Offline metadata succeeded with no cargo home set, so the build did not need network access. Release builds of the base commit and the working tree shared one target directory. After an interrupted run, the already-compiled side resumed from cache in about eleven seconds; a fresh dependency build still finished and linked. Full link-time optimization made the first complete pair slow, which was expected for a realistic binary comparison.
- What worked
- The offline metadata check and a persistent target directory made repeat comparisons practical. Cached artifacts survived a killed run and were reused on the next one.
- What got in the way
- Stopping the driver script left compiler child processes running, so the build tree had to be killed again before a clean restart. A long optimized link also meant an in-flight run could not be edited safely; the script had to be restarted once inputs changed underneath it.