[wip,nomerge,rfc] build: Require C++23 compiler #36033

C++23 for Bitcoin Core is mostly a "style update" on top of C++20. However, the workarounds to avoid C++23 keep accumulating and some parts of the code already use C++23 features, such as lambda attributes (https://github.com/bitcoin-core/libmultiprocess/commit/bdd0cd69418d189f62699d274a751cbf6d36bb43).

I don't know when it is fine to switch, but at some point, I think it is fine to require a C++23 compiler, so that new stuff is unlocked. Of course this requires bumping the minimum required compiler versions:

• GCC: 13
• Clang: 19

There are some C++23 features that aren't implemented (such as <stacktrace> not really shipped in any vanilla stdlib today), or e.g. ranges::starts_with not implemented until libstdc++-16. But overall I think we are better off using C++23 without those few features instead of waiting longer?

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External sites

• Code coverage & benchmarks: https://corecheck.dev/bitcoin/bitcoin/pulls/36033
• Ralph review <img src=https://review.fish.foo/assets/bitcoin/bitcoin/36033.png alt="Ralph review status"> https://git.fish.foo/bitcoin/bitcoin/pulls/36033#author-ralph

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Conflicts

Reviewers, this pull request conflicts with the following ones:

• #36480 _{<img src="https://drahtbot.space/ack_count/bitcoin/bitcoin/36480.svg">} (txospenderindex: hash keys and pack positions to reduce disk usage by arejula27)
• #36255 _{<img src="https://drahtbot.space/ack_count/bitcoin/bitcoin/36255.svg">} (Refactor CoinGrinder tests by murchandamus)
• #34132 _{<img src="https://drahtbot.space/ack_count/bitcoin/bitcoin/34132.svg">} (coins, dbwrapper: remove error catcher, make point-read failures fatal by l0rinc)
• #31507 _{<img src="https://drahtbot.space/ack_count/bitcoin/bitcoin/31507.svg">} (build: Use clang-cl to build on Windows natively by hebasto)

If you consider this pull request important, please also help to review the conflicting pull requests. Ideally, start with the one that should be merged first.

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🚧 At least one of the CI tasks failed. _{Task NetBSD Cross: https://github.com/bitcoin/bitcoin/actions/runs/32352184973/job/96373551351} _{LLM reason (✨ experimental): CI failed due to a C++ build error: std::ranges::views::zip is not available (no member named 'zip' in namespace 'std::ranges::views').}

<details><summary>Hints</summary>

Try to run the tests locally, according to the documentation. However, a CI failure may still happen due to a number of reasons, for example:

• Possibly due to a silent merge conflict (the changes in this pull request being incompatible with the current code in the target branch). If so, make sure to rebase on the latest commit of the target branch.

• A sanitizer issue, which can only be found by compiling with the sanitizer and running the affected test.

• An intermittent issue.

Leave a comment here, if you need help tracking down a confusing failure.

</details>

Concept ACK

edede385cab47020124bba6db98d69319168afb5

iwyu incorrectly suggests to remove the util/expected include

This looks like IWYU's "Automatic re-export: function return values" heuristics in action.