8000 bpo-45383: Inherit MetaClass from bases in FromSpec API by seberg · Pull Request #28748 · python/cpython · GitHub
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bpo-45383: Inherit MetaClass from bases in FromSpec API #28748

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Merged
merged 19 commits into from
Jun 9, 2022
Merged

bpo-45383: Inherit MetaClass from bases in FromSpec API #28748

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67c8a97
BUG: Inherit MetaClass from bases in FromSpec API
seberg Oct 5, 2021
2012aaa
📜🤖 Added by blurb_it.
blurb-it[bot] Oct 5, 2021
881ba13
MAINT: Address review comments
seberg Oct 20, 2021
6fd1926
Merge in the main branch
encukou May 27, 2022
aad7456
Disallow non-type metaclasses
encukou May 27, 2022
aba4208
Use custom metaclasses for the tests, rather than stuff from ctypes
encukou May 27, 2022
4eb003a
Make PyType_FromMetaclass refcounting easier to follow
encukou May 27, 2022
1ae7969
Adjust documentation
encukou May 27, 2022
6001a33
Fix type warning
encukou May 31, 2022
1ad0eca
Remove unused includes from _testcapimodule.c
encukou May 31, 2022
ea69819
Use an explicit role in the News entry
encukou May 31, 2022
cb1527f
Test that __subclasses__ is updated properly
encukou May 31, 2022
f86d2b5
Document caveats, suggest that PyType_From* is not for user-provided …
encukou May 31, 2022
93c65e8
Remove unused variable
encukou May 31, 2022
d881750
Move bases calculation before the allocation
encukou May 31, 2022
a7af972
Fix compiler warning for Py_NewRef result
encukou Jun 1, 2022
2f47be3
Use PyErr_Occurred rather than a variable
encukou Jun 9, 2022
ef6bcce
Use PEP 7 style
encukou Jun 9, 2022
6b31880
Replace duplicate Py_TPFLAGS_BASETYPE check with an assert
encukou Jun 9, 2022
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BUG: Inherit MetaClass from bases in FromSpec API 
This checks the bases of of a type created using the FromSpec
API to inherit the bases metaclasses.  The MetaClasses alloc
function will be called as is done in `tp_new` for classes
created in Python.
  • Loading branch information
@seberg
seberg committed Oct 5, 2021
commit 67c8a97affcb9dbb12f44fdb7767e756b82ea34b
142 changes: 142 additions & 0 deletions Modules/_testcapimodule.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1173,6 +1173,143 @@ test_get_type_name(PyObject *self, PyObject *Py_UNUSED(ignored))
}


/*
* Small helper to import abc.ABC and ctypes.Array for testing. Both
* are (incompatible) MetaClass instances. If Array is NULL it is not filled.
*/
static int
import_abc_and_array(PyObject **ABC, PyObject **Array)
{
PyObject *abc_mod = PyImport_ImportModule("abc");
if (abc_mod == NULL) {
return -1;
}
*ABC = PyObject_GetAttrString(abc_mod, "ABC");
Py_DECREF(abc_mod);
if (*ABC == NULL) {
return -1;
}
if (Array == NULL) {
return 0;
}

PyObject *ctypes_mod = PyImport_ImportModule("ctypes");
if (ctypes_mod == NULL) {
Py_CLEAR(*ABC);
return -1;
}
*Array = PyObject_GetAttrString(ctypes_mod, "Array");
Py_DECREF(ctypes_mod);
if (*Array == NULL) {
Py_CLEAR(*ABC);
return -1;
}
return 0;
}


static PyType_Slot MinimalType_slots[] = {
{0, 0},
};

static PyType_Spec MinimalType_spec = {
"_testcapi.MinimalSpecType",
0,
0,
Py_TPFLAGS_DEFAULT,
MinimalType_slots
};


static PyObject *
test_from_spec_metatype_inheritance(PyObject *self, PyObject *Py_UNUSED(ignored))
{
/* Get two (incompatible) MetaTypes */
PyObject *ABC;
if (import_abc_and_array(&ABC, NULL) < 0) {
return NULL;
}

PyObject *bases = PyTuple_Pack(1, ABC);
if (bases == NULL) {
Py_DECREF(ABC);
return NULL;
}
PyObject *new = PyType_FromSpecWithBases(&MinimalType_spec, bases);
Py_DECREF(bases);
if (new == NULL) {
Py_DECREF(ABC);
return NULL;
}
if (Py_TYPE(new) != Py_TYPE(ABC)) {
PyErr_SetString(PyExc_AssertionError,
"MetaType appears not correctly inherited from ABC!");
Py_DECREF(ABC);
Py_DECREF(new);
return NULL;
}
Py_DECREF(ABC);
Py_DECREF(new);
Py_RETURN_NONE;
}


static PyObject *
test_from_spec_invalid_metatype_inheritance(PyObject *self, PyObject *Py_UNUSED(ignored))
{
/* Get two (incompatible) MetaTypes */
PyObject *ABC, *Array;

if (import_abc_and_array(&ABC, &Array) < 0) {
return NULL;
}

PyObject *bases = PyTuple_Pack(2, ABC, Array);
Py_DECREF(ABC);
Py_DECREF(Array);
if (bases == NULL) {
return NULL;
}
/*
* The following should raise a TypeError due to a MetaClass conflict.
*/
PyObject *new = PyType_FromSpecWithBases(&MinimalType_spec, bases);
Py_DECREF(bases);
if (new != NULL) {
Py_DECREF(new);
PyErr_SetString(PyExc_AssertionError,
"MetaType conflict not recognized by PyType_FromSpecWithBases");
return NULL;
}
if (PyErr_ExceptionMatches(PyExc_TypeError)) {
PyObject *type, *value, *traceback, *meta_error_string;

