[3.14] gh-152785: Upgrade Ubuntu from 24.04 to 26.04 in GitHub Actions (#152717) (#153416)

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gh-152785: Upgrade Ubuntu from 24.04 to 26.04 in GitHub Actions (#152717)

• Replace "ubuntu-24.04" with "ubuntu-26.04" on most jobs.
• Replace "ubuntu-latest" with "ubuntu-26.04" for Cross build Linux.
• Replace "ubuntu-latest" with "ubuntu-slim" for small workloads.
• Update ".github/actionlint.yaml" to allow "ubuntu-26.04" and "ubuntu-26.04-arm" images.

Backport changes:

• Keep Ubuntu 24.04 with llvm.sh script to install LLVM 19 and LLVM 20.
• WASI uses ubuntu-26.04, not ubuntu-26.04-arm.

(cherry picked from commit 4c79929)

(cherry picked from commit da999e6)

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I kept https://apt.llvm.org/llvm.sh in jobs which install LLVM 19 and LLVM 20.

Note: WASI uses ubuntu-26.04, whereas ubuntu-26.04-arm is used in 3.15 and main branches.

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Oh, multiple jobs failed when running https://apt.llvm.org/llvm.sh:

+ add-apt-repository -y 'deb https://apt.llvm.org/resolute/ llvm-toolchain-resolute-19 main'
Get:1 file:/etc/apt/apt-mirrors.txt Mirrorlist [144 B]
Hit:6 https://packages.microsoft.com/repos/azure-cli jammy InRelease
Hit:7 https://packages.microsoft.com/ubuntu/26.04/prod resolute InRelease
Hit:8 https://dl.google.com/linux/chrome-stable/deb stable InRelease
Hit:2 http://azure.archive.ubuntu.com/ubuntu resolute InRelease
Hit:3 http://azure.archive.ubuntu.com/ubuntu resolute-updates InRelease
Hit:4 http://azure.archive.ubuntu.com/ubuntu resolute-backports InRelease
Hit:5 http://azure.archive.ubuntu.com/ubuntu resolute-security InRelease
Ign:9 https://apt.llvm.org/resolute llvm-toolchain-resolute-19 InRelease
Err:10 https://apt.llvm.org/resolute llvm-toolchain-resolute-19 Release
404 Not Found [IP: 146.75.106.49 443]
Reading package lists...
E: The repository 'https://apt.llvm.org/resolute llvm-toolchain-resolute-19 Release' does not have a Release file.
Repository: 'deb https://apt.llvm.org/resolute/ llvm-toolchain-resolute-19 main'
Description:
Archive for codename: llvm-toolchain-resolute-19 components: main
More info: https://apt.llvm.org/resolute/
Adding repository.
Adding deb entry to /etc/apt/sources.list.d/archive_uri-https_apt_llvm_org_resolute_-resolute.list
Adding disabled deb-src entry to /etc/apt/sources.list.d/archive_uri-https_apt_llvm_org_resolute_-resolute.list
+ apt-get update
Get:1 file:/etc/apt/apt-mirrors.txt Mirrorlist [144 B]
Hit:2 http://azure.archive.ubuntu.com/ubuntu resolute InRelease
Hit:3 http://azure.archive.ubuntu.com/ubuntu resolute-updates InRelease
Hit:6 https://packages.microsoft.com/repos/azure-cli jammy InRelease
Hit:4 http://azure.archive.ubuntu.com/ubuntu resolute-backports InRelease
Hit:5 http://azure.archive.ubuntu.com/ubuntu resolute-security InRelease
Hit:7 https://packages.microsoft.com/ubuntu/26.04/prod resolute InRelease
Ign:8 https://apt.llvm.org/resolute llvm-toolchain-resolute-19 InRelease
Err:9 https://apt.llvm.org/resolute llvm-toolchain-resolute-19 Release
404 Not Found [IP: 146.75.106.49 443]
Hit:10 https://dl.google.com/linux/chrome-stable/deb stable InRelease
Reading package lists...
E: The repository 'https://apt.llvm.org/resolute llvm-toolchain-resolute-19 Release' does not have a Release file.
Error: Process completed with exit code 100.

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Right now, https://apt.llvm.org/resolute/dists/ as an "Index of" listing:

llvm-toolchain-resolute/ 07-Jul-2026 15:05 -
llvm-toolchain-resolute-21/ 29-May-2026 03:38 -
llvm-toolchain-resolute-22/ 13-Jun-2026 13:38 -

llvm-toolchain-resolute-19 and llvm-toolchain-resolute-20 are missing. Is it a temporary or permanent issue?

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https://apt.llvm.org/noble/dists/ is an "Index of" page listing:

llvm-toolchain-noble/ 07-Jul-2026 12:24 -
llvm-toolchain-noble-17/ 19-Feb-2026 22:37 -
llvm-toolchain-noble-18/ 10-May-2026 09:15 -
llvm-toolchain-noble-19/ 19-Feb-2026 22:37 -
llvm-toolchain-noble-20/ 19-Feb-2026 22:37 -
llvm-toolchain-noble-21/ 19-Feb-2026 22:37 -
llvm-toolchain-noble-22/ 14-Jun-2026 00:14 -

So https://apt.llvm.org/ supports more LLVM versions on Ubuntu 24.04 (Noble) (LLVM 17 to 22) than on Ubuntu 26.04 (Resolute) (LLVM 21 and 22).

The problem is that in Python 3.14, the JIT uses LLVM 19 (LLVM_VERSION: 19 in .github/workflows/jit.yml, and _LLVM_VERSION = 19 in Tools/jit/_llvm.py). If I understand correctly, https://apt.llvm.org/ only provides LLVM 20, 21 and 22 on Ubuntu 26.04, whereas some CI jobs need LLVM 19 (like the JIT jobs).

I see different options:

• Stick to Ubuntu 24.04 on Python 3.14 jobs which need LLVM 19 and 20
• Install LLVM 19 differently (how?) on Python 3.14
• Upgrade LLVM in some jobs

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I mark the PR as a draft until the CI jobs pass.

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@hugovk@corona10: In .github/workflows/build.yml, the build-ubuntu should use Ubuntu 24.04 for BOLT jobs. But I don't know if it would be possible to upgrade to Ubuntu 26.04 for non-BOLT jobs? I don't know well the GitHub Action syntax to do that.

Stick to Ubuntu 24.04 on Python 3.14 jobs which need LLVM 19 and 20

That's what I did: jobs using LLVM 19 and LLVM 20 continue using Ubuntu 24.04.

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CI jobs pass, the PR is now ready for review :-)

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Ah, and see #152211 for CIFuzz failures on the 3.14 branch.

[hugovk]

Thanks!

[vstinner]

Merged. Thanks for the review.

If someone see how to use Ubuntu 26.04 on Ubuntu jobs, but keep Ubuntu 24.04 for BOLT jobs, go ahead and submit a PR!