Function live_locals_at 

pub(crate) fn live_locals_at(
    tcx: TyCtxt<'_>,
    caller: DefId,
    call_block: BasicBlock,
    statement_index: usize,
    seed_params: bool,
    track_moves: bool,
) -> HashSet<Local>

Compute the set of locals that are live (between StorageLive and StorageDead) at the deref point (call_block, statement_index), scanning the function in execution order up to that point. Used by the callsite shared-XOR-mutable check to ignore temporaries that have already gone dead (e.g. a method call’s &self receiver).