compiler/rustc_data_structures/src/unord.rs - toolchain/rustc - Git at Google

 //! This module contains collection types that don't expose their internal
 //! ordering. This is a useful property for deterministic computations, such
 //! as required by the query system.

 use rustc_hash::{FxHashMap, FxHashSet};
 use smallvec::SmallVec;
 use std::{
     borrow::Borrow,
     collections::hash_map::Entry,
     hash::Hash,
     iter::{Product, Sum},
     ops::Index,
 };

 use crate::{
     fingerprint::Fingerprint,
     stable_hasher::{HashStable, StableHasher, StableOrd, ToStableHashKey},
 };

 /// `UnordItems` is the order-less version of `Iterator`. It only contains methods
 /// that don't (easily) expose an ordering of the underlying items.
 ///
 /// Most methods take an `Fn` where the `Iterator`-version takes an `FnMut`. This
 /// is to reduce the risk of accidentally leaking the internal order via the closure
 /// environment. Otherwise one could easily do something like
 ///
 /// ```rust,ignore (pseudo code)
 /// let mut ordered = vec![];
 /// unordered_items.all(|x| ordered.push(x));
 /// ```
 ///
 /// It's still possible to do the same thing with an `Fn` by using interior mutability,
 /// but the chance of doing it accidentally is reduced.
 #[derive(Clone)]
 pub struct UnordItems<T, I: Iterator<Item = T>>(I);

 impl<T, I: Iterator<Item = T>> UnordItems<T, I> {
     #[inline]
     pub fn map<U, F: Fn(T) -> U>(self, f: F) -> UnordItems<U, impl Iterator<Item = U>> {
         UnordItems(self.0.map(f))
     }

     #[inline]
     pub fn all<F: Fn(T) -> bool>(mut self, f: F) -> bool {
         self.0.all(f)
     }

     #[inline]
     pub fn any<F: Fn(T) -> bool>(mut self, f: F) -> bool {
         self.0.any(f)
     }

     #[inline]
     pub fn filter<F: Fn(&T) -> bool>(self, f: F) -> UnordItems<T, impl Iterator<Item = T>> {
         UnordItems(self.0.filter(f))
     }

     #[inline]
     pub fn filter_map<U, F: Fn(T) -> Option<U>>(
         self,
         f: F,
     ) -> UnordItems<U, impl Iterator<Item = U>> {
         UnordItems(self.0.filter_map(f))
     }

     #[inline]
     pub fn max(self) -> Option<T>
     where
         T: Ord,
     {
         self.0.max()
     }

     #[inline]
     pub fn min(self) -> Option<T>
     where
         T: Ord,
     {
         self.0.min()
     }

     #[inline]
     pub fn sum<S>(self) -> S
     where
         S: Sum<T>,
     {
         self.0.sum()
     }

     #[inline]
     pub fn product<S>(self) -> S
     where
         S: Product<T>,
     {
         self.0.product()
     }

     #[inline]
     pub fn count(self) -> usize {
         self.0.count()
     }

     #[inline]
     pub fn flat_map<U, F, O>(self, f: F) -> UnordItems<O, impl Iterator<Item = O>>
     where
         U: IntoIterator<Item = O>,
         F: Fn(T) -> U,
     {
         UnordItems(self.0.flat_map(f))
     }

     pub fn collect<C: From<UnordItems<T, I>>>(self) -> C {
         self.into()
     }
 }

 impl<T> UnordItems<T, std::iter::Empty<T>> {
     pub fn empty() -> Self {
         UnordItems(std::iter::empty())
     }
 }

 impl<'a, T: Clone + 'a, I: Iterator<Item = &'a T>> UnordItems<&'a T, I> {
     #[inline]
     pub fn cloned(self) -> UnordItems<T, impl Iterator<Item = T>> {
         UnordItems(self.0.cloned())
     }
 }

 impl<'a, T: Copy + 'a, I: Iterator<Item = &'a T>> UnordItems<&'a T, I> {
     #[inline]
     pub fn copied(self) -> UnordItems<T, impl Iterator<Item = T>> {
         UnordItems(self.0.copied())
     }
 }

 impl<T: Ord, I: Iterator<Item = T>> UnordItems<T, I> {
     pub fn into_sorted<HCX>(self, hcx: &HCX) -> Vec<T>
     where
         T: ToStableHashKey<HCX>,
     {
         let mut items: Vec<T> = self.0.collect();
         items.sort_by_cached_key(|x| x.to_stable_hash_key(hcx));
         items
     }

     #[inline]
     pub fn into_sorted_stable_ord(self) -> Vec<T>
     where
         T: Ord + StableOrd,
     {
         let mut items: Vec<T> = self.0.collect();
         if !T::CAN_USE_UNSTABLE_SORT {
             items.sort();
         } else {
             items.sort_unstable()
         }
         items
     }

     pub fn into_sorted_small_vec<HCX, const LEN: usize>(self, hcx: &HCX) -> SmallVec<[T; LEN]>
     where
         T: ToStableHashKey<HCX>,
     {
         let mut items: SmallVec<[T; LEN]> = self.0.collect();
         items.sort_by_cached_key(|x| x.to_stable_hash_key(hcx));
         items
     }
 }

 /// A marker trait specifying that `Self` can consume `UnordItems<_>` without
 /// exposing any internal ordering.
 ///
 /// Note: right now this is just a marker trait. It could be extended to contain
 /// some useful, common methods though, like `len`, `clear`, or the various
 /// kinds of `to_sorted`.
 trait UnordCollection {}

