feat: add display UI with splash screen, dashboard, and RSSI sparkline

Implement full SSD1306 OLED display support:
- Splash screen on boot (1.5s) with project name, version, board
- Dashboard showing radio state, config, counters, RSSI/SNR
- RSSI history sparkline (64-sample ring buffer, 2px-wide bars)
- DisplayOn/DisplayOff host commands routed via dedicated channel
- Pure render functions against generic DrawTarget (no hardware coupling)
- Display on/off control bypasses radio task entirely

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

vendor/hashbrown/src/control/bitmask.rs

@@ -0,0 +1,117 @@
+use super::group::{
+    BitMaskWord, NonZeroBitMaskWord, BITMASK_ITER_MASK, BITMASK_MASK, BITMASK_STRIDE,
+};
+
+/// A bit mask which contains the result of a `Match` operation on a `Group` and
+/// allows iterating through them.
+///
+/// The bit mask is arranged so that low-order bits represent lower memory
+/// addresses for group match results.
+///
+/// For implementation reasons, the bits in the set may be sparsely packed with
+/// groups of 8 bits representing one element. If any of these bits are non-zero
+/// then this element is considered to true in the mask. If this is the
+/// case, `BITMASK_STRIDE` will be 8 to indicate a divide-by-8 should be
+/// performed on counts/indices to normalize this difference. `BITMASK_MASK` is
+/// similarly a mask of all the actually-used bits.
+///
+/// To iterate over a bit mask, it must be converted to a form where only 1 bit
+/// is set per element. This is done by applying `BITMASK_ITER_MASK` on the
+/// mask bits.
+#[derive(Copy, Clone)]
+pub(crate) struct BitMask(pub(crate) BitMaskWord);
+
+#[allow(clippy::use_self)]
+impl BitMask {
+    /// Returns a new `BitMask` with all bits inverted.
+    #[inline]
+    #[must_use]
+    #[allow(dead_code)]
+    pub(crate) fn invert(self) -> Self {
+        BitMask(self.0 ^ BITMASK_MASK)
+    }
+
+    /// Returns a new `BitMask` with the lowest bit removed.
+    #[inline]
+    #[must_use]
+    fn remove_lowest_bit(self) -> Self {
+        BitMask(self.0 & (self.0 - 1))
+    }
+
+    /// Returns whether the `BitMask` has at least one set bit.
+    #[inline]
+    pub(crate) fn any_bit_set(self) -> bool {
+        self.0 != 0
+    }
+
+    /// Returns the first set bit in the `BitMask`, if there is one.
+    #[inline]
+    pub(crate) fn lowest_set_bit(self) -> Option<usize> {
+        if let Some(nonzero) = NonZeroBitMaskWord::new(self.0) {
+            Some(Self::nonzero_trailing_zeros(nonzero))
+        } else {
+            None
+        }
+    }
+
+    /// Returns the number of trailing zeroes in the `BitMask`.
+    #[inline]
+    pub(crate) fn trailing_zeros(self) -> usize {
+        // ARM doesn't have a trailing_zeroes instruction, and instead uses
+        // reverse_bits (RBIT) + leading_zeroes (CLZ). However older ARM
+        // versions (pre-ARMv7) don't have RBIT and need to emulate it
+        // instead. Since we only have 1 bit set in each byte on ARM, we can
+        // use swap_bytes (REV) + leading_zeroes instead.
+        if cfg!(target_arch = "arm") && BITMASK_STRIDE % 8 == 0 {
+            self.0.swap_bytes().leading_zeros() as usize / BITMASK_STRIDE
+        } else {
+            self.0.trailing_zeros() as usize / BITMASK_STRIDE
+        }
+    }
+
+    /// Same as above but takes a `NonZeroBitMaskWord`.
+    #[inline]
+    fn nonzero_trailing_zeros(nonzero: NonZeroBitMaskWord) -> usize {
+        if cfg!(target_arch = "arm") && BITMASK_STRIDE % 8 == 0 {
+            // SAFETY: A byte-swapped non-zero value is still non-zero.
+            let swapped = unsafe { NonZeroBitMaskWord::new_unchecked(nonzero.get().swap_bytes()) };
+            swapped.leading_zeros() as usize / BITMASK_STRIDE
+        } else {
+            nonzero.trailing_zeros() as usize / BITMASK_STRIDE
+        }
+    }
+
+    /// Returns the number of leading zeroes in the `BitMask`.
+    #[inline]
+    pub(crate) fn leading_zeros(self) -> usize {
+        self.0.leading_zeros() as usize / BITMASK_STRIDE
+    }
+}
+
+impl IntoIterator for BitMask {
+    type Item = usize;
+    type IntoIter = BitMaskIter;
+
+    #[inline]
+    fn into_iter(self) -> BitMaskIter {
+        // A BitMask only requires each element (group of bits) to be non-zero.
+        // However for iteration we need each element to only contain 1 bit.
+        BitMaskIter(BitMask(self.0 & BITMASK_ITER_MASK))
+    }
+}
+
+/// Iterator over the contents of a `BitMask`, returning the indices of set
+/// bits.
+#[derive(Clone)]
+pub(crate) struct BitMaskIter(pub(crate) BitMask);
+
+impl Iterator for BitMaskIter {
+    type Item = usize;
+
+    #[inline]
+    fn next(&mut self) -> Option<usize> {
+        let bit = self.0.lowest_set_bit()?;
+        self.0 = self.0.remove_lowest_bit();
+        Some(bit)
+    }
+}

vendor/hashbrown/src/control/group/generic.rs

@@ -0,0 +1,154 @@
+use super::super::{BitMask, Tag};
+use core::{mem, ptr};
+
+// Use the native word size as the group size. Using a 64-bit group size on
+// a 32-bit architecture will just end up being more expensive because
+// shifts and multiplies will need to be emulated.
+
+cfg_if! {
+    if #[cfg(any(
+        target_pointer_width = "64",
+        target_arch = "aarch64",
+        target_arch = "x86_64",
+        target_arch = "wasm32",
+    ))] {
+        type GroupWord = u64;
+        type NonZeroGroupWord = core::num::NonZeroU64;
+    } else {
+        type GroupWord = u32;
+        type NonZeroGroupWord = core::num::NonZeroU32;
+    }
+}
+
+pub(crate) type BitMaskWord = GroupWord;
+pub(crate) type NonZeroBitMaskWord = NonZeroGroupWord;
+pub(crate) const BITMASK_STRIDE: usize = 8;
+// We only care about the highest bit of each tag for the mask.
+#[allow(clippy::cast_possible_truncation, clippy::unnecessary_cast)]
+pub(crate) const BITMASK_MASK: BitMaskWord = u64::from_ne_bytes([Tag::DELETED.0; 8]) as GroupWord;
+pub(crate) const BITMASK_ITER_MASK: BitMaskWord = !0;
+
+/// Helper function to replicate a tag across a `GroupWord`.
+#[inline]
+fn repeat(tag: Tag) -> GroupWord {
+    GroupWord::from_ne_bytes([tag.0; Group::WIDTH])
+}
+
+/// Abstraction over a group of control tags which can be scanned in
+/// parallel.
+///
+/// This implementation uses a word-sized integer.
+#[derive(Copy, Clone)]
+pub(crate) struct Group(GroupWord);
+
+// We perform all operations in the native endianness, and convert to
+// little-endian just before creating a BitMask. The can potentially
+// enable the compiler to eliminate unnecessary byte swaps if we are
+// only checking whether a BitMask is empty.
+#[allow(clippy::use_self)]
+impl Group {
+    /// Number of bytes in the group.
+    pub(crate) const WIDTH: usize = mem::size_of::<Self>();
+
+    /// Returns a full group of empty tags, suitable for use as the initial
+    /// value for an empty hash table.
+    ///
+    /// This is guaranteed to be aligned to the group size.
+    #[inline]
+    pub(crate) const fn static_empty() -> &'static [Tag; Group::WIDTH] {
+        #[repr(C)]
+        struct AlignedTags {
+            _align: [Group; 0],
+            tags: [Tag; Group::WIDTH],
+        }
+        const ALIGNED_TAGS: AlignedTags = AlignedTags {
+            _align: [],
+            tags: [Tag::EMPTY; Group::WIDTH],
+        };
+        &ALIGNED_TAGS.tags
+    }
+
+    /// Loads a group of tags starting at the given address.
+    #[inline]
+    #[allow(clippy::cast_ptr_alignment)] // unaligned load
+    pub(crate) unsafe fn load(ptr: *const Tag) -> Self {
+        Group(ptr::read_unaligned(ptr.cast()))
+    }
+
+    /// Loads a group of tags starting at the given address, which must be
+    /// aligned to `mem::align_of::<Group>()`.
+    #[inline]
+    #[allow(clippy::cast_ptr_alignment)]
+    pub(crate) unsafe fn load_aligned(ptr: *const Tag) -> Self {
+        debug_assert_eq!(ptr.align_offset(mem::align_of::<Self>()), 0);
+        Group(ptr::read(ptr.cast()))
+    }
+
+    /// Stores the group of tags to the given address, which must be
+    /// aligned to `mem::align_of::<Group>()`.
+    #[inline]
+    #[allow(clippy::cast_ptr_alignment)]
+    pub(crate) unsafe fn store_aligned(self, ptr: *mut Tag) {
+        debug_assert_eq!(ptr.align_offset(mem::align_of::<Self>()), 0);
+        ptr::write(ptr.cast(), self.0);
+    }
+
+    /// Returns a `BitMask` indicating all tags in the group which *may*
+    /// have the given value.
+    ///
+    /// This function may return a false positive in certain cases where
+    /// the tag in the group differs from the searched value only in its
+    /// lowest bit. This is fine because:
+    /// - This never happens for `EMPTY` and `DELETED`, only full entries.
+    /// - The check for key equality will catch these.
+    /// - This only happens if there is at least 1 true match.
+    /// - The chance of this happening is very low (< 1% chance per tag).
+    #[inline]
+    pub(crate) fn match_tag(self, tag: Tag) -> BitMask {
+        // This algorithm is derived from
+        // https://graphics.stanford.edu/~seander/bithacks.html##ValueInWord
+        let cmp = self.0 ^ repeat(tag);
+        BitMask((cmp.wrapping_sub(repeat(Tag(0x01))) & !cmp & repeat(Tag::DELETED)).to_le())
+    }
+
+    /// Returns a `BitMask` indicating all tags in the group which are
+    /// `EMPTY`.
+    #[inline]
+    pub(crate) fn match_empty(self) -> BitMask {
+        // If the high bit is set, then the tag must be either:
+        // 1111_1111 (EMPTY) or 1000_0000 (DELETED).
+        // So we can just check if the top two bits are 1 by ANDing them.
+        BitMask((self.0 & (self.0 << 1) & repeat(Tag::DELETED)).to_le())
+    }
+
+    /// Returns a `BitMask` indicating all tags in the group which are
+    /// `EMPTY` or `DELETED`.
+    #[inline]
+    pub(crate) fn match_empty_or_deleted(self) -> BitMask {
+        // A tag is EMPTY or DELETED iff the high bit is set
+        BitMask((self.0 & repeat(Tag::DELETED)).to_le())
+    }
+
+    /// Returns a `BitMask` indicating all tags in the group which are full.
+    #[inline]
+    pub(crate) fn match_full(self) -> BitMask {
+        self.match_empty_or_deleted().invert()
+    }
+
+    /// Performs the following transformation on all tags in the group:
+    /// - `EMPTY => EMPTY`
+    /// - `DELETED => EMPTY`
+    /// - `FULL => DELETED`
+    #[inline]
+    pub(crate) fn convert_special_to_empty_and_full_to_deleted(self) -> Self {
+        // Map high_bit = 1 (EMPTY or DELETED) to 1111_1111
+        // and high_bit = 0 (FULL) to 1000_0000
+        //
+        // Here's this logic expanded to concrete values:
+        //   let full = 1000_0000 (true) or 0000_0000 (false)
+        //   !1000_0000 + 1 = 0111_1111 + 1 = 1000_0000 (no carry)
+        //   !0000_0000 + 0 = 1111_1111 + 0 = 1111_1111 (no carry)
+        let full = !self.0 & repeat(Tag::DELETED);
+        Group(!full + (full >> 7))
+    }
+}

