opp-repl-overlay-builds

To test patches without modifying the source checkout, you use a writable overlay layer over a read-only checkout. This approach isolates patch changes, preserving pristine sources while enabling safe testing and cross-commit comparisons.

A writable overlay build is a technique that creates a writable layer over a read-only source tree using fuse-overlayfs. You need it for patch testing, multi-mode builds, and parallel testing across commits without altering original files.

To set up fuse-overlayfs for cross-commit build comparisons, define an overlay_name in your .opp file and run build commands. This per-user workflow isolates overlays and caches overlay roots for reproducible builds.

Yes, fuse-overlayfs supports parallel multi-mode builds across different commits. By creating distinct writable overlays, you can test multiple build modes simultaneously without source tree conflicts.

You manage and clean up overlay layers after patch tests using the provided management API. Functions like list_overlays, cleanup_overlays, and clear_build_root allow you to control and remove overlay layers.