 /// This is a set collection type that tries very hard to not expose
 /// any internal iteration. This is a useful property when trying to
 /// uphold the determinism invariants imposed by the query system.
 ///
 /// This collection type is a good choice for set-like collections the
 /// keys of which don't have a semantic ordering.
 ///
 /// See [MCP 533](https://github.com/rust-lang/compiler-team/issues/533)
 /// for more information.
 #[derive(Debug, Eq, PartialEq, Clone, Encodable, Decodable)]
 pub struct UnordSet<V: Eq + Hash> {
     inner: FxHashSet<V>,
 }

 impl<V: Eq + Hash> UnordCollection for UnordSet<V> {}

 impl<V: Eq + Hash> Default for UnordSet<V> {
     #[inline]
     fn default() -> Self {
         Self { inner: FxHashSet::default() }
     }
 }

 impl<V: Eq + Hash> UnordSet<V> {
     #[inline]
     pub fn new() -> Self {
         Self { inner: Default::default() }
     }

     #[inline]
     pub fn with_capacity(capacity: usize) -> Self {
         Self { inner: FxHashSet::with_capacity_and_hasher(capacity, Default::default()) }
     }

     #[inline]
     pub fn len(&self) -> usize {
         self.inner.len()
     }

     #[inline]
     pub fn is_empty(&self) -> bool {
         self.inner.is_empty()
     }

     #[inline]
     pub fn insert(&mut self, v: V) -> bool {
         self.inner.insert(v)
     }

     #[inline]
     pub fn contains<Q: ?Sized>(&self, v: &Q) -> bool
     where
         V: Borrow<Q>,
         Q: Hash + Eq,
     {
         self.inner.contains(v)
     }

     #[inline]
     pub fn remove<Q: ?Sized>(&mut self, k: &Q) -> bool
     where
         V: Borrow<Q>,
         Q: Hash + Eq,
     {
         self.inner.remove(k)
     }

     #[inline]
     pub fn items(&self) -> UnordItems<&V, impl Iterator<Item = &V>> {
         UnordItems(self.inner.iter())
     }

     #[inline]
     pub fn into_items(self) -> UnordItems<V, impl Iterator<Item = V>> {
         UnordItems(self.inner.into_iter())
     }

     /// Returns the items of this set in stable sort order (as defined by `ToStableHashKey`).
     ///
     /// The `cache_sort_key` parameter controls if [slice::sort_by_cached_key] or
     /// [slice::sort_unstable_by_key] will be used for sorting the vec. Use
     /// `cache_sort_key` when the [ToStableHashKey::to_stable_hash_key] implementation
     /// for `V` is expensive (e.g. a `DefId -> DefPathHash` lookup).
     #[inline]
     pub fn to_sorted<HCX>(&self, hcx: &HCX, cache_sort_key: bool) -> Vec<&V>
     where
         V: ToStableHashKey<HCX>,
     {
         to_sorted_vec(hcx, self.inner.iter(), cache_sort_key, |&x| x)
     }

     /// Returns the items of this set in stable sort order (as defined by
     /// `StableOrd`). This method is much more efficient than
     /// `into_sorted` because it does not need to transform keys to their
     /// `ToStableHashKey` equivalent.
     #[inline]
     pub fn to_sorted_stable_ord(&self) -> Vec<V>
     where
         V: Ord + StableOrd + Clone,
     {
         let mut items: Vec<V> = self.inner.iter().cloned().collect();
         items.sort_unstable();
         items
     }

     /// Returns the items of this set in stable sort order (as defined by `ToStableHashKey`).
     ///
     /// The `cache_sort_key` parameter controls if [slice::sort_by_cached_key] or
     /// [slice::sort_unstable_by_key] will be used for sorting the vec. Use
     /// `cache_sort_key` when the [ToStableHashKey::to_stable_hash_key] implementation
     /// for `V` is expensive (e.g. a `DefId -> DefPathHash` lookup).
     #[inline]
     pub fn into_sorted<HCX>(self, hcx: &HCX, cache_sort_key: bool) -> Vec<V>
     where
         V: ToStableHashKey<HCX>,
     {
         to_sorted_vec(hcx, self.inner.into_iter(), cache_sort_key, |x| x)
     }

     #[inline]
     pub fn clear(&mut self) {
         self.inner.clear();
     }
 }

 pub trait ExtendUnord<T> {
     /// Extend this unord collection with the given `UnordItems`.
     /// This method is called `extend_unord` instead of just `extend` so it
     /// does not conflict with `Extend::extend`. Otherwise there would be many
     /// places where the two methods would have to be explicitly disambiguated
     /// via UFCS.
     fn extend_unord<I: Iterator<Item = T>>(&mut self, items: UnordItems<T, I>);
 }

 // Note: it is important that `C` implements `UnordCollection` in addition to
 // `Extend`, otherwise this impl would leak the internal iteration order of
 // `items`, e.g. when calling `some_vec.extend_unord(some_unord_items)`.
 impl<C: Extend<T> + UnordCollection, T> ExtendUnord<T> for C {
     #[inline]
     fn extend_unord<I: Iterator<Item = T>>(&mut self, items: UnordItems<T, I>) {
         self.extend(items.0)
     }
 }

 impl<V: Hash + Eq> Extend<V> for UnordSet<V> {
     #[inline]
     fn extend<T: IntoIterator<Item = V>>(&mut self, iter: T) {
         self.inner.extend(iter)
     }
 }

 impl<V: Hash + Eq> FromIterator<V> for UnordSet<V> {
     #[inline]
     fn from_iter<T: IntoIterator<Item = V>>(iter: T) -> Self {
         UnordSet { inner: FxHashSet::from_iter(iter) }
     }
 }

 impl<V: Hash + Eq> From<FxHashSet<V>> for UnordSet<V> {
     fn from(value: FxHashSet<V>) -> Self {
         UnordSet { inner: value }
     }
 }

 impl<V: Hash + Eq, I: Iterator<Item = V>> From<UnordItems<V, I>> for UnordSet<V> {
     fn from(value: UnordItems<V, I>) -> Self {
         UnordSet { inner: FxHashSet::from_iter(value.0) }
     }
 }

 impl<HCX, V: Hash + Eq + HashStable<HCX>> HashStable<HCX> for UnordSet<V> {
     #[inline]
     fn hash_stable(&self, hcx: &mut HCX, hasher: &mut StableHasher) {
         hash_iter_order_independent(self.inner.iter(), hcx, hasher);
     }
 }

