Function find_nodes_to_ignore 

fn find_nodes_to_ignore<'tcx>(
    tcx: TyCtxt<'tcx>,
    def_id: LocalDefId,
    hir_body: &'tcx Body<'tcx>,
) -> FxHashSet<HirId>

Use heuristics to detect HIR expression nodes that should be ignored during spans-from-MIR extraction.