Fix performance backlash of #74762

ssomers · ssomers · commit c1c211aa37ff · 2020-08-05T10:36:12.000+02:00
diff --git a/library/alloc/src/collections/btree/map.rs b/library/alloc/src/collections/btree/map.rs
@@ -2669,8 +2669,8 @@ impl<'a, K: Ord, V> OccupiedEntry<'a, K, V> {
         *self.length -= 1;
 
         let RemoveResult { old_kv, pos, emptied_internal_root } = self.handle.remove_kv_tracking();
-        let root = pos.into_node().into_root_mut();
         if emptied_internal_root {
+            let root = pos.into_node().into_root_mut();
             root.pop_internal_level();
         }
         old_kv

Original file line number	Diff line number	Diff line change
`@@ -2669,8 +2669,8 @@ impl<'a, K: Ord, V> OccupiedEntry<'a, K, V> {`
`2669`	`2669`	`*self.length -= 1;`
`2670`	`2670`
`2671`	`2671`	`let RemoveResult { old_kv, pos, emptied_internal_root } = self.handle.remove_kv_tracking();`
`2672`		`- let root = pos.into_node().into_root_mut();`
`2673`	`2672`	`if emptied_internal_root {`
	`2673`	`+ let root = pos.into_node().into_root_mut();`
`2674`	`2674`	`root.pop_internal_level();`
`2675`	`2675`	`}`
`2676`	`2676`	`old_kv`