_sysconfigdata.py wrong on AIX installations

[DavidEdelsohn]

BPO	18235
Nosy	@malemburg, @larryhastings, @merwok, @ericvw, @haubi, @vadmium, @pelson, @aixtools
Files	issue18235.patch

^{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 = None
closed_at = None
created_at = <Date 2013-06-17.00:33:21.908>
labels = ['type-bug', '3.7', 'build']
title = '_sysconfigdata.py wrong on AIX installations'
updated_at = <Date 2017-01-24.17:37:35.737>
user = 'https://bugs.python.org/DavidEdelsohn'

bugs.python.org fields:

activity = <Date 2017-01-24.17:37:35.737>
actor = 'ericvw'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Build']
creation = <Date 2013-06-17.00:33:21.908>
creator = 'David.Edelsohn'
dependencies = []
files = ['32229']
hgrepos = []
issue_num = 18235
keywords = ['patch']
message_count = 54.0
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nosy_count = 11.0
nosy_names = ['lemburg', 'larry', 'eric.araujo', 'ericvw', 'haubi', 'python-dev', 'martin.panter', 'pelson', 'David.Edelsohn', 'Michael.Felt', 'aixtools@gmail.com']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'patch review'
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue18235'
versions = ['Python 2.7', 'Python 3.5', 'Python 3.6', 'Python 3.7']

[DavidEdelsohn]

_sysconfigdata.py includes information about how to build extension modules. On AIX this requires a wrapper script to build shared libraries. The file includes definitions like:

'BLDSHARED': './Modules/ld_so_aix gcc -pthread -bI:./Modules/python.exp',
'LDSHARED': './Modules/ld_so_aix gcc -pthread -bI:./Modules/python.exp',
'LINKCC': './Modules/makexp_aix Modules/python.exp . libpython3.4dm.a; gcc '
'-pthread',
'MAKESETUP': './Modules/makesetup',

which is correct in the build directory, but is not correct for the install directory. The paths do not correspond to the installed location of ld_so_aix and makexp_aix in lib/pythonX.Y/config .

[DavidEdelsohn]

This is the cause of the failures in test_distutils.

[merwok]

Can you suggest how to fix this?

[DavidEdelsohn]

It looks like someone already tried to fix part of this, but reversed the assignment

diff -r a089a8b1f93d Lib/sysconfig.py
--- a/Lib/sysconfig.py  Fri Jun 21 18:37:02 2013 -0400
+++ b/Lib/sysconfig.py  Fri Jun 21 22:33:15 2013 -0700
@@ -368,7 +368,7 @@
     # -- these paths are relative to the Python source, but when installed
     # the scripts are in another directory.
     if _PYTHON_BUILD:
-        vars['LDSHARED'] = vars['BLDSHARED']
+        vars['BLDSHARED'] = vars['LDSHARED']
 
     # There's a chicken-and-egg situation on OS X with regards to the
     # _sysconfigdata module after the changes introduced by python/cpython#59503:

BLDSHARED is relative to srcdir and LDSHARED is relative to the install directory BINLIBDEST.

LDSHARED=       $(BINLIBDEST)/config/ld_so_aix $(CC) -bI:$(BINLIBDEST)/config/python.exp $(PY_LDFLAGS)
BLDSHARED=      $(srcdir)/Modules/ld_so_aix $(CC) -bI:$(srcdir)/Modules/python.exp $(PY_LDFLAGS)

[DavidEdelsohn]

Patch against current trunk

[DavidEdelsohn]

With my patch applied, _sysconfig.py looks like

'BLDSHARED': '/usr/local/lib/python3.4/config/ld_so_aix gcc -pthread '
'-bI:/usr/local/lib/python3.4/config/python.exp',
'LDSHARED': '/usr/local/lib/python3.4/config/ld_so_aix gcc -pthread '
'-bI:/usr/local/lib/python3.4/config/python.exp',

[pitrou]

Ha, that code dates back to 2000 and 2001 (f1e40abbedb3 and c958678720fd, respectively).

[python-dev]

New changeset c554194240fc by Antoine Pitrou in branch '3.3':
Issue bpo-18235: Fix the sysconfig variables LDSHARED and BLDSHARED under AIX.
http://hg.python.org/cpython/rev/c554194240fc

New changeset e3ac917fcf9c by Antoine Pitrou in branch 'default':
Issue bpo-18235: Fix the sysconfig variables LDSHARED and BLDSHARED under AIX.
http://hg.python.org/cpython/rev/e3ac917fcf9c

[pitrou]

Committed the patch. I trust you that you got it right!

[DavidEdelsohn]

I think I see the source of the confusion. test_distutils fails because it runs in the build tree and without files installed. The test does not use the installed version of sysconfig, so it looks for ./Modules/ld_so_aix, which fails. The kludge from 2000 was trying to make the test work. But after installation, the kludge defines variables incorrectly to build Modules after Python is installed.

Because the distutils test is testing in tree and not the installed version of Python, it is not testing what the end user will experience. I am unsure about the best way to make the test pass.