Update the C-like style check to an ARM-compatible clang-format version

[coderabbitai]

Summary

Update the C-like coding-style check to use a newer clang-format version on the Ubuntu 24.04 ARM runner.

The current workflow configures DoozyX/clang-format-lint-action with clangFormatVersion: 14. Version 14 was selected for Ubuntu 22.04 LTS. The job now uses ubuntu-24.04-arm.

Rationale

The Docker action copies bundled clang-format executables into its image. The ARM runner cannot rely on a bundled executable unless that executable supports ARM64.

Ubuntu 24.04 provides an ARM64-native clang-format-18 package. This is a newer supported version and is an ARM-compatible path for the workflow.

Affected area

• .github/workflows/coding-style-check.yml
• check-c-like-style job

Required changes

Replace or adapt the formatter invocation so that the ARM job installs and uses the Ubuntu 24.04 ARM64 clang-format-18 package. Do not depend on an architecture-specific formatter binary from the current action unless ARM64 support is verified.

Review and apply any formatting changes that version 18 requires.

Acceptance criteria

• The C-like style job runs successfully on ubuntu-24.04-arm.
• The job uses clang-format version 18 or another explicitly verified newer ARM64-compatible version.
• The job checks .cpp, .h, and .mm files with the existing repository style configuration.
• Required formatting updates are included or tracked before the version change is enabled.

Research

Ubuntu's package index lists clang-format-18 for Ubuntu 24.04 (noble) on arm64.

• https://packages.ubuntu.com/clang-format
• https://launchpad.net/ubuntu/noble/arm64/clang-format/1:18.0-59~exp2

Backlinks

• Requested by @ann0see in Switch runners to ARM if possible #3954 (comment)
• Related PR: Switch runners to ARM if possible #3954

[mcfnord]

🤖 AI:

Easy version

The formatter behind this check arrives as a pre-built bundle that the action copies into its image, and every copy of clang-format inside it — twenty of them, versions 5 through 20 — is compiled for x86-64. An x86-64 binary cannot execute on ubuntu-24.04-arm at all, so this job breaks there whatever clangFormatVersion is set to. The runner itself already carries clang-format 18.1.3, so nothing needs fetching: calling it directly and dropping the action is the fix. Going 14 → 18 is not free, though — it reformats 24 files, and most of that is the project's own //### TODO ###// markers being rewritten. One line of config prevents that part.

Hard version

The architecture, not the version. All twenty vendored binaries carry e_machine = 0x3e, x86-64 — 18.1.3 and 18.1.8 among them. Version 18 is therefore already reachable inside the action and fixes nothing on ARM. Twenty binaries, twenty identical ELF headers; the research stopped at the version numbers in the filenames.

Nothing to install. The image ships Clang-format 16.0.6, 17.0.6 and 18.1.3 preinstalled; an apt-get install for a binary already on PATH is a no-op with extra steps, billed by the minute. The Launchpad page cited as evidence is the clang-format metapackage at 1:18.0-59~exp2, not clang-format-18 at 1:18.1.3-1ubuntu1 — one link, wrong package, filed under Research.

What "apply any formatting changes that version 18 requires" costs. Over the 81 .cpp/.h/.mm files outside libs/ at cc40a8a9, on x86-64 and reproduced file-for-file on ARM:

formatter	files changed	changed lines
14.0.0, the binary CI runs today	0	0
18.1.3	24	286
18.1.3 + CommentPragmas: '^#'	8	46

240 of those 286 lines are comments: 18.1.3 rewrites the //### TODO ###// markers to // ### TODO and re-indents everything beneath them — the markers that replaced clang-format off/on in #2600. CommentPragmas: '^#' protects them and leaves 14.0.0 byte-clean, so that one line can land before any version bump. The remaining 46 lines reverse configured style: operator<( gains a space, <<-chained string literals collapse onto one line, and two aligned declarations in main.cpp lose their alignment. The config itself is accepted by 18.1.3 without a single warning.

The acceptance criterion, observed. The paths filter is **.cpp, **.h, **.mm, **.sh, **.py, so this workflow never ran on #3954 and will not run on any PR that only edits it; workflow_dispatch on a branch does run it. Done that way on ubuntu-24.04-arm, with the runner's preinstalled 18.1.3 and nothing fetched, the job is green — FILES_DIFFERING=0 across all 81 files, once CommentPragmas: '^#' and the 8 files 18 still rewrites are committed. While that file is open: the contributor pointer sends readers to coding-style-check.yml#L20 — a branches: entry — for a version that lives at L43.