PyErr_Fetch(&type, &value, &traceback);
Py_DECREF(type);
Py_XDECREF(traceback);

meta_error_string = PyUnicode_FromString("metaclass conflict:");
if (meta_error_string == NULL) {
Py_DECREF(value);
return NULL;
}
int res = PyUnicode_Contains(value, meta_error_string);
Py_DECREF(value);
Py_DECREF(meta_error_string);
if (res < 0) {
return NULL;
}
if (res == 0) {
PyErr_SetString(PyExc_AssertionError,
"TypeError did not inlclude expected message.");
return NULL;
}
Py_RETURN_NONE;
}
return NULL;
}


static PyObject *
test_get_type_qualname(PyObject *self, PyObject *Py_UNUSED(ignored))
{
Expand Down Expand Up @@ -5722,6 +5859,11 @@ static PyMethodDef TestMethods[] = {
{"get_args", get_args, METH_VARARGS},
{"test_get_statictype_slots", test_get_statictype_slots, METH_NOARGS},
{"test_get_type_name", test_get_type_name, METH_NOARGS},
{"test_from_spec_metatype_inheritance", test_from_spec_metatype_inheritance,
METH_NOARGS},
{"test_from_spec_invalid_metatype_inheritance",
test_from_spec_invalid_metatype_inheritance,
METH_NOARGS},
{"test_get_type_qualname", test_get_type_qualname, METH_NOARGS},
{"get_kwargs", (PyCFunction)(void(*)(void))get_kwargs,
METH_VARARGS|METH_KEYWORDS},
Expand Down
68 changes: 39 additions & 29 deletions Objects/typeobject.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -3398,37 +3398,12 @@ PyType_FromModuleAndSpec(PyObject *module, PyType_Spec *spec, PyObject *bases)
}
}

res = (PyHeapTypeObject*)PyType_GenericAlloc(&PyType_Type, nmembers);
if (res == NULL)
return NULL;
res_start = (char*)res;

if (spec->name == NULL) {
PyErr_SetString(PyExc_SystemError,
"Type spec does not define the name field.");
goto fail;
return NULL;
}

/* Set the type name and qualname */
const char *s = strrchr(spec->name, '.');
if (s == NULL)
s = spec->name;
else
s++;

type = &res->ht_type;
/* The flags must be initialized early, before the GC traverses us */
type->tp_flags = spec->flags | Py_TPFLAGS_HEAPTYPE;
res->ht_name = PyUnicode_FromString(s);
if (!res->ht_name)
goto fail;
res->ht_qualname = res->ht_name;
Py_INCREF(res->ht_qualname);
type->tp_name = spec->name;

Py_XINCREF(module);
res->ht_module = module;

/* Adjust for empty tuple bases */
if (!bases) {
base = &PyBaseObject_Type;
Expand All @@ -3443,11 +3418,11 @@ PyType_FromModuleAndSpec(PyObject *module, PyType_Spec *spec, PyObject *bases)
if (!bases) {
bases = PyTuple_Pack(1, base);
if (!bases)
goto fail;
return NULL;
}
else if (!PyTuple_Check(bases)) {
PyErr_SetString(PyExc_SystemError, "Py_tp_bases is not a tuple");
goto fail;
return NULL;
}
else {
Py_INCREF(bases);
Expand All @@ -3456,12 +3431,47 @@ PyType_FromModuleAndSpec(PyObject *module, PyType_Spec *spec, PyObject *bases)
else if (!PyTuple_Check(bases)) {
bases = PyTuple_Pack(1, bases);
if (!bases)
goto fail;
return NULL;
}
else {
Py_INCREF(bases);
}

/* NOTE: Missing API to replace `&PyType_Type` below, see bpo-15870 */
PyTypeObject *metatype = _PyType_CalculateMetaclass(&PyType_Type, bases);
if (metatype == NULL) {
Py_DECREF(bases);
return NULL;
}
res = (PyHeapTypeObject*)metatype->tp_alloc(metatype, nmembers);
if (res == NULL) {
Py_DECREF(bases);
return NULL;
}
res_start = (char*)res;

/* Set the type name and qualname */
const char *s = strrchr(spec->name, '.');
if (s == NULL)
s = spec->name;
else
s++;

type = &res->ht_type;
/* The flags must be initialized early, before the GC traverses us */
type->tp_flags = spec->flags | Py_TPFLAGS_HEAPTYPE;
res->ht_name = PyUnicode_FromString(s);
if (!res->ht_name) {
Py_DECREF(bases);
goto fail;
}
res->ht_qualname = res->ht_name;
Py_INCREF(res->ht_qualname);
type->tp_name = spec->name;

Py_XINCREF(module);
res->ht_module = module;

/* Calculate best base, and check that all bases are type objects */
base = best_base(bases);
if (base == NULL) {
Expand Down
0