OverflowError: Python int too large to convert to C long

[hgc2002]

This error happening just importing the av library (on Python 3.4.3), not even starting using it.

File "av/enums.pyx", line 145, in av.enums.EnumItem.cinit

The full trace:

File "/usr/local/lib/python3.4/dist-packages/av/__init__.py", line 15, in <module>
    from av.audio.fifo import AudioFifo
  File "/usr/local/lib/python3.4/dist-packages/av/audio/__init__.py", line 1, in <module>
    from .frame import AudioFrame
  File "av/audio/frame.pyx", line 1, in init av.audio.frame
  File "av/codec/codec.pxd", line 6, in init av.frame
  File "/usr/local/lib/python3.4/dist-packages/av/codec/__init__.py", line 1, in <module>
    from .codec import Codec, codecs_available, codec_descriptor
  File "av/descriptor.pxd", line 4, in init av.codec.codec
  File "av/option.pxd", line 4, in init av.descriptor
  File "av/option.pyx", line 18, in init av.option
  File "av/enums.pyx", line 225, in av.enums.define_enum
  File "av/enums.pyx", line 28, in av.enums.EnumType._init
  File "av/enums.pyx", line 32, in av.enums.EnumType._create
  File "av/enums.pyx", line 145, in av.enums.EnumItem.__cinit__
OverflowError: Python int too large to convert to C long

Here is where the trace points to:

cdef class EnumItem(object):

    cdef readonly str name
    cdef readonly long value #int
    cdef long _hash

    def __cinit__(self, sentinel_, name, value):

        if sentinel_ is not sentinel:
            raise RuntimeError("Cannot instantiate {}.".format(self.__class__.__name__))
        self.name = name
        self.value = value

        # Establish a hash that doesn't collide with anything that would return
        # true from __eq__.
        hash_ = id(self)
        name_hash = hash(name)
        value_hash = hash(value)
        while hash_ == name_hash or hash_ == value_hash:
            hash_ += 1
        self._hash = hash_ # <--- here is where the trace points to !!!

I've tried lot of things but nothing goes. Any idea?
Thanks!

[hgc2002]

More info: i'm using FFmpeg 4.0 and PyAv compiled (both) directly on local.
PyAv comes directly from Github, version 0.4.1

[Kamekameha]

I don't know about the size of long in this case but maybe EnumItem._hash should be cdef-ed as Py_ssize_t? At least that's what CPython typedefs Py_hash_t as, Py_hash_t being the return type of the PyTypeObject.tp_hash slot, and considering this hash value is computed from the object's address.

[mikeboers]

That sounds very reasonable.

[mikeboers]

Thanks @hgc2002 @Kamekameha and @tshirtman for the dicussion and PRs.

I've typed _hash as Py_hash_t, and also simplified the calculation so that it starts at value + 1. Then it only needs to compare once against the hash of name, and we know it will be unique. Everything is cdef-ed, so it will all be the right size and wrap around if it needs to.