Revert "Backport METH_FASTCALL from Python 3.7 (#328)"

This reverts commit cf73bbd678.

third_party/python/Modules/_functoolsmodule.c

@@ -43,7 +43,6 @@ typedef struct {
     PyObject *kw;
     PyObject *dict;
     PyObject *weakreflist; /* List of weak references */
-    int use_fastcall;
 } partialobject;
 
 static PyTypeObject partial_type;
@@ -136,7 +135,6 @@ partial_new(PyTypeObject *type, PyObject *args, PyObject *kw)
         return NULL;
     }
 
-    pto->use_fastcall = _PyObject_HasFastCall(func);
     return (PyObject *)pto;
 }
 
@@ -155,110 +153,66 @@ partial_dealloc(partialobject *pto)
 }
 
 static PyObject *
-partial_fastcall(partialobject *pto, PyObject **args, Py_ssize_t nargs,
-                 PyObject *kwargs)
+partial_call(partialobject *pto, PyObject *args, PyObject *kw)
 {
-    PyObject *small_stack[_PY_FASTCALL_SMALL_STACK];
     PyObject *ret;
-    PyObject **stack, **stack_buf = NULL;
-    Py_ssize_t nargs2, pto_nargs;
-
-    pto_nargs = PyTuple_GET_SIZE(pto->args);
-    nargs2 = pto_nargs + nargs;
-
-    if (pto_nargs == 0) {
-        stack = args;
-    }
-    else if (nargs == 0) {
-        stack = &PyTuple_GET_ITEM(pto->args, 0);
-    }
-    else {
-        if (nargs2 <= (Py_ssize_t)Py_ARRAY_LENGTH(small_stack)) {
-            stack = small_stack;
-        }
-        else {
-            stack_buf = PyMem_Malloc(nargs2 * sizeof(PyObject *));
-            if (stack_buf == NULL) {
-                PyErr_NoMemory();
-                return NULL;
-            }
-            stack = stack_buf;
-        }
-
-        /* use borrowed references */
-        memcpy(stack,
-               &PyTuple_GET_ITEM(pto->args, 0),
-               pto_nargs * sizeof(PyObject*));
-        memcpy(&stack[pto_nargs],
-               args,
-               nargs * sizeof(PyObject*));
-    }
-
-    ret = _PyObject_FastCallDict(pto->fn, stack, nargs2, kwargs);
-    PyMem_Free(stack_buf);
-    return ret;
-}
-
-static PyObject *
-partial_call_impl(partialobject *pto, PyObject *args, PyObject *kwargs)
-{
-    PyObject *ret, *args2;
-
-    /* Note: tupleconcat() is optimized for empty tuples */
-    args2 = PySequence_Concat(pto->args, args);
-    if (args2 == NULL) {
-        return NULL;
-    }
-    assert(PyTuple_Check(args2));
-
-    ret = PyObject_Call(pto->fn, args2, kwargs);
-    Py_DECREF(args2);
-    return ret;
-}
-
-static PyObject *
-partial_call(partialobject *pto, PyObject *args, PyObject *kwargs)
-{
-    PyObject *kwargs2, *res;
+    PyObject *argappl, *kwappl;
+    PyObject **stack;
+    Py_ssize_t nargs;
 
     assert (PyCallable_Check(pto->fn));
     assert (PyTuple_Check(pto->args));
     assert (PyDict_Check(pto->kw));
 
-    if (PyDict_GET_SIZE(pto->kw) == 0) {
-        /* kwargs can be NULL */
-        kwargs2 = kwargs;
-        Py_XINCREF(kwargs2);
+    if (PyTuple_GET_SIZE(pto->args) == 0) {
+        stack = &PyTuple_GET_ITEM(args, 0);
+        nargs = PyTuple_GET_SIZE(args);
+        argappl = NULL;
+    }
+    else if (PyTuple_GET_SIZE(args) == 0) {
+        stack = &PyTuple_GET_ITEM(pto->args, 0);
+        nargs = PyTuple_GET_SIZE(pto->args);
+        argappl = NULL;
     }
     else {
-        /* bpo-27840, bpo-29318: dictionary of keyword parameters must be
-           copied, because a function using "**kwargs" can modify the
-           dictionary. */
-        kwargs2 = PyDict_Copy(pto->kw);
-        if (kwargs2 == NULL) {
+        stack = NULL;
+        argappl = PySequence_Concat(pto->args, args);
+        if (argappl == NULL) {
             return NULL;
         }
 
-        if (kwargs != NULL) {
-            if (PyDict_Merge(kwargs2, kwargs, 1) != 0) {
-                Py_DECREF(kwargs2);
+        assert(PyTuple_Check(argappl));
+    }
+
+    if (PyDict_Size(pto->kw) == 0) {
+        kwappl = kw;
+        Py_XINCREF(kwappl);
+    }
+    else {
+        kwappl = PyDict_Copy(pto->kw);
+        if (kwappl == NULL) {
+            Py_XDECREF(argappl);
+            return NULL;
+        }
+
+        if (kw != NULL) {
+            if (PyDict_Merge(kwappl, kw, 1) != 0) {
+                Py_XDECREF(argappl);
+                Py_DECREF(kwappl);
                 return NULL;
             }
         }
     }
 
-
-    if (pto->use_fastcall) {
-        res = partial_fastcall(pto,
-                               &PyTuple_GET_ITEM(args, 0),
-                               PyTuple_GET_SIZE(args),
-                               kwargs2);
+    if (stack) {
+        ret = _PyObject_FastCallDict(pto->fn, stack, nargs, kwappl);
     }
     else {
-        res = partial_call_impl(pto, args, kwargs2);
+        ret = PyObject_Call(pto->fn, argappl, kwappl);
+        Py_DECREF(argappl);
     }
-    Py_XDECREF(kwargs2);
-    return res;
+    Py_XDECREF(kwappl);
+    return ret;
 }
 
 static int
@@ -387,13 +341,12 @@ partial_setstate(partialobject *pto, PyObject *state)
         return NULL;
     }
 
+    Py_INCREF(fn);
     if (dict == Py_None)
         dict = NULL;
     else
         Py_INCREF(dict);
 
-    Py_INCREF(fn);
-    pto->use_fastcall = _PyObject_HasFastCall(fn);
     Py_SETREF(pto->fn, fn);
     Py_SETREF(pto->args, fnargs);
     Py_SETREF(pto->kw, kw);