What causes "TODO: handle working and living in the same building" in a-b-street/abstreet?

Resample the work (or home) building when it equals the home building

TODO: handle working and living in the same building

Error message

TODO: handle working and living in the same building

What it means

create_prole (used by proletariat_robot) builds a synthetic person from a home and work endpoint, but the case where a person's home and work are the same building is not yet implemented, so it deliberately fails with a TODO error. The code even suggests such a person would likely just stay near home.

Solutions

Resample the work (or home) building when it equals the home building
Skip or merge such individuals during population generation before calling create_prole
Implement the TODO: treat the person as staying home / no commute trip

Example fix

// before
let person = create_prole(map, rng, home, work, ...)?;
// after
let work = if work == home { sample_other_building(map, rng, &home) } else { work };
let person = create_prole(map, rng, home, work, ...)?;

Defensive patterns

Strategy: validation

Validate before calling

if home == work {
    work = sample_distinct_building(map, rng, &home);
}

Try / catch

match create_prole(map, rng, home, work, ...) {
    Ok(p) => Some(p),
    Err(e) if e.to_string().contains("same building") => None, // skip
    Err(e) => return Err(e),
}

Prevention

Sample home and work from disjoint building sets
Resample or skip individuals whose workplace equals their residence
Handle the same-building case in your generator before calling create_prole

When it happens

Trigger: Generating a synthetic population where a sampled job and residence resolve to the identical building, e.g. dense mixed-use OSM areas or a small map where everyone works where they live.

Common situations: Small test maps with few buildings, OSM imports where shops with residences produce home==work matches, population generators that sample home and work independently without exclusion.

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

AI-assisted analysis of a-b-street/abstreet@0964f29315 (2026-09-13). Data as JSON: /api/errors/282f39714707ffe4. Report an issue: GitHub.

Appendix: source

Thrown at synthpop/src/make/activity_model.rs:212

            prettyprint_usize(num_trips_passthru),
            prettyprint_usize(num_trips - s.people.len()),
            prettyprint_usize(residents.len()),
            prettyprint_usize(workers.len()),
        );
        s
    }
}

fn create_prole(
    home: TripEndpoint,
    work: TripEndpoint,
    map: &Map,
    rng: &mut XorShiftRng,
) -> Result<PersonSpec> {
    if home == work {
        // TODO: handle edge-case of working and living in the same building...  maybe more likely
        // to go for a walk later in the day or something
        bail!("TODO: handle working and living in the same building");
    }

    let mode = match (&home, &work) {
        // commuting entirely within map
        (TripEndpoint::Building(home_bldg), TripEndpoint::Building(work_bldg)) => {
            // Decide mode based on walking distance. If the buildings aren't connected,
            // probably a bug in importing; just skip this person.
            let dist = if let Some(path) = PathRequest::between_buildings(
                map,
                *home_bldg,
                *work_bldg,
                PathConstraints::Pedestrian,
            )
            .and_then(|req| map.pathfind(req).ok())
            {
                path.total_length()
            } else {
                bail!("no path found");

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