vendor/hashbrown/src/control/group/lsx.rs

@@ -0,0 +1,128 @@
+use super::super::{BitMask, Tag};
+use core::mem;
+use core::num::NonZeroU16;
+
+use core::arch::loongarch64::*;
+
+pub(crate) type BitMaskWord = u16;
+pub(crate) type NonZeroBitMaskWord = NonZeroU16;
+pub(crate) const BITMASK_STRIDE: usize = 1;
+pub(crate) const BITMASK_MASK: BitMaskWord = 0xffff;
+pub(crate) const BITMASK_ITER_MASK: BitMaskWord = !0;
+
+/// Abstraction over a group of control tags which can be scanned in
+/// parallel.
+///
+/// This implementation uses a 128-bit LSX value.
+#[derive(Copy, Clone)]
+pub(crate) struct Group(m128i);
+
+// FIXME: https://github.com/rust-lang/rust-clippy/issues/3859
+#[allow(clippy::use_self)]
+impl Group {
+    /// Number of bytes in the group.
+    pub(crate) const WIDTH: usize = mem::size_of::<Self>();
+
+    /// Returns a full group of empty tags, suitable for use as the initial
+    /// value for an empty hash table.
+    ///
+    /// This is guaranteed to be aligned to the group size.
+    #[inline]
+    #[allow(clippy::items_after_statements)]
+    pub(crate) const fn static_empty() -> &'static [Tag; Group::WIDTH] {
+        #[repr(C)]
+        struct AlignedTags {
+            _align: [Group; 0],
+            tags: [Tag; Group::WIDTH],
+        }
+        const ALIGNED_TAGS: AlignedTags = AlignedTags {
+            _align: [],
+            tags: [Tag::EMPTY; Group::WIDTH],
+        };
+        &ALIGNED_TAGS.tags
+    }
+
+    /// Loads a group of tags starting at the given address.
+    #[inline]
+    #[allow(clippy::cast_ptr_alignment)] // unaligned load
+    pub(crate) unsafe fn load(ptr: *const Tag) -> Self {
+        Group(lsx_vld::<0>(ptr.cast()))
+    }
+
+    /// Loads a group of tags starting at the given address, which must be
+    /// aligned to `mem::align_of::<Group>()`.
+    #[inline]
+    #[allow(clippy::cast_ptr_alignment)]
+    pub(crate) unsafe fn load_aligned(ptr: *const Tag) -> Self {
+        debug_assert_eq!(ptr.align_offset(mem::align_of::<Self>()), 0);
+        Group(lsx_vld::<0>(ptr.cast()))
+    }
+
+    /// Stores the group of tags to the given address, which must be
+    /// aligned to `mem::align_of::<Group>()`.
+    #[inline]
+    #[allow(clippy::cast_ptr_alignment)]
+    pub(crate) unsafe fn store_aligned(self, ptr: *mut Tag) {
+        debug_assert_eq!(ptr.align_offset(mem::align_of::<Self>()), 0);
+        lsx_vst::<0>(self.0, ptr.cast());
+    }
+
+    /// Returns a `BitMask` indicating all tags in the group which have
+    /// the given value.
+    #[inline]
+    pub(crate) fn match_tag(self, tag: Tag) -> BitMask {
+        unsafe {
+            let cmp = lsx_vseq_b(self.0, lsx_vreplgr2vr_b(tag.0 as i32));
+            BitMask(lsx_vpickve2gr_hu::<0>(lsx_vmskltz_b(cmp)) as u16)
+        }
+    }
+
+    /// Returns a `BitMask` indicating all tags in the group which are
+    /// `EMPTY`.
+    #[inline]
+    pub(crate) fn match_empty(self) -> BitMask {
+        unsafe {
+            let cmp = lsx_vseqi_b::<{ Tag::EMPTY.0 as i8 as i32 }>(self.0);
+            BitMask(lsx_vpickve2gr_hu::<0>(lsx_vmskltz_b(cmp)) as u16)
+        }
+    }
+
+    /// Returns a `BitMask` indicating all tags in the group which are
+    /// `EMPTY` or `DELETED`.
+    #[inline]
+    pub(crate) fn match_empty_or_deleted(self) -> BitMask {
+        unsafe {
+            // A tag is EMPTY or DELETED iff the high bit is set
+            BitMask(lsx_vpickve2gr_hu::<0>(lsx_vmskltz_b(self.0)) as u16)
+        }
+    }
+
+    /// Returns a `BitMask` indicating all tags in the group which are full.
+    #[inline]
+    pub(crate) fn match_full(&self) -> BitMask {
+        unsafe {
+            // A tag is EMPTY or DELETED iff the high bit is set
+            BitMask(lsx_vpickve2gr_hu::<0>(lsx_vmskgez_b(self.0)) as u16)
+        }
+    }
+
+    /// Performs the following transformation on all tags in the group:
+    /// - `EMPTY => EMPTY`
+    /// - `DELETED => EMPTY`
+    /// - `FULL => DELETED`
+    #[inline]
+    pub(crate) fn convert_special_to_empty_and_full_to_deleted(self) -> Self {
+        // Map high_bit = 1 (EMPTY or DELETED) to 1111_1111
+        // and high_bit = 0 (FULL) to 1000_0000
+        //
+        // Here's this logic expanded to concrete values:
+        //   let special = 0 > tag = 1111_1111 (true) or 0000_0000 (false)
+        //   1111_1111 | 1000_0000 = 1111_1111
+        //   0000_0000 | 1000_0000 = 1000_0000
+        unsafe {
+            let zero = lsx_vreplgr2vr_b(0);
+            let special = lsx_vslt_b(self.0, zero);
+            Group(lsx_vor_v(special, lsx_vreplgr2vr_b(Tag::DELETED.0 as i32)))
+        }
+    }
+}

vendor/hashbrown/src/control/group/mod.rs

@@ -0,0 +1,43 @@
+cfg_if! {
+    // Use the SSE2 implementation if possible: it allows us to scan 16 buckets
+    // at once instead of 8. We don't bother with AVX since it would require
+    // runtime dispatch and wouldn't gain us much anyways: the probability of
+    // finding a match drops off drastically after the first few buckets.
+    //
+    // I attempted an implementation on ARM using NEON instructions, but it
+    // turns out that most NEON instructions have multi-cycle latency, which in
+    // the end outweighs any gains over the generic implementation.
+    if #[cfg(all(
+        target_feature = "sse2",
+        any(target_arch = "x86", target_arch = "x86_64"),
+        not(miri),
+    ))] {
+        mod sse2;
+        use sse2 as imp;
+    } else if #[cfg(all(
+        target_arch = "aarch64",
+        target_feature = "neon",
+        // NEON intrinsics are currently broken on big-endian targets.
+        // See https://github.com/rust-lang/stdarch/issues/1484.
+        target_endian = "little",
+        not(miri),
+    ))] {
+        mod neon;
+        use neon as imp;
+    } else if #[cfg(all(
+        feature = "nightly",
+        target_arch = "loongarch64",
+        target_feature = "lsx",
+        not(miri),
+    ))] {
+        mod lsx;
+        use lsx as imp;
+    } else {
+        mod generic;
+        use generic as imp;
+    }
+}
+pub(crate) use self::imp::Group;
+pub(super) use self::imp::{
+    BitMaskWord, NonZeroBitMaskWord, BITMASK_ITER_MASK, BITMASK_MASK, BITMASK_STRIDE,
+};

vendor/hashbrown/src/control/group/neon.rs

@@ -0,0 +1,121 @@
+use super::super::{BitMask, Tag};
+use core::arch::aarch64 as neon;
+use core::mem;
+use core::num::NonZeroU64;
+
+pub(crate) type BitMaskWord = u64;
+pub(crate) type NonZeroBitMaskWord = NonZeroU64;
+pub(crate) const BITMASK_STRIDE: usize = 8;
+pub(crate) const BITMASK_MASK: BitMaskWord = !0;
+pub(crate) const BITMASK_ITER_MASK: BitMaskWord = 0x8080_8080_8080_8080;
+
+/// Abstraction over a group of control tags which can be scanned in
+/// parallel.
+///
+/// This implementation uses a 64-bit NEON value.
+#[derive(Copy, Clone)]
+pub(crate) struct Group(neon::uint8x8_t);
+
+#[allow(clippy::use_self)]
+impl Group {
+    /// Number of bytes in the group.
+    pub(crate) const WIDTH: usize = mem::size_of::<Self>();
+
+    /// Returns a full group of empty tags, suitable for use as the initial
+    /// value for an empty hash table.
+    ///
+    /// This is guaranteed to be aligned to the group size.
+    #[inline]
+    pub(crate) const fn static_empty() -> &'static [Tag; Group::WIDTH] {
+        #[repr(C)]
+        struct AlignedTags {
+            _align: [Group; 0],
+            tags: [Tag; Group::WIDTH],
+        }
+        const ALIGNED_TAGS: AlignedTags = AlignedTags {
+            _align: [],
+            tags: [Tag::EMPTY; Group::WIDTH],
+        };
+        &ALIGNED_TAGS.tags
+    }
+
+    /// Loads a group of tags starting at the given address.
+    #[inline]
+    #[allow(clippy::cast_ptr_alignment)] // unaligned load
+    pub(crate) unsafe fn load(ptr: *const Tag) -> Self {
+        Group(neon::vld1_u8(ptr.cast()))
+    }
+
+    /// Loads a group of tags starting at the given address, which must be
+    /// aligned to `mem::align_of::<Group>()`.
+    #[inline]
+    #[allow(clippy::cast_ptr_alignment)]
+    pub(crate) unsafe fn load_aligned(ptr: *const Tag) -> Self {
+        debug_assert_eq!(ptr.align_offset(mem::align_of::<Self>()), 0);
+        Group(neon::vld1_u8(ptr.cast()))
+    }
+
+    /// Stores the group of tags to the given address, which must be
+    /// aligned to `mem::align_of::<Group>()`.
+    #[inline]
+    #[allow(clippy::cast_ptr_alignment)]
+    pub(crate) unsafe fn store_aligned(self, ptr: *mut Tag) {
+        debug_assert_eq!(ptr.align_offset(mem::align_of::<Self>()), 0);
+        neon::vst1_u8(ptr.cast(), self.0);
+    }
+
+    /// Returns a `BitMask` indicating all tags in the group which *may*
+    /// have the given value.
+    #[inline]
+    pub(crate) fn match_tag(self, tag: Tag) -> BitMask {
+        unsafe {
+            let cmp = neon::vceq_u8(self.0, neon::vdup_n_u8(tag.0));
+            BitMask(neon::vget_lane_u64(neon::vreinterpret_u64_u8(cmp), 0))
+        }
+    }
+
+    /// Returns a `BitMask` indicating all tags in the group which are
+    /// `EMPTY`.
+    #[inline]
+    pub(crate) fn match_empty(self) -> BitMask {
+        self.match_tag(Tag::EMPTY)
+    }
+
+    /// Returns a `BitMask` indicating all tags in the group which are
+    /// `EMPTY` or `DELETED`.
+    #[inline]
+    pub(crate) fn match_empty_or_deleted(self) -> BitMask {
+        unsafe {
+            let cmp = neon::vcltz_s8(neon::vreinterpret_s8_u8(self.0));
+            BitMask(neon::vget_lane_u64(neon::vreinterpret_u64_u8(cmp), 0))
+        }
+    }
+
+    /// Returns a `BitMask` indicating all tags in the group which are full.
+    #[inline]
+    pub(crate) fn match_full(self) -> BitMask {
+        unsafe {
+            let cmp = neon::vcgez_s8(neon::vreinterpret_s8_u8(self.0));
+            BitMask(neon::vget_lane_u64(neon::vreinterpret_u64_u8(cmp), 0))
+        }
+    }
+
+    /// Performs the following transformation on all tags in the group:
+    /// - `EMPTY => EMPTY`
+    /// - `DELETED => EMPTY`
+    /// - `FULL => DELETED`
+    #[inline]
+    pub(crate) fn convert_special_to_empty_and_full_to_deleted(self) -> Self {
+        // Map high_bit = 1 (EMPTY or DELETED) to 1111_1111
+        // and high_bit = 0 (FULL) to 1000_0000
+        //
+        // Here's this logic expanded to concrete values:
+        //   let special = 0 > tag = 1111_1111 (true) or 0000_0000 (false)
+        //   1111_1111 | 1000_0000 = 1111_1111
+        //   0000_0000 | 1000_0000 = 1000_0000
+        unsafe {
+            let special = neon::vcltz_s8(neon::vreinterpret_s8_u8(self.0));
+            Group(neon::vorr_u8(special, neon::vdup_n_u8(0x80)))
+        }
+    }
+}

vendor/hashbrown/src/control/group/sse2.rs

@@ -0,0 +1,146 @@
+use super::super::{BitMask, Tag};
+use core::mem;
+use core::num::NonZeroU16;
+
+#[cfg(target_arch = "x86")]
+use core::arch::x86;
+#[cfg(target_arch = "x86_64")]
+use core::arch::x86_64 as x86;
+
+pub(crate) type BitMaskWord = u16;
+pub(crate) type NonZeroBitMaskWord = NonZeroU16;
+pub(crate) const BITMASK_STRIDE: usize = 1;
+pub(crate) const BITMASK_MASK: BitMaskWord = 0xffff;
+pub(crate) const BITMASK_ITER_MASK: BitMaskWord = !0;
+
+/// Abstraction over a group of control tags which can be scanned in
+/// parallel.
+///
+/// This implementation uses a 128-bit SSE value.
+#[derive(Copy, Clone)]
+pub(crate) struct Group(x86::__m128i);
+
+// FIXME: https://github.com/rust-lang/rust-clippy/issues/3859
+#[allow(clippy::use_self)]
+impl Group {
+    /// Number of bytes in the group.
+    pub(crate) const WIDTH: usize = mem::size_of::<Self>();
+
+    /// Returns a full group of empty tags, suitable for use as the initial
+    /// value for an empty hash table.
+    ///
+    /// This is guaranteed to be aligned to the group size.
+    #[inline]
+    #[allow(clippy::items_after_statements)]
+    pub(crate) const fn static_empty() -> &'static [Tag; Group::WIDTH] {
+        #[repr(C)]
+        struct AlignedTags {
+            _align: [Group; 0],
+            tags: [Tag; Group::WIDTH],
+        }
+        const ALIGNED_TAGS: AlignedTags = AlignedTags {
+            _align: [],
+            tags: [Tag::EMPTY; Group::WIDTH],
+        };
+        &ALIGNED_TAGS.tags
+    }
+
+    /// Loads a group of tags starting at the given address.
+    #[inline]
+    #[allow(clippy::cast_ptr_alignment)] // unaligned load
+    pub(crate) unsafe fn load(ptr: *const Tag) -> Self {
+        Group(x86::_mm_loadu_si128(ptr.cast()))
+    }
+
+    /// Loads a group of tags starting at the given address, which must be
+    /// aligned to `mem::align_of::<Group>()`.
+    #[inline]
+    #[allow(clippy::cast_ptr_alignment)]
+    pub(crate) unsafe fn load_aligned(ptr: *const Tag) -> Self {
+        debug_assert_eq!(ptr.align_offset(mem::align_of::<Self>()), 0);
+        Group(x86::_mm_load_si128(ptr.cast()))
+    }
+
+    /// Stores the group of tags to the given address, which must be
+    /// aligned to `mem::align_of::<Group>()`.
+    #[inline]
+    #[allow(clippy::cast_ptr_alignment)]
+    pub(crate) unsafe fn store_aligned(self, ptr: *mut Tag) {
+        debug_assert_eq!(ptr.align_offset(mem::align_of::<Self>()), 0);
+        x86::_mm_store_si128(ptr.cast(), self.0);
+    }
+
+    /// Returns a `BitMask` indicating all tags in the group which have
+    /// the given value.
+    #[inline]
+    pub(crate) fn match_tag(self, tag: Tag) -> BitMask {
+        #[allow(
+            clippy::cast_possible_wrap, // tag.0: Tag as i8
+            // tag: i32 as u16
+            //   note: _mm_movemask_epi8 returns a 16-bit mask in a i32, the
+            //   upper 16-bits of the i32 are zeroed:
+            clippy::cast_sign_loss,
+            clippy::cast_possible_truncation
+        )]
+        unsafe {
+            let cmp = x86::_mm_cmpeq_epi8(self.0, x86::_mm_set1_epi8(tag.0 as i8));
+            BitMask(x86::_mm_movemask_epi8(cmp) as u16)
+        }
+    }
+
+    /// Returns a `BitMask` indicating all tags in the group which are
+    /// `EMPTY`.
+    #[inline]
+    pub(crate) fn match_empty(self) -> BitMask {
+        self.match_tag(Tag::EMPTY)
+    }
+
+    /// Returns a `BitMask` indicating all tags in the group which are
+    /// `EMPTY` or `DELETED`.
+    #[inline]
+    pub(crate) fn match_empty_or_deleted(self) -> BitMask {
+        #[allow(
+            // tag: i32 as u16
+            //   note: _mm_movemask_epi8 returns a 16-bit mask in a i32, the
+            //   upper 16-bits of the i32 are zeroed:
+            clippy::cast_sign_loss,
+            clippy::cast_possible_truncation
+        )]
+        unsafe {
+            // A tag is EMPTY or DELETED iff the high bit is set
+            BitMask(x86::_mm_movemask_epi8(self.0) as u16)
+        }
+    }
+
+    /// Returns a `BitMask` indicating all tags in the group which are full.
+    #[inline]
+    pub(crate) fn match_full(&self) -> BitMask {
+        self.match_empty_or_deleted().invert()
+    }
+
+    /// Performs the following transformation on all tags in the group:
+    /// - `EMPTY => EMPTY`
+    /// - `DELETED => EMPTY`
+    /// - `FULL => DELETED`
+    #[inline]
+    pub(crate) fn convert_special_to_empty_and_full_to_deleted(self) -> Self {
+        // Map high_bit = 1 (EMPTY or DELETED) to 1111_1111
+        // and high_bit = 0 (FULL) to 1000_0000
+        //
+        // Here's this logic expanded to concrete values:
+        //   let special = 0 > tag = 1111_1111 (true) or 0000_0000 (false)
+        //   1111_1111 | 1000_0000 = 1111_1111
+        //   0000_0000 | 1000_0000 = 1000_0000
+        #[allow(
+            clippy::cast_possible_wrap, // tag: Tag::DELETED.0 as i8
+        )]
+        unsafe {
+            let zero = x86::_mm_setzero_si128();
+            let special = x86::_mm_cmpgt_epi8(zero, self.0);
+            Group(x86::_mm_or_si128(
+                special,
+                x86::_mm_set1_epi8(Tag::DELETED.0 as i8),
+            ))
+        }
+    }
+}

