rust-archive-build-binding

Bind the binary actually tested to the intended source, features, toolchain and flags.

Cargo commonly checks source modification times against dependency information. An archive can restore different source with older timestamps and leave an incorrectly reusable artifact. A clean source hash alone does not establish which source produced the executable. See Cargo's fingerprint documentation.

When reusing a target directory across archived revisions:

1. Freeze source/archive and patch hashes, toolchain, feature selection and compiler flags before building. Keep benchmark binaries outside target.
2. Restore into an owned source tree with fresh modification times, for example tar -xmzf source.tar.gz -C owned-checkout. Check for obsolete files not in the archive; extraction does not remove them. Preserve other workers' trees.
3. Confirm the affected crates rebuild. If source and compiler diagnostics disagree, inspect Cargo fingerprints and mtimes before changing correct source. Use a clean target when the binding remains uncertain.
4. Save the successful build log and hash each copied executable. Freeze those hashes through correctness checks and timed runs. Compare both arms with identical flags and features; build/check/test artifacts are not interchangeable.
5. Exclude results from a build whose source binding is unresolved. Rebuild and rerun the necessary gates after repair; a later successful build does not retroactively validate earlier results.

For source archives crossing case-sensitive filesystems or containing Git symlinks, read references/archive-transfer.md before extraction.

For cold multi-role builds under nested time limits, read references/cold-build-timeouts.md before sizing the run or interpreting a timeout.