fix(ci): stop interpolating the LLVM version into the pwsh setup step

[proggeramlug]

zizmor has been red on main for roughly 40 consecutive commits — since #7353 created setup-llvm22/action.yml. #7388 and #7393 are innocent; bisecting the run history shows last green 17a39fce7, first red 249459556, with the identical 4 findings in that run's log and only line numbers shifting since.

One properly fixed

template-injection @ 84:21 — $ver = "${{ inputs.version }}" interpolated a composite-action input as raw text into a pwsh script body. Now passed via an env: block and read as $env:LLVM_VERSION.

Three suppressed, and I want that to be explicit

The github-env findings are suppressed via a scoped ratchet entry, not fixed. The agent tested whether they were fixable and they are not, while writing GITHUB_ENV at all: a dynamic value always reports, and the pwsh arm reports even for a static literal because zizmor can't evaluate Out-File.

The only clean form is $GITHUB_OUTPUT + composite outputs. That was measured, not guessed: 44 jobs would need an id: and 140 downstream steps an env: LLVM_SYS_221_PREFIX:, because llvm-sys reads the prefix from the environment at build time — recreating exactly the "44 inline recipes" this action's own header says it exists to delete.

Judged a bad trade for a Low-confidence finding about filesystem paths from locally-installed toolchains, on an action whose callers run only under pull_request/push. The entry carries a dated reason and a delete-condition, per the file's existing convention. Flagging for a maintainer call — if you want the outputs refactor it's mechanical, but only verifiable in CI.

Verified as an A/B, not a single check

Which also proves the template-injection fix is real and not absorbed by the suppression:

arm	result
pristine main config + the action.yml fix	exit 14, 3 high findings, 119 ignored
this branch	exit 0, no findings, 122 ignored

ignored rises by exactly 3 — the entry is not over-broad. Re-verified against the committed tree via git archive HEAD, not the working tree.

Summary by CodeRabbit

• Security
  • Improved the safety of Windows LLVM setup by passing version information through an environment variable.
  • Added targeted security-tool configuration and documentation for low-confidence findings.
• Documentation
  • Added a changelog entry describing the security remediation and verification results.

[coderabbitai]

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 09a2a77d-be5c-46d5-b89a-fc608a01346c

📥 Commits

Reviewing files that changed from the base of the PR and between 1e838b4 and 7636a73.

📒 Files selected for processing (3)

• .github/actions/setup-llvm22/action.yml
• .github/zizmor.yml
• changelog.d/TMP.md

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📝 Walkthrough

Walkthrough

The Windows LLVM setup action now passes its version through LLVM_VERSION. Zizmor configuration adds a scoped exemption for related environment-file writes. The changelog records the remediation and verification results.

Changes

LLVM setup zizmor remediation

Layer / File(s)	Summary
Windows LLVM version input handling .github/actions/setup-llvm22/action.yml	The Windows PowerShell step reads inputs.version through the LLVM_VERSION environment variable instead of direct script interpolation.
Zizmor exemption and remediation record .github/zizmor.yml, changelog.d/TMP.md	The configuration adds a scoped github-env exemption for the composite action. The changelog records the rationale, removal condition, and verification results.

Estimated code review effort: 2 (Simple) | ~10 minutes

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/zizmor-template-injection

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