cryptography is failing to install

As it turns out pycparser-2.11 is the culprit for this error message/bug.

pip uninstall pycparser && pip install -Iv pycparser==2.10

and permanently pinning pycparser to 2.10 or earlier fixes the issue

The bug is in cryptography https://github.com/pyca/cryptography/issues/1858

I hit the same issue.

with latest devstack, hit such issue

      from cryptography.hazmat.bindings.commoncrypto.binding import (
    File "/tmp/pip-build-ivmMZs/cryptography/src/cryptography/hazmat/bindings/commoncrypto/binding.py", line 14, in <module>
      class Binding(object):
    File "/tmp/pip-build-ivmMZs/cryptography/src/cryptography/hazmat/bindings/commoncrypto/binding.py", line 36, in Binding
      "-framework", "Security", "-framework", "CoreFoundation"
    File "/tmp/pip-build-ivmMZs/cryptography/src/cryptography/hazmat/bindings/utils.py", line 97, in build_ffi_for_binding
      extra_link_args=extra_link_args,
    File "/tmp/pip-build-ivmMZs/cryptography/src/cryptography/hazmat/bindings/utils.py", line 106, in build_ffi
      ffi.cdef(cdef_source)
    File "/tmp/pip-build-ivmMZs/cryptography/.eggs/cffi-0.9.2-py2.7-linux-x86_64.egg/cffi/api.py", line 106, in cdef
      self._parser.parse(csource, override=override, packed=packed)
    File "/tmp/pip-build-ivmMZs/cryptography/.eggs/cffi-0.9.2-py2.7-linux-x86_64.egg/cffi/cparser.py", line 165, in parse
      self._internal_parse(csource)
    File "/tmp/pip-build-ivmMZs/cryptography/.eggs/cffi-0.9.2-py2.7-linux-x86_64.egg/cffi/cparser.py", line 199, in _internal_parse
      realtype = self._get_type(decl.type, name=decl.name)
    File "/tmp/pip-build-ivmMZs/cryptography/.eggs/cffi-0.9.2-py2.7-linux-x86_64.egg/cffi/cparser.py", line 360, in _get_type
      return self._get_struct_union_enum_type('struct', type, name)
    File "/tmp/pip-build-ivmMZs/cryptography/.eggs/cffi-0.9.2-py2.7-linux-x86_64.egg/cffi/cparser.py", line 434, in _get_struct_union_enum_type
      return self._structnode2type[type]
    File "/usr/lib/python2.7/weakref.py", line 315, in __getitem__
      return self.data[ref(key)]
  TypeError: cannot create weak reference to 'Struct' object

i hit it too. Tried the workaround and still can't get past it.

work around worked - i just needed to re-create my venv.

There's an issue further upstream in pycparser: https://github.com/eliben/pycparser/issues/76

the above work-around not worked : pip uninstall pycparser && pip install -Iv pycparser==2.10

as it still failed in tempest install stage in devstack:
    Complete output from command /opt/stack/tempest/.tox/full/bin/python -c "import setuptools, tokenize;__file__='/tmp/pip-build-vweh8l/cryptography/setup.py';exec(compile(getattr(tokenize, 'open', open)(__file__).read().replace('\r\n', '\n'), __file__, 'exec'))" install --record /tmp/pip-g9w1On-record/install-record.txt --single-version-externally-managed --compile --install-headers /opt/stack/tempest/.tox/full/include/site/python2.7/cryptography:
    running install
    Traceback (most recent call last):
      File "<string>", line 1, in <module>
      File "/tmp/pip-build-vweh8l/cryptography/setup.py", line 342, in <module>
        **keywords_with_side_effects(sys.argv)
      File "/usr/lib/python2.7/distutils/core.py", line 151, in setup
        dist.run_commands()
      File "/usr/lib/python2.7/distutils/dist.py", line 953, in run_commands
        self.run_command(cmd)
      File "/usr/lib/python2.7/distutils/dist.py", line 971, in run_command
        cmd_obj.ensure_finalized()
      File "/usr/lib/python2.7/distutils/cmd.py", line 109, in ensure_finalized
        self.finalize_options()
      File "/tmp/pip-build-vweh8l/cryptography/setup.py", line 119, in finalize_options
        self.distribution.ext_modules = get_ext_modules()
      File "/tmp/pip-build-vweh8l/cryptography/setup.py", line 78, in get_ext_modules
        from cryptography.hazmat.bindings.commoncrypto.binding import (
      File "/tmp/pip-build-vweh8l/cryptography/src/cryptography/hazmat/bindings/commoncrypto/binding.py", line 14, in <module>
        class Binding(object):
      File "/tmp/pip-build-vweh8l/cryptography/src/cryptography/hazmat/bindings/commoncrypto/binding.py", line 36, in Binding
        "-framework", "Security", "-framework", "CoreFoundation"
      File "/tmp/pip-build-vweh8l/cryptography/src/cryptography/hazmat/bindings/utils.py", line 97, in build_ffi_for_binding
        extra_link_args=extra_link_args,
      File "/tmp/pip-build-vweh8l/cryptography/src/cryptography/hazmat/bindings/utils.py", line 106, in build_ffi
        ffi.cdef(cdef_source)
      File "/opt/stack/tempest/.tox/full/local/lib/python2.7/site-packages/cffi/api.py", line 106, in cdef
        self._parser.parse(csource, override=override, packed=packed)
      File "/opt/stack/tempest/.tox/full/local/lib/python2.7/site-packages/cffi/cparser.py", line 165, in parse
        self._internal_parse(csource)
      File "/opt/stack/tempest/.tox/full/local/lib/python2.7/site-packages/cffi/cparser.py", line 199, in _internal_parse
        realtype = self._get_type(decl.type, name=decl.name)
      File "/opt/stack/tempest/.tox/full/local/lib/python2.7/site-packages/cffi/cparser.py", line 360, in _get_type
        return self._get_struct_union_enum_type('struct', type, name)
      File "/opt/stack/tempest/.tox/full/local/lib/python2.7/site-packages/cffi/cparser.py", line 434, in _get_struct_union_enum_type
        return self._structnode2type[type]
      File "/usr/lib/python2.7/weakref.py", line 315, in __getitem__
        return self.data[ref(ke...

Fixed: https://github.com/eliben/pycparser/issues/76