
if (_PyObject_LookupAttrId(p, &PyId___qualname__, &qualname) < 0) {
goto exit;
}
if (qualname == NULL) {
goto use_repr;
}
if (_PyObject_LookupAttrId(p, &PyId___module__, &module) < 0) {
goto exit;
}
if (module == NULL || module == Py_None) {
goto use_repr;
}
// Looks like a class
if (PyUnicode_Check(module) &&
_PyUnicode_EqualToASCIIString(module, "builtins"))
{
// builtins don't need a module name
r = PyObject_Str(qualname);
goto exit;
}
else {
r = PyUnicode_FromFormat("%S.%S", module, qualname);
goto exit;
}
use_repr:
r = PyObject_Repr(p);
exit:
Py_XDECREF(qualname);
Py_XDECREF(module);
if (r == NULL) {
return -1;
}
err = _PyUnicodeWriter_WriteStr(writer, r);
Py_DECREF(r);
return err;
}
static PyObject *
union_repr(PyObject *self)
{
unionobject *alias = (unionobject *)self;
Py_ssize_t len = PyTuple_GET_SIZE(alias->args);
_PyUnicodeWriter writer;
_PyUnicodeWriter_Init(&writer);
for (Py_ssize_t i = 0; i < len; i++) {
if (i > 0 && _PyUnicodeWriter_WriteASCIIString(&writer, " | ", 3) < 0) {
goto error;
}
PyObject *p = PyTuple_GET_ITEM(alias->args, i);
if (union_repr_item(&writer, p) < 0) {
goto error;
}
}
return _PyUnicodeWriter_Finish(&writer);
error:
_PyUnicodeWriter_Dealloc(&writer);
return NULL;
}
static PyMemberDef union_members[] = {
{"__args__", T_OBJECT, offsetof(unionobject, args), READONLY},
{0}
};
static PyMethodDef union_methods[] = {
{"__instancecheck__", union_instancecheck, METH_O},
{"__subclasscheck__", union_subclasscheck, METH_O},
{0}};
static PyNumberMethods union_as_number = {
.nb_or = _Py_union_type_or, // Add __or__ function
};
PyTypeObject _Py_UnionType = {
PyVarObject_HEAD_INIT(&PyType_Type, 0)
.tp_name = "types.Union",
.tp_doc = "Represent a PEP 604 union type\n"
"\n"
"E.g. for int | str",
.tp_basicsize = sizeof(unionobject),
.tp_dealloc = unionobject_dealloc,
.tp_alloc = PyType_GenericAlloc,
.tp_free = PyObject_Del,
.tp_flags = Py_TPFLAGS_DEFAULT,
.tp_hash = union_hash,
.tp_getattro = PyObject_GenericGetAttr,
.tp_members = union_members,
.tp_methods = union_methods,
.tp_richcompare = union_richcompare,
.tp_as_number = &union_as_number,
.tp_repr = union_repr,
};
PyObject *
_Py_Union(PyObject *args)
{
assert(PyTuple_CheckExact(args));
unionobject* result = NULL;
// Check arguments are unionable.
Py_ssize_t nargs = PyTuple_GET_SIZE(args);
for (Py_ssize_t iarg = 0; iarg < nargs; iarg++) {
PyObject *arg = PyTuple_GET_ITEM(args, iarg);
if (arg == NULL) {
return NULL;
}
int is_arg_unionable = is_unionable(arg);
if (is_arg_unionable < 0) {
return NULL;
}
if (!is_arg_unionable) {
Py_INCREF(Py_NotImplemented);
return Py_NotImplemented;
}
}
result = PyObject_New(unionobject, &_Py_UnionType);
if (result == NULL) {
return NULL;
}
result->args = dedup_and_flatten_args(args);
if (result->args == NULL) {
Py_DECREF(result);
return NULL;
}
return (PyObject*)result;
}