 /// This is a map collection type that tries very hard to not expose
 /// any internal iteration. This is a useful property when trying to
 /// uphold the determinism invariants imposed by the query system.
 ///
 /// This collection type is a good choice for map-like collections the
 /// keys of which don't have a semantic ordering.
 ///
 /// See [MCP 533](https://github.com/rust-lang/compiler-team/issues/533)
 /// for more information.
 #[derive(Debug, Eq, PartialEq, Clone, Encodable, Decodable)]
 pub struct UnordMap<K: Eq + Hash, V> {
     inner: FxHashMap<K, V>,
 }

 impl<K: Eq + Hash, V> UnordCollection for UnordMap<K, V> {}

 impl<K: Eq + Hash, V> Default for UnordMap<K, V> {
     #[inline]
     fn default() -> Self {
         Self { inner: FxHashMap::default() }
     }
 }

 impl<K: Hash + Eq, V> Extend<(K, V)> for UnordMap<K, V> {
     #[inline]
     fn extend<T: IntoIterator<Item = (K, V)>>(&mut self, iter: T) {
         self.inner.extend(iter)
     }
 }

 impl<K: Hash + Eq, V> FromIterator<(K, V)> for UnordMap<K, V> {
     #[inline]
     fn from_iter<T: IntoIterator<Item = (K, V)>>(iter: T) -> Self {
         UnordMap { inner: FxHashMap::from_iter(iter) }
     }
 }

 impl<K: Hash + Eq, V, I: Iterator<Item = (K, V)>> From<UnordItems<(K, V), I>> for UnordMap<K, V> {
     #[inline]
     fn from(items: UnordItems<(K, V), I>) -> Self {
         UnordMap { inner: FxHashMap::from_iter(items.0) }
     }
 }

 impl<K: Eq + Hash, V> UnordMap<K, V> {
     #[inline]
     pub fn with_capacity(capacity: usize) -> Self {
         Self { inner: FxHashMap::with_capacity_and_hasher(capacity, Default::default()) }
     }

     #[inline]
     pub fn len(&self) -> usize {
         self.inner.len()
     }

     #[inline]
     pub fn insert(&mut self, k: K, v: V) -> Option<V> {
         self.inner.insert(k, v)
     }

     #[inline]
     pub fn contains_key<Q: ?Sized>(&self, k: &Q) -> bool
     where
         K: Borrow<Q>,
         Q: Hash + Eq,
     {
         self.inner.contains_key(k)
     }

     #[inline]
     pub fn is_empty(&self) -> bool {
         self.inner.is_empty()
     }

     #[inline]
     pub fn entry(&mut self, key: K) -> Entry<'_, K, V> {
         self.inner.entry(key)
     }

     #[inline]
     pub fn get<Q: ?Sized>(&self, k: &Q) -> Option<&V>
     where
         K: Borrow<Q>,
         Q: Hash + Eq,
     {
         self.inner.get(k)
     }

     #[inline]
     pub fn get_mut<Q: ?Sized>(&mut self, k: &Q) -> Option<&mut V>
     where
         K: Borrow<Q>,
         Q: Hash + Eq,
     {
         self.inner.get_mut(k)
     }

     #[inline]
     pub fn remove<Q: ?Sized>(&mut self, k: &Q) -> Option<V>
     where
         K: Borrow<Q>,
         Q: Hash + Eq,
     {
         self.inner.remove(k)
     }

     #[inline]
     pub fn items(&self) -> UnordItems<(&K, &V), impl Iterator<Item = (&K, &V)>> {
         UnordItems(self.inner.iter())
     }

     #[inline]
     pub fn into_items(self) -> UnordItems<(K, V), impl Iterator<Item = (K, V)>> {
         UnordItems(self.inner.into_iter())
     }

     /// Returns the entries of this map in stable sort order (as defined by `ToStableHashKey`).
     ///
     /// The `cache_sort_key` parameter controls if [slice::sort_by_cached_key] or
     /// [slice::sort_unstable_by_key] will be used for sorting the vec. Use
     /// `cache_sort_key` when the [ToStableHashKey::to_stable_hash_key] implementation
     /// for `K` is expensive (e.g. a `DefId -> DefPathHash` lookup).
     #[inline]
     pub fn to_sorted<HCX>(&self, hcx: &HCX, cache_sort_key: bool) -> Vec<(&K, &V)>
     where
         K: ToStableHashKey<HCX>,
     {
         to_sorted_vec(hcx, self.inner.iter(), cache_sort_key, |&(k, _)| k)
     }

     /// Returns the entries of this map in stable sort order (as defined by `StableOrd`).
     /// This method can be much more efficient than `into_sorted` because it does not need
     /// to transform keys to their `ToStableHashKey` equivalent.
     #[inline]
     pub fn to_sorted_stable_ord(&self) -> Vec<(K, &V)>
     where
         K: Ord + StableOrd + Copy,
     {
         let mut items: Vec<(K, &V)> = self.inner.iter().map(|(&k, v)| (k, v)).collect();
         items.sort_unstable_by_key(|&(k, _)| k);
         items
     }

     /// Returns the entries of this map in stable sort order (as defined by `ToStableHashKey`).
     ///
     /// The `cache_sort_key` parameter controls if [slice::sort_by_cached_key] or
     /// [slice::sort_unstable_by_key] will be used for sorting the vec. Use
     /// `cache_sort_key` when the [ToStableHashKey::to_stable_hash_key] implementation
     /// for `K` is expensive (e.g. a `DefId -> DefPathHash` lookup).
     #[inline]
     pub fn into_sorted<HCX>(self, hcx: &HCX, cache_sort_key: bool) -> Vec<(K, V)>
     where
         K: ToStableHashKey<HCX>,
     {
         to_sorted_vec(hcx, self.inner.into_iter(), cache_sort_key, |(k, _)| k)
     }

