Five call sites spelled out the same walk by hand — `path_to_root`, reverse, `filter_map` the names — before rendering it as `::`-joined text: `ModuleDef::canonical_path`, `cli::full_name_of_item`, two in `analysis_stats`, and hover's path rendering. `Module::path_segments` names that walk once and returns `Name`s rather than a finished `String`: the call sites disagree on the edition to display with (the CLI ones pin `Edition::LATEST`, hover takes it as a parameter), so joining inside the helper would have fit none of them. `ModuleDef::canonical_module_path` is the nearby sibling that yields the `Module`s themselves; it does not serve these sites. Four of the five hold only a `Module`, and it hangs off `ModuleDef` — while routing the fifth, `canonical_path`, through it would put the `filter_map` this change removes straight back. The two are cross-referenced in the docs instead. Left alone: the two walks in `runnables`, which display each segment with its own module's edition and so need the `Module`, not just its name. No behavior change, with one wrinkle: `canonical_path` now renders each segment into a `String` before joining. The iterator is lazy and owns its `Name`s, so a borrowed `impl Display` cannot escape the closure — the old code got away with it by collecting into a `Vec` first. The other four sites already did this. This change was written with the assistance of an AI coding agent (Claude); a human directed and reviewed the work. Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>