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test_buffer can fail when run on an OS X 64-/32-bit universal build of Python is run in 32-bit mode.
$ /usr/local/bin/python3.3 -m test test_buffer
[1/1] test_buffer
1 test OK.
$ /usr/local/bin/python3.3-32 -m test -v test_buffer
== CPython 3.3.0a3 (v3.3.0a3:0b53b70a40a0, May 1 2012, 11:39:35) [GCC 4.2.1 (Apple Inc. build 5666) (dot 3)]
== Darwin-11.4.0-x86_64-i386-64bit little-endian
== /private/var/folders/fm/9wjgctqx61n796zt88qmmnxc0000gn/T/test_python_56263
Testing with flags: sys.flags(debug=0, inspect=0, interactive=0, optimize=0, dont_write_bytecode=0, no_user_site=0, no_site=0, ignore_environment=0, verbose=0, bytes_warning=0, quiet=0, hash_randomization=1)
[1/1] test_buffer
[...]
test_memoryview_construction (test.test_buffer.TestBufferProtocol) ... FAIL
test_ndarray_format_shape (test.test_buffer.TestBufferProtocol) ... FAIL
test_ndarray_format_strides (test.test_buffer.TestBufferProtocol) ... FAIL
test_ndarray_getbuf (test.test_buffer.TestBufferProtocol) ... FAIL
test_ndarray_multidim (test.test_buffer.TestBufferProtocol) ... FAIL
test_ndarray_slice_assign_single (test.test_buffer.TestBufferProtocol) ... FAIL
[...]
The test is incorrectly testing a compile-time configuration variable which is not meaningful for universal builds since each architecture can have different values. Further, the platform.architecture fallback test is also unreliable; as noted in the docs for the platform module, sys.maxsize should be used for run-time tests. The attached patch fixes the test for OS X.

The sysconfig docs say: "configuration variables relevant for the
current platform"
If get_config_var('SIZEOF_VOID_P') is meaningless for universal builds,
then IMO it should return None. None would then mean either "not found"
or "irrelevant".

Well, no need to ever use SIZEOF_VOID_P. sys.maxsize should always tell you whether the build is 32-bit or 64-bit.

The tests for arrays with suboffsets literally need sizeof(void *).
I don't think C guarantees SIZEOF_VOID_P == SIZEOF_SIZE_T. If HAVE_SSIZE_T
is defined in pyport.h, AFAICS no such check is made.
Of course these concerns may be entirely theoretical. :)

New changeset 8f22e5be18c8 by Stefan Krah in branch 'default':
Issue #14779: Do not use get_config_var('SIZEOF_VOID_P') on OS X 64-/32-bit
http://hg.python.org/cpython/rev/8f22e5be18c8 

Apparently the AS/400 had 128 bit pointers and IBM's "System i" still has them:
http://comments.gmane.org/gmane.comp.programming.garbage-collection.boehmgc/651
http://www-01.ibm.com/support/docview.wss?uid=swg27019425
So I'll leave the SIZEOF_VOID_P test as the preferred method. Perhaps
the best way to sidestep all these issues would be to write a small
C module for getting type sizes.

New changeset 967b06d56a69 by Stefan Krah in branch 'default':
Issue #14779: Get sizeof(void *) directly rather than relying on sysconfig.
http://hg.python.org/cpython/rev/967b06d56a69