     /// Returns the values of this map in stable sort order (as defined by K's
     /// `ToStableHashKey` implementation).
     ///
     /// The `cache_sort_key` parameter controls if [slice::sort_by_cached_key] or
     /// [slice::sort_unstable_by_key] will be used for sorting the vec. Use
     /// `cache_sort_key` when the [ToStableHashKey::to_stable_hash_key] implementation
     /// for `K` is expensive (e.g. a `DefId -> DefPathHash` lookup).
     #[inline]
     pub fn values_sorted<HCX>(&self, hcx: &HCX, cache_sort_key: bool) -> impl Iterator<Item = &V>
     where
         K: ToStableHashKey<HCX>,
     {
         to_sorted_vec(hcx, self.inner.iter(), cache_sort_key, |&(k, _)| k)
             .into_iter()
             .map(|(_, v)| v)
     }
 }

 impl<K, Q: ?Sized, V> Index<&Q> for UnordMap<K, V>
 where
     K: Eq + Hash + Borrow<Q>,
     Q: Eq + Hash,
 {
     type Output = V;

     #[inline]
     fn index(&self, key: &Q) -> &V {
         &self.inner[key]
     }
 }

 impl<HCX, K: Hash + Eq + HashStable<HCX>, V: HashStable<HCX>> HashStable<HCX> for UnordMap<K, V> {
     #[inline]
     fn hash_stable(&self, hcx: &mut HCX, hasher: &mut StableHasher) {
         hash_iter_order_independent(self.inner.iter(), hcx, hasher);
     }
 }

 /// This is a collection type that tries very hard to not expose
 /// any internal iteration. This is a useful property when trying to
 /// uphold the determinism invariants imposed by the query system.
 ///
 /// This collection type is a good choice for collections the
 /// keys of which don't have a semantic ordering and don't implement
 /// `Hash` or `Eq`.
 ///
 /// See [MCP 533](https://github.com/rust-lang/compiler-team/issues/533)
 /// for more information.
 #[derive(Default, Debug, Eq, PartialEq, Clone, Encodable, Decodable)]
 pub struct UnordBag<V> {
     inner: Vec<V>,
 }

 impl<V> UnordBag<V> {
     #[inline]
     pub fn new() -> Self {
         Self { inner: Default::default() }
     }

     #[inline]
     pub fn len(&self) -> usize {
         self.inner.len()
     }

     #[inline]
     pub fn push(&mut self, v: V) {
         self.inner.push(v);
     }

     #[inline]
     pub fn items(&self) -> UnordItems<&V, impl Iterator<Item = &V>> {
         UnordItems(self.inner.iter())
     }

     #[inline]
     pub fn into_items(self) -> UnordItems<V, impl Iterator<Item = V>> {
         UnordItems(self.inner.into_iter())
     }
 }

 impl<T> UnordCollection for UnordBag<T> {}

 impl<T> Extend<T> for UnordBag<T> {
     fn extend<I: IntoIterator<Item = T>>(&mut self, iter: I) {
         self.inner.extend(iter)
     }
 }

 impl<T, I: Iterator<Item = T>> From<UnordItems<T, I>> for UnordBag<T> {
     fn from(value: UnordItems<T, I>) -> Self {
         UnordBag { inner: Vec::from_iter(value.0) }
     }
 }

 impl<HCX, V: Hash + Eq + HashStable<HCX>> HashStable<HCX> for UnordBag<V> {
     #[inline]
     fn hash_stable(&self, hcx: &mut HCX, hasher: &mut StableHasher) {
         hash_iter_order_independent(self.inner.iter(), hcx, hasher);
     }
 }

 #[inline]
 fn to_sorted_vec<HCX, T, K, I>(
     hcx: &HCX,
     iter: I,
     cache_sort_key: bool,
     extract_key: fn(&T) -> &K,
 ) -> Vec<T>
 where
     I: Iterator<Item = T>,
     K: ToStableHashKey<HCX>,
 {
     let mut items: Vec<T> = iter.collect();
     if cache_sort_key {
         items.sort_by_cached_key(|x| extract_key(x).to_stable_hash_key(hcx));
     } else {
         items.sort_unstable_by_key(|x| extract_key(x).to_stable_hash_key(hcx));
     }

     items
 }

 fn hash_iter_order_independent<
     HCX,
     T: HashStable<HCX>,
     I: Iterator<Item = T> + ExactSizeIterator,
 >(
     mut it: I,
     hcx: &mut HCX,
     hasher: &mut StableHasher,
 ) {
     let len = it.len();
     len.hash_stable(hcx, hasher);

     match len {
         0 => {
             // We're done
         }
         1 => {
             // No need to instantiate a hasher
             it.next().unwrap().hash_stable(hcx, hasher);
         }
         _ => {
             let mut accumulator = Fingerprint::ZERO;
             for item in it {
                 let mut item_hasher = StableHasher::new();
                 item.hash_stable(hcx, &mut item_hasher);
                 let item_fingerprint: Fingerprint = item_hasher.finish();
                 accumulator = accumulator.combine_commutative(item_fingerprint);
             }
             accumulator.hash_stable(hcx, hasher);
         }
     }
 }

 // Do not implement IntoIterator for the collections in this module.
 // They only exist to hide iteration order in the first place.
 impl<T> !IntoIterator for UnordBag<T> {}
 impl<V> !IntoIterator for UnordSet<V> {}
 impl<K, V> !IntoIterator for UnordMap<K, V> {}
 impl<T, I> !IntoIterator for UnordItems<T, I> {}
	//! This module contains collection types that don't expose their internal
	//! ordering. This is a useful property for deterministic computations, such
	//! as required by the query system.

