From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ricardo Wurmus <rekado@elephly.net>
Subject: bug#22533: Python bytecode reproducibility
Date: Sat, 03 Mar 2018 23:37:29 +0100
Message-ID: <87606c23bq.fsf@elephly.net>
References: <20160202051544.GA11744@jasmine> <87bmqfu44s.fsf@fastmail.com>
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To: Marius Bakke <mbakke@fastmail.com>
Cc: 22533@debbugs.gnu.org

Hi Guix,

Marius Bakke <mbakke@fastmail.com> writes:

> It would be great to revive this longstanding bug!

Indeed.

Here=E2=80=99s another attempt.  As far as I understand, the timestamp in t=
he
pyc files only affects the header.

Up until Python 3.6 (incl) the header looks like this:

  magic | timestamp | size

Since Python 3.7 the header may either contain a timestamp or a hash:

  magic | 00000000000000000000000000000000 | timestamp | size
  magic | 00000000000000000000000000000001 | hash      | size

This means we likely won=E2=80=99t have this problem any more with Python 3=
.7.
For Python 3.6 I guess we could add a final build phase that overwrites
the timestamp in the *binary*.  This needs to happen before any of the
compiled files are wrapped up in a wheel.

Should we just wait for Python 3.7 which is expected to be released in
June 2018?  We=E2=80=99d still have to deal with this problem in Python 2,
though.

Is it a bad idea to override the timestamps in the generated binaries?
I think that we could avoid the recency check then, which was an
obstacle to resetting the timestamps of the source files.

--
Ricardo

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