New issue 2826: Tuple hash inconsistent when used with struct.unpack_from
https://bitbucket.org/pypy/pypy/issues/2826/tuple-hash-inconsistent-when-used-with
drwaopfer:
Found a divergence from CPython: some tuples of integers that compare equal
won't hash the same. Caused when some of the integers come from
`struct.unpack_from`. I found this when my application unpacked values from a
msgpack payload. I distilled my scenario into a minimal testcase below.
```python
import struct
packed = b"\x92\xcfp\x91|\x8b\x13n\xf8\xd0\x00"
regular_version = (8111401340639312080, 0)
p_up_version = (struct.unpack_from(">Q", packed, 2)[0], packed[10])
print(regular_version, "==" if regular_version == p_up_version else "!=",
p_up_version)
print(
hash(regular_version),
"==" if hash(regular_version) == hash(p_up_version) else "!=",
hash(p_up_version),
)
```
```
$ python --version
Python 3.5.5 :: Anaconda, Inc.
$ python testcase.py
(8111401340639312080, 0) == (8111401340639312080, 0)
-4258064001062497448 == -4258064001062497448
$ pypy3 --version
Python 3.5.3 (fdd60ed87e94, Apr 24 2018, 06:10:04)
[PyPy 6.0.0 with GCC 6.2.0 20160901]
$ pypy3 testcase.py
(8111401340639312080, 0) == (8111401340639312080, 0)
7271147797421229587 != -4258064001062497448
```
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