vendor/hashbrown/src/control/mod.rs

@@ -0,0 +1,10 @@
+mod bitmask;
+mod group;
+mod tag;
+
+use self::bitmask::BitMask;
+pub(crate) use self::{
+    bitmask::BitMaskIter,
+    group::Group,
+    tag::{Tag, TagSliceExt},
+};

vendor/hashbrown/src/control/tag.rs

@@ -0,0 +1,83 @@
+use core::{fmt, mem};
+
+/// Single tag in a control group.
+#[derive(Copy, Clone, PartialEq, Eq)]
+#[repr(transparent)]
+pub(crate) struct Tag(pub(super) u8);
+impl Tag {
+    /// Control tag value for an empty bucket.
+    pub(crate) const EMPTY: Tag = Tag(0b1111_1111);
+
+    /// Control tag value for a deleted bucket.
+    pub(crate) const DELETED: Tag = Tag(0b1000_0000);
+
+    /// Checks whether a control tag represents a full bucket (top bit is clear).
+    #[inline]
+    pub(crate) const fn is_full(self) -> bool {
+        self.0 & 0x80 == 0
+    }
+
+    /// Checks whether a control tag represents a special value (top bit is set).
+    #[inline]
+    pub(crate) const fn is_special(self) -> bool {
+        self.0 & 0x80 != 0
+    }
+
+    /// Checks whether a special control value is EMPTY (just check 1 bit).
+    #[inline]
+    pub(crate) const fn special_is_empty(self) -> bool {
+        debug_assert!(self.is_special());
+        self.0 & 0x01 != 0
+    }
+
+    /// Creates a control tag representing a full bucket with the given hash.
+    #[inline]
+    #[allow(clippy::cast_possible_truncation)]
+    pub(crate) const fn full(hash: u64) -> Tag {
+        // Constant for function that grabs the top 7 bits of the hash.
+        const MIN_HASH_LEN: usize = if mem::size_of::<usize>() < mem::size_of::<u64>() {
+            mem::size_of::<usize>()
+        } else {
+            mem::size_of::<u64>()
+        };
+
+        // Grab the top 7 bits of the hash. While the hash is normally a full 64-bit
+        // value, some hash functions (such as FxHash) produce a usize result
+        // instead, which means that the top 32 bits are 0 on 32-bit platforms.
+        // So we use MIN_HASH_LEN constant to handle this.
+        let top7 = hash >> (MIN_HASH_LEN * 8 - 7);
+        Tag((top7 & 0x7f) as u8) // truncation
+    }
+}
+impl fmt::Debug for Tag {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        if self.is_special() {
+            if self.special_is_empty() {
+                f.pad("EMPTY")
+            } else {
+                f.pad("DELETED")
+            }
+        } else {
+            f.debug_tuple("full").field(&(self.0 & 0x7F)).finish()
+        }
+    }
+}
+
+/// Extension trait for slices of tags.
+pub(crate) trait TagSliceExt {
+    /// Fills the control with the given tag.
+    fn fill_tag(&mut self, tag: Tag);
+
+    /// Clears out the control.
+    #[inline]
+    fn fill_empty(&mut self) {
+        self.fill_tag(Tag::EMPTY)
+    }
+}
+impl TagSliceExt for [Tag] {
+    #[inline]
+    fn fill_tag(&mut self, tag: Tag) {
+        // SAFETY: We have access to the entire slice, so, we can write to the entire slice.
+        unsafe { self.as_mut_ptr().write_bytes(tag.0, self.len()) }
+    }
+}

vendor/hashbrown/src/external_trait_impls/mod.rs

@@ -0,0 +1,4 @@
+#[cfg(feature = "rayon")]
+pub(crate) mod rayon;
+#[cfg(feature = "serde")]
+mod serde;

vendor/hashbrown/src/external_trait_impls/rayon/helpers.rs

@@ -0,0 +1,13 @@
+use alloc::collections::LinkedList;
+use alloc::vec::Vec;
+
+use rayon::iter::{IntoParallelIterator, ParallelIterator};
+
+/// Helper for collecting parallel iterators to an intermediary
+#[allow(clippy::linkedlist)] // yes, we need linked list here for efficient appending!
+pub(super) fn collect<I: IntoParallelIterator>(iter: I) -> (LinkedList<Vec<I::Item>>, usize) {
+    let list = iter.into_par_iter().collect_vec_list();
+
+    let len = list.iter().map(Vec::len).sum();
+    (list, len)
+}

