Function read_stage_paths 

pub fn read_stage_paths(crate_name: &str, stage: &str) -> Vec<PathBuf>

Read the manifest of output paths previously written for the given stage.

Returns an empty Vec when the manifest does not exist (either the stage has never been generated for this crate, or the cache predates the manifest format introduced in 0.18.1). Callers should use this to repopulate current_gen_paths on a cache hit so the orphan-cleanup pass does not delete files that the previous run wrote but the current run skipped.