Feat: clang-tidy for linting of C/C++ code

[peakschris]

Support clang-tidy for linting of C++ code.

Inspired by and containing some code from bazel_clang_tidy repo. This integration has been discussed by maintainers of both repos in erenon/bazel_clang_tidy#35.

This PR replaces #284, which had become noisy with too many commits. Since then, the code has been rewritten to return a single report for each target.

Fixes #178

---

Changes are visible to end-users: yes

• Searched for relevant documentation and updated as needed: yes
• Breaking change (forces users to change their own code or config): no
• Suggested release notes appear below: todo

Test plan

• New test cases added
• Extra test cases could be added but need discussion; what is possible in CI?

Code used from bazel_clang_tidy repo

bazel_clang_tidy repo helped:

• two helper functions toolchain_flags and safe_flags
• some lines in get_args
• inspiration & learning

The bulk of the code is implemented by following existing rules_lint code such as ruff.bzl and eslint.bzl.

Input into release notes (will reformat)

• warning that git bash does not handle arguments correctly and --fix may have issues on Windows. msys64 bash (already recommended by Bazel is ok).

[peakschris]

I'm fairly happy with this, it's getting closer now...

Supported:

• bash lint.sh //src/... (windows)
• ./lint.sh //src/... (linux)
• ./lint.sh --fix //src:hello_cc (linux)
• ./lint.sh --fix //src/cpp/... (linux)

Needs discussion:

• some todo statements in clang_tidy_aspect_impl, need to decide which targets are ignored
• error code handling in clang_tidy_wrapper.sh, I am distinguishing fatal from user-selected errors

Known limitations:

• no packaged clang-tidy.exe on windows as llvm_toolchain doesn't support windows at present

Separate and general windows issues (to be tackled separately)

• bash lint.sh --fix //src:hello_cc fails on windows due to missing node.bat: FATAL: aspect_rules_js[js_binary]: node wrapper '/d/udu/b/l2x2bhay/execroot/_main/./external/aspect_rules_lint~/lint/private/patcher_node_bin/node.bat' not found
• example/.bazeliskrc causes builds to fail as aspect-cli doesn't support windows
• example/.bazelversion causes builds to fail as bazelisk doesn't support ../ notation
• bazel run //docs:update_10 fails:

Target //docs:update_10 failed to build
Use --verbose_failures to see the command lines of failed build steps.
ERROR: Analysis of target '//docs:update_10' failed; build aborted: Target //docs:update_10 is incompatible and cannot be built, but was explicitly requested.
Dependency chain:
    //docs:update_10 (2bc110)
    //docs:clang-tidy-docgen.md (2bc110)
    //docs:clang-tidy (2bc110)   <-- target platform (@@local_config_platform//:host) didn't satisfy constraint @@platforms//:incompatible

• cd example; bazel test //... fails (e.g. buf target, which isn't configured on windows)

[alexeagle]

I'm okay landing this without windows support, we don't have testing there currently https://github.com/aspect-build/rules_lint/blob/main/.bcr/presubmit.yml#L5 so there's an existing project to fix it. Not many OSS contributors enthusiastic about both Bazel and Windows because so much is broken, but I hope to help fix that :)

make example repo support windows by default and remove this

Yes let's make a separate PR to add Windows testing for existing code

[peakschris]

@alexeagle thanks, agreed we need separate tracking for windows. Would be good to get this in for linux for now. I've removed the windows_workaround.bat.

Please would you restart CI? I've fixed some of the failures.

[alexeagle]

Awesome, excited to have this. /cc @jsharpe

[peakschris]

@alexeagle looks like there are 3 ci pipelines failing... are they due to this PR? I couldn't see the relationship between this change and the starlark failures... Can I run the integration tests myself, to see what the issue is there?

[peakschris]

@alexeagle have pushed a fix for latest ci run

[alexeagle]

I ran buildifier locally and corrected what it pointed out, see the most recent commit.

[peakschris]

Awesome, thanks for your help @alexeagle. What are your thoughts? I'm happy to do more work if needed on this, either before or after merge.

[alexeagle]

LGTM let's ship and get some user feedback 👍🏻

[peakschris]

Amazing! Thank you for your help with this 🥳