vendor/hashbrown/src/external_trait_impls/rayon/map.rs

@@ -0,0 +1,721 @@
+//! Rayon extensions for `HashMap`.
+
+use super::raw::{RawIntoParIter, RawParDrain, RawParIter};
+use crate::hash_map::HashMap;
+use crate::raw::{Allocator, Global};
+use core::fmt;
+use core::hash::{BuildHasher, Hash};
+use core::marker::PhantomData;
+use rayon::iter::plumbing::UnindexedConsumer;
+use rayon::iter::{FromParallelIterator, IntoParallelIterator, ParallelExtend, ParallelIterator};
+
+/// Parallel iterator over shared references to entries in a map.
+///
+/// This iterator is created by the [`par_iter`] method on [`HashMap`]
+/// (provided by the [`IntoParallelRefIterator`] trait).
+/// See its documentation for more.
+///
+/// [`par_iter`]: /hashbrown/struct.HashMap.html#method.par_iter
+/// [`HashMap`]: /hashbrown/struct.HashMap.html
+/// [`IntoParallelRefIterator`]: https://docs.rs/rayon/1.0/rayon/iter/trait.IntoParallelRefIterator.html
+pub struct ParIter<'a, K, V> {
+    inner: RawParIter<(K, V)>,
+    marker: PhantomData<(&'a K, &'a V)>,
+}
+
+impl<'a, K: Sync, V: Sync> ParallelIterator for ParIter<'a, K, V> {
+    type Item = (&'a K, &'a V);
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.inner
+            .map(|x| unsafe {
+                let r = x.as_ref();
+                (&r.0, &r.1)
+            })
+            .drive_unindexed(consumer)
+    }
+}
+
+impl<K, V> Clone for ParIter<'_, K, V> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn clone(&self) -> Self {
+        Self {
+            inner: self.inner.clone(),
+            marker: PhantomData,
+        }
+    }
+}
+
+impl<K: fmt::Debug + Eq + Hash, V: fmt::Debug> fmt::Debug for ParIter<'_, K, V> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let iter = unsafe { self.inner.iter() }.map(|x| unsafe {
+            let r = x.as_ref();
+            (&r.0, &r.1)
+        });
+        f.debug_list().entries(iter).finish()
+    }
+}
+
+/// Parallel iterator over shared references to keys in a map.
+///
+/// This iterator is created by the [`par_keys`] method on [`HashMap`].
+/// See its documentation for more.
+///
+/// [`par_keys`]: /hashbrown/struct.HashMap.html#method.par_keys
+/// [`HashMap`]: /hashbrown/struct.HashMap.html
+pub struct ParKeys<'a, K, V> {
+    inner: RawParIter<(K, V)>,
+    marker: PhantomData<(&'a K, &'a V)>,
+}
+
+impl<'a, K: Sync, V: Sync> ParallelIterator for ParKeys<'a, K, V> {
+    type Item = &'a K;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.inner
+            .map(|x| unsafe { &x.as_ref().0 })
+            .drive_unindexed(consumer)
+    }
+}
+
+impl<K, V> Clone for ParKeys<'_, K, V> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn clone(&self) -> Self {
+        Self {
+            inner: self.inner.clone(),
+            marker: PhantomData,
+        }
+    }
+}
+
+impl<K: fmt::Debug + Eq + Hash, V> fmt::Debug for ParKeys<'_, K, V> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let iter = unsafe { self.inner.iter() }.map(|x| unsafe { &x.as_ref().0 });
+        f.debug_list().entries(iter).finish()
+    }
+}
+
+/// Parallel iterator over shared references to values in a map.
+///
+/// This iterator is created by the [`par_values`] method on [`HashMap`].
+/// See its documentation for more.
+///
+/// [`par_values`]: /hashbrown/struct.HashMap.html#method.par_values
+/// [`HashMap`]: /hashbrown/struct.HashMap.html
+pub struct ParValues<'a, K, V> {
+    inner: RawParIter<(K, V)>,
+    marker: PhantomData<(&'a K, &'a V)>,
+}
+
+impl<'a, K: Sync, V: Sync> ParallelIterator for ParValues<'a, K, V> {
+    type Item = &'a V;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.inner
+            .map(|x| unsafe { &x.as_ref().1 })
+            .drive_unindexed(consumer)
+    }
+}
+
+impl<K, V> Clone for ParValues<'_, K, V> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn clone(&self) -> Self {
+        Self {
+            inner: self.inner.clone(),
+            marker: PhantomData,
+        }
+    }
+}
+
+impl<K: Eq + Hash, V: fmt::Debug> fmt::Debug for ParValues<'_, K, V> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let iter = unsafe { self.inner.iter() }.map(|x| unsafe { &x.as_ref().1 });
+        f.debug_list().entries(iter).finish()
+    }
+}
+
+/// Parallel iterator over mutable references to entries in a map.
+///
+/// This iterator is created by the [`par_iter_mut`] method on [`HashMap`]
+/// (provided by the [`IntoParallelRefMutIterator`] trait).
+/// See its documentation for more.
+///
+/// [`par_iter_mut`]: /hashbrown/struct.HashMap.html#method.par_iter_mut
+/// [`HashMap`]: /hashbrown/struct.HashMap.html
+/// [`IntoParallelRefMutIterator`]: https://docs.rs/rayon/1.0/rayon/iter/trait.IntoParallelRefMutIterator.html
+pub struct ParIterMut<'a, K, V> {
+    inner: RawParIter<(K, V)>,
+    marker: PhantomData<(&'a K, &'a mut V)>,
+}
+
+impl<'a, K: Sync, V: Send> ParallelIterator for ParIterMut<'a, K, V> {
+    type Item = (&'a K, &'a mut V);
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.inner
+            .map(|x| unsafe {
+                let r = x.as_mut();
+                (&r.0, &mut r.1)
+            })
+            .drive_unindexed(consumer)
+    }
+}
+
+impl<K: fmt::Debug + Eq + Hash, V: fmt::Debug> fmt::Debug for ParIterMut<'_, K, V> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        ParIter {
+            inner: self.inner.clone(),
+            marker: PhantomData,
+        }
+        .fmt(f)
+    }
+}
+
+/// Parallel iterator over mutable references to values in a map.
+///
+/// This iterator is created by the [`par_values_mut`] method on [`HashMap`].
+/// See its documentation for more.
+///
+/// [`par_values_mut`]: /hashbrown/struct.HashMap.html#method.par_values_mut
+/// [`HashMap`]: /hashbrown/struct.HashMap.html
+pub struct ParValuesMut<'a, K, V> {
+    inner: RawParIter<(K, V)>,
+    marker: PhantomData<(&'a K, &'a mut V)>,
+}
+
+impl<'a, K: Sync, V: Send> ParallelIterator for ParValuesMut<'a, K, V> {
+    type Item = &'a mut V;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.inner
+            .map(|x| unsafe { &mut x.as_mut().1 })
+            .drive_unindexed(consumer)
+    }
+}
+
+impl<K: Eq + Hash, V: fmt::Debug> fmt::Debug for ParValuesMut<'_, K, V> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        ParValues {
+            inner: self.inner.clone(),
+            marker: PhantomData,
+        }
+        .fmt(f)
+    }
+}
+
+/// Parallel iterator over entries of a consumed map.
+///
+/// This iterator is created by the [`into_par_iter`] method on [`HashMap`]
+/// (provided by the [`IntoParallelIterator`] trait).
+/// See its documentation for more.
+///
+/// [`into_par_iter`]: /hashbrown/struct.HashMap.html#method.into_par_iter
+/// [`HashMap`]: /hashbrown/struct.HashMap.html
+/// [`IntoParallelIterator`]: https://docs.rs/rayon/1.0/rayon/iter/trait.IntoParallelIterator.html
+pub struct IntoParIter<K, V, A: Allocator = Global> {
+    inner: RawIntoParIter<(K, V), A>,
+}
+
+impl<K: Send, V: Send, A: Allocator + Send> ParallelIterator for IntoParIter<K, V, A> {
+    type Item = (K, V);
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.inner.drive_unindexed(consumer)
+    }
+}
+
+impl<K: fmt::Debug + Eq + Hash, V: fmt::Debug, A: Allocator> fmt::Debug for IntoParIter<K, V, A> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        ParIter {
+            inner: unsafe { self.inner.par_iter() },
+            marker: PhantomData,
+        }
+        .fmt(f)
+    }
+}
+
+/// Parallel draining iterator over entries of a map.
+///
+/// This iterator is created by the [`par_drain`] method on [`HashMap`].
+/// See its documentation for more.
+///
+/// [`par_drain`]: /hashbrown/struct.HashMap.html#method.par_drain
+/// [`HashMap`]: /hashbrown/struct.HashMap.html
+pub struct ParDrain<'a, K, V, A: Allocator = Global> {
+    inner: RawParDrain<'a, (K, V), A>,
+}
+
+impl<K: Send, V: Send, A: Allocator + Sync> ParallelIterator for ParDrain<'_, K, V, A> {
+    type Item = (K, V);
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.inner.drive_unindexed(consumer)
+    }
+}
+
+impl<K: fmt::Debug + Eq + Hash, V: fmt::Debug, A: Allocator> fmt::Debug for ParDrain<'_, K, V, A> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        ParIter {
+            inner: unsafe { self.inner.par_iter() },
+            marker: PhantomData,
+        }
+        .fmt(f)
+    }
+}
+
+impl<K: Sync, V: Sync, S, A: Allocator> HashMap<K, V, S, A> {
+    /// Visits (potentially in parallel) immutably borrowed keys in an arbitrary order.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn par_keys(&self) -> ParKeys<'_, K, V> {
+        ParKeys {
+            inner: unsafe { self.table.par_iter() },
+            marker: PhantomData,
+        }
+    }
+
+    /// Visits (potentially in parallel) immutably borrowed values in an arbitrary order.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn par_values(&self) -> ParValues<'_, K, V> {
+        ParValues {
+            inner: unsafe { self.table.par_iter() },
+            marker: PhantomData,
+        }
+    }
+}
+
+impl<K: Send, V: Send, S, A: Allocator> HashMap<K, V, S, A> {
+    /// Visits (potentially in parallel) mutably borrowed values in an arbitrary order.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn par_values_mut(&mut self) -> ParValuesMut<'_, K, V> {
+        ParValuesMut {
+            inner: unsafe { self.table.par_iter() },
+            marker: PhantomData,
+        }
+    }
+
+    /// Consumes (potentially in parallel) all values in an arbitrary order,
+    /// while preserving the map's allocated memory for reuse.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn par_drain(&mut self) -> ParDrain<'_, K, V, A> {
+        ParDrain {
+            inner: self.table.par_drain(),
+        }
+    }
+}
+
+impl<K, V, S, A> HashMap<K, V, S, A>
+where
+    K: Eq + Hash + Sync,
+    V: PartialEq + Sync,
+    S: BuildHasher + Sync,
+    A: Allocator + Sync,
+{
+    /// Returns `true` if the map is equal to another,
+    /// i.e. both maps contain the same keys mapped to the same values.
+    ///
+    /// This method runs in a potentially parallel fashion.
+    pub fn par_eq(&self, other: &Self) -> bool {
+        self.len() == other.len()
+            && self
+                .into_par_iter()
+                .all(|(key, value)| other.get(key).map_or(false, |v| *value == *v))
+    }
+}
+
+impl<K: Send, V: Send, S, A: Allocator + Send> IntoParallelIterator for HashMap<K, V, S, A> {
+    type Item = (K, V);
+    type Iter = IntoParIter<K, V, A>;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn into_par_iter(self) -> Self::Iter {
+        IntoParIter {
+            inner: self.table.into_par_iter(),
+        }
+    }
+}
+
+impl<'a, K: Sync, V: Sync, S, A: Allocator> IntoParallelIterator for &'a HashMap<K, V, S, A> {
+    type Item = (&'a K, &'a V);
+    type Iter = ParIter<'a, K, V>;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn into_par_iter(self) -> Self::Iter {
+        ParIter {
+            inner: unsafe { self.table.par_iter() },
+            marker: PhantomData,
+        }
+    }
+}
+
+impl<'a, K: Sync, V: Send, S, A: Allocator> IntoParallelIterator for &'a mut HashMap<K, V, S, A> {
+    type Item = (&'a K, &'a mut V);
+    type Iter = ParIterMut<'a, K, V>;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn into_par_iter(self) -> Self::Iter {
+        ParIterMut {
+            inner: unsafe { self.table.par_iter() },
+            marker: PhantomData,
+        }
+    }
+}
+
+/// Collect (key, value) pairs from a parallel iterator into a
+/// hashmap. If multiple pairs correspond to the same key, then the
+/// ones produced earlier in the parallel iterator will be
+/// overwritten, just as with a sequential iterator.
+impl<K, V, S> FromParallelIterator<(K, V)> for HashMap<K, V, S, Global>
+where
+    K: Eq + Hash + Send,
+    V: Send,
+    S: BuildHasher + Default,
+{
+    fn from_par_iter<P>(par_iter: P) -> Self
+    where
+        P: IntoParallelIterator<Item = (K, V)>,
+    {
+        let mut map = HashMap::default();
+        map.par_extend(par_iter);
+        map
+    }
+}
+
+/// Extend a hash map with items from a parallel iterator.
+impl<K, V, S, A> ParallelExtend<(K, V)> for HashMap<K, V, S, A>
+where
+    K: Eq + Hash + Send,
+    V: Send,
+    S: BuildHasher,
+    A: Allocator,
+{
+    fn par_extend<I>(&mut self, par_iter: I)
+    where
+        I: IntoParallelIterator<Item = (K, V)>,
+    {
+        extend(self, par_iter);
+    }
+}
+
+/// Extend a hash map with copied items from a parallel iterator.
+impl<'a, K, V, S, A> ParallelExtend<(&'a K, &'a V)> for HashMap<K, V, S, A>
+where
+    K: Copy + Eq + Hash + Sync,
+    V: Copy + Sync,
+    S: BuildHasher,
+    A: Allocator,
+{
+    fn par_extend<I>(&mut self, par_iter: I)
+    where
+        I: IntoParallelIterator<Item = (&'a K, &'a V)>,
+    {
+        extend(self, par_iter);
+    }
+}
+
+// This is equal to the normal `HashMap` -- no custom advantage.
+fn extend<K, V, S, A, I>(map: &mut HashMap<K, V, S, A>, par_iter: I)
+where
+    K: Eq + Hash,
+    S: BuildHasher,
+    I: IntoParallelIterator,
+    A: Allocator,
+    HashMap<K, V, S, A>: Extend<I::Item>,
+{
+    let (list, len) = super::helpers::collect(par_iter);
+
+    // Keys may be already present or show multiple times in the iterator.
+    // Reserve the entire length if the map is empty.
+    // Otherwise reserve half the length (rounded up), so the map
+    // will only resize twice in the worst case.
+    let reserve = if map.is_empty() { len } else { (len + 1) / 2 };
+    map.reserve(reserve);
+    for vec in list {
+        map.extend(vec);
+    }
+}
+
+#[cfg(test)]
+mod test_par_map {
+    use alloc::vec::Vec;
+    use core::hash::{Hash, Hasher};
+    use core::sync::atomic::{AtomicUsize, Ordering};
+
+    use rayon::prelude::*;
+
+    use crate::hash_map::HashMap;
+
+    struct Droppable<'a> {
+        k: usize,
+        counter: &'a AtomicUsize,
+    }
+
+    impl Droppable<'_> {
+        fn new(k: usize, counter: &AtomicUsize) -> Droppable<'_> {
+            counter.fetch_add(1, Ordering::Relaxed);
+
+            Droppable { k, counter }
+        }
+    }
+
+    impl Drop for Droppable<'_> {
+        fn drop(&mut self) {
+            self.counter.fetch_sub(1, Ordering::Relaxed);
+        }
+    }
+
+    impl Clone for Droppable<'_> {
+        fn clone(&self) -> Self {
+            Droppable::new(self.k, self.counter)
+        }
+    }
+
+    impl Hash for Droppable<'_> {
+        fn hash<H>(&self, state: &mut H)
+        where
+            H: Hasher,
+        {
+            self.k.hash(state);
+        }
+    }
+
+    impl PartialEq for Droppable<'_> {
+        fn eq(&self, other: &Self) -> bool {
+            self.k == other.k
+        }
+    }
+
+    impl Eq for Droppable<'_> {}
+
+    #[test]
+    fn test_into_iter_drops() {
+        let key = AtomicUsize::new(0);
+        let value = AtomicUsize::new(0);
+
+        let hm = {
+            let mut hm = HashMap::new();
+
+            assert_eq!(key.load(Ordering::Relaxed), 0);
+            assert_eq!(value.load(Ordering::Relaxed), 0);
+
+            for i in 0..100 {
+                let d1 = Droppable::new(i, &key);
+                let d2 = Droppable::new(i + 100, &value);
+                hm.insert(d1, d2);
+            }
+
+            assert_eq!(key.load(Ordering::Relaxed), 100);
+            assert_eq!(value.load(Ordering::Relaxed), 100);
+
+            hm
+        };
+
+        // By the way, ensure that cloning doesn't screw up the dropping.
+        drop(hm.clone());
+
+        assert_eq!(key.load(Ordering::Relaxed), 100);
+        assert_eq!(value.load(Ordering::Relaxed), 100);
+
+        // Ensure that dropping the iterator does not leak anything.
+        drop(hm.clone().into_par_iter());
+
+        {
+            assert_eq!(key.load(Ordering::Relaxed), 100);
+            assert_eq!(value.load(Ordering::Relaxed), 100);
+
+            // retain only half
+            let _v: Vec<_> = hm.into_par_iter().filter(|(key, _)| key.k < 50).collect();
+
+            assert_eq!(key.load(Ordering::Relaxed), 50);
+            assert_eq!(value.load(Ordering::Relaxed), 50);
+        };
+
+        assert_eq!(key.load(Ordering::Relaxed), 0);
+        assert_eq!(value.load(Ordering::Relaxed), 0);
+    }
+
+    #[test]
+    fn test_drain_drops() {
+        let key = AtomicUsize::new(0);
+        let value = AtomicUsize::new(0);
+
+        let mut hm = {
+            let mut hm = HashMap::new();
+
+            assert_eq!(key.load(Ordering::Relaxed), 0);
+            assert_eq!(value.load(Ordering::Relaxed), 0);
+
+            for i in 0..100 {
+                let d1 = Droppable::new(i, &key);
+                let d2 = Droppable::new(i + 100, &value);
+                hm.insert(d1, d2);
+            }
+
+            assert_eq!(key.load(Ordering::Relaxed), 100);
+            assert_eq!(value.load(Ordering::Relaxed), 100);
+
+            hm
+        };
+
+        // By the way, ensure that cloning doesn't screw up the dropping.
+        drop(hm.clone());
+
+        assert_eq!(key.load(Ordering::Relaxed), 100);
+        assert_eq!(value.load(Ordering::Relaxed), 100);
+
+        // Ensure that dropping the drain iterator does not leak anything.
+        drop(hm.clone().par_drain());
+
+        {
+            assert_eq!(key.load(Ordering::Relaxed), 100);
+            assert_eq!(value.load(Ordering::Relaxed), 100);
+
+            // retain only half
+            let _v: Vec<_> = hm.drain().filter(|(key, _)| key.k < 50).collect();
+            assert!(hm.is_empty());
+
+            assert_eq!(key.load(Ordering::Relaxed), 50);
+            assert_eq!(value.load(Ordering::Relaxed), 50);
+        };
+
+        assert_eq!(key.load(Ordering::Relaxed), 0);
+        assert_eq!(value.load(Ordering::Relaxed), 0);
+    }
+
+    #[test]
+    fn test_empty_iter() {
+        let mut m: HashMap<isize, bool> = HashMap::new();
+        assert_eq!(m.par_drain().count(), 0);
+        assert_eq!(m.par_keys().count(), 0);
+        assert_eq!(m.par_values().count(), 0);
+        assert_eq!(m.par_values_mut().count(), 0);
+        assert_eq!(m.par_iter().count(), 0);
+        assert_eq!(m.par_iter_mut().count(), 0);
+        assert_eq!(m.len(), 0);
+        assert!(m.is_empty());
+        assert_eq!(m.into_par_iter().count(), 0);
+    }
+
+    #[test]
+    fn test_iterate() {
+        let mut m = HashMap::with_capacity(4);
+        for i in 0..32 {
+            assert!(m.insert(i, i * 2).is_none());
+        }
+        assert_eq!(m.len(), 32);
+
+        let observed = AtomicUsize::new(0);
+
+        m.par_iter().for_each(|(k, v)| {
+            assert_eq!(*v, *k * 2);
+            observed.fetch_or(1 << *k, Ordering::Relaxed);
+        });
+        assert_eq!(observed.into_inner(), 0xFFFF_FFFF);
+    }
+
+    #[test]
+    fn test_keys() {
+        let vec = vec![(1, 'a'), (2, 'b'), (3, 'c')];
+        let map: HashMap<_, _> = vec.into_par_iter().collect();
+        let keys: Vec<_> = map.par_keys().cloned().collect();
+        assert_eq!(keys.len(), 3);
+        assert!(keys.contains(&1));
+        assert!(keys.contains(&2));
+        assert!(keys.contains(&3));
+    }
+
+    #[test]
+    fn test_values() {
+        let vec = vec![(1, 'a'), (2, 'b'), (3, 'c')];
+        let map: HashMap<_, _> = vec.into_par_iter().collect();
+        let values: Vec<_> = map.par_values().cloned().collect();
+        assert_eq!(values.len(), 3);
+        assert!(values.contains(&'a'));
+        assert!(values.contains(&'b'));
+        assert!(values.contains(&'c'));
+    }
+
+    #[test]
+    fn test_values_mut() {
+        let vec = vec![(1, 1), (2, 2), (3, 3)];
+        let mut map: HashMap<_, _> = vec.into_par_iter().collect();
+        map.par_values_mut().for_each(|value| *value *= 2);
+        let values: Vec<_> = map.par_values().cloned().collect();
+        assert_eq!(values.len(), 3);
+        assert!(values.contains(&2));
+        assert!(values.contains(&4));
+        assert!(values.contains(&6));
+    }
+
+    #[test]
+    fn test_eq() {
+        let mut m1 = HashMap::new();
+        m1.insert(1, 2);
+        m1.insert(2, 3);
+        m1.insert(3, 4);
+
+        let mut m2 = HashMap::new();
+        m2.insert(1, 2);
+        m2.insert(2, 3);
+
+        assert!(!m1.par_eq(&m2));
+
+        m2.insert(3, 4);
+
+        assert!(m1.par_eq(&m2));
+    }
+
+    #[test]
+    fn test_from_iter() {
+        let xs = [(1, 1), (2, 2), (3, 3), (4, 4), (5, 5), (6, 6)];
+
+        let map: HashMap<_, _> = xs.par_iter().cloned().collect();
+
+        for &(k, v) in &xs {
+            assert_eq!(map.get(&k), Some(&v));
+        }
+    }
+
+    #[test]
+    fn test_extend_ref() {
+        let mut a = HashMap::new();
+        a.insert(1, "one");
+        let mut b = HashMap::new();
+        b.insert(2, "two");
+        b.insert(3, "three");
+
+        a.par_extend(&b);
+
+        assert_eq!(a.len(), 3);
+        assert_eq!(a[&1], "one");
+        assert_eq!(a[&2], "two");
+        assert_eq!(a[&3], "three");
+    }
+}

