readline fails to parse some forms of .editrc under editline (libedit) emulation on Mac OS X

[zvezdan]

BPO	13631
Nosy	@ronaldoussoren, @ned-deily, @merwok, @bitdancer, @zvezdan, @berkerpeksag
PRs	bpo-13631: Fix the order of initialization for readline/editline. #6915 [3.7] bpo-13631: Fix the order of initialization for readline libedit on macOS. (GH-6915) #6928
Files	readline-2.7.patch: readline.c patch for python-2.7 readline-3.2.patch: readline.c patch for python-3.2

^{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/ronaldoussoren'
closed_at = <Date 2018-05-17.07:33:38.025>
created_at = <Date 2011-12-19.04:05:36.802>
labels = ['OS-mac', '3.8', 'type-bug', '3.7']
title = 'readline fails to parse some forms of .editrc under editline (libedit) emulation on Mac OS X'
updated_at = <Date 2018-05-17.07:33:38.022>
user = 'https://github.com/zvezdan'

bugs.python.org fields:

activity = <Date 2018-05-17.07:33:38.022>
actor = 'ned.deily'
assignee = 'ronaldoussoren'
closed = True
closed_date = <Date 2018-05-17.07:33:38.025>
closer = 'ned.deily'
components = ['macOS']
creation = <Date 2011-12-19.04:05:36.802>
creator = 'zvezdan'
dependencies = []
files = ['24043', '24044']
hgrepos = []
issue_num = 13631
keywords = ['patch', 'needs review']
message_count = 10.0
messages = ['149813', '150945', '150957', '151133', '193093', '219561', '219735', '316885', '316894', '316895']
nosy_count = 6.0
nosy_names = ['ronaldoussoren', 'ned.deily', 'eric.araujo', 'r.david.murray', 'zvezdan', 'berker.peksag']
pr_nums = ['6915', '6928']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue13631'
versions = ['Python 3.7', 'Python 3.8']

[zvezdan]

Problem
=======

The changes in r87356 for py3k and r87358 for python-2.7 described in bpo-9907 have broken parsing of the initialization file .editrc under editline emulation of readline on Mac OS X.

Background
==========

Both readline and editline allow settings customized per program.
For example, .inputrc file for readline::

$if Python
    set editing-mode vi
$endif

will be applied only to Python processes.

Similarly, .editrc file for editline::

python:bind -v
python:bind ^I rl_complete

will be applied only to Python processes on Mac OS X.

This works fine on python-2.6.

It's broken on 2.7 and 3.2 and later because the change in bpo-9907 moved the rl_initialize() call towards the beginning of the setup function.

Solution
========

The rl_readline_name variable must be set to "python" **before** the call to rl_initialize(). Attached are patches for 2.7 and 3.2.

[merwok]

Thanks for the analysis and patch. Have you tested that your patch does not break the readline module when linking against GNU readline? If not, I can do it.

[zvezdan]

I did not test against a readline build.

[merwok]

I applied your patch and built the readline module against libreadline and imported it successfully. (I did not try the special parsing feature, but I don’t think it’s needed.)

[ronaldoussoren]

I can confirm the problem and that the patch fixes the issue.

I'll try to commit a fix later this week.

[ned-deily]

It appears that Apple's update to editline in OS X 10.9 Mavericks has also broken this patch; with refreshing, it still works with the system editline in 10.8. So, like the fix for bpo-18458, we need to make sure that the fix works with either version of a dynamically loaded libedit.

Zvezdan, it would be good if you would be willing to sign the Python contributor agreement for your patch: https://www.python.org/psf/contrib/contrib-form/

[zvezdan]

Ned,

I just signed the contributor agreement form.

[ned-deily]

New changeset c2f082e by Ned Deily (Zvezdan Petkovic) in branch 'master':
bpo-13631: Fix the order of initialization for readline libedit on macOS. (GH-6915)
c2f082e

[ned-deily]

New changeset d504108 by Ned Deily (Miss Islington (bot)) in branch '3.7':
bpo-13631: Fix the order of initialization for readline libedit on macOS. (GH-6915) (GH-6928)
d504108

[ned-deily]

Thanks for the patch and PR, Zvezdan! Merged for 3.7.0 and 3.8.0.