bpo-12159: Document sys.maxsize limit in len() function reference (GH-17934)
diff --git a/Doc/library/functions.rst b/Doc/library/functions.rst
index dc3391f..cc48597 100644
--- a/Doc/library/functions.rst
+++ b/Doc/library/functions.rst
@@ -892,6 +892,11 @@
sequence (such as a string, bytes, tuple, list, or range) or a collection
(such as a dictionary, set, or frozen set).
+ .. impl-detail::
+
+ ``len`` raises :exc:`OverflowError` on lengths larger than
+ :data:`sys.maxsize`, such as :class:`range(2 ** 100) <range>`.
+
.. _func-list:
.. class:: list([iterable])