On 30-Jul-16 02:51, Martin Panter wrote:
> Martin Panter added the comment:
>
> Looks like your Python 3 build is messed up. Maybe it doesn’t like running from a different directory. I would try from the main build directory, and note the test_bitfields has an S:
I would not know why - it is just a copy of the sources and then 
configure, make, make DESTDIR=/some/where install (rather than make 
install).
Same procedure I use for python2.7.

>
> ./python -m unittest -v ctypes.test.test_bitfields
No changes: 3.5.1

root@x064:[/data/prj/aixtools/python/python-3.5.1.2]./python -m unittest 
-v ctypes.test.test_bitfields
test_anon_bitfields (ctypes.test.test_bitfields.BitFieldTest) ... ok
test_c_wchar (ctypes.test.test_bitfields.BitFieldTest) ... ok
test_longlong (ctypes.test.test_bitfields.BitFieldTest) ... ok
test_mixed_1 (ctypes.test.test_bitfields.BitFieldTest) ... ok
test_mixed_2 (ctypes.test.test_bitfields.BitFieldTest) ... ok
test_mixed_3 (ctypes.test.test_bitfields.BitFieldTest) ... ok
test_mixed_4 (ctypes.test.test_bitfields.BitFieldTest) ... ok
test_multi_bitfields_size (ctypes.test.test_bitfields.BitFieldTest) ... ok
test_nonint_types (ctypes.test.test_bitfields.BitFieldTest) ... ok
test_signed (ctypes.test.test_bitfields.BitFieldTest) ... ok
test_single_bitfield_size (ctypes.test.test_bitfields.BitFieldTest) ... ok
test_uint32 (ctypes.test.test_bitfields.BitFieldTest) ... ok
test_uint32_swap_big_endian (ctypes.test.test_bitfields.BitFieldTest) ... ok
test_uint32_swap_little_endian (ctypes.test.test_bitfields.BitFieldTest) 
... ok
test_uint64 (ctypes.test.test_bitfields.BitFieldTest) ... ok
test_ulonglong (ctypes.test.test_bitfields.BitFieldTest) ... ok
test_unsigned (ctypes.test.test_bitfields.BitFieldTest) ... ok
test_ints (ctypes.test.test_bitfields.C_Test) ... FAIL
test_shorts (ctypes.test.test_bitfields.C_Test) ... FAIL

======================================================================
FAIL: test_ints (ctypes.test.test_bitfields.C_Test)
----------------------------------------------------------------------
Traceback (most recent call last):
   File 
"/data/prj/aixtools/python/python-3.5.1.2/Lib/ctypes/test/test_bitfields.py", 
line 41, in test_ints
     self.assertEqual(getattr(b, name), func(byref(b), 
name.encode('ascii')))
AssertionError: -1 != 1

======================================================================
FAIL: test_shorts (ctypes.test.test_bitfields.C_Test)
----------------------------------------------------------------------
Traceback (most recent call last):
   File 
"/data/prj/aixtools/python/python-3.5.1.2/Lib/ctypes/test/test_bitfields.py", 
line 48, in test_shorts
     self.assertEqual(getattr(b, name), func(byref(b), 
name.encode('ascii')))
AssertionError: -1 != 1

----------------------------------------------------------------------
Ran 19 tests in 0.013s

FAILED (failures=2)

> What I am suggesting as a fix is to change line 381 from plain “int” to “signed int”, and 382 to “signed short”. I can make a patch later if that will help. Hopefully with these changes the C compiler will use signed integer logic, matching what I believe the ctypes library uses for c_int and c_short.
Working from Python-2.7.12 - added your changes, test still fails:

root@x064:[/data/prj/aixtools/python/python-2.7.12.0]./python -m 
unittest -v ctypes.test.test_bitfields
test_anon_bitfields (ctypes.test.test_bitfields.BitFieldTest) ... ok
test_c_wchar (ctypes.test.test_bitfields.BitFieldTest) ... ok
test_longlong (ctypes.test.test_bitfields.BitFieldTest) ... ok
test_mixed_1 (ctypes.test.test_bitfields.BitFieldTest) ... ok
test_mixed_2 (ctypes.test.test_bitfields.BitFieldTest) ... ok
test_mixed_3 (ctypes.test.test_bitfields.BitFieldTest) ... ok
test_mixed_4 (ctypes.test.test_bitfields.BitFieldTest) ... ok
test_multi_bitfields_size (ctypes.test.test_bitfields.BitFieldTest) ... ok
test_nonint_types (ctypes.test.test_bitfields.BitFieldTest) ... ok
test_signed (ctypes.test.test_bitfields.BitFieldTest) ... ok
test_single_bitfield_size (ctypes.test.test_bitfields.BitFieldTest) ... ok
test_uint32 (ctypes.test.test_bitfields.BitFieldTest) ... ok
test_uint32_swap_big_endian (ctypes.test.test_bitfields.BitFieldTest) ... ok
test_uint32_swap_little_endian (ctypes.test.test_bitfields.BitFieldTest) 
... ok
test_uint64 (ctypes.test.test_bitfields.BitFieldTest) ... ok
test_ulonglong (ctypes.test.test_bitfields.BitFieldTest) ... ok
test_unsigned (ctypes.test.test_bitfields.BitFieldTest) ... ok
test_ints (ctypes.test.test_bitfields.C_Test) ... ok
test_shorts (ctypes.test.test_bitfields.C_Test) ... FAIL

======================================================================
FAIL: test_shorts (ctypes.test.test_bitfields.C_Test)
----------------------------------------------------------------------
Traceback (most recent call last):
   File 
"/data/prj/aixtools/python/python-2.7.12.0/Lib/ctypes/test/test_bitfields.py", 
line 48, in test_shorts
     self.assertEqual((name, i, getattr(b, name)), (name, i, 
func(byref(b), name)))
AssertionError: Tuples differ: ('M', 1, -1) != ('M', 1, 1)

First differing element 2:
-1
1

- ('M', 1, -1)
?          -

+ ('M', 1, 1)

----------------------------------------------------------------------
Ran 19 tests in 0.068s

FAILED (failures=1)

> Using a type other than short is not right, because the Python test is explicitly trying to test c_short behaviour. If your compiler does not support “signed short” bitfields, maybe we just have to accept that ctypes supports it even though the compiler doesn’t, and skip the test.
Looks like this may be the approach: as signed int, signed short give 
the same message - it seems that xlc (and maybe Sun C) does not accept 
"short" as a bitfield type.

skipping test - only if compiler is not gcc, as when using gcc, test 
works fine.

> ----------
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> <http://bugs.python.org/issue27643>
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