error: usage of `contains_key` followed by `insert` on a `BTreeMap` --> $DIR/entry_btree.rs:10:5 | LL | / if !m.contains_key(&k) { LL | | m.insert(k, v); LL | | foo(); LL | | } | |_____^ | = note: `-D clippy::map-entry` implied by `-D warnings` = help: to override `-D warnings` add `#[allow(clippy::map_entry)]` help: try | LL ~ if let std::collections::btree_map::Entry::Vacant(e) = m.entry(k) { LL + e.insert(v); LL + foo(); LL + } | error: aborting due to previous error