	use rustc_hash::{FxHashMap, FxHashSet};
	use smallvec::SmallVec;
	use std::{
	borrow::Borrow,
	collections::hash_map::Entry,
	hash::Hash,
	iter::{Product, Sum},
	ops::Index,
	};

	use crate::{
	fingerprint::Fingerprint,
	stable_hasher::{HashStable, StableHasher, StableOrd, ToStableHashKey},
	};

	/// `UnordItems` is the order-less version of `Iterator`. It only contains methods
	/// that don't (easily) expose an ordering of the underlying items.
	///
	/// Most methods take an `Fn` where the `Iterator`-version takes an `FnMut`. This
	/// is to reduce the risk of accidentally leaking the internal order via the closure
	/// environment. Otherwise one could easily do something like
	///
	/// ```rust,ignore (pseudo code)
	/// let mut ordered = vec![];
	/// unordered_items.all(\|x\| ordered.push(x));
	/// ```
	///
	/// It's still possible to do the same thing with an `Fn` by using interior mutability,
	/// but the chance of doing it accidentally is reduced.
	#[derive(Clone)]
	pub struct UnordItems<T, I: Iterator<Item = T>>(I);

	impl<T, I: Iterator<Item = T>> UnordItems<T, I> {
	#[inline]
	pub fn map<U, F: Fn(T) -> U>(self, f: F) -> UnordItems<U, impl Iterator<Item = U>> {
	UnordItems(self.0.map(f))
	}

	#[inline]
	pub fn all<F: Fn(T) -> bool>(mut self, f: F) -> bool {
	self.0.all(f)
	}

	#[inline]
	pub fn any<F: Fn(T) -> bool>(mut self, f: F) -> bool {
	self.0.any(f)
	}

	#[inline]
	pub fn filter<F: Fn(&T) -> bool>(self, f: F) -> UnordItems<T, impl Iterator<Item = T>> {
	UnordItems(self.0.filter(f))
	}

	#[inline]
	pub fn filter_map<U, F: Fn(T) -> Option<U>>(
	self,
	f: F,
	) -> UnordItems<U, impl Iterator<Item = U>> {
	UnordItems(self.0.filter_map(f))
	}

	#[inline]
	pub fn max(self) -> Option<T>
	where
	T: Ord,
	{
	self.0.max()
	}

	#[inline]
	pub fn min(self) -> Option<T>
	where
	T: Ord,
	{
	self.0.min()
	}

	#[inline]
	pub fn sum<S>(self) -> S
	where
	S: Sum<T>,
	{
	self.0.sum()
	}

	#[inline]
	pub fn product<S>(self) -> S
	where
	S: Product<T>,
	{
	self.0.product()
	}

	#[inline]
	pub fn count(self) -> usize {
	self.0.count()
	}

	#[inline]
	pub fn flat_map<U, F, O>(self, f: F) -> UnordItems<O, impl Iterator<Item = O>>
	where
	U: IntoIterator<Item = O>,
	F: Fn(T) -> U,
	{
	UnordItems(self.0.flat_map(f))
	}

	pub fn collect<C: From<UnordItems<T, I>>>(self) -> C {
	self.into()
	}
	}

	impl<T> UnordItems<T, std::iter::Empty<T>> {
	pub fn empty() -> Self {
	UnordItems(std::iter::empty())
	}
	}

	impl<'a, T: Clone + 'a, I: Iterator<Item = &'a T>> UnordItems<&'a T, I> {
	#[inline]
	pub fn cloned(self) -> UnordItems<T, impl Iterator<Item = T>> {
	UnordItems(self.0.cloned())
	}
	}

	impl<'a, T: Copy + 'a, I: Iterator<Item = &'a T>> UnordItems<&'a T, I> {
	#[inline]
	pub fn copied(self) -> UnordItems<T, impl Iterator<Item = T>> {
	UnordItems(self.0.copied())
	}
	}

	impl<T: Ord, I: Iterator<Item = T>> UnordItems<T, I> {
	pub fn into_sorted<HCX>(self, hcx: &HCX) -> Vec<T>
	where
	T: ToStableHashKey<HCX>,
	{
	let mut items: Vec<T> = self.0.collect();
	items.sort_by_cached_key(\|x\| x.to_stable_hash_key(hcx));
	items
	}

	#[inline]
	pub fn into_sorted_stable_ord(self) -> Vec<T>
	where
	T: Ord + StableOrd,
	{
	let mut items: Vec<T> = self.0.collect();
	if !T::CAN_USE_UNSTABLE_SORT {
	items.sort();
	} else {
	items.sort_unstable()
	}
	items
	}

	pub fn into_sorted_small_vec<HCX, const LEN: usize>(self, hcx: &HCX) -> SmallVec<[T; LEN]>
	where
	T: ToStableHashKey<HCX>,
	{
	let mut items: SmallVec<[T; LEN]> = self.0.collect();
	items.sort_by_cached_key(\|x\| x.to_stable_hash_key(hcx));
	items
	}
	}

	/// A marker trait specifying that `Self` can consume `UnordItems<_>` without
	/// exposing any internal ordering.
	///
	/// Note: right now this is just a marker trait. It could be extended to contain
	/// some useful, common methods though, like `len`, `clear`, or the various
	/// kinds of `to_sorted`.
	trait UnordCollection {}

