From 78d7745b4f8ac6d072d6916d8164f0dc712caea7 Mon Sep 17 00:00:00 2001
From: Petr Viktorin <encukou@gmail.com>
Date: Sat, 17 May 2025 19:07:15 +0200
Subject: [PATCH] gh-57089: Note _layout_ in the bitfield docs

Co-Authored-By: Meador Inge <meadori@gmail.com>
---
 Doc/library/ctypes.rst | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/Doc/library/ctypes.rst b/Doc/library/ctypes.rst
index 5b733d5321e907..889c6b76aafc8f 100644
--- a/Doc/library/ctypes.rst
+++ b/Doc/library/ctypes.rst
@@ -714,10 +714,16 @@ item in the :attr:`~Structure._fields_` tuples::
    ...                 ("second_16", c_int, 16)]
    ...
    >>> print(Int.first_16)
-   <Field type=c_long, ofs=0:0, bits=16>
+   <ctypes.CField 'first_16' type=c_int, ofs=0, bit_size=16, bit_offset=0>
    >>> print(Int.second_16)
-   <Field type=c_long, ofs=0:16, bits=16>
-   >>>
+   <ctypes.CField 'second_16' type=c_int, ofs=0, bit_size=16, bit_offset=16>
+
+It is important to note that bit field allocation and layout in memory is not
+defined as a C standard; its implementation is compiler-specific.
+By default, Python will attempt to match the behavior of a "native" compiler
+for the current platform.
+See the :attr:`~Structure._layout_` attribute for details on the default
+behavior and how to change it.
 
 
 .. _ctypes-arrays: