From 490cf4472ec1d5ce70f7e4817b47c392f22d579c Mon Sep 17 00:00:00 2001 From: Eli Bendersky Date: Sat, 9 Mar 2013 05:54:00 -0800 Subject: [PATCH] Add warning in ctypes documentation for #16575 and #16576 --- Doc/library/ctypes.rst | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/Doc/library/ctypes.rst b/Doc/library/ctypes.rst index 486c9635573..6f093fe1cf5 100644 --- a/Doc/library/ctypes.rst +++ b/Doc/library/ctypes.rst @@ -603,6 +603,13 @@ for debugging because they can provide useful information:: .. _ctypes-structureunion-alignment-byte-order: +.. warning:: + + :mod:`ctypes` does not support passing unions or structures with bit-fields + to functions by value. While this may work on 32-bit x86, it's not + guaranteed by the library to work in the general case. Unions and + structures with bit-fields should always be passed to functions by pointer. + Structure/union alignment and byte order ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^