zig 0.14's cache corrupts under concurrent `zig cc` (ziglang/zig#18763):
with ~60 cc-compiling cargo build scripts running in parallel, cache
manifests end up referencing evicted objects ("failed to open
.../scanner.o: FileNotFound") and kill the build. Patch the hermetic
wrapper via single_version_override so compile-only steps (-c/-E/-S) get
private throwaway caches under the system tmp dir — cold vs warm is
~25ms for compiles, measured — while links keep the shared cache for
compiler-rt/crt reuse (~6s cold, 25ms warm) under zig's per-artifact
locking.
can1357
7c82297c9e