vendor/hashbrown/src/external_trait_impls/rayon/mod.rs

@@ -0,0 +1,5 @@
+mod helpers;
+pub(crate) mod map;
+pub(crate) mod raw;
+pub(crate) mod set;
+pub(crate) mod table;

vendor/hashbrown/src/external_trait_impls/rayon/raw.rs

@@ -0,0 +1,230 @@
+use crate::raw::Bucket;
+use crate::raw::{Allocator, Global, RawIter, RawIterRange, RawTable};
+use crate::scopeguard::guard;
+use core::marker::PhantomData;
+use core::mem;
+use core::ptr::NonNull;
+use rayon::iter::{
+    plumbing::{self, Folder, UnindexedConsumer, UnindexedProducer},
+    ParallelIterator,
+};
+
+/// Parallel iterator which returns a raw pointer to every full bucket in the table.
+pub struct RawParIter<T> {
+    iter: RawIterRange<T>,
+}
+
+impl<T> RawParIter<T> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub(super) unsafe fn iter(&self) -> RawIterRange<T> {
+        self.iter.clone()
+    }
+}
+
+impl<T> Clone for RawParIter<T> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn clone(&self) -> Self {
+        Self {
+            iter: self.iter.clone(),
+        }
+    }
+}
+
+impl<T> From<RawIter<T>> for RawParIter<T> {
+    fn from(it: RawIter<T>) -> Self {
+        RawParIter { iter: it.iter }
+    }
+}
+
+impl<T> ParallelIterator for RawParIter<T> {
+    type Item = Bucket<T>;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        let producer = ParIterProducer { iter: self.iter };
+        plumbing::bridge_unindexed(producer, consumer)
+    }
+}
+
+/// Producer which returns a `Bucket<T>` for every element.
+struct ParIterProducer<T> {
+    iter: RawIterRange<T>,
+}
+
+impl<T> UnindexedProducer for ParIterProducer<T> {
+    type Item = Bucket<T>;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn split(self) -> (Self, Option<Self>) {
+        let (left, right) = self.iter.split();
+        let left = ParIterProducer { iter: left };
+        let right = right.map(|right| ParIterProducer { iter: right });
+        (left, right)
+    }
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn fold_with<F>(self, folder: F) -> F
+    where
+        F: Folder<Self::Item>,
+    {
+        folder.consume_iter(self.iter)
+    }
+}
+
+/// Parallel iterator which consumes a table and returns elements.
+pub struct RawIntoParIter<T, A: Allocator = Global> {
+    table: RawTable<T, A>,
+}
+
+impl<T, A: Allocator> RawIntoParIter<T, A> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub(super) unsafe fn par_iter(&self) -> RawParIter<T> {
+        self.table.par_iter()
+    }
+}
+
+impl<T: Send, A: Allocator + Send> ParallelIterator for RawIntoParIter<T, A> {
+    type Item = T;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        let iter = unsafe { self.table.iter().iter };
+        let _guard = guard(self.table.into_allocation(), |alloc| {
+            if let Some((ptr, layout, ref alloc)) = *alloc {
+                unsafe {
+                    alloc.deallocate(ptr, layout);
+                }
+            }
+        });
+        let producer = ParDrainProducer { iter };
+        plumbing::bridge_unindexed(producer, consumer)
+    }
+}
+
+/// Parallel iterator which consumes elements without freeing the table storage.
+pub struct RawParDrain<'a, T, A: Allocator = Global> {
+    // We don't use a &'a mut RawTable<T> because we want RawParDrain to be
+    // covariant over T.
+    table: NonNull<RawTable<T, A>>,
+    marker: PhantomData<&'a RawTable<T, A>>,
+}
+
+unsafe impl<T: Send, A: Allocator> Send for RawParDrain<'_, T, A> {}
+
+impl<T, A: Allocator> RawParDrain<'_, T, A> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub(super) unsafe fn par_iter(&self) -> RawParIter<T> {
+        self.table.as_ref().par_iter()
+    }
+}
+
+impl<T: Send, A: Allocator> ParallelIterator for RawParDrain<'_, T, A> {
+    type Item = T;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        let _guard = guard(self.table, |table| unsafe {
+            table.as_mut().clear_no_drop();
+        });
+        let iter = unsafe { self.table.as_ref().iter().iter };
+        mem::forget(self);
+        let producer = ParDrainProducer { iter };
+        plumbing::bridge_unindexed(producer, consumer)
+    }
+}
+
+impl<T, A: Allocator> Drop for RawParDrain<'_, T, A> {
+    fn drop(&mut self) {
+        // If drive_unindexed is not called then simply clear the table.
+        unsafe {
+            self.table.as_mut().clear();
+        }
+    }
+}
+
+/// Producer which will consume all elements in the range, even if it is dropped
+/// halfway through.
+struct ParDrainProducer<T> {
+    iter: RawIterRange<T>,
+}
+
+impl<T: Send> UnindexedProducer for ParDrainProducer<T> {
+    type Item = T;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn split(self) -> (Self, Option<Self>) {
+        let (left, right) = self.iter.clone().split();
+        mem::forget(self);
+        let left = ParDrainProducer { iter: left };
+        let right = right.map(|right| ParDrainProducer { iter: right });
+        (left, right)
+    }
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn fold_with<F>(mut self, mut folder: F) -> F
+    where
+        F: Folder<Self::Item>,
+    {
+        // Make sure to modify the iterator in-place so that any remaining
+        // elements are processed in our Drop impl.
+        for item in &mut self.iter {
+            folder = folder.consume(unsafe { item.read() });
+            if folder.full() {
+                return folder;
+            }
+        }
+
+        // If we processed all elements then we don't need to run the drop.
+        mem::forget(self);
+        folder
+    }
+}
+
+impl<T> Drop for ParDrainProducer<T> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drop(&mut self) {
+        // Drop all remaining elements
+        if mem::needs_drop::<T>() {
+            for item in &mut self.iter {
+                unsafe {
+                    item.drop();
+                }
+            }
+        }
+    }
+}
+
+impl<T, A: Allocator> RawTable<T, A> {
+    /// Returns a parallel iterator over the elements in a `RawTable`.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub unsafe fn par_iter(&self) -> RawParIter<T> {
+        RawParIter {
+            iter: self.iter().iter,
+        }
+    }
+
+    /// Returns a parallel iterator over the elements in a `RawTable`.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn into_par_iter(self) -> RawIntoParIter<T, A> {
+        RawIntoParIter { table: self }
+    }
+
+    /// Returns a parallel iterator which consumes all elements of a `RawTable`
+    /// without freeing its memory allocation.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn par_drain(&mut self) -> RawParDrain<'_, T, A> {
+        RawParDrain {
+            table: NonNull::from(self),
+            marker: PhantomData,
+        }
+    }
+}

