Fix issue #3547 for MingW, update comments.

diff --git a/Lib/ctypes/test/test_bitfields.py b/Lib/ctypes/test/test_bitfields.py
index ddd753ea09b0c835a55654ea825cdbfca790948a..96cd7c6442061a2f18fdd0e559038ca7ce834318 100644 (file)
--- a/Lib/ctypes/test/test_bitfields.py
+++ b/Lib/ctypes/test/test_bitfields.py
@@ -223,8 +223,9 @@ class BitFieldTest(unittest.TestCase):
                         ("d", c_short, 4),
                         ("e", c_short, 4),
                         ("f", c_int, 24)]
-        # MS compilers do NOT combine c_short and c_int into
-        # one field, gcc does.
+        # MSVC does NOT combine c_short and c_int into one field, GCC
+        # does (unless GCC is run with '-mms-bitfields' which
+        # produces code compatible with MSVC).
         if os.name in ("nt", "ce"):
             self.failUnlessEqual(sizeof(X), sizeof(c_int) * 4)
         else:

diff --git a/Modules/_ctypes/cfield.c b/Modules/_ctypes/cfield.c
index b9024bb7491a9584d95248646e612fe26c1ffdfa..ef85b87cbf282783d9b27e4002f7fc5f35a3bfcd 100644 (file)
--- a/Modules/_ctypes/cfield.c
+++ b/Modules/_ctypes/cfield.c
@@ -65,10 +65,12 @@ CField_FromDesc(PyObject *desc, Py_ssize_t index,
        }
        if (bitsize /* this is a bitfield request */
            && *pfield_size /* we have a bitfield open */
-#if defined(MS_WIN32) && !defined(__MINGW32__)
-           && dict->size * 8 == *pfield_size /* MSVC */
+#ifdef MS_WIN32
+           /* MSVC, GCC with -mms-bitfields */
+           && dict->size * 8 == *pfield_size
 #else
-           && dict->size * 8 <= *pfield_size /* GCC, MINGW */
+           /* GCC */
+           && dict->size * 8 <= *pfield_size 
 #endif
            && (*pbitofs + bitsize) <= *pfield_size) {
                /* continue bit field */