	/// This is a set collection type that tries very hard to not expose
	/// any internal iteration. This is a useful property when trying to
	/// uphold the determinism invariants imposed by the query system.
	///
	/// This collection type is a good choice for set-like collections the
	/// keys of which don't have a semantic ordering.
	///
	/// See [MCP 533](https://github.com/rust-lang/compiler-team/issues/533)
	/// for more information.
	#[derive(Debug, Eq, PartialEq, Clone, Encodable, Decodable)]
	pub struct UnordSet<V: Eq + Hash> {
	inner: FxHashSet<V>,
	}

	impl<V: Eq + Hash> UnordCollection for UnordSet<V> {}

	impl<V: Eq + Hash> Default for UnordSet<V> {
	#[inline]
	fn default() -> Self {
	Self { inner: FxHashSet::default() }
	}
	}

	impl<V: Eq + Hash> UnordSet<V> {
	#[inline]
	pub fn new() -> Self {
	Self { inner: Default::default() }
	}

	#[inline]
	pub fn with_capacity(capacity: usize) -> Self {
	Self { inner: FxHashSet::with_capacity_and_hasher(capacity, Default::default()) }
	}

	#[inline]
	pub fn len(&self) -> usize {
	self.inner.len()
	}

	#[inline]
	pub fn is_empty(&self) -> bool {
	self.inner.is_empty()
	}

	#[inline]
	pub fn insert(&mut self, v: V) -> bool {
	self.inner.insert(v)
	}

	#[inline]
	pub fn contains<Q: ?Sized>(&self, v: &Q) -> bool
	where
	V: Borrow<Q>,
	Q: Hash + Eq,
	{
	self.inner.contains(v)
	}

	#[inline]
	pub fn remove<Q: ?Sized>(&mut self, k: &Q) -> bool
	where
	V: Borrow<Q>,
	Q: Hash + Eq,
	{
	self.inner.remove(k)
	}

	#[inline]
	pub fn items(&self) -> UnordItems<&V, impl Iterator<Item = &V>> {
	UnordItems(self.inner.iter())
	}

	#[inline]
	pub fn into_items(self) -> UnordItems<V, impl Iterator<Item = V>> {
	UnordItems(self.inner.into_iter())
	}

	/// Returns the items of this set in stable sort order (as defined by `ToStableHashKey`).
	///
	/// The `cache_sort_key` parameter controls if [slice::sort_by_cached_key] or
	/// [slice::sort_unstable_by_key] will be used for sorting the vec. Use
	/// `cache_sort_key` when the [ToStableHashKey::to_stable_hash_key] implementation
	/// for `V` is expensive (e.g. a `DefId -> DefPathHash` lookup).
	#[inline]
	pub fn to_sorted<HCX>(&self, hcx: &HCX, cache_sort_key: bool) -> Vec<&V>
	where
	V: ToStableHashKey<HCX>,
	{
	to_sorted_vec(hcx, self.inner.iter(), cache_sort_key, \|&x\| x)
	}

	/// Returns the items of this set in stable sort order (as defined by
	/// `StableOrd`). This method is much more efficient than
	/// `into_sorted` because it does not need to transform keys to their
	/// `ToStableHashKey` equivalent.
	#[inline]
	pub fn to_sorted_stable_ord(&self) -> Vec<V>
	where
	V: Ord + StableOrd + Clone,
	{
	let mut items: Vec<V> = self.inner.iter().cloned().collect();
	items.sort_unstable();
	items
	}

	/// Returns the items of this set in stable sort order (as defined by `ToStableHashKey`).
	///
	/// The `cache_sort_key` parameter controls if [slice::sort_by_cached_key] or
	/// [slice::sort_unstable_by_key] will be used for sorting the vec. Use
	/// `cache_sort_key` when the [ToStableHashKey::to_stable_hash_key] implementation
	/// for `V` is expensive (e.g. a `DefId -> DefPathHash` lookup).
	#[inline]
	pub fn into_sorted<HCX>(self, hcx: &HCX, cache_sort_key: bool) -> Vec<V>
	where
	V: ToStableHashKey<HCX>,
	{
	to_sorted_vec(hcx, self.inner.into_iter(), cache_sort_key, \|x\| x)
	}

	#[inline]
	pub fn clear(&mut self) {
	self.inner.clear();
	}
	}

	pub trait ExtendUnord<T> {
	/// Extend this unord collection with the given `UnordItems`.
	/// This method is called `extend_unord` instead of just `extend` so it
	/// does not conflict with `Extend::extend`. Otherwise there would be many
	/// places where the two methods would have to be explicitly disambiguated
	/// via UFCS.
	fn extend_unord<I: Iterator<Item = T>>(&mut self, items: UnordItems<T, I>);
	}

	// Note: it is important that `C` implements `UnordCollection` in addition to
	// `Extend`, otherwise this impl would leak the internal iteration order of
	// `items`, e.g. when calling `some_vec.extend_unord(some_unord_items)`.
	impl<C: Extend<T> + UnordCollection, T> ExtendUnord<T> for C {
	#[inline]
	fn extend_unord<I: Iterator<Item = T>>(&mut self, items: UnordItems<T, I>) {
	self.extend(items.0)
	}
	}

	impl<V: Hash + Eq> Extend<V> for UnordSet<V> {
	#[inline]
	fn extend<T: IntoIterator<Item = V>>(&mut self, iter: T) {
	self.inner.extend(iter)
	}
	}

	impl<V: Hash + Eq> FromIterator<V> for UnordSet<V> {
	#[inline]
	fn from_iter<T: IntoIterator<Item = V>>(iter: T) -> Self {
	UnordSet { inner: FxHashSet::from_iter(iter) }
	}
	}

	impl<V: Hash + Eq> From<FxHashSet<V>> for UnordSet<V> {
	fn from(value: FxHashSet<V>) -> Self {
	UnordSet { inner: value }
	}
	}

	impl<V: Hash + Eq, I: Iterator<Item = V>> From<UnordItems<V, I>> for UnordSet<V> {
	fn from(value: UnordItems<V, I>) -> Self {
	UnordSet { inner: FxHashSet::from_iter(value.0) }
	}
	}

	impl<HCX, V: Hash + Eq + HashStable<HCX>> HashStable<HCX> for UnordSet<V> {
	#[inline]
	fn hash_stable(&self, hcx: &mut HCX, hasher: &mut StableHasher) {
	hash_iter_order_independent(self.inner.iter(), hcx, hasher);
	}
	}

