[eserscor]

Description

Remove the unused Setup Rust step from both lint workflows:

• Python format in .github/workflows/lint.yml.
• Suggest fixes in .github/workflows/pr_checks.yml.

The configured linters are RUFF, RUFF-FORMAT, and CLANGFORMAT; their Python packages provide prebuilt wheels, and none invokes rustfmt. No lint rules, suggestion behavior, or SARIF handling are changed.

Validation:

• actionlint.exe -config-file <temporary-config> -shellcheck= -pyflakes= .github\workflows\lint.yml .github\workflows\pr_checks.yml — passed with actionlint 1.7.12. The temporary configuration declares the existing custom runner label; optional ShellCheck/Pyflakes integrations were disabled.
• A temporary fixture harness executed the workflows' lint/format/conversion shell commands under WSL Ubuntu 24.04 / Python 3.12.3, with rustup, rustc, rustfmt, and cargo unavailable on PATH. lintrunner init passed.
• lintrunner --force-color --all-files --tee-json=lint.json -v followed by python -m lintrunner_adapters to-sarif lint.json lintrunner.sarif — formatting-error and non-formatting Ruff-error fixtures correctly returned lint exit 1 and produced valid nonempty SARIF; clean files returned lint exit 0 and valid empty SARIF.
• The unchanged PR Checks command tail, set +e; lintrunner f --all-files -v; exit 0 — passed on formatting-error and clean fixtures. The error fixture was correctly formatted, and both runs returned exit 0 without Rust.
• Injected dependency-install failure — correctly remained failing, with lint skipped and the existing secondary missing-adapter SARIF failure reproduced. This reporting behavior is intentionally unchanged.
• git diff --check — passed.
• Runner-side positive control on the first commit: Python format passed, including dependency installation, all-files lint, SARIF conversion, and SARIF upload; Rust setup was absent. The subsequent commit adds the same removal to PR Checks; its automatic CI is pending and is not covered by that earlier result.

Local fixture tests are not a full repository lint run. An isolated intentional-formatting-failure branch is being exercised separately as an automation negative control; its fixture is not included in this PR.

Motivation and Context

Both workflows share the same unnecessary Rust bootstrap and moving stable channel dependency. Six observed Lint / Python format runs failed during Rust setup and passed on retry at the identical merge commit. Failed attempts stopped in bootstrap-download retries before lintrunner ran; successful retries reported No lint issues. The PR Checks investigation independently found the same mechanism.

Representative failed attempt and successful retry. The missing lintrunner.sarif was secondary: dependency installation was skipped after Rust setup failed. Removing the unused toolchain eliminates that dependency rather than caching a tool neither workflow consumes.

[Copilot]

🟢 Approval recommended

The narrow deletions remove an unused dependency without changing downstream lint behavior, and no actionable issues were identified.

No open issues 🎉

What changed in this PR

Removes unused Rust setup from ONNX Runtime’s two lint workflows, eliminating a bootstrap dependency that caused intermittent failures.

Changes:

• Removes Rust toolchain and rustfmt installation from both lint jobs.
• Leaves lint rules, formatting suggestions, and SARIF handling unchanged.

File	Description
.github/​workflows/​pr_checks.yml	Removes Rust setup from the Suggest fixes job.
.github/​workflows/​lint.yml	Removes Rust setup from the Python format job.

_{Review effort: Balanced}