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Switching the windows-latest matrix entry to windows-2022 didn't bust the vcpkg/CMake build caches, since runner.os is "Windows" either way. The job restored a CMakeCache.txt configured under the old runner's VS 2026 generator, which CMake then refuses to reuse under VS 2022: "Does not match the generator used previously". Keying on matrix.os (the concrete label) ties the cache to the actual toolchain instead.
The pinned baseline (5bf0c55, 2025-11-28) resolves benchmark to a revision whose portfile passes "-Werror=old-style-cast" as a bare CMake CLI argument instead of a compiler flag. CMake only recognizes its own warning categories (dev, deprecated) for -Werror=<name>, so it rejects the arg outright: "The warning category "old-style-cast" is not known." This broke arm64-osx (and any triplet building benchmark fresh) at configure time. Verified locally that the pinned commit's portfile contains the bad OPTIONS entry, and that the new baseline's benchmark (1.9.5) plus gtest/pybind11/python3 all install and build cleanly.
Every job's vcpkg cache used a restore-keys prefix fallback. The builtin-baseline bump changed vcpkg.json's content hash, missing the exact-match key, and the fallback restored a stale $VCPKG_ROOT clone predating that change. Its git history didn't contain the newly pinned baseline commit, so lukka/run-vcpkg's "Set up vcpkg" step failed outright (git exit 128) instead of falling back to a fresh clone. This broke every job across every OS in the last run. Dropping restore-keys means a cache miss just re-clones/rebuilds vcpkg from scratch (a few extra minutes) instead of risking a wrong-vintage clone that can't resolve the pinned baseline.
The previous baseline (bba3de2) was grabbed from a local vcpkg checkout that was actually sitting on a personal working branch (bbalouki-itch, tracking a fork) with local-only history layered on top of upstream - that commit was never pushed to microsoft/vcpkg. Every job's "Set up vcpkg" step failed identically (git exit 128, "fatal: unable to read tree") because a genuine clone of microsoft/vcpkg.git can never find a commit that only exists locally. Verified this one for real: fetched origin/master directly, confirmed bba3de2 is NOT an ancestor of it, then built the manifest (gtest, benchmark) against 43643e1 in an isolated git worktree bootstrapped from scratch, independent of any pre-existing local vcpkg state.
juniorep
approved these changes
Jul 16, 2026
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