pythongh-93649: Split vectorcall testing from _testcapimodule.c

The _testcapimodule.c file is getting too large to work with effectively.
Vectorcall tests aren't the biggest issue -- it's just an area I want to work
on next, so I started there.
It does make it clear that MethodDescriptor2 is related to testing vectorcall,
which wasn't clear before (the /* Test PEP 590 */ section had an ambiguous end).

This PR lays out a general structure of how tests can be split up,
with more splitting to come later if the structure is OK.

Modules/Setup.stdlib.in

@@ -168,7 +168,7 @@
 @MODULE__XXTESTFUZZ_TRUE@_xxtestfuzz _xxtestfuzz/_xxtestfuzz.c _xxtestfuzz/fuzzer.c
 @MODULE__TESTBUFFER_TRUE@_testbuffer _testbuffer.c
 @MODULE__TESTINTERNALCAPI_TRUE@_testinternalcapi _testinternalcapi.c
-@MODULE__TESTCAPI_TRUE@_testcapi _testcapimodule.c
+@MODULE__TESTCAPI_TRUE@_testcapi _testcapimodule.c _testcapi/test_vectorcall.c
 
 # Some testing modules MUST be built as shared libraries.
 *shared*

Modules/_testcapi/README.txt

@@ -0,0 +1,3 @@
+Tests in this directory are compiled into the _testcapi extension.
+The main file for the extension is Modules/_testcapimodule.c, which
+calls `_PyTestCapi_Init_*` from these functions.

