Hey Mitchell,
No, the autopkgtests re-run for python2.7/focal are done and OK ('they continue
to fail').
Link: [1] (see the Focal results on diff archs have 'migration-reference/0' and
'mfo').
The autopkgtests point pending is a clarification on the
database/results, ie, whether we can trust the report pages (pending-
sru, update_excuses).
We'll check that. Thanks!
[1] https://autopkgtest.ubuntu.com/packages/python2.7
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https://bugs.launchpad.net/bugs/2002043
Title:
Python extension modules get built using wrong compiler flags with
python2
Status in python2.7 package in Ubuntu:
Invalid
Status in python2.7 source package in Bionic:
Won't Fix
Status in python2.7 source package in Focal:
Fix Committed
Status in python2.7 source package in Jammy:
Fix Committed
Status in python2.7 source package in Kinetic:
Invalid
Status in python2.7 source package in Lunar:
Invalid
Status in python2.7 source package in Mantic:
Invalid
Bug description:
[ Impact ]
When compiling Python extensions using Python2, CFLAGS optimization
flags are dropped.
This behavior has been caused by our update in this patch
http://archive.ubuntu.com/ubuntu/pool/universe/p/python2.7/python2.7_2.7.18-1~20.04.3.diff.gz
which differs from upstream.
The fix modifies the portion of code in Lib/distutils/sysconfig.py
which gets the cflags from the environments, and includes the dropped
OPT flag from get_config_vars().
[ Test Plan ]
There will be 2 separate tests for this bug:
* Ensuring no-change rebuilds are not changed
* Ensuring local builds are not changed unless environment variable is set
Test 1) No-change rebuilds
To test that no-change rebuilds are not changed, the package python-
stdlib-extensions will be built against the new python2.7, and confirm
the compiler flags are not altered. This will be a manual test and
visual inspection of the build logs.
Test 2) Functional test
1. Create test container
$ lxc launch ubuntu:jammy jammy-2002043
$ lxc shell jammy-2002043
2. Install required packages
For Jammy
# apt update -y && apt install -y python2 python-pip
For Focal
# apt update -y && apt install -y python2 python-setuptools gcc
3. Create test files
# mkdir testprog
# cd testprog
# cat >setup.py <<EOL
from setuptools import setup, Extension
setup(
name="test",
ext_modules=[Extension("test", sources=["testmodule.c"])],
zip_safe=False
)
EOL
# cat >testmodule.c <<EOL
#include <stdio.h>
int main(void)
{
printf("This is test program");
return 0;
}
EOL
4. Compile a test program
# python2 setup.py build_ext --inplace
5. Check CFLAGS
# python2 -c "import sysconfig; print(sysconfig.get_config_var('CFLAGS'))"
-fno-strict-aliasing -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict-prototypes
-Wdate-time -D_FORTIFY_SOURCE=2 -g
-ffile-prefix-map=/build/python2.7-W40Ff2/python2.7-2.7.18=. -flto=auto
-ffat-lto-objects -flto=auto -ffat-lto-objects -fstack-protector-strong
-Wformat -Werror=format-security
6. Check the flags used to compile the test wheel
# strings build/lib.linux-x86_64-2.7/test.so | grep -- -O
GNU GIMPLE 11.4.0 -mtune=generic -march=x86-64 -g -g -g -g -O2 -fno-openmp
-fno-openacc -fcf-protection=full -fno-strict-aliasing -fwrapv
-fstack-protector-strong -ffat-lto-objects -fstack-protector-strong -fPIC
-fltrans
7. Install fixed python
Once updated, this will simply be an apt update && apt upgrade
# add-apt-repository ppa:mitchdz/python2.7-optimization-flags -y
# apt install -y python2.7
# dpkg -s python2.7 | grep Version:
Version: 2.7.18-13ubuntu1.2~jammy9
8. Clean build
# rm -rf build/ test.so
9. Enable opt-in environment variable
# export APPLY_LP2002043_UBUNTU_CFLAGS_WORKAROUND=""
9. Rebuild with new python2.7 installed
# python2 setup.py build_ext --inplace
10. Check build flags
# strings build/lib.linux-x86_64-2.7/test.so | grep -- -O
GNU GIMPLE 11.4.0 -mtune=generic -march=x86-64 -g -g -g -g -O2 -O2
-fno-openmp -fno-openacc -fcf-protection=full -fno-strict-aliasing -fwrapv
-fstack-protector-strong -ffat-lto-objects -fstack-protector-strong -fPIC
-fltrans
GNU C17 11.4.0 -mtune=generic -march=x86-64 -g -g -O2 -fno-strict-aliasing
-fwrapv -flto -flto -ffat-lto-objects -fstack-protector-strong -fPIC
-fasynchronous-unwind-tables -fstack-protector-strong -fstack-clash-protection
-fcf-protection
[ Where problems could occur ]
* Changing optimization flags can cause a myriad of unattended side effects,
but the change being opt-in means the users should be aware a change is being
made
* The change is opt-in, so an informative message is printed to the console
to spread awareness of the issue and how to use the workaround. A questionably
made CI/CD system might see the new console output and flag it as a failure, so
it is important to choose wording carefully.
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https://bugs.launchpad.net/ubuntu/+source/python2.7/+bug/2002043/+subscriptions
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