GNU bug report logs - #22533
Non-determinism in python-3 ".pyc" bytecode

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From: Leo Famulari <leo <at> famulari.name>
To: Ludovic Courtès <ludo <at> gnu.org>
Cc: 22533 <at> debbugs.gnu.org
Subject: bug#22533: Non-determinism in python-3 ".pyc" bytecode
Date: Thu, 4 Feb 2016 18:17:08 -0500

[Message part 1 (text/plain, inline)]

On Tue, Feb 02, 2016 at 09:41:19PM +0100, Ludovic Courtès wrote:
> Could you give it a try and refine as needed?  :-)

I altered your example as shown in the attached patch. It causes some
tests related to timestamps to fail, so I disabled them in a very crude
way. The final patch should address those tests more carefully.

But, the patch doesn't seem to have the desired effect so I'm asking for
help!

Here is how I tested the patch:

I build python-3 with it, and then `export SOURCE_DATE_EPOCH=1` and
enter the resulting Python shell. I manually define the '_w_long'
function used by the patched function. Then: 

print (_w_long(locale.atoi(os.getenv('SOURCE_DATE_EPOCH'))))
b'\x01\x00\x00\x00'

But, when I leave the Python shell and issue `python3 -m compileall
helloworld.py`, the timestamps are present in the compiled bytecode. I
can watch the clock "tick" by doing this repeatedly:

$ touch helloworld.py && rm -r __pycache__ && \
python3 -m compileall helloworld.py &&  \
hexdump __pycache__/helloworld.cpython-34.pyc | head -n1

I'm not much of a Python programmer, so I'm stumped.

[0001-SOURCE_DATE_EPOCH.patch (text/x-diff, attachment)]

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