vendor/hashbrown/src/external_trait_impls/rayon/set.rs

@@ -0,0 +1,659 @@
+//! Rayon extensions for `HashSet`.
+
+use super::map;
+use crate::hash_set::HashSet;
+use crate::raw::{Allocator, Global};
+use core::hash::{BuildHasher, Hash};
+use rayon::iter::plumbing::UnindexedConsumer;
+use rayon::iter::{FromParallelIterator, IntoParallelIterator, ParallelExtend, ParallelIterator};
+
+/// Parallel iterator over elements of a consumed set.
+///
+/// This iterator is created by the [`into_par_iter`] method on [`HashSet`]
+/// (provided by the [`IntoParallelIterator`] trait).
+/// See its documentation for more.
+///
+/// [`into_par_iter`]: /hashbrown/struct.HashSet.html#method.into_par_iter
+/// [`HashSet`]: /hashbrown/struct.HashSet.html
+/// [`IntoParallelIterator`]: https://docs.rs/rayon/1.0/rayon/iter/trait.IntoParallelIterator.html
+pub struct IntoParIter<T, A: Allocator = Global> {
+    inner: map::IntoParIter<T, (), A>,
+}
+
+impl<T: Send, A: Allocator + Send> ParallelIterator for IntoParIter<T, A> {
+    type Item = T;
+
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.inner.map(|(k, _)| k).drive_unindexed(consumer)
+    }
+}
+
+/// Parallel draining iterator over entries of a set.
+///
+/// This iterator is created by the [`par_drain`] method on [`HashSet`].
+/// See its documentation for more.
+///
+/// [`par_drain`]: /hashbrown/struct.HashSet.html#method.par_drain
+/// [`HashSet`]: /hashbrown/struct.HashSet.html
+pub struct ParDrain<'a, T, A: Allocator = Global> {
+    inner: map::ParDrain<'a, T, (), A>,
+}
+
+impl<T: Send, A: Allocator + Send + Sync> ParallelIterator for ParDrain<'_, T, A> {
+    type Item = T;
+
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.inner.map(|(k, _)| k).drive_unindexed(consumer)
+    }
+}
+
+/// Parallel iterator over shared references to elements in a set.
+///
+/// This iterator is created by the [`par_iter`] method on [`HashSet`]
+/// (provided by the [`IntoParallelRefIterator`] trait).
+/// See its documentation for more.
+///
+/// [`par_iter`]: /hashbrown/struct.HashSet.html#method.par_iter
+/// [`HashSet`]: /hashbrown/struct.HashSet.html
+/// [`IntoParallelRefIterator`]: https://docs.rs/rayon/1.0/rayon/iter/trait.IntoParallelRefIterator.html
+pub struct ParIter<'a, T> {
+    inner: map::ParKeys<'a, T, ()>,
+}
+
+impl<'a, T: Sync> ParallelIterator for ParIter<'a, T> {
+    type Item = &'a T;
+
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.inner.drive_unindexed(consumer)
+    }
+}
+
+/// Parallel iterator over shared references to elements in the difference of
+/// sets.
+///
+/// This iterator is created by the [`par_difference`] method on [`HashSet`].
+/// See its documentation for more.
+///
+/// [`par_difference`]: /hashbrown/struct.HashSet.html#method.par_difference
+/// [`HashSet`]: /hashbrown/struct.HashSet.html
+pub struct ParDifference<'a, T, S, A: Allocator = Global> {
+    a: &'a HashSet<T, S, A>,
+    b: &'a HashSet<T, S, A>,
+}
+
+impl<'a, T, S, A> ParallelIterator for ParDifference<'a, T, S, A>
+where
+    T: Eq + Hash + Sync,
+    S: BuildHasher + Sync,
+    A: Allocator + Sync,
+{
+    type Item = &'a T;
+
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.a
+            .into_par_iter()
+            .filter(|&x| !self.b.contains(x))
+            .drive_unindexed(consumer)
+    }
+}
+
+/// Parallel iterator over shared references to elements in the symmetric
+/// difference of sets.
+///
+/// This iterator is created by the [`par_symmetric_difference`] method on
+/// [`HashSet`].
+/// See its documentation for more.
+///
+/// [`par_symmetric_difference`]: /hashbrown/struct.HashSet.html#method.par_symmetric_difference
+/// [`HashSet`]: /hashbrown/struct.HashSet.html
+pub struct ParSymmetricDifference<'a, T, S, A: Allocator = Global> {
+    a: &'a HashSet<T, S, A>,
+    b: &'a HashSet<T, S, A>,
+}
+
+impl<'a, T, S, A> ParallelIterator for ParSymmetricDifference<'a, T, S, A>
+where
+    T: Eq + Hash + Sync,
+    S: BuildHasher + Sync,
+    A: Allocator + Sync,
+{
+    type Item = &'a T;
+
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.a
+            .par_difference(self.b)
+            .chain(self.b.par_difference(self.a))
+            .drive_unindexed(consumer)
+    }
+}
+
+/// Parallel iterator over shared references to elements in the intersection of
+/// sets.
+///
+/// This iterator is created by the [`par_intersection`] method on [`HashSet`].
+/// See its documentation for more.
+///
+/// [`par_intersection`]: /hashbrown/struct.HashSet.html#method.par_intersection
+/// [`HashSet`]: /hashbrown/struct.HashSet.html
+pub struct ParIntersection<'a, T, S, A: Allocator = Global> {
+    a: &'a HashSet<T, S, A>,
+    b: &'a HashSet<T, S, A>,
+}
+
+impl<'a, T, S, A> ParallelIterator for ParIntersection<'a, T, S, A>
+where
+    T: Eq + Hash + Sync,
+    S: BuildHasher + Sync,
+    A: Allocator + Sync,
+{
+    type Item = &'a T;
+
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.a
+            .into_par_iter()
+            .filter(|&x| self.b.contains(x))
+            .drive_unindexed(consumer)
+    }
+}
+
+/// Parallel iterator over shared references to elements in the union of sets.
+///
+/// This iterator is created by the [`par_union`] method on [`HashSet`].
+/// See its documentation for more.
+///
+/// [`par_union`]: /hashbrown/struct.HashSet.html#method.par_union
+/// [`HashSet`]: /hashbrown/struct.HashSet.html
+pub struct ParUnion<'a, T, S, A: Allocator = Global> {
+    a: &'a HashSet<T, S, A>,
+    b: &'a HashSet<T, S, A>,
+}
+
+impl<'a, T, S, A> ParallelIterator for ParUnion<'a, T, S, A>
+where
+    T: Eq + Hash + Sync,
+    S: BuildHasher + Sync,
+    A: Allocator + Sync,
+{
+    type Item = &'a T;
+
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        // We'll iterate one set in full, and only the remaining difference from the other.
+        // Use the smaller set for the difference in order to reduce hash lookups.
+        let (smaller, larger) = if self.a.len() <= self.b.len() {
+            (self.a, self.b)
+        } else {
+            (self.b, self.a)
+        };
+        larger
+            .into_par_iter()
+            .chain(smaller.par_difference(larger))
+            .drive_unindexed(consumer)
+    }
+}
+
+impl<T, S, A> HashSet<T, S, A>
+where
+    T: Eq + Hash + Sync,
+    S: BuildHasher + Sync,
+    A: Allocator + Sync,
+{
+    /// Visits (potentially in parallel) the values representing the union,
+    /// i.e. all the values in `self` or `other`, without duplicates.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn par_union<'a>(&'a self, other: &'a Self) -> ParUnion<'a, T, S, A> {
+        ParUnion { a: self, b: other }
+    }
+
+    /// Visits (potentially in parallel) the values representing the difference,
+    /// i.e. the values that are in `self` but not in `other`.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn par_difference<'a>(&'a self, other: &'a Self) -> ParDifference<'a, T, S, A> {
+        ParDifference { a: self, b: other }
+    }
+
+    /// Visits (potentially in parallel) the values representing the symmetric
+    /// difference, i.e. the values that are in `self` or in `other` but not in both.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn par_symmetric_difference<'a>(
+        &'a self,
+        other: &'a Self,
+    ) -> ParSymmetricDifference<'a, T, S, A> {
+        ParSymmetricDifference { a: self, b: other }
+    }
+
+    /// Visits (potentially in parallel) the values representing the
+    /// intersection, i.e. the values that are both in `self` and `other`.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn par_intersection<'a>(&'a self, other: &'a Self) -> ParIntersection<'a, T, S, A> {
+        ParIntersection { a: self, b: other }
+    }
+
+    /// Returns `true` if `self` has no elements in common with `other`.
+    /// This is equivalent to checking for an empty intersection.
+    ///
+    /// This method runs in a potentially parallel fashion.
+    pub fn par_is_disjoint(&self, other: &Self) -> bool {
+        self.into_par_iter().all(|x| !other.contains(x))
+    }
+
+    /// Returns `true` if the set is a subset of another,
+    /// i.e. `other` contains at least all the values in `self`.
+    ///
+    /// This method runs in a potentially parallel fashion.
+    pub fn par_is_subset(&self, other: &Self) -> bool {
+        if self.len() <= other.len() {
+            self.into_par_iter().all(|x| other.contains(x))
+        } else {
+            false
+        }
+    }
+
+    /// Returns `true` if the set is a superset of another,
+    /// i.e. `self` contains at least all the values in `other`.
+    ///
+    /// This method runs in a potentially parallel fashion.
+    pub fn par_is_superset(&self, other: &Self) -> bool {
+        other.par_is_subset(self)
+    }
+
+    /// Returns `true` if the set is equal to another,
+    /// i.e. both sets contain the same values.
+    ///
+    /// This method runs in a potentially parallel fashion.
+    pub fn par_eq(&self, other: &Self) -> bool {
+        self.len() == other.len() && self.par_is_subset(other)
+    }
+}
+
+impl<T, S, A> HashSet<T, S, A>
+where
+    T: Eq + Hash + Send,
+    A: Allocator + Send,
+{
+    /// Consumes (potentially in parallel) all values in an arbitrary order,
+    /// while preserving the set's allocated memory for reuse.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn par_drain(&mut self) -> ParDrain<'_, T, A> {
+        ParDrain {
+            inner: self.map.par_drain(),
+        }
+    }
+}
+
+impl<T: Send, S, A: Allocator + Send> IntoParallelIterator for HashSet<T, S, A> {
+    type Item = T;
+    type Iter = IntoParIter<T, A>;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn into_par_iter(self) -> Self::Iter {
+        IntoParIter {
+            inner: self.map.into_par_iter(),
+        }
+    }
+}
+
+impl<'a, T: Sync, S, A: Allocator> IntoParallelIterator for &'a HashSet<T, S, A> {
+    type Item = &'a T;
+    type Iter = ParIter<'a, T>;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn into_par_iter(self) -> Self::Iter {
+        ParIter {
+            inner: self.map.par_keys(),
+        }
+    }
+}
+
+/// Collect values from a parallel iterator into a hashset.
+impl<T, S> FromParallelIterator<T> for HashSet<T, S, Global>
+where
+    T: Eq + Hash + Send,
+    S: BuildHasher + Default,
+{
+    fn from_par_iter<P>(par_iter: P) -> Self
+    where
+        P: IntoParallelIterator<Item = T>,
+    {
+        let mut set = HashSet::default();
+        set.par_extend(par_iter);
+        set
+    }
+}
+
+/// Extend a hash set with items from a parallel iterator.
+impl<T, S> ParallelExtend<T> for HashSet<T, S, Global>
+where
+    T: Eq + Hash + Send,
+    S: BuildHasher,
+{
+    fn par_extend<I>(&mut self, par_iter: I)
+    where
+        I: IntoParallelIterator<Item = T>,
+    {
+        extend(self, par_iter);
+    }
+}
+
+/// Extend a hash set with copied items from a parallel iterator.
+impl<'a, T, S> ParallelExtend<&'a T> for HashSet<T, S, Global>
+where
+    T: 'a + Copy + Eq + Hash + Sync,
+    S: BuildHasher,
+{
+    fn par_extend<I>(&mut self, par_iter: I)
+    where
+        I: IntoParallelIterator<Item = &'a T>,
+    {
+        extend(self, par_iter);
+    }
+}
+
+// This is equal to the normal `HashSet` -- no custom advantage.
+fn extend<T, S, I, A>(set: &mut HashSet<T, S, A>, par_iter: I)
+where
+    T: Eq + Hash,
+    S: BuildHasher,
+    A: Allocator,
+    I: IntoParallelIterator,
+    HashSet<T, S, A>: Extend<I::Item>,
+{
+    let (list, len) = super::helpers::collect(par_iter);
+
+    // Values may be already present or show multiple times in the iterator.
+    // Reserve the entire length if the set is empty.
+    // Otherwise reserve half the length (rounded up), so the set
+    // will only resize twice in the worst case.
+    let reserve = if set.is_empty() { len } else { (len + 1) / 2 };
+    set.reserve(reserve);
+    for vec in list {
+        set.extend(vec);
+    }
+}
+
+#[cfg(test)]
+mod test_par_set {
+    use alloc::vec::Vec;
+    use core::sync::atomic::{AtomicUsize, Ordering};
+
+    use rayon::prelude::*;
+
+    use crate::hash_set::HashSet;
+
+    #[test]
+    fn test_disjoint() {
+        let mut xs = HashSet::new();
+        let mut ys = HashSet::new();
+        assert!(xs.par_is_disjoint(&ys));
+        assert!(ys.par_is_disjoint(&xs));
+        assert!(xs.insert(5));
+        assert!(ys.insert(11));
+        assert!(xs.par_is_disjoint(&ys));
+        assert!(ys.par_is_disjoint(&xs));
+        assert!(xs.insert(7));
+        assert!(xs.insert(19));
+        assert!(xs.insert(4));
+        assert!(ys.insert(2));
+        assert!(ys.insert(-11));
+        assert!(xs.par_is_disjoint(&ys));
+        assert!(ys.par_is_disjoint(&xs));
+        assert!(ys.insert(7));
+        assert!(!xs.par_is_disjoint(&ys));
+        assert!(!ys.par_is_disjoint(&xs));
+    }
+
+    #[test]
+    fn test_subset_and_superset() {
+        let mut a = HashSet::new();
+        assert!(a.insert(0));
+        assert!(a.insert(5));
+        assert!(a.insert(11));
+        assert!(a.insert(7));
+
+        let mut b = HashSet::new();
+        assert!(b.insert(0));
+        assert!(b.insert(7));
+        assert!(b.insert(19));
+        assert!(b.insert(250));
+        assert!(b.insert(11));
+        assert!(b.insert(200));
+
+        assert!(!a.par_is_subset(&b));
+        assert!(!a.par_is_superset(&b));
+        assert!(!b.par_is_subset(&a));
+        assert!(!b.par_is_superset(&a));
+
+        assert!(b.insert(5));
+
+        assert!(a.par_is_subset(&b));
+        assert!(!a.par_is_superset(&b));
+        assert!(!b.par_is_subset(&a));
+        assert!(b.par_is_superset(&a));
+    }
+
+    #[test]
+    fn test_iterate() {
+        let mut a = HashSet::new();
+        for i in 0..32 {
+            assert!(a.insert(i));
+        }
+        let observed = AtomicUsize::new(0);
+        a.par_iter().for_each(|k| {
+            observed.fetch_or(1 << *k, Ordering::Relaxed);
+        });
+        assert_eq!(observed.into_inner(), 0xFFFF_FFFF);
+    }
+
+    #[test]
+    fn test_intersection() {
+        let mut a = HashSet::new();
+        let mut b = HashSet::new();
+
+        assert!(a.insert(11));
+        assert!(a.insert(1));
+        assert!(a.insert(3));
+        assert!(a.insert(77));
+        assert!(a.insert(103));
+        assert!(a.insert(5));
+        assert!(a.insert(-5));
+
+        assert!(b.insert(2));
+        assert!(b.insert(11));
+        assert!(b.insert(77));
+        assert!(b.insert(-9));
+        assert!(b.insert(-42));
+        assert!(b.insert(5));
+        assert!(b.insert(3));
+
+        let expected = [3, 5, 11, 77];
+        let i = a
+            .par_intersection(&b)
+            .map(|x| {
+                assert!(expected.contains(x));
+                1
+            })
+            .sum::<usize>();
+        assert_eq!(i, expected.len());
+    }
+
+    #[test]
+    fn test_difference() {
+        let mut a = HashSet::new();
+        let mut b = HashSet::new();
+
+        assert!(a.insert(1));
+        assert!(a.insert(3));
+        assert!(a.insert(5));
+        assert!(a.insert(9));
+        assert!(a.insert(11));
+
+        assert!(b.insert(3));
+        assert!(b.insert(9));
+
+        let expected = [1, 5, 11];
+        let i = a
+            .par_difference(&b)
+            .map(|x| {
+                assert!(expected.contains(x));
+                1
+            })
+            .sum::<usize>();
+        assert_eq!(i, expected.len());
+    }
+
+    #[test]
+    fn test_symmetric_difference() {
+        let mut a = HashSet::new();
+        let mut b = HashSet::new();
+
+        assert!(a.insert(1));
+        assert!(a.insert(3));
+        assert!(a.insert(5));
+        assert!(a.insert(9));
+        assert!(a.insert(11));
+
+        assert!(b.insert(-2));
+        assert!(b.insert(3));
+        assert!(b.insert(9));
+        assert!(b.insert(14));
+        assert!(b.insert(22));
+
+        let expected = [-2, 1, 5, 11, 14, 22];
+        let i = a
+            .par_symmetric_difference(&b)
+            .map(|x| {
+                assert!(expected.contains(x));
+                1
+            })
+            .sum::<usize>();
+        assert_eq!(i, expected.len());
+    }
+
+    #[test]
+    fn test_union() {
+        let mut a = HashSet::new();
+        let mut b = HashSet::new();
+
+        assert!(a.insert(1));
+        assert!(a.insert(3));
+        assert!(a.insert(5));
+        assert!(a.insert(9));
+        assert!(a.insert(11));
+        assert!(a.insert(16));
+        assert!(a.insert(19));
+        assert!(a.insert(24));
+
+        assert!(b.insert(-2));
+        assert!(b.insert(1));
+        assert!(b.insert(5));
+        assert!(b.insert(9));
+        assert!(b.insert(13));
+        assert!(b.insert(19));
+
+        let expected = [-2, 1, 3, 5, 9, 11, 13, 16, 19, 24];
+        let i = a
+            .par_union(&b)
+            .map(|x| {
+                assert!(expected.contains(x));
+                1
+            })
+            .sum::<usize>();
+        assert_eq!(i, expected.len());
+    }
+
+    #[test]
+    fn test_from_iter() {
+        let xs = [1, 2, 3, 4, 5, 6, 7, 8, 9];
+
+        let set: HashSet<_> = xs.par_iter().cloned().collect();
+
+        for x in &xs {
+            assert!(set.contains(x));
+        }
+    }
+
+    #[test]
+    fn test_move_iter() {
+        let hs = {
+            let mut hs = HashSet::new();
+
+            hs.insert('a');
+            hs.insert('b');
+
+            hs
+        };
+
+        let v = hs.into_par_iter().collect::<Vec<char>>();
+        assert!(v == ['a', 'b'] || v == ['b', 'a']);
+    }
+
+    #[test]
+    fn test_eq() {
+        // These constants once happened to expose a bug in insert().
+        // I'm keeping them around to prevent a regression.
+        let mut s1 = HashSet::new();
+
+        s1.insert(1);
+        s1.insert(2);
+        s1.insert(3);
+
+        let mut s2 = HashSet::new();
+
+        s2.insert(1);
+        s2.insert(2);
+
+        assert!(!s1.par_eq(&s2));
+
+        s2.insert(3);
+
+        assert!(s1.par_eq(&s2));
+    }
+
+    #[test]
+    fn test_extend_ref() {
+        let mut a = HashSet::new();
+        a.insert(1);
+
+        a.par_extend(&[2, 3, 4][..]);
+
+        assert_eq!(a.len(), 4);
+        assert!(a.contains(&1));
+        assert!(a.contains(&2));
+        assert!(a.contains(&3));
+        assert!(a.contains(&4));
+
+        let mut b = HashSet::new();
+        b.insert(5);
+        b.insert(6);
+
+        a.par_extend(&b);
+
+        assert_eq!(a.len(), 6);
+        assert!(a.contains(&1));
+        assert!(a.contains(&2));
+        assert!(a.contains(&3));
+        assert!(a.contains(&4));
+        assert!(a.contains(&5));
+        assert!(a.contains(&6));
+    }
+}

