Upgrade to hashbrown 0.12

Cargo.toml

@@ -23,7 +23,7 @@ rayon = { version = "1.4.1", optional = true }
 rustc-rayon = { version = "0.3", optional = true }
 
 [dependencies.hashbrown]
-version = "0.11"
+version = "0.12"
 default-features = false
 features = ["raw"]
 

src/map/core.rs

@@ -18,7 +18,7 @@ use core::mem::replace;
 use core::ops::RangeBounds;
 
 use crate::equivalent::Equivalent;
-use crate::util::{enumerate, simplify_range};
+use crate::util::simplify_range;
 use crate::{Bucket, Entries, HashValue};
 
 /// Core of the map that does not depend on S
@@ -185,9 +185,7 @@ impl<K, V> IndexMapCore<K, V> {
  let entries = self.entries.split_off(at);
 
  let mut indices = RawTable::with_capacity(entries.len());
- for (i, entry) in enumerate(&entries) {
- indices.insert_no_grow(entry.hash.get(), i);
- }
+ raw::insert_bulk_no_grow(&mut indices, &entries);
  Self { indices, entries }
  }
 
@@ -372,15 +370,9 @@ impl<K, V> IndexMapCore<K, V> {
  // Reinsert everything, as there are few kept indices
  self.indices.clear();
 
- // Reinsert stable indices
- for (i, entry) in enumerate(start_entries) {
- self.indices.insert_no_grow(entry.hash.get(), i);
- }
-
- // Reinsert shifted indices
- for (i, entry) in (start..).zip(shifted_entries) {
- self.indices.insert_no_grow(entry.hash.get(), i);
- }
+ // Reinsert stable indices, then shifted indices
+ raw::insert_bulk_no_grow(&mut self.indices, start_entries);
+ raw::insert_bulk_no_grow(&mut self.indices, shifted_entries);
  } else if erased + shifted < half_capacity {
  // Find each affected index, as there are few to adjust
 
@@ -429,11 +421,7 @@ impl<K, V> IndexMapCore<K, V> {
 
  fn rebuild_hash_table(&mut self) {
  self.indices.clear();
- debug_assert!(self.indices.capacity() >= self.entries.len());
- for (i, entry) in enumerate(&self.entries) {
- // We should never have to reallocate, so there's no need for a real hasher.
- self.indices.insert_no_grow(entry.hash.get(), i);
- }
+ raw::insert_bulk_no_grow(&mut self.indices, &self.entries);
  }
 
  pub(crate) fn reverse(&mut self) {

src/map/core/raw.rs

@@ -2,13 +2,26 @@
 //! This module encapsulates the `unsafe` access to `hashbrown::raw::RawTable`,
 //! mostly in dealing with its bucket "pointers".
 
-use super::{equivalent, Entry, HashValue, IndexMapCore, VacantEntry};
+use super::{equivalent, Bucket, Entry, HashValue, IndexMapCore, VacantEntry};
 use core::fmt;
 use core::mem::replace;
 use hashbrown::raw::RawTable;
 
 type RawBucket = hashbrown::raw::Bucket<usize>;
 
+/// Inserts many entries into a raw table without reallocating.
+///
+/// ***Panics*** if there is not sufficient capacity already.
+pub(super) fn insert_bulk_no_grow<K, V>(indices: &mut RawTable<usize>, entries: &[Bucket<K, V>]) {
+ assert!(indices.capacity() - indices.len() >= entries.len());
+ for entry in entries {
+ // SAFETY: we asserted that sufficient capacity exists for all entries.
+ unsafe {
+ indices.insert_no_grow(entry.hash.get(), indices.len());
+ }
+ }
+}
+
 pub(super) struct DebugIndices<'a>(pub &'a RawTable<usize>);
 impl fmt::Debug for DebugIndices<'_> {
  fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {