Fix archive verification on Linux and Windows

[cb1kenobi]

⊙ Problem

The first real dispatch of the two-variant prebuild (run 37855264608, v11.8.1-perf-context-test) passed both macOS targets and failed the other eight, all in the Verify release archive step that #27 added. build.yml runs only on schedule and workflow_dispatch, so no PR can exercise that step and both defects reached main.

The feature itself was fine on all ten targets. windows-arm64 shows the whole mechanism working: vcpkg remove, both variants built from the one portfile, the portfile guard firing in both directions, byte-identical headers, and correct Windows naming. Only the checker was broken.

❓ Your call: This fixes the failures as they stand. The deeper issue is that a step which can only run post-merge got merged on the strength of a single-platform local run. A dry-run branch with the release job disabled gives all ten targets as workflow artifacts without publishing anything, and would have caught both of these. Worth making that a standard step before merging anything that touches the build or verification scripts?

💡 Solution

Two independent causes, both in code added by #27.

The probe did not compile on GCC or MSVC. tools/perf-context-probe/CMakeLists.txt pinned CMAKE_CXX_STANDARD to 17. RocksDB builds itself at 20 and its installed headers use C++20 constructs — a defaulted operator== in compression_type.h, a using-declaration naming a scoped enumerator in db.h — but it exports no target_compile_features, so nothing communicates that to a consumer. AppleClang accepts those headers at 17, which is exactly why the macOS targets passed and the local testing was green. The probe now asks for 20, matching what RocksDB compiled.

tar cannot open a Windows backslash path. GITHUB_WORKSPACE is D:\a\..., and extraction failed with tar: D\:\a\...: Cannot open. That is before the probe runs, which is why the two targets with run_probe: false failed as well. #27 converted paths only where they were handed to CMake, on the assumption that git-bash tolerates backslashes elsewhere; it does for test and mkdir, not for tar. Each path is now rewritten ahead of its first reader — and only on a Windows shell, since a backslash is an ordinary filename character everywhere else.

🔧 Changes

File	What changed
tools/perf-context-probe/CMakeLists.txt	CMAKE_CXX_STANDARD 17 → 20, the standard RocksDB built its own headers with.
.github/scripts/verify-prebuild-archive.sh	A one-time shell check decides whether backslashes mean separators here, and ARCHIVE is rewritten under it before the existence check that previously read an unconverted path. PROBE_DIR and SCRATCH follow once their defaults resolve. The per-call cmake_path helper is removed as redundant.

✅ Verification

Route: local rebuild and archive verification on darwin-arm64, plus targeted path cases. The platforms that actually failed cannot be reproduced locally — that is the point of the judgment call above.

• Full rebuild of both variants and archive verification pass with the C++20 probe: counter-name markers 1 vs 0, nm references 59 vs 0, probe user_key_comparison_count 40,959 vs 0.
• A forced-Windows run with backslashes in both ARCHIVE and SCRATCH converts and verifies, covering the ordering defect the review found.
• An archive under a directory literally named back\slash-test is found and verified. Under the unconditional rewrite the review caught, it resolved to /tmp/back/slash-test/… and exited 2.
• A missing archive still reports no such archive: … rather than failing obscurely.
• An ordinary Unix path is unaffected.
• shellcheck clean.

Not verified here: MSVC, Alpine GCC and real Windows tar. The next dispatch is the first execution of all three. The /Z7 CodeView marker-count reasoning in verify-prebuild-archive.sh is also still unproven, because every Windows job died at extraction before reaching it.

_{🤖 Generated by Claude (Anthropic); posted via @cb1kenobi.}

Related PRs: #27 overlaps (this repairs the verification step it added; merged), #26 overlaps (merged; its own changes contain neither defect)
Complexity: medium

_{Review-Coverage: authored=claude; ran=cursor-composer,codex,gemini,cursor-muse; adjudicated=domain; declined=cursor-grok,cursor-kimi; rounds=8; full=2 @ 98e1fc9}

_{Review-Attention: read ~3m (decisions: cxx20-at-consumer, release-time-proof, document-not-convert-extra-args) @ 98e1fc9}

[gemini-code-assist]

Code Review

This pull request refactors path handling in .github/scripts/verify-prebuild-archive.sh to convert Windows backslash paths to Unix-style forward slashes on entry, and updates the C++ standard to 20 in tools/perf-context-probe/CMakeLists.txt. The review feedback suggests optimizing the path conversion in the shell script by using native Bash parameter expansion directly instead of a helper function and command substitution, which avoids subshell overhead.