Switch from c++17 to c++20 and reactivate fully static builds

[clonker]

• switches from c++17 to c++20 compilation mode
• removes b_ubu_cxx20 job
• b_ubu_static has its imaged bumped from ubuntu_2004 to ubuntu_2404
• re-enables fully static binaries
• bumps minimum requirements for gcc to 11 and for clang to 14
• check nightly

PR adding the ubuntu2204 image: #15753
Depends on PR adding ubuntu2204 build jobs: #15754

[ekpyron]

Does this mean we drop support for Ubuntu 20.04 focal?
If so, we'll also need to add Focal to the list here https://github.com/ethereum/solidity/blob/a28b2b1c89c4b8f7cdb7b171dc06925c85ae8c10/ReleaseChecklist.md?plain=1#L97, bump this https://github.com/ethereum/solidity/blob/a28b2b1c89c4b8f7cdb7b171dc06925c85ae8c10/scripts/release_ppa.sh#L69 to noble (we can since we're fully static again) and remove it from the list here https://github.com/ethereum/solidity/blob/a28b2b1c89c4b8f7cdb7b171dc06925c85ae8c10/scripts/release_ppa.sh#L71.
We can also drop it here then https://github.com/ethereum/solidity/blob/a28b2b1c89c4b8f7cdb7b171dc06925c85ae8c10/scripts/deps-ppa/static_z3.sh#L44

I need to think whether that's all. We should generally check the release builds where possible - I guess you can trigger a dry-run docker build? Depending on the answer here, I can trigger a PPA prerelease build once things are updated (since that requires launchpad permissions)

[ekpyron]

If we drop focal, we can also drop https://github.com/ethereum/solidity/blob/develop/scripts/docker/buildpack-deps/Dockerfile.ubuntu2004 entirely.
Respectively, what's the GCC version in ubuntu 22.04 jammy, is that enough? If so, we could bump the image to that instead and have a CI run for it - would be good to have a run close to the minimal required versions, if feasible.

[ekpyron]

Ah, that's actually an issue - https://packages.ubuntu.com/jammy/gcc looks like it's at GCC 11 only - but GCC 11 probably has sufficient C++20 support already? If so, we could still lower the requirement to GCC 11 only, add a jammy CI run and keep it in the PPA release list - otherwise, we would need to not only move focal, but also jammy to the "copy static binaries" method in the release checklist.

[clonker]

Yeah, gcc11 should be enough actually. I just set it to 12 because that's what is contained in the current debian stable.

[clonker]

I just ran

docker build -t "ethereum/solc":build -f scripts/Dockerfile . --progress plain

and that went through fine.

[r0qs]

Nice :D

[clonker]

Nightlies are green on this branch: https://app.circleci.com/pipelines/github/ethereum/solidity/37773/workflows/d5733444-a7ec-4439-a61d-fbf04673b8a5

[ekpyron]

That's maybe a bit too inaccurate :-). I also just noticed that I actually never added a changelog entry for the switch to only semi-static builds either :-). We had

 * Build System: Optionally support dynamic loading of Z3 and use that mechanism for Linux release builds.

in 0.7.6

Maybe it should rather say something like

Suggested change

	* Switch back to fully static binaries on Ubuntu.
	* Static release builds for Linux no longer depend on ``glibc``.

or something like that - it's not really about Ubuntu and it's not all Ubuntu binaries.
I'm not too happy about the phrasing of my own suggestion either, but something along those lines.

This also overlaps with the SMTChecker changelog entry we added earlier, it's just the build system bit of that...

[clonker]

Yeah that is fair enough :). Your phrasing is at least better than mine. Although I think even calling it static build when it depends on glibc is questionable. :D

[ekpyron]

We can drop static actually -

Linux release binaries no longer depend on ``glibc``.

optinonally with a "are fully static again and" in between or so.

[clonker]

I like that phrasing, nice. Fixed.