Issue #15475: Add __sizeof__ implementations for itertools objects.
diff --git a/Modules/itertoolsmodule.c b/Modules/itertoolsmodule.c
index 8be62ce..db7cdfe 100644
--- a/Modules/itertoolsmodule.c
+++ b/Modules/itertoolsmodule.c
@@ -2057,6 +2057,18 @@
     Py_TYPE(lz)->tp_free(lz);
 }
 
+static PyObject *
+product_sizeof(productobject *lz, void *unused)
+{
+    Py_ssize_t res;
+
+    res = sizeof(productobject);
+    res += PyTuple_GET_SIZE(lz->pools) * sizeof(Py_ssize_t);
+    return PyLong_FromSsize_t(res);
+}
+
+PyDoc_STRVAR(sizeof_doc, "Returns size in memory, in bytes.");
+
 static int
 product_traverse(productobject *lz, visitproc visit, void *arg)
 {
@@ -2226,6 +2238,8 @@
      reduce_doc},
     {"__setstate__",    (PyCFunction)product_setstate,    METH_O,
      setstate_doc},
+    {"__sizeof__",      (PyCFunction)product_sizeof,      METH_NOARGS,
+     sizeof_doc},
     {NULL,              NULL}   /* sentinel */
 };
 
@@ -2366,6 +2380,16 @@
     Py_TYPE(co)->tp_free(co);
 }
 
+static PyObject *
+combinations_sizeof(combinationsobject *co, void *unused)
+{
+    Py_ssize_t res;
+
+    res = sizeof(combinationsobject);
+    res += co->r * sizeof(Py_ssize_t);
+    return PyLong_FromSsize_t(res);
+}
+
 static int
 combinations_traverse(combinationsobject *co, visitproc visit, void *arg)
 {
@@ -2537,6 +2561,8 @@
      reduce_doc},
     {"__setstate__",    (PyCFunction)combinations_setstate,    METH_O,
      setstate_doc},
+    {"__sizeof__",      (PyCFunction)combinations_sizeof,      METH_NOARGS,
+     sizeof_doc},
     {NULL,              NULL}   /* sentinel */
 };
 
@@ -2695,6 +2721,16 @@
     Py_TYPE(co)->tp_free(co);
 }
 
+static PyObject *
+cwr_sizeof(cwrobject *co, void *unused)
+{
+    Py_ssize_t res;
+
+    res = sizeof(cwrobject);
+    res += co->r * sizeof(Py_ssize_t);
+    return PyLong_FromSsize_t(res);
+}
+
 static int
 cwr_traverse(cwrobject *co, visitproc visit, void *arg)
 {
@@ -2854,6 +2890,8 @@
      reduce_doc},
     {"__setstate__",    (PyCFunction)cwr_setstate,    METH_O,
      setstate_doc},
+    {"__sizeof__",      (PyCFunction)cwr_sizeof,      METH_NOARGS,
+     sizeof_doc},
     {NULL,              NULL}   /* sentinel */
 };
 
@@ -3030,6 +3068,17 @@
     Py_TYPE(po)->tp_free(po);
 }
 
+static PyObject *
+permutations_sizeof(permutationsobject *po, void *unused)
+{
+    Py_ssize_t res;
+
+    res = sizeof(permutationsobject);
+    res += PyTuple_GET_SIZE(po->pool) * sizeof(Py_ssize_t);
+    res += po->r * sizeof(Py_ssize_t);
+    return PyLong_FromSsize_t(res);
+}
+
 static int
 permutations_traverse(permutationsobject *po, visitproc visit, void *arg)
 {
@@ -3235,6 +3284,8 @@
      reduce_doc},
     {"__setstate__",    (PyCFunction)permutations_setstate,    METH_O,
      setstate_doc},
+    {"__sizeof__",      (PyCFunction)permutations_sizeof,      METH_NOARGS,
+     sizeof_doc},
     {NULL,              NULL}   /* sentinel */
 };