exception __suppress_context__ test failures on OS X ppc systems

[ned-deily]

BPO	15597
Nosy	@birkenfeld, @pitrou, @vstinner, @benjaminp, @ned-deily
Files	char.patch exception.patch

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2012-08-09.00:23:07.525>
created_at = <Date 2012-08-08.23:16:48.217>
labels = ['type-bug']
title = 'exception __suppress_context__ test failures on OS X ppc systems'
updated_at = <Date 2012-08-09.01:14:20.679>
user = 'https://github.com/ned-deily'

bugs.python.org fields:

activity = <Date 2012-08-09.01:14:20.679>
actor = 'ned.deily'
assignee = 'none'
closed = True
closed_date = <Date 2012-08-09.00:23:07.525>
closer = 'python-dev'
components = []
creation = <Date 2012-08-08.23:16:48.217>
creator = 'ned.deily'
dependencies = []
files = ['26731', '26732']
hgrepos = []
issue_num = 15597
keywords = ['patch']
message_count = 6.0
messages = ['167734', '167738', '167739', '167740', '167743', '167749']
nosy_count = 6.0
nosy_names = ['georg.brandl', 'pitrou', 'vstinner', 'benjamin.peterson', 'ned.deily', 'python-dev']
pr_nums = []
priority = 'critical'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue15597'
versions = ['Python 3.3']

[ned-deily]

== CPython 3.3.0b1 (default:efb30bdcfa1e, Aug 8 2012, 15:43:49) [GCC 4.0.1 (Apple Inc. build 5493)]
== Darwin-8.11.0-Power_Macintosh-powerpc-32bit big-endian
== /private/tmp/test_python_13864
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)
[...]
======================================================================
FAIL: testChainingDescriptors (test.test_exceptions.ExceptionTests)
----------------------------------------------------------------------

Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/3.3/lib/python3.3/test/test_exceptions.py", line 432, in testChainingDescriptors
    self.assertTrue(e.__suppress_context__)
AssertionError: False is not true

---

Other similar test failures include multiple test cases in test_ipaddress, test_raise, and test_traceback, for example:

======================================================================
FAIL: test_address_errors (test.test_ipaddress.NetworkTestCase_v6)
----------------------------------------------------------------------

Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/3.3/lib/python3.3/ipaddress.py", line 1580, in _ip_int_from_string
    ip_int |= self._parse_hextet(parts[i])
  File "/Library/Frameworks/Python.framework/Versions/3.3/lib/python3.3/ipaddress.py", line 1605, in _parse_hextet
    raise ValueError("Only hex digits permitted in %r" % hextet_str)
ValueError: Only hex digits permitted in 'axy'

During handling of the above exception, another exception occurred:

ipaddress.AddressValueError: Only hex digits permitted in 'axy' in '1234:axy::b'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/3.3/lib/python3.3/test/test_ipaddress.py", line 439, in test_address_errors
    assertBadAddress("1234:axy::b", "Only hex digits")
  File "/Library/Frameworks/Python.framework/Versions/3.3/lib/python3.3/test/test_ipaddress.py", line 432, in assertBadAddress
    self.factory(addr)
  File "/Library/Frameworks/Python.framework/Versions/3.3/lib/python3.3/contextlib.py", line 66, in __exit__
    self.gen.throw(type, value, traceback)
  File "/Library/Frameworks/Python.framework/Versions/3.3/lib/python3.3/test/test_ipaddress.py", line 50, in assertCleanError
    self.assertTrue(exc.exception.__suppress_context__)
AssertionError: False is not true

The same universal build runs without error on an Intel Mac with the same os version. The ppc failures are seen on both PPC OS X 10.5 and 10.4 systems.

[ned-deily]

It appears similar failures are occuring on Sparc platforms (see bpo-15589) another big-endian platform.

[benjaminp]

Does this fix it?

[vstinner]

__suppress_context__ is a member using T_BOOL type. T_BOOL expects the C type "char", whereas the field in the PyBaseExceptionObject is a C "int". Attached patch changes the type and should fix the issue.

The test fails because writing into the field uses:

*(char*)field = value;

Which does not work in big endian if the field is a pointer to an int.

[python-dev]

New changeset e2df976b8a33 by Benjamin Peterson in branch 'default':
use char instead of int to please T_BOOL (closes bpo-15597)
http://hg.python.org/cpython/rev/e2df976b8a33

[ned-deily]

The patch does indeed fix all of the __suppress_context__ related test failures previously seen, i.e. test_exceptions, test_ipaddress, test_raise, and test_traceback.