Revision as of 10:44, 14 February 2017

Change Proposal Name

Summary

Force C.UTF-8 when Python 3 is run under the C locale

Owner

Name: Charalampos Stratakis
Name: Nick Coghlan
Email: cstratak AT redhat.com
Email: ncoghlan AT redhat.com
Release notes owner:

Current status

Targeted release: Fedora 26
Last updated: 2017-02-14
Tracker bug: <will be assigned by the Wrangler>

Detailed Description

When run under the C locale, Python 3 doesn't work properly on systems where UTF-8 is the correct encoding for interacting with the rest of the system.

This is described in detail by Armin Ronacher in the click documentation: http://click.pocoo.org/5/python3/#python-3-surrogate-handling

This proposed change for the system Python 3 that assumes the current process is misconfigured when it detects that "LC_CTYPE" refers to the "C" locale, and in that case, prints a warnings to stderr and forces the use of the C.UTF-8 locale instead.

To avoid unintended side effects, it *solely* changes the actual python3.6 command line utility - nothing changes for cases where CPython is used as a dynamically linked library.

Behaviour with the patch:

$ LANG=C python -c 'import click; cli = click.command()(lambda:None); cli()'

Python detected LC_CTYPE=C. Setting LC_ALL & LANG to C.UTF-8.

Behaviour without the patch:

$ LANG=C /usr/bin/python3 -c 'import click; cli = click.command()(lambda:None); cli()'

Traceback (most recent call last):

 File "<string>", line 1, in <module>
 File "/home/ncoghlan/.local/lib/python3.5/site-packages/click/core.py", line 716, in __call__
   return self.main(*args, **kwargs)
 File "/home/ncoghlan/.local/lib/python3.5/site-packages/click/core.py", line 675, in main
   _verify_python3_env()
 File "/home/ncoghlan/.local/lib/python3.5/site-packages/click/_unicodefun.py", line 119, in _verify_python3_env
   'mitigation steps.' + extra)

RuntimeError: Click will abort further execution because Python 3 was configured to use ASCII as encoding for the environment. Either run this under Python 2 or consult http://click.pocoo.org/python3/ for mitigation steps.

This system supports the C.UTF-8 locale which is recommended. You might be able to resolve your issue by exporting the following environment variables:

export LC_ALL=C.UTF-8 export LANG=C.UTF-8

Benefit to Fedora

Scope

Proposal owners:

A patch will be backported to Fedora's Python 3.6 from the upstream PEP 538 which target Python 3.7

Release engineering: No impact with release engineering