_frozen_importlib should not have a __file__ attribute

[ncoghlan]

BPO	20942
Nosy	@brettcannon, @ncoghlan, @ericsnowcurrently
Files	no_frozen__file__.diff no_frozen__file__.diff

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = 'https://github.com/brettcannon'
closed_at = <Date 2014-04-04.14:22:05.901>
created_at = <Date 2014-03-16.05:42:27.173>
labels = ['interpreter-core', 'type-bug']
title = '_frozen_importlib should not have a __file__ attribute'
updated_at = <Date 2014-04-04.20:22:50.553>
user = 'https://github.com/ncoghlan'

bugs.python.org fields:

activity = <Date 2014-04-04.20:22:50.553>
actor = 'Arfrever'
assignee = 'brett.cannon'
closed = True
closed_date = <Date 2014-04-04.14:22:05.901>
closer = 'brett.cannon'
components = ['Interpreter Core']
creation = <Date 2014-03-16.05:42:27.173>
creator = 'ncoghlan'
dependencies = []
files = ['34555', '34650']
hgrepos = []
issue_num = 20942
keywords = ['patch']
message_count = 15.0
messages = ['213719', '214399', '214926', '215044', '215045', '215046', '215053', '215060', '215061', '215064', '215090', '215122', '215394', '215395', '215524']
nosy_count = 6.0
nosy_names = ['brett.cannon', 'ncoghlan', 'Arfrever', 'python-dev', 'eric.snow', 'Zvezdoslovec']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue20942'
versions = ['Python 3.4', 'Python 3.5']

[ncoghlan]

As part of the PEP-451 changes, frozen imports were updated to avoid setting the __file__ attribute, as that attribute makes no sense for frozen modules.

However, _frozen_importlib isn't loaded through the normal mechanisms (they don't exist yet!), so it is still getting a __file__ attribute set. (This was discovered while investigating bpo-20884)

This is a fairly harmless state of affairs, so I suggest we leave it alone in the 3.4 maintenance releases, and just tidy it up in 3.5. However, I'm also open to fixing it in 3.4.1.

[brettcannon]

Here is a patch to change PyImport_ImportFrozenModuleObject() to not set __file__. Had to refactor some things as PyImport_ExecCodeModuleObject() was setting __file__ no matter what, so to avoid it even being used during import I had to change some things.

[ericsnowcurrently]

Review posted.

[brettcannon]

New version based on Eric's review.

[Zvezdoslovec]

This patch can easily be incorporated into Python 3.4.1. It doesn't break backwards compatibility.

[brettcannon]

It actually does break backwards-compatibility as an attribute will disappear on frozen modules for anyone who uses the imp API. While the chances of actually breaking someone's code is very small, there is still a chance. But I'm only -0 on backporting so other core devs could convince me that I'm being overly cautious.

[Zvezdoslovec]

I would say go for it. I don't think anyone's code would break.

Anyway, if people see that something in the new version of Python breaks their code, they down-grade; otherwise they read the changelog and fix their code accordingly. So no worries here. :)

[ericsnowcurrently]

Latest patch LGTM.

[ericsnowcurrently]

As I've thought about it, I've gone from -0 to +1 on applying this to both 3.4 and 3.5. The bug and fix should impact very little* code. In fact, I doubt anyone would have noticed if Nick hadn't. :) It would be nice to have this right in 3.4.

• Effectively this is limited to consumers of imp.init_frozen(), PyImport_ImportFrozenModule(), and PyImport_ImportFrozenModule(). That includes importing frozen importlib and Py_FrozenMain().

[Zvezdoslovec]

I'm setting Python 3.4 to also be affected by this issue. Thank you, Brett, for making the patch. I hope this gets commited soon.

[ncoghlan]

Yeah, as noted in my original comment, +0 for "it's just a bug" from me, as it was a quirk of the way this particular frozen module is initialised.

[Zvezdoslovec]

Haven't we forget something in the patch for the docs?

+ .. versionchanged:: 3.5

•  The ``__file__`` attribute is no longer set on the module.
  

Where's 3.4 mentioned? Should we add the mention? Like...
+ .. versionchanged:: 3.4

[Zvezdoslovec]

No one interested in fixing this anymore, despite the patch and all?