vendor/hashbrown/src/external_trait_impls/rayon/table.rs

@@ -0,0 +1,249 @@
+//! Rayon extensions for `HashTable`.
+
+use super::raw::{RawIntoParIter, RawParDrain, RawParIter};
+use crate::hash_table::HashTable;
+use crate::raw::{Allocator, Global};
+use core::fmt;
+use core::marker::PhantomData;
+use rayon::iter::plumbing::UnindexedConsumer;
+use rayon::iter::{IntoParallelIterator, ParallelIterator};
+
+/// Parallel iterator over shared references to entries in a map.
+///
+/// This iterator is created by the [`par_iter`] method on [`HashTable`]
+/// (provided by the [`IntoParallelRefIterator`] trait).
+/// See its documentation for more.
+///
+/// [`par_iter`]: /hashbrown/struct.HashTable.html#method.par_iter
+/// [`HashTable`]: /hashbrown/struct.HashTable.html
+/// [`IntoParallelRefIterator`]: https://docs.rs/rayon/1.0/rayon/iter/trait.IntoParallelRefIterator.html
+pub struct ParIter<'a, T> {
+    inner: RawParIter<T>,
+    marker: PhantomData<&'a T>,
+}
+
+impl<'a, T: Sync> ParallelIterator for ParIter<'a, T> {
+    type Item = &'a T;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.inner
+            .map(|x| unsafe { x.as_ref() })
+            .drive_unindexed(consumer)
+    }
+}
+
+impl<T> Clone for ParIter<'_, T> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn clone(&self) -> Self {
+        Self {
+            inner: self.inner.clone(),
+            marker: PhantomData,
+        }
+    }
+}
+
+impl<T: fmt::Debug> fmt::Debug for ParIter<'_, T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let iter = unsafe { self.inner.iter() }.map(|x| unsafe { x.as_ref() });
+        f.debug_list().entries(iter).finish()
+    }
+}
+
+/// Parallel iterator over mutable references to entries in a map.
+///
+/// This iterator is created by the [`par_iter_mut`] method on [`HashTable`]
+/// (provided by the [`IntoParallelRefMutIterator`] trait).
+/// See its documentation for more.
+///
+/// [`par_iter_mut`]: /hashbrown/struct.HashTable.html#method.par_iter_mut
+/// [`HashTable`]: /hashbrown/struct.HashTable.html
+/// [`IntoParallelRefMutIterator`]: https://docs.rs/rayon/1.0/rayon/iter/trait.IntoParallelRefMutIterator.html
+pub struct ParIterMut<'a, T> {
+    inner: RawParIter<T>,
+    marker: PhantomData<&'a mut T>,
+}
+
+impl<'a, T: Send> ParallelIterator for ParIterMut<'a, T> {
+    type Item = &'a mut T;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.inner
+            .map(|x| unsafe { x.as_mut() })
+            .drive_unindexed(consumer)
+    }
+}
+
+impl<T: fmt::Debug> fmt::Debug for ParIterMut<'_, T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        ParIter {
+            inner: self.inner.clone(),
+            marker: PhantomData,
+        }
+        .fmt(f)
+    }
+}
+
+/// Parallel iterator over entries of a consumed map.
+///
+/// This iterator is created by the [`into_par_iter`] method on [`HashTable`]
+/// (provided by the [`IntoParallelIterator`] trait).
+/// See its documentation for more.
+///
+/// [`into_par_iter`]: /hashbrown/struct.HashTable.html#method.into_par_iter
+/// [`HashTable`]: /hashbrown/struct.HashTable.html
+/// [`IntoParallelIterator`]: https://docs.rs/rayon/1.0/rayon/iter/trait.IntoParallelIterator.html
+pub struct IntoParIter<T, A: Allocator = Global> {
+    inner: RawIntoParIter<T, A>,
+}
+
+impl<T: Send, A: Allocator + Send> ParallelIterator for IntoParIter<T, A> {
+    type Item = T;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.inner.drive_unindexed(consumer)
+    }
+}
+
+impl<T: fmt::Debug, A: Allocator> fmt::Debug for IntoParIter<T, A> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        ParIter {
+            inner: unsafe { self.inner.par_iter() },
+            marker: PhantomData,
+        }
+        .fmt(f)
+    }
+}
+
+/// Parallel draining iterator over entries of a map.
+///
+/// This iterator is created by the [`par_drain`] method on [`HashTable`].
+/// See its documentation for more.
+///
+/// [`par_drain`]: /hashbrown/struct.HashTable.html#method.par_drain
+/// [`HashTable`]: /hashbrown/struct.HashTable.html
+pub struct ParDrain<'a, T, A: Allocator = Global> {
+    inner: RawParDrain<'a, T, A>,
+}
+
+impl<T: Send, A: Allocator + Sync> ParallelIterator for ParDrain<'_, T, A> {
+    type Item = T;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.inner.drive_unindexed(consumer)
+    }
+}
+
+impl<T: fmt::Debug, A: Allocator> fmt::Debug for ParDrain<'_, T, A> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        ParIter {
+            inner: unsafe { self.inner.par_iter() },
+            marker: PhantomData,
+        }
+        .fmt(f)
+    }
+}
+
+impl<T: Send, A: Allocator> HashTable<T, A> {
+    /// Consumes (potentially in parallel) all values in an arbitrary order,
+    /// while preserving the map's allocated memory for reuse.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn par_drain(&mut self) -> ParDrain<'_, T, A> {
+        ParDrain {
+            inner: self.raw.par_drain(),
+        }
+    }
+}
+
+impl<T: Send, A: Allocator + Send> IntoParallelIterator for HashTable<T, A> {
+    type Item = T;
+    type Iter = IntoParIter<T, A>;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn into_par_iter(self) -> Self::Iter {
+        IntoParIter {
+            inner: self.raw.into_par_iter(),
+        }
+    }
+}
+
+impl<'a, T: Sync, A: Allocator> IntoParallelIterator for &'a HashTable<T, A> {
+    type Item = &'a T;
+    type Iter = ParIter<'a, T>;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn into_par_iter(self) -> Self::Iter {
+        ParIter {
+            inner: unsafe { self.raw.par_iter() },
+            marker: PhantomData,
+        }
+    }
+}
+
+impl<'a, T: Send, A: Allocator> IntoParallelIterator for &'a mut HashTable<T, A> {
+    type Item = &'a mut T;
+    type Iter = ParIterMut<'a, T>;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn into_par_iter(self) -> Self::Iter {
+        ParIterMut {
+            inner: unsafe { self.raw.par_iter() },
+            marker: PhantomData,
+        }
+    }
+}
+
+#[cfg(test)]
+mod test_par_table {
+    use alloc::vec::Vec;
+    use core::sync::atomic::{AtomicUsize, Ordering};
+
+    use rayon::prelude::*;
+
+    use crate::{hash_map::make_hash, hash_table::HashTable, DefaultHashBuilder};
+
+    #[test]
+    fn test_iterate() {
+        let hasher = DefaultHashBuilder::default();
+        let mut a = HashTable::new();
+        for i in 0..32 {
+            a.insert_unique(make_hash(&hasher, &i), i, |x| make_hash(&hasher, x));
+        }
+        let observed = AtomicUsize::new(0);
+        a.par_iter().for_each(|k| {
+            observed.fetch_or(1 << *k, Ordering::Relaxed);
+        });
+        assert_eq!(observed.into_inner(), 0xFFFF_FFFF);
+    }
+
+    #[test]
+    fn test_move_iter() {
+        let hasher = DefaultHashBuilder::default();
+        let hs = {
+            let mut hs = HashTable::new();
+
+            hs.insert_unique(make_hash(&hasher, &'a'), 'a', |x| make_hash(&hasher, x));
+            hs.insert_unique(make_hash(&hasher, &'b'), 'b', |x| make_hash(&hasher, x));
+
+            hs
+        };
+
+        let v = hs.into_par_iter().collect::<Vec<char>>();
+        assert!(v == ['a', 'b'] || v == ['b', 'a']);
+    }
+}

vendor/hashbrown/src/external_trait_impls/serde.rs

@@ -0,0 +1,220 @@
+mod size_hint {
+    use core::cmp;
+
+    /// This presumably exists to prevent denial of service attacks.
+    ///
+    /// Original discussion: https://github.com/serde-rs/serde/issues/1114.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub(super) fn cautious(hint: Option<usize>) -> usize {
+        cmp::min(hint.unwrap_or(0), 4096)
+    }
+}
+
+mod map {
+    use crate::raw::Allocator;
+    use core::fmt;
+    use core::hash::{BuildHasher, Hash};
+    use core::marker::PhantomData;
+    use serde_core::de::{Deserialize, Deserializer, MapAccess, Visitor};
+    use serde_core::ser::{Serialize, Serializer};
+
+    use crate::hash_map::HashMap;
+
+    use super::size_hint;
+
+    impl<K, V, H, A> Serialize for HashMap<K, V, H, A>
+    where
+        K: Serialize + Eq + Hash,
+        V: Serialize,
+        H: BuildHasher,
+        A: Allocator,
+    {
+        #[cfg_attr(feature = "inline-more", inline)]
+        fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+        where
+            S: Serializer,
+        {
+            serializer.collect_map(self)
+        }
+    }
+
+    impl<'de, K, V, S, A> Deserialize<'de> for HashMap<K, V, S, A>
+    where
+        K: Deserialize<'de> + Eq + Hash,
+        V: Deserialize<'de>,
+        S: BuildHasher + Default,
+        A: Allocator + Default,
+    {
+        fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+        where
+            D: Deserializer<'de>,
+        {
+            struct MapVisitor<K, V, S, A>
+            where
+                A: Allocator,
+            {
+                marker: PhantomData<HashMap<K, V, S, A>>,
+            }
+
+            impl<'de, K, V, S, A> Visitor<'de> for MapVisitor<K, V, S, A>
+            where
+                K: Deserialize<'de> + Eq + Hash,
+                V: Deserialize<'de>,
+                S: BuildHasher + Default,
+                A: Allocator + Default,
+            {
+                type Value = HashMap<K, V, S, A>;
+
+                fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
+                    formatter.write_str("a map")
+                }
+
+                #[cfg_attr(feature = "inline-more", inline)]
+                fn visit_map<M>(self, mut map: M) -> Result<Self::Value, M::Error>
+                where
+                    M: MapAccess<'de>,
+                {
+                    let mut values = HashMap::with_capacity_and_hasher_in(
+                        size_hint::cautious(map.size_hint()),
+                        S::default(),
+                        A::default(),
+                    );
+
+                    while let Some((key, value)) = map.next_entry()? {
+                        values.insert(key, value);
+                    }
+
+                    Ok(values)
+                }
+            }
+
+            let visitor = MapVisitor {
+                marker: PhantomData,
+            };
+            deserializer.deserialize_map(visitor)
+        }
+    }
+}
+
+mod set {
+    use crate::raw::Allocator;
+    use core::fmt;
+    use core::hash::{BuildHasher, Hash};
+    use core::marker::PhantomData;
+    use serde_core::de::{Deserialize, Deserializer, SeqAccess, Visitor};
+    use serde_core::ser::{Serialize, Serializer};
+
+    use crate::hash_set::HashSet;
+
+    use super::size_hint;
+
+    impl<T, H, A> Serialize for HashSet<T, H, A>
+    where
+        T: Serialize + Eq + Hash,
+        H: BuildHasher,
+        A: Allocator,
+    {
+        #[cfg_attr(feature = "inline-more", inline)]
+        fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+        where
+            S: Serializer,
+        {
+            serializer.collect_seq(self)
+        }
+    }
+
+    impl<'de, T, S, A> Deserialize<'de> for HashSet<T, S, A>
+    where
+        T: Deserialize<'de> + Eq + Hash,
+        S: BuildHasher + Default,
+        A: Allocator + Default,
+    {
+        fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+        where
+            D: Deserializer<'de>,
+        {
+            struct SeqVisitor<T, S, A>
+            where
+                A: Allocator,
+            {
+                marker: PhantomData<HashSet<T, S, A>>,
+            }
+
+            impl<'de, T, S, A> Visitor<'de> for SeqVisitor<T, S, A>
+            where
+                T: Deserialize<'de> + Eq + Hash,
+                S: BuildHasher + Default,
+                A: Allocator + Default,
+            {
+                type Value = HashSet<T, S, A>;
+
+                fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
+                    formatter.write_str("a sequence")
+                }
+
+                #[cfg_attr(feature = "inline-more", inline)]
+                fn visit_seq<M>(self, mut seq: M) -> Result<Self::Value, M::Error>
+                where
+                    M: SeqAccess<'de>,
+                {
+                    let mut values = HashSet::with_capacity_and_hasher_in(
+                        size_hint::cautious(seq.size_hint()),
+                        S::default(),
+                        A::default(),
+                    );
+
+                    while let Some(value) = seq.next_element()? {
+                        values.insert(value);
+                    }
+
+                    Ok(values)
+                }
+            }
+
+            let visitor = SeqVisitor {
+                marker: PhantomData,
+            };
+            deserializer.deserialize_seq(visitor)
+        }
+
+        #[allow(clippy::missing_errors_doc)]
+        fn deserialize_in_place<D>(deserializer: D, place: &mut Self) -> Result<(), D::Error>
+        where
+            D: Deserializer<'de>,
+        {
+            struct SeqInPlaceVisitor<'a, T, S, A>(&'a mut HashSet<T, S, A>)
+            where
+                A: Allocator;
+
+            impl<'de, T, S, A> Visitor<'de> for SeqInPlaceVisitor<'_, T, S, A>
+            where
+                T: Deserialize<'de> + Eq + Hash,
+                S: BuildHasher + Default,
+                A: Allocator,
+            {
+                type Value = ();
+
+                fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
+                    formatter.write_str("a sequence")
+                }
+
+                #[cfg_attr(feature = "inline-more", inline)]
+                fn visit_seq<M>(self, mut seq: M) -> Result<Self::Value, M::Error>
+                where
+                    M: SeqAccess<'de>,
+                {
+                    self.0.clear();
+                    self.0.reserve(size_hint::cautious(seq.size_hint()));
+
+                    while let Some(value) = seq.next_element()? {
+                        self.0.insert(value);
+                    }
+
+                    Ok(())
+                }
+            }
+
+            deserializer.deserialize_seq(SeqInPlaceVisitor(place))
+        }
+    }
+}

