clang-format 18

[graebm]

Issue:
We used clang-format 9 since forever, but it's not easy for people to get such an old version anymore.

Description of Changes:

• Use clang-format 18 (latest), instead of 9
• Use jidicula/clang-format-action Github Action in CI, instead of DoozyX/clang-format-lint-action which doesn't support 18 yet
• Add -i option to format-check script, to edit files inplace
  • Also, rewrite script in python, so it can run on Windows, and because our team isn't great at shell scripts
• Annoyingly, there are some differences between clang-format 18.1.3 (used by jidicula/clang-format-action and by the VSCode C/C++ extension) and clang-format 18.1.5 (default in Homebrew on Mac). I turned off formatting for those bits where they disagree.

Updating your Machine:

• MacOS:
  • if you have clang-format 9 from homebrew, uninstall it: brew uninstall llvm@9
  • install 18: brew install clang-format
• Any other machine:
  • uninstall any pre-existing clang-format versions
  • Just use VSCode's C/C++ extension to format, which uses clang-format 18 by default

Research:
We want to update to the newest version that can easily be installed on the platforms/IDEs we develop on:

• macOS:8, 11, 18 (default) via homebrew
• Windows: Not sure how to install it, but 18 is available via VSCode extension
• Amazon Linux 2: 11 only via yum install clang-tools-extra
• Amazon Linux 2023: 15 only via dnf install clang-tools-extra
• Ubuntu 24: 18 via apt install clang-format
• VSCode: 18 is bundled into the C/C++ extension, and it's what gets used if you don't have clang-format installed
  • Located here: ~/.vscode/extensions/ms-vscode.cpptools-1.20.5-darwin-x64/LLVM/bin/clang-format.

Since 18 is latest, and easily available on all platforms via the VSCode extension, let's use that.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 83.12%. Comparing base (24ac711) to head (32d5212).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1113   +/-   ##
=======================================
  Coverage   83.12%   83.12%           
=======================================
  Files          56       56           
  Lines        5754     5754           
=======================================
  Hits         4783     4783           
  Misses        971      971           

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[waahm7]

Having to do this across 20 different repos and any new code we write is going to be annoying. Can we look into getting 18.1.5 in CI? Some options that I can think of

• A docker image in builder and use that.
• Install clang-format from pip https://pypi.org/project/clang-format/.

[waahm7]

Interesting: You can use pipx to run clang-format, as well. For example, pipx run clang-format <args> will run clang-format without any previous install required on any machine with pipx (including all default GitHub Actions / Azure runners, avoiding requiring a pre-install step or even actions/setup-python).

[graebm]

I already fixed up all the other repos on my machine. There's just one code pattern that's causing all these differences between 18.1.3 and 18.1.5. It's when we use a macro to init the fields of a structure. aws-c-common has way more instances of this than any other repo

[graebm]

I'll look into the pip thing...