[BUG] GLIBCXX_3.4.29 not found on Ubuntu 20.04 with `--pre`.

[mmmarinho]

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Acceptance of the Code of Conduct

Leave these in your bug report, read, and check them.

• [X] I understand that support for DQRobotics is given voluntarily.
• [X] In understand that any possible response and its timeliness will be based on the relevance, accuracy, and politeness of my request and the following discussion.
• [X] If a DQRobotics member replies, I will let them know, politely, if their response solves my issue or not.

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Bug description

When installing the DQRobotics library in Python on Ubuntu 20.04 (development branch), as follows python3 -m pip install dqrobotics --pre

and running

python3
from dqrobotics import *

results in an error ImportError saying GLIBCXX_3.4.29 not found

Environment:

• OS: Ubuntu 20.04
• dqrobotics version: --pre now defaulting to 22.10.0a2
• Python version: 3.8

Additional context This error is most likely related to the gcc version on the CI machines have been recently updated and above the version expected in 20.04. Before the next release, this needs to be corrected.

[mmmarinho]

For now it can be fixed by installing it locally so that the gcc version matches:

Example:

sudo apt update && sudo apt upgrade -y
sudo apt install git g++ cmake python3-dev python3-wheel
git clone https://github.com/dqrobotics/python.git --recursive
python3 -m pip install ./python

[mmmarinho]

Some notes to back up the current course of action:

• Oldest supported Ubuntu is 20.04 (Focal)
• In that system, the default gcc is 9.3.0 (https://packages.ubuntu.com/focal/gcc)
• The CI seems to be using gcc 11 to compile everything (https://gcc.gnu.org/onlinedocs/libstdc++/manual/abi.html), which breaks the system.

We can either ask the users to install gcc11 -> Not good because its a moving goalpost with GithubActions CI updates. Compile with several versions with gcc -> Not scalable and somewhat arbitrary

For now I'll go with

• Compile with the oldest gcc version in the supported Ubuntu versions and we bump this with each EOL.

Reasons in favor:

• The PyPi versions are automatically built and should just work.
• It should (will?) work because a binary compiled with a couple of distros old gcc should work just fine. (See PEP 600)

Reasons against:

• Newest systems might not take advantage of newer gcc versions. (With all said and done if one cares this much about gcc's version they are surely capable of building dqrobotics python locally by themselves, the PyPI version is for the general user.)
• gcc version must be updated manually-(ish) in the CI. (it's either this or asking python users to install gcc11). Forgetting to update this is not a major issue.

Conclusion: In this current scenario I think that this is the most reasonable solution, with the least impact to the userbase, and easiest implementation.

[mmmarinho]

What to do when a current LTS distro, ubuntu-old reaches EOL.

1. Check for the End of Standard Support date in https://wiki.ubuntu.com/Releases. They might change this naming in the future, but it's whatever end date comes first in the table.
2. Check https://github.com/actions/runner-images and find the correct string for the oldest currently supported EOL, let's call it ubuntu-new
3. Replace the existing string ubuntu-old with ubuntu-new in .github/workflows/python_package.yml.