Modules/_testcapi/test_vectorcall.c

@@ -0,0 +1,270 @@
+#include "testcapimodule_parts.h"
+#include <stddef.h>  // offsetof
+
+
+/* Test PEP 590 - Vectorcall */
+
+static int
+fastcall_args(PyObject *args, PyObject ***stack, Py_ssize_t *nargs)
+{
+    if (args == Py_None) {
+        *stack = NULL;
+        *nargs = 0;
+    }
+    else if (PyTuple_Check(args)) {
+        *stack = ((PyTupleObject *)args)->ob_item;
+        *nargs = PyTuple_GET_SIZE(args);
+    }
+    else {
+        PyErr_SetString(PyExc_TypeError, "args must be None or a tuple");
+        return -1;
+    }
+    return 0;
+}
+
+
+static PyObject *
+test_pyobject_fastcall(PyObject *self, PyObject *args)
+{
+    PyObject *func, *func_args;
+    PyObject **stack;
+    Py_ssize_t nargs;
+
+    if (!PyArg_ParseTuple(args, "OO", &func, &func_args)) {
+        return NULL;
+    }
+
+    if (fastcall_args(func_args, &stack, &nargs) < 0) {
+        return NULL;
+    }
+    return _PyObject_FastCall(func, stack, nargs);
+}
+
+static PyObject *
+test_pyobject_fastcalldict(PyObject *self, PyObject *args)
+{
+    PyObject *func, *func_args, *kwargs;
+    PyObject **stack;
+    Py_ssize_t nargs;
+
+    if (!PyArg_ParseTuple(args, "OOO", &func, &func_args, &kwargs)) {
+        return NULL;
+    }
+
+    if (fastcall_args(func_args, &stack, &nargs) < 0) {
+        return NULL;
+    }
+
+    if (kwargs == Py_None) {
+        kwargs = NULL;
+    }
+    else if (!PyDict_Check(kwargs)) {
+        PyErr_SetString(PyExc_TypeError, "kwnames must be None or a dict");
+        return NULL;
+    }
+
+    return PyObject_VectorcallDict(func, stack, nargs, kwargs);
+}
+
+static PyObject *
+test_pyobject_vectorcall(PyObject *self, PyObject *args)
+{
+    PyObject *func, *func_args, *kwnames = NULL;
+    PyObject **stack;
+    Py_ssize_t nargs, nkw;
+
+    if (!PyArg_ParseTuple(args, "OOO", &func, &func_args, &kwnames)) {
+        return NULL;
+    }
+
+    if (fastcall_args(func_args, &stack, &nargs) < 0) {
+        return NULL;
+    }
+
+    if (kwnames == Py_None) {
+        kwnames = NULL;
+    }
+    else if (PyTuple_Check(kwnames)) {
+        nkw = PyTuple_GET_SIZE(kwnames);
+        if (nargs < nkw) {
+            PyErr_SetString(PyExc_ValueError, "kwnames longer than args");
+            return NULL;
+        }
+        nargs -= nkw;
+    }
+    else {
+        PyErr_SetString(PyExc_TypeError, "kwnames must be None or a tuple");
+        return NULL;
+    }
+    return PyObject_Vectorcall(func, stack, nargs, kwnames);
+}
+
+static PyObject *
+test_pyvectorcall_call(PyObject *self, PyObject *args)
+{
+    PyObject *func;
+    PyObject *argstuple;
+    PyObject *kwargs = NULL;
+
+    if (!PyArg_ParseTuple(args, "OO|O", &func, &argstuple, &kwargs)) {
+        return NULL;
+    }
+
+    if (!PyTuple_Check(argstuple)) {
+        PyErr_SetString(PyExc_TypeError, "args must be a tuple");
+        return NULL;
+    }
+    if (kwargs != NULL && !PyDict_Check(kwargs)) {
+        PyErr_SetString(PyExc_TypeError, "kwargs must be a dict");
+        return NULL;
+    }
+
+    return PyVectorcall_Call(func, argstuple, kwargs);
+}
+
+static PyMethodDef TestMethods[] = {
+    {"pyobject_fastcall", test_pyobject_fastcall, METH_VARARGS},
+    {"pyobject_fastcalldict", test_pyobject_fastcalldict, METH_VARARGS},
+    {"pyobject_vectorcall", test_pyobject_vectorcall, METH_VARARGS},
+    {"pyvectorcall_call", test_pyvectorcall_call, METH_VARARGS},
+    {NULL},
+};
+
+
+typedef struct {
+    PyObject_HEAD
+    vectorcallfunc vectorcall;
+} MethodDescriptorObject;
+
+static PyObject *
+MethodDescriptor_vectorcall(PyObject *callable, PyObject *const *args,
+                            size_t nargsf, PyObject *kwnames)
+{
+    /* True if using the vectorcall function in MethodDescriptorObject
+     * but False for MethodDescriptor2Object */
+    MethodDescriptorObject *md = (MethodDescriptorObject *)callable;
+    return PyBool_FromLong(md->vectorcall != NULL);
+}
+
+static PyObject *
+MethodDescriptor_new(PyTypeObject* type, PyObject* args, PyObject *kw)
+{
+    MethodDescriptorObject *op = (MethodDescriptorObject *)type->tp_alloc(type, 0);
+    op->vectorcall = MethodDescriptor_vectorcall;
+    return (PyObject *)op;
+}
+
+static PyObject *
+func_descr_get(PyObject *func, PyObject *obj, PyObject *type)
+{
+    if (obj == Py_None || obj == NULL) {
+        Py_INCREF(func);
+        return func;
+    }
+    return PyMethod_New(func, obj);
+}
+
+static PyObject *
+nop_descr_get(PyObject *func, PyObject *obj, PyObject *type)
+{
+    Py_INCREF(func);
+    return func;
+}
+
+static PyObject *
+call_return_args(PyObject *self, PyObject *args, PyObject *kwargs)
+{
+    Py_INCREF(args);
+    return args;
+}
+
+static PyTypeObject MethodDescriptorBase_Type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "MethodDescriptorBase",
+    sizeof(MethodDescriptorObject),
+    .tp_new = MethodDescriptor_new,
+    .tp_call = PyVectorcall_Call,
+    .tp_vectorcall_offset = offsetof(MethodDescriptorObject, vectorcall),
+    .tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE |
+                Py_TPFLAGS_METHOD_DESCRIPTOR | Py_TPFLAGS_HAVE_VECTORCALL,
+    .tp_descr_get = func_descr_get,
+};
+
+static PyTypeObject MethodDescriptorDerived_Type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "MethodDescriptorDerived",
+    .tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,
+};
+
+static PyTypeObject MethodDescriptorNopGet_Type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "MethodDescriptorNopGet",
+    .tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,
+    .tp_call = call_return_args,
+    .tp_descr_get = nop_descr_get,
+};
+
+typedef struct {
+    MethodDescriptorObject base;
+    vectorcallfunc vectorcall;
+} MethodDescriptor2Object;
+
+static PyObject *
+MethodDescriptor2_new(PyTypeObject* type, PyObject* args, PyObject *kw)
+{
+    MethodDescriptor2Object *op = PyObject_New(MethodDescriptor2Object, type);
+    op->base.vectorcall = NULL;
+    op->vectorcall = MethodDescriptor_vectorcall;
+    return (PyObject *)op;
+}
+
+static PyTypeObject MethodDescriptor2_Type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "MethodDescriptor2",
+    sizeof(MethodDescriptor2Object),
+    .tp_new = MethodDescriptor2_new,
+    .tp_call = PyVectorcall_Call,
+    .tp_vectorcall_offset = offsetof(MethodDescriptor2Object, vectorcall),
+    .tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HAVE_VECTORCALL,
+};
+
+
+int
+_PyTestCapi_Init_Vectorcall(PyObject *m) {
+    if (PyModule_AddFunctions(m, TestMethods) < 0) {
+        return -1;
+    }
+
+    if (PyType_Ready(&MethodDescriptorBase_Type) < 0) {
+        return -1;
+    }
+    if (PyModule_AddType(m, &MethodDescriptorBase_Type) < 0) {
+        return -1;
+    }
+
+    MethodDescriptorDerived_Type.tp_base = &MethodDescriptorBase_Type;
+    if (PyType_Ready(&MethodDescriptorDerived_Type) < 0) {
+        return -1;
+    }
+    if (PyModule_AddType(m, &MethodDescriptorDerived_Type) < 0) {
+        return -1;
+    }
+
+    MethodDescriptorNopGet_Type.tp_base = &MethodDescriptorBase_Type;
+    if (PyType_Ready(&MethodDescriptorNopGet_Type) < 0) {
+        return -1;
+    }
+    if (PyModule_AddType(m, &MethodDescriptorNopGet_Type) < 0) {
+        return -1;
+    }
+
+    MethodDescriptor2_Type.tp_base = &MethodDescriptorBase_Type;
+    if (PyType_Ready(&MethodDescriptor2_Type) < 0) {
+        return -1;
+    }
+    if (PyModule_AddType(m, &MethodDescriptor2_Type) < 0) {
+        return -1;
+    }
+
+    return 0;
+}

Modules/_testcapi/testcapimodule_parts.h

@@ -0,0 +1,3 @@
+#include "Python.h"
+
+PyAPI_FUNC(int) _PyTestCapi_Init_Vectorcall(PyObject *module);