sccache 0.19.0

Summary

sccache 0.19.0 is mostly a correctness and robustness release: multi-arch caching no longer
risks stale universal objects, remote storage errors are no longer hidden as cache misses, the
multi-level cache tolerates unavailable optional levels, and distributed compilation got a long
list of fixes.

Highlights:

• Cache-key correctness: with SCCACHE_CACHE_MULTIARCH, gcc/clang compilations with several
  -arch values are now preprocessed once per architecture, so code guarded by __aarch64__,
  __SSE2__ and the like reaches the hash. Older single-pass preprocessor cache entries are not
  reused, and multi-arch compilations are no longer distributed (#2871). Include validation in
  the preprocessor cache is fixed (#2740).
• Rust: dep-info is written locally instead of being restored from the cache, so an entry
  produced in another checkout or on another machine no longer points cargo at paths that don't
  exist (#2894). .rmeta artifact notifications are streamed to cargo before the compile
  finishes, including on cache misses and in client-side mode, so pipelining isn't held back
  (#2875). Rust outputs are computed while the rest of the hashing runs (#2465).
• MSVC: C++20 named modules built with clang-cl are cached (#2876), the CL and _CL_
  environment variables are honored (#2886), /Tc and /Tp are handled as input arguments
  (#2904), and a -Fd pointing to a directory no longer turns a successful compile into a fatal
  error (#2933).
• Storage: remote read errors (credentials, network) are reported as cache errors instead of
  silently counted as misses (#2928). A multi-level cache can start when a level that its write
  policy treats as optional is unavailable (#2890), and client-side raw hits are backfilled into
  faster levels with per-level stats (#2913, #2915). TLS trust roots are restored after the
  reqwest 0.13 upgrade (#2917). WebDAV gained SCCACHE_WEBDAV_DISABLE_CREATE_DIR (#2872).
• Distributed compilation: Rust toolchains are packaged more selectively and work with distro
  toolchains in lib64 (#2852), crates without a metadata hash are packaged correctly (#2921),
  evicted toolchain archives are repackaged (#2893), job IDs no longer collide across scheduler
  restarts (#2895), the Rust sysroot is part of the weak toolchain key (#2900), and the overlay
  builder resolves toolchain and input paths from inside a chroot (#2908). Remote compile
  failures now report the real exit code instead of "killed by signal" (#2932).
• Stats: --show-stats now shows the effective cache mode (#2914), and Rust compilations
  that couldn't be cached are broken down by crate type (#2897).

Welcome to 14 new contributors!

Features

• feat: stream .rmeta artifact notifications for rustc by @weihanglo in #2875
• Calculate rustc outputs concurrently with other hashing tasks by @DaniPopes in #2465
• webdav: add SCCACHE_WEBDAV_DISABLE_CREATE_DIR option by @ChriFo in #2872
• dist: honor SCCACHE_DIST_CLIENT_CACHE_DIR by @codeandsolder in #2896
• stats: expose non-cacheable Rust crate types by @codeandsolder in #2897
• stats: expose effective cache access mode by @codeandsolder in #2914
• Package rust toolchain more selectively by @pprkut in #2852

Compiler support

• msvc: cache C++20 named modules built with clang-cl by @Kataglyphis in #2876
• msvc: support CL and CL env variables by @AJIOB in #2886
• msvc: handle /Tc and /Tp as input file arguments by @bhaskargurram-ai in #2904

Fixes

• gcc, clang: preprocess multi-arch compilations once per -arch by @francoisgirinon-netizen in #2871
• Fix preprocessor cache include validation by @fallintoplace in #2740
• fix(rust): write dep-info locally not restoring from cache by @weihanglo in #2894
• util: strip basedirs from glued values starting with a drive letter by @stemann in #2883
• commands: use the configured cache dir in --debug-preprocessor-cache by @devtechedge in #2881
• msvc: do not expect a program database next to a -Fd directory by @451891358 in #2933
• nvcc: report subcommand exit codes as exit codes, not signals by @bernardladenthin in #2932
• cache: report remote read errors instead of treating them as misses by @seungpyoson in #2928
• multilevel: tolerate unavailable optional cache levels by @codeandsolder in #2890
• cache: backfill client-side multi-level raw hits by @codeandsolder in #2913
• cache: record per-level stats for client-side raw reads by @codeandsolder in #2915
• http: restore TLS trust roots with reqwest 0.13 by @codeandsolder in #2917
• fix: Fix Rust dist packaging for dependencies without metadata hashes by @codeandsolder in #2921
• dist: reject assignments reaped during allocation by @codeandsolder in #2891
• dist: retry expired client state in dist-status by @codeandsolder in #2892
• dist: repackage toolchains after archive eviction by @codeandsolder in #2893
• dist: namespace job IDs across scheduler restarts by @codeandsolder in #2895
• dist: include Rust sysroot in weak toolchain key by @codeandsolder in #2900
• dist: validate the toolchain archive id format by @sylvestre in #2907
• sccache-dist: resolve toolchain and input paths from a chroot in the overlay builder by @sylvestre in #2908

Dependencies

• chore(deps): update rust crate tar to v0.4.45 by @xtqqczze in #2655
• Update typed-path dependency to 0.13 by @musicinmybrain in #2924

Tests & CI

• test: return target-libdir in rustc cache-miss mock by @weihanglo in #2885
• Look up true on PATH in the symlinked libdir test by @badumbatish in #2926

Cleanup

• Use cfg_aliases to reduce boilerplate by @Felixoid in #2644
• Add CacheConfigs.cache_type_by_name to reduce boilerplate by @Felixoid in #2905
• clippy: iterate map values directly in disk_mappings by @PHPCraftdream in #2877
• chore: Remove dependency status badge by @xtqqczze in #2856
• Direct mode stats by @badumbatish in #2844
• Revert "Direct mode stats" by @sylvestre in #2858
• Release 0.19.0 by @sylvestre in #2937

New Contributors

• @badumbatish made their first contribution in #2844
• @fallintoplace made their first contribution in #2740
• @ChriFo made their first contribution in #2872
• @francoisgirinon-netizen made their first contribution in #2871
• @DaniPopes made their first contribution in #2465
• @pprkut made their first contribution in #2852
• @PHPCraftdream made their first contribution in #2877
• @codeandsolder made their first contribution in #2892
• @stemann made their first contribution in #2883
• @bhaskargurram-ai made their first contribution in #2904
• @devtechedge made their first contribution in #2881
• @seungpyoson made their first contribution in #2928
• @451891358 made their first contribution in #2933
• @bernardladenthin made their first contribution in #2932

Full Changelog: v0.18.0...v0.19.0