error: assigning the result of `Clone::clone()` may be inefficient
   --> couchstore/src/btree_modify.rs:418:13
    |
418 |             final_key = value.key.clone();
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `clone_from()`: `final_key.clone_from(&value.key)`
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#assigning_clones

error: assigning the result of `Clone::clone()` may be inefficient
   --> couchstore/src/btree_modify.rs:106:17
    |
106 |                 new_root = root_result.values.back().unwrap().pointer.clone();
    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `clone_from()`: `new_root.clone_from(&root_result.values.back().unwrap().pointer)`
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#assigning_clones
    = note: `-D clippy::assigning-clones` implied by `-D warnings`
    = help: to override `-D warnings` add `#[allow(clippy::assigning_clones)]`

error: trait `Modifier` is never used
  --> couchstore/src/btree_modify.rs:36:7
   |
36 | trait Modifier: Sized {
   |       ^^^^^^^^
   |
   = note: `-D dead-code` implied by `-D warnings`
   = help: to override `-D warnings` add `#[allow(dead_code)]`