	/// This is a map collection type that tries very hard to not expose
	/// any internal iteration. This is a useful property when trying to
	/// uphold the determinism invariants imposed by the query system.
	///
	/// This collection type is a good choice for map-like collections the
	/// keys of which don't have a semantic ordering.
	///
	/// See [MCP 533](https://github.com/rust-lang/compiler-team/issues/533)
	/// for more information.
	#[derive(Debug, Eq, PartialEq, Clone, Encodable, Decodable)]
	pub struct UnordMap<K: Eq + Hash, V> {
	inner: FxHashMap<K, V>,
	}

	impl<K: Eq + Hash, V> UnordCollection for UnordMap<K, V> {}

	impl<K: Eq + Hash, V> Default for UnordMap<K, V> {
	#[inline]
	fn default() -> Self {
	Self { inner: FxHashMap::default() }
	}
	}

	impl<K: Hash + Eq, V> Extend<(K, V)> for UnordMap<K, V> {
	#[inline]
	fn extend<T: IntoIterator<Item = (K, V)>>(&mut self, iter: T) {
	self.inner.extend(iter)
	}
	}

	impl<K: Hash + Eq, V> FromIterator<(K, V)> for UnordMap<K, V> {
	#[inline]
	fn from_iter<T: IntoIterator<Item = (K, V)>>(iter: T) -> Self {
	UnordMap { inner: FxHashMap::from_iter(iter) }
	}
	}

	impl<K: Hash + Eq, V, I: Iterator<Item = (K, V)>> From<UnordItems<(K, V), I>> for UnordMap<K, V> {
	#[inline]
	fn from(items: UnordItems<(K, V), I>) -> Self {
	UnordMap { inner: FxHashMap::from_iter(items.0) }
	}
	}

	impl<K: Eq + Hash, V> UnordMap<K, V> {
	#[inline]
	pub fn with_capacity(capacity: usize) -> Self {
	Self { inner: FxHashMap::with_capacity_and_hasher(capacity, Default::default()) }
	}

	#[inline]
	pub fn len(&self) -> usize {
	self.inner.len()
	}

	#[inline]
	pub fn insert(&mut self, k: K, v: V) -> Option<V> {
	self.inner.insert(k, v)
	}

	#[inline]
	pub fn contains_key<Q: ?Sized>(&self, k: &Q) -> bool
	where
	K: Borrow<Q>,
	Q: Hash + Eq,
	{
	self.inner.contains_key(k)
	}

	#[inline]
	pub fn is_empty(&self) -> bool {
	self.inner.is_empty()
	}

	#[inline]
	pub fn entry(&mut self, key: K) -> Entry<'_, K, V> {
	self.inner.entry(key)
	}

	#[inline]
	pub fn get<Q: ?Sized>(&self, k: &Q) -> Option<&V>
	where
	K: Borrow<Q>,
	Q: Hash + Eq,
	{
	self.inner.get(k)
	}

	#[inline]
	pub fn get_mut<Q: ?Sized>(&mut self, k: &Q) -> Option<&mut V>
	where
	K: Borrow<Q>,
	Q: Hash + Eq,
	{
	self.inner.get_mut(k)
	}

	#[inline]
	pub fn remove<Q: ?Sized>(&mut self, k: &Q) -> Option<V>
	where
	K: Borrow<Q>,
	Q: Hash + Eq,
	{
	self.inner.remove(k)
	}

	#[inline]
	pub fn items(&self) -> UnordItems<(&K, &V), impl Iterator<Item = (&K, &V)>> {
	UnordItems(self.inner.iter())
	}

	#[inline]
	pub fn into_items(self) -> UnordItems<(K, V), impl Iterator<Item = (K, V)>> {
	UnordItems(self.inner.into_iter())
	}

	/// Returns the entries of this map in stable sort order (as defined by `ToStableHashKey`).
	///
	/// The `cache_sort_key` parameter controls if [slice::sort_by_cached_key] or
	/// [slice::sort_unstable_by_key] will be used for sorting the vec. Use
	/// `cache_sort_key` when the [ToStableHashKey::to_stable_hash_key] implementation
	/// for `K` is expensive (e.g. a `DefId -> DefPathHash` lookup).
	#[inline]
	pub fn to_sorted<HCX>(&self, hcx: &HCX, cache_sort_key: bool) -> Vec<(&K, &V)>
	where
	K: ToStableHashKey<HCX>,
	{
	to_sorted_vec(hcx, self.inner.iter(), cache_sort_key, \|&(k, _)\| k)
	}

	/// Returns the entries of this map in stable sort order (as defined by `StableOrd`).
	/// This method can be much more efficient than `into_sorted` because it does not need
	/// to transform keys to their `ToStableHashKey` equivalent.
	#[inline]
	pub fn to_sorted_stable_ord(&self) -> Vec<(K, &V)>
	where
	K: Ord + StableOrd + Copy,
	{
	let mut items: Vec<(K, &V)> = self.inner.iter().map(\|(&k, v)\| (k, v)).collect();
	items.sort_unstable_by_key(\|&(k, _)\| k);
	items
	}

	/// Returns the entries of this map in stable sort order (as defined by `ToStableHashKey`).
	///
	/// The `cache_sort_key` parameter controls if [slice::sort_by_cached_key] or
	/// [slice::sort_unstable_by_key] will be used for sorting the vec. Use
	/// `cache_sort_key` when the [ToStableHashKey::to_stable_hash_key] implementation
	/// for `K` is expensive (e.g. a `DefId -> DefPathHash` lookup).
	#[inline]
	pub fn into_sorted<HCX>(self, hcx: &HCX, cache_sort_key: bool) -> Vec<(K, V)>
	where
	K: ToStableHashKey<HCX>,
	{
	to_sorted_vec(hcx, self.inner.into_iter(), cache_sort_key, \|(k, _)\| k)
	}

