Function rustc_resolve::late::lifetimes::resolve_lifetimes_for

fn resolve_lifetimes_for<'tcx>(
    tcx: TyCtxt<'tcx>,
    def_id: LocalDefId
) -> &'tcx ResolveLifetimes

Given any owner (structs, traits, trait methods, etc.), does lifetime resolution. There are two important things this does. First, we have to resolve lifetimes for the entire Item that contains this owner, because that’s the largest “scope” where we can have relevant lifetimes. Second, if we are asking for lifetimes in a trait definition, we use resolve_lifetimes_trait_definition instead of resolve_lifetimes, which does not descend into the trait items and does not emit diagnostics. This allows us to avoid cycles. Importantly, if we ask for lifetimes for lifetimes that have an owner other than the trait itself (like the trait methods or associated types), then we just use the regular resolve_lifetimes.