Switch from gcc 13 to gcc 12 in ubuntu-latest

[wantehchang]

gcc-13 was removed from the ubuntu-22.04 os image. See actions/runner-images#8555 (comment)

[wantehchang]

@vrabaud @y-guyon FYI.

There are two other options:
actions/runner-images#9866 (comment)

[jzern]

lgtm.

[wantehchang]

Note that the ubuntu-latest alias is still pointing to ubuntu-22.04. It is ubuntu-22.04 itself that changed.

[vrabaud]

Why even mention a specific version ? Doesn't the default gcc work anyway ?

[kmilos]

Why even mention a specific version ?

More recent versions are generally more strict (upgrading warnings to errors), thus providing slightly better coverage hopefully. The default in 22.04 is 11 AFAIK...

Note that there is now the ubuntu-24.04 runner available in beta that provides 13 by default, and 14.

[vrabaud]

gcc is indeed at 11.2 by default: https://github.com/actions/runner-images/blob/main/images/ubuntu/Ubuntu2204-Readme.md
Ubuntu 24.04 is deployed: https://github.com/actions/runner-images?tab=readme-ov-file#available-images so we might as well use it: #2165

[wantehchang]

Vincent:

The use of a specific version of gcc started in the very first version of these CI workflow files (.github/workflows/ci.yml):
0f8fcf8db

I guess the reason was what Miloš said, to use the newest version of gcc in the os image, rather than the default version.

The ubuntu-24.04 os image still has the "beta" status. That's why I didn't consider it yesterday. I probably would wait until ubuntu-24.04 goes out of beta, but we can certainly volunteer to be a beta tester.