Function rustc_resolve::diagnostics::show_candidates

fn show_candidates(
    tcx: TyCtxt<'_>,
    err: &mut Diagnostic,
    use_placement_span: Option<Span>,
    candidates: &[ImportSuggestion],
    instead: Instead,
    found_use: FoundUse,
    mode: DiagnosticMode,
    path: Vec<Segment>,
    append: &str
) -> bool

When an entity with a given name is not available in scope, we search for entities with that name in all crates. This method allows outputting the results of this search in a programmer-friendly way. If any entities are found and suggested, returns true, otherwise returns false.