clang-format: bump to llvm 18 toolchain

[wirew0rm]

Use the latest released clang-format-18 version.

Note that in the ubuntu world this is for now only available in the noble development version, so projects that have a contribution forkflow that requires contributors to run formatting locally should probably explicitly opt for an older version (see #550).

[pbrisbin]

projects that have a contribution forkflow that requires contributors to run formatting locally

Makes sense.

Just for additional context, there are two options for forkflows (love that word) that count as local formatting, but would not require they install the correct version of clang-format:

1. Use restyle-path
2. Apply the patch Restyled produces (and logs a URL to) with git

[wirew0rm]

Thanks for the quick merge and the additional information!

I really like the apply patch method, since it only uses git tooling and is very easy to explain. I didn't know about restyle-path might come in handy at some point.

Most annoyances with contributors not having access to the repo standard clang-format is for bigger PRs with more than a single commit and big diffs. This gets annoying pretty soon if the clang-format in the IDE and in the restyler disagree :)

[pbrisbin]

This gets annoying pretty soon if the clang-format in the IDE and in the restyler disagree :)

Yeah, 100%. It's always been a semi-dream to have (something like) restyle-path set up as an editor plugin option. That way it does what it does locally just as well as on PRs. There are a lot of steps between here and there, and I just haven't pursued it in earnest. Sometimes I wonder if it'd be worth the work or not. 🤷