ci: disable Swatinem/rust-cache cache-bin to fix macOS flake#48
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`Swatinem/rust-cache@v2` defaults to `cache-bin: true`, which caches `~/.cargo/bin/`. Its proxy-detection logic for the rustup shims is unreliable on macos-arm64 hosted runners: it can save the `rustup-init` proxy into the cache and, on a later run, restore that stale binary on top of the freshly installed `cargo`. The next `cargo test` invocation then resolves to `rustup-init` and fails with: error: unexpected argument 'test' found Usage: rustup-init[EXE] [OPTIONS] Re-runs "usually" fix it because a healthy save can overwrite a poisoned one, but a single bad save poisons every subsequent restore until the cache key changes (i.e., a Rust version bump). PR46 (switching from dtolnay/rust-toolchain to actions-rust-lang/setup-rust-toolchain) did not address this — the toolchain step succeeds and is then clobbered by the cache restore. Disable `cache-bin` on every `Swatinem/rust-cache@v2` step in `ci.yml` (test/rustfmt/clippy/docs). We have no installed bin tools worth caching in any of these jobs — `cargo-llvm-cov` is installed via `taiki-e/install-action`, which has its own caching. Leaves the mutation workflow untouched (ubuntu-only and benefits from caching `cargo-mutants`). Co-authored-by: Cursor <cursoragent@cursor.com>
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Summary
Follow-up to PR46. The macOS test job is still hitting the same flake (e.g. https://github.com/mcarvin8/config-disassembler/actions/runs/25860900445/job/75990262606?pr=47):
PR46 confirmed the toolchain install itself succeeds — the runner reports
rustc 1.95.0/cargo 1.95.0immediately before tests. The failure happens in the next ~4s window, which is whenSwatinem/rust-cache@v2restores its cache.Root cause
Swatinem/rust-cache@v2defaults tocache-bin: true, which caches~/.cargo/bin/. Its rustup-proxy exclusion is unreliable on macos-arm64 runners and can save the rawrustup-initbinary into the cache. On a later run, the cache restore overwrites the freshly installedcargoproxy with that stalerustup-init, so the nextcargo testresolves torustup-initand exits 1.This matches the user-observed "re-runs usually fix it" pattern: a healthy save can overwrite a poisoned one, but a single bad save then poisons every subsequent restore until the cache key changes (i.e. a Rust version bump).
Fix
Pass
cache-bin: falseto everySwatinem/rust-cache@v2step inci.yml(test/rustfmt/clippy/docs). The matrix has no installed bin tools worth caching:cargo-llvm-covviataiki-e/install-action, which has its own caching.mutation.ymlandrelease-plz.ymlare untouched — both are ubuntu-only and the mutation workflow benefits from caching the compiledcargo-mutantsbinary.Test plan
rustup-initerror