- Issue #18440: Clarify that `hash()` can truncate the value returned from an

  object's custom `__hash__()` method.

1 files changed, 9 insertions, 4 deletions

diff --git a/Doc/library/functions.rst b/Doc/library/functions.rst
index 3d239ec..a37d496 100644
--- a/Doc/library/functions.rst
+++ b/Doc/library/functions.rst
@@ -587,11 +587,16 @@ are always available.  They are listed here in alphabetical order.
 
 .. function:: hash(object)
 
-   Return the hash value of the object (if it has one).  Hash values are integers.
-   They are used to quickly compare dictionary keys during a dictionary lookup.
-   Numeric values that compare equal have the same hash value (even if they are of
-   different types, as is the case for 1 and 1.0).
+   Return the hash value of the object (if it has one).  Hash values are
+   integers.  They are used to quickly compare dictionary keys during a
+   dictionary lookup.  Numeric values that compare equal have the same hash
+   value (even if they are of different types, as is the case for 1 and 1.0).
 
+  .. note::
+
+    For object's with custom :meth:`__hash__` methods, note that :func:`hash`
+    truncates the return value based on the bit width of the host machine.
+    See :meth:`__hash__` for details.
 
 .. function:: help([object])