	/// Returns the values of this map in stable sort order (as defined by K's
	/// `ToStableHashKey` implementation).
	///
	/// The `cache_sort_key` parameter controls if [slice::sort_by_cached_key] or
	/// [slice::sort_unstable_by_key] will be used for sorting the vec. Use
	/// `cache_sort_key` when the [ToStableHashKey::to_stable_hash_key] implementation
	/// for `K` is expensive (e.g. a `DefId -> DefPathHash` lookup).
	#[inline]
	pub fn values_sorted<HCX>(&self, hcx: &HCX, cache_sort_key: bool) -> impl Iterator<Item = &V>
	where
	K: ToStableHashKey<HCX>,
	{
	to_sorted_vec(hcx, self.inner.iter(), cache_sort_key, \|&(k, _)\| k)
	.into_iter()
	.map(\|(_, v)\| v)
	}
	}

	impl<K, Q: ?Sized, V> Index<&Q> for UnordMap<K, V>
	where
	K: Eq + Hash + Borrow<Q>,
	Q: Eq + Hash,
	{
	type Output = V;

	#[inline]
	fn index(&self, key: &Q) -> &V {
	&self.inner[key]
	}
	}

	impl<HCX, K: Hash + Eq + HashStable<HCX>, V: HashStable<HCX>> HashStable<HCX> for UnordMap<K, V> {
	#[inline]
	fn hash_stable(&self, hcx: &mut HCX, hasher: &mut StableHasher) {
	hash_iter_order_independent(self.inner.iter(), hcx, hasher);
	}
	}

	/// This is a collection type that tries very hard to not expose
	/// any internal iteration. This is a useful property when trying to
	/// uphold the determinism invariants imposed by the query system.
	///
	/// This collection type is a good choice for collections the
	/// keys of which don't have a semantic ordering and don't implement
	/// `Hash` or `Eq`.
	///
	/// See [MCP 533](https://github.com/rust-lang/compiler-team/issues/533)
	/// for more information.
	#[derive(Default, Debug, Eq, PartialEq, Clone, Encodable, Decodable)]
	pub struct UnordBag<V> {
	inner: Vec<V>,
	}

	impl<V> UnordBag<V> {
	#[inline]
	pub fn new() -> Self {
	Self { inner: Default::default() }
	}

	#[inline]
	pub fn len(&self) -> usize {
	self.inner.len()
	}

	#[inline]
	pub fn push(&mut self, v: V) {
	self.inner.push(v);
	}

	#[inline]
	pub fn items(&self) -> UnordItems<&V, impl Iterator<Item = &V>> {
	UnordItems(self.inner.iter())
	}

	#[inline]
	pub fn into_items(self) -> UnordItems<V, impl Iterator<Item = V>> {
	UnordItems(self.inner.into_iter())
	}
	}

	impl<T> UnordCollection for UnordBag<T> {}

	impl<T> Extend<T> for UnordBag<T> {
	fn extend<I: IntoIterator<Item = T>>(&mut self, iter: I) {
	self.inner.extend(iter)
	}
	}

	impl<T, I: Iterator<Item = T>> From<UnordItems<T, I>> for UnordBag<T> {
	fn from(value: UnordItems<T, I>) -> Self {
	UnordBag { inner: Vec::from_iter(value.0) }
	}
	}

	impl<HCX, V: Hash + Eq + HashStable<HCX>> HashStable<HCX> for UnordBag<V> {
	#[inline]
	fn hash_stable(&self, hcx: &mut HCX, hasher: &mut StableHasher) {
	hash_iter_order_independent(self.inner.iter(), hcx, hasher);
	}
	}

	#[inline]
	fn to_sorted_vec<HCX, T, K, I>(
	hcx: &HCX,
	iter: I,
	cache_sort_key: bool,
	extract_key: fn(&T) -> &K,
	) -> Vec<T>
	where
	I: Iterator<Item = T>,
	K: ToStableHashKey<HCX>,
	{
	let mut items: Vec<T> = iter.collect();
	if cache_sort_key {
	items.sort_by_cached_key(\|x\| extract_key(x).to_stable_hash_key(hcx));
	} else {
	items.sort_unstable_by_key(\|x\| extract_key(x).to_stable_hash_key(hcx));
	}

	items
	}

	fn hash_iter_order_independent<
	HCX,
	T: HashStable<HCX>,
	I: Iterator<Item = T> + ExactSizeIterator,
	>(
	mut it: I,
	hcx: &mut HCX,
	hasher: &mut StableHasher,
	) {
	let len = it.len();
	len.hash_stable(hcx, hasher);

	match len {
	0 => {
	// We're done
	}
	1 => {
	// No need to instantiate a hasher
	it.next().unwrap().hash_stable(hcx, hasher);
	}
	_ => {
	let mut accumulator = Fingerprint::ZERO;
	for item in it {
	let mut item_hasher = StableHasher::new();
	item.hash_stable(hcx, &mut item_hasher);
	let item_fingerprint: Fingerprint = item_hasher.finish();
	accumulator = accumulator.combine_commutative(item_fingerprint);
	}
	accumulator.hash_stable(hcx, hasher);
	}
	}
	}

	// Do not implement IntoIterator for the collections in this module.
	// They only exist to hide iteration order in the first place.
	impl<T> !IntoIterator for UnordBag<T> {}
	impl<V> !IntoIterator for UnordSet<V> {}
	impl<K, V> !IntoIterator for UnordMap<K, V> {}
	impl<T, I> !IntoIterator for UnordItems<T, I> {}