Function sync_drop_record 

pub fn sync_drop_record(
    graph: &AliasGraph<'_>,
    drop_record: &mut Vec<DropRecord>,
)

Extends drop_record to match graph.values.len(). For each new index, if the value’s father is dropped, copies from the father’s drop_record; otherwise creates a false_record. A father that only has a dropped field says nothing about this one.