prefer-ccache-action-1-2-20-on-windows

Why it matters

The same Visual Studio compiler binary can have different modification times on different hosted Windows runner images. Older ccache-action defaults can therefore cause unnecessary compilation cache misses or duplicate entries. Version 1.2.20 sets compiler_check=content on Windows instead.

What it flags

Pinned hendrikmuhs/ccache-action versions below 1.2.20 in jobs with literal Windows runner labels or a simple runner matrix containing Windows. Findings are warnings, once per job. The sccache variant, explicit compiler-check configuration, disabled steps/jobs, self-hosted runners, and disabled cache restoration are excluded.

Suggested action

Upgrade to v1.2.20 or a later compatible release, preserving keys, size limits, matrix conditions, and ccache configuration. This rule concerns the Action version, not the installed ccache executable version.

Verification

Compare hit/miss statistics and warm compile duration across fresh Windows runners. Content hashing has a cost; check total build time, not just hit rate.

What the scanner does

Only full numeric tags or SHA pins with an exact full-version comment are compared. Floating v1/v1.2 tags, branches, prereleases, and unknown SHA pins are not stale version evidence. Matrix detection supports matrix.<field> with literal axis values or include records; dynamic expressions and exclusion combinations may need manual review. Conditions explicitly excluding Windows are skipped.

References:

• 1.2.20 release
• Compiler mtime investigation
• Content-check fix