vendor/hashbrown/src/hasher.rs

@@ -0,0 +1,77 @@
+#[cfg(feature = "default-hasher")]
+use {
+    core::hash::{BuildHasher, Hasher},
+    foldhash::fast::RandomState,
+};
+
+/// Default hash builder for the `S` type parameter of
+/// [`HashMap`](crate::HashMap) and [`HashSet`](crate::HashSet).
+///
+/// This only implements `BuildHasher` when the "default-hasher" crate feature
+/// is enabled; otherwise it just serves as a placeholder, and a custom `S` type
+/// must be used to have a fully functional `HashMap` or `HashSet`.
+#[derive(Clone, Debug, Default)]
+pub struct DefaultHashBuilder {
+    #[cfg(feature = "default-hasher")]
+    inner: RandomState,
+}
+
+#[cfg(feature = "default-hasher")]
+impl BuildHasher for DefaultHashBuilder {
+    type Hasher = DefaultHasher;
+
+    #[inline(always)]
+    fn build_hasher(&self) -> Self::Hasher {
+        DefaultHasher {
+            inner: self.inner.build_hasher(),
+        }
+    }
+}
+
+/// Default hasher for [`HashMap`](crate::HashMap) and [`HashSet`](crate::HashSet).
+#[cfg(feature = "default-hasher")]
+#[derive(Clone)]
+pub struct DefaultHasher {
+    inner: <RandomState as BuildHasher>::Hasher,
+}
+
+#[cfg(feature = "default-hasher")]
+macro_rules! forward_writes {
+    ($( $write:ident ( $ty:ty ) , )*) => {$(
+        #[inline(always)]
+        fn $write(&mut self, arg: $ty) {
+            self.inner.$write(arg);
+        }
+    )*}
+}
+
+#[cfg(feature = "default-hasher")]
+impl Hasher for DefaultHasher {
+    forward_writes! {
+        write(&[u8]),
+        write_u8(u8),
+        write_u16(u16),
+        write_u32(u32),
+        write_u64(u64),
+        write_u128(u128),
+        write_usize(usize),
+        write_i8(i8),
+        write_i16(i16),
+        write_i32(i32),
+        write_i64(i64),
+        write_i128(i128),
+        write_isize(isize),
+    }
+
+    // feature(hasher_prefixfree_extras)
+    #[cfg(feature = "nightly")]
+    forward_writes! {
+        write_length_prefix(usize),
+        write_str(&str),
+    }
+
+    #[inline(always)]
+    fn finish(&self) -> u64 {
+        self.inner.finish()
+    }
+}

vendor/hashbrown/src/lib.rs

@@ -0,0 +1,190 @@
+//! This crate is a Rust port of Google's high-performance [SwissTable] hash
+//! map, adapted to make it a drop-in replacement for Rust's standard `HashMap`
+//! and `HashSet` types.
+//!
+//! The original C++ version of [SwissTable] can be found [here], and this
+//! [CppCon talk] gives an overview of how the algorithm works.
+//!
+//! [SwissTable]: https://abseil.io/blog/20180927-swisstables
+//! [here]: https://github.com/abseil/abseil-cpp/blob/master/absl/container/internal/raw_hash_set.h
+//! [CppCon talk]: https://www.youtube.com/watch?v=ncHmEUmJZf4
+
+#![no_std]
+#![cfg_attr(
+    feature = "nightly",
+    feature(
+        test,
+        core_intrinsics,
+        dropck_eyepatch,
+        min_specialization,
+        trivial_clone,
+        extend_one,
+        allocator_api,
+        slice_ptr_get,
+        maybe_uninit_array_assume_init,
+        strict_provenance_lints
+    )
+)]
+#![cfg_attr(feature = "rustc-dep-of-std", feature(rustc_attrs))]
+#![allow(
+    clippy::doc_markdown,
+    clippy::module_name_repetitions,
+    clippy::must_use_candidate,
+    clippy::option_if_let_else,
+    clippy::redundant_else,
+    clippy::manual_map,
+    clippy::missing_safety_doc,
+    clippy::missing_errors_doc
+)]
+#![warn(missing_docs)]
+#![warn(rust_2018_idioms)]
+#![cfg_attr(feature = "nightly", warn(fuzzy_provenance_casts))]
+#![cfg_attr(
+    feature = "nightly",
+    allow(clippy::incompatible_msrv, internal_features)
+)]
+#![cfg_attr(
+    all(feature = "nightly", target_arch = "loongarch64"),
+    feature(stdarch_loongarch)
+)]
+#![cfg_attr(
+    all(feature = "nightly", feature = "default-hasher"),
+    feature(hasher_prefixfree_extras)
+)]
+
+#[cfg(test)]
+#[macro_use]
+extern crate std;
+
+#[cfg_attr(test, macro_use)]
+#[cfg_attr(feature = "rustc-dep-of-std", allow(unused_extern_crates))]
+extern crate alloc;
+
+#[doc = include_str!("../README.md")]
+#[cfg(doctest)]
+pub struct ReadmeDoctests;
+
+#[macro_use]
+mod macros;
+
+mod control;
+mod hasher;
+mod raw;
+mod util;
+
+mod external_trait_impls;
+mod map;
+#[cfg(feature = "raw-entry")]
+mod raw_entry;
+#[cfg(feature = "rustc-internal-api")]
+mod rustc_entry;
+mod scopeguard;
+mod set;
+mod table;
+
+pub use crate::hasher::DefaultHashBuilder;
+#[cfg(feature = "default-hasher")]
+pub use crate::hasher::DefaultHasher;
+
+pub mod hash_map {
+    //! A hash map implemented with quadratic probing and SIMD lookup.
+    pub use crate::map::*;
+
+    #[cfg(feature = "rustc-internal-api")]
+    pub use crate::rustc_entry::*;
+
+    #[cfg(feature = "rayon")]
+    /// [rayon]-based parallel iterator types for hash maps.
+    /// You will rarely need to interact with it directly unless you have need
+    /// to name one of the iterator types.
+    ///
+    /// [rayon]: https://docs.rs/rayon/1.0/rayon
+    pub mod rayon {
+        pub use crate::external_trait_impls::rayon::map::*;
+    }
+}
+pub mod hash_set {
+    //! A hash set implemented as a `HashMap` where the value is `()`.
+    pub use crate::set::*;
+
+    #[cfg(feature = "rayon")]
+    /// [rayon]-based parallel iterator types for hash sets.
+    /// You will rarely need to interact with it directly unless you have need
+    /// to name one of the iterator types.
+    ///
+    /// [rayon]: https://docs.rs/rayon/1.0/rayon
+    pub mod rayon {
+        pub use crate::external_trait_impls::rayon::set::*;
+    }
+}
+pub mod hash_table {
+    //! A hash table implemented with quadratic probing and SIMD lookup.
+    pub use crate::table::*;
+
+    #[cfg(feature = "rayon")]
+    /// [rayon]-based parallel iterator types for hash tables.
+    /// You will rarely need to interact with it directly unless you have need
+    /// to name one of the iterator types.
+    ///
+    /// [rayon]: https://docs.rs/rayon/1.0/rayon
+    pub mod rayon {
+        pub use crate::external_trait_impls::rayon::table::*;
+    }
+}
+
+pub use crate::map::HashMap;
+pub use crate::set::HashSet;
+pub use crate::table::HashTable;
+
+#[cfg(feature = "equivalent")]
+pub use equivalent::Equivalent;
+
+// This is only used as a fallback when building as part of `std`.
+#[cfg(not(feature = "equivalent"))]
+/// Key equivalence trait.
+///
+/// This trait defines the function used to compare the input value with the
+/// map keys (or set values) during a lookup operation such as [`HashMap::get`]
+/// or [`HashSet::contains`].
+/// It is provided with a blanket implementation based on the
+/// [`Borrow`](core::borrow::Borrow) trait.
+///
+/// # Correctness
+///
+/// Equivalent values must hash to the same value.
+pub trait Equivalent<K: ?Sized> {
+    /// Checks if this value is equivalent to the given key.
+    ///
+    /// Returns `true` if both values are equivalent, and `false` otherwise.
+    ///
+    /// # Correctness
+    ///
+    /// When this function returns `true`, both `self` and `key` must hash to
+    /// the same value.
+    fn equivalent(&self, key: &K) -> bool;
+}
+
+#[cfg(not(feature = "equivalent"))]
+impl<Q: ?Sized, K: ?Sized> Equivalent<K> for Q
+where
+    Q: Eq,
+    K: core::borrow::Borrow<Q>,
+{
+    fn equivalent(&self, key: &K) -> bool {
+        self == key.borrow()
+    }
+}
+
+/// The error type for `try_reserve` methods.
+#[derive(Clone, PartialEq, Eq, Debug)]
+pub enum TryReserveError {
+    /// Error due to the computed capacity exceeding the collection's maximum
+    /// (usually `isize::MAX` bytes).
+    CapacityOverflow,
+
+    /// The memory allocator returned an error
+    AllocError {
+        /// The layout of the allocation request that failed.
+        layout: alloc::alloc::Layout,
+    },
+}

vendor/hashbrown/src/macros.rs

@@ -0,0 +1,70 @@
+// See the cfg-if crate.
+#[allow(unused_macro_rules)]
+macro_rules! cfg_if {
+    // match if/else chains with a final `else`
+    ($(
+        if #[cfg($($meta:meta),*)] { $($it:item)* }
+    ) else * else {
+        $($it2:item)*
+    }) => {
+        cfg_if! {
+            @__items
+            () ;
+            $( ( ($($meta),*) ($($it)*) ), )*
+            ( () ($($it2)*) ),
+        }
+    };
+
+    // match if/else chains lacking a final `else`
+    (
+        if #[cfg($($i_met:meta),*)] { $($i_it:item)* }
+        $(
+            else if #[cfg($($e_met:meta),*)] { $($e_it:item)* }
+        )*
+    ) => {
+        cfg_if! {
+            @__items
+            () ;
+            ( ($($i_met),*) ($($i_it)*) ),
+            $( ( ($($e_met),*) ($($e_it)*) ), )*
+            ( () () ),
+        }
+    };
+
+    // Internal and recursive macro to emit all the items
+    //
+    // Collects all the negated cfgs in a list at the beginning and after the
+    // semicolon is all the remaining items
+    (@__items ($($not:meta,)*) ; ) => {};
+    (@__items ($($not:meta,)*) ; ( ($($m:meta),*) ($($it:item)*) ), $($rest:tt)*) => {
+        // Emit all items within one block, applying an appropriate #[cfg]. The
+        // #[cfg] will require all `$m` matchers specified and must also negate
+        // all previous matchers.
+        cfg_if! { @__apply cfg(all($($m,)* not(any($($not),*)))), $($it)* }
+
+        // Recurse to emit all other items in `$rest`, and when we do so add all
+        // our `$m` matchers to the list of `$not` matchers as future emissions
+        // will have to negate everything we just matched as well.
+        cfg_if! { @__items ($($not,)* $($m,)*) ; $($rest)* }
+    };
+
+    // Internal macro to Apply a cfg attribute to a list of items
+    (@__apply $m:meta, $($it:item)*) => {
+        $(#[$m] $it)*
+    };
+}
+
+// Helper macro for specialization. This also helps avoid parse errors if the
+// default fn syntax for specialization changes in the future.
+#[cfg(feature = "nightly")]
+macro_rules! default_fn {
+	(#[$($a:tt)*] $($tt:tt)*) => {
+        #[$($a)*] default $($tt)*
+    }
+}
+#[cfg(not(feature = "nightly"))]
+macro_rules! default_fn {
+	($($tt:tt)*) => {
+        $($tt)*
+    }
+}

vendor/hashbrown/src/raw/alloc.rs

@@ -0,0 +1,103 @@
+#[cfg(test)]
+pub(crate) use self::inner::AllocError;
+pub(crate) use self::inner::{do_alloc, Allocator, Global};
+
+// Nightly-case.
+// Use unstable `allocator_api` feature.
+// This is compatible with `allocator-api2` which can be enabled or not.
+// This is used when building for `std`.
+#[cfg(feature = "nightly")]
+mod inner {
+    #[cfg(test)]
+    pub use crate::alloc::alloc::AllocError;
+    use crate::alloc::alloc::Layout;
+    pub use crate::alloc::alloc::{Allocator, Global};
+    use core::ptr::NonNull;
+
+    #[allow(clippy::map_err_ignore)]
+    pub(crate) fn do_alloc<A: Allocator>(alloc: &A, layout: Layout) -> Result<NonNull<[u8]>, ()> {
+        match alloc.allocate(layout) {
+            Ok(ptr) => Ok(ptr),
+            Err(_) => Err(()),
+        }
+    }
+}
+
+// Basic non-nightly case.
+// This uses `allocator-api2` enabled by default.
+// If any crate enables "nightly" in `allocator-api2`,
+// this will be equivalent to the nightly case,
+// since `allocator_api2::alloc::Allocator` would be re-export of
+// `core::alloc::Allocator`.
+#[cfg(all(not(feature = "nightly"), feature = "allocator-api2"))]
+mod inner {
+    use crate::alloc::alloc::Layout;
+    #[cfg(test)]
+    pub use allocator_api2::alloc::AllocError;
+    pub use allocator_api2::alloc::{Allocator, Global};
+    use core::ptr::NonNull;
+
+    #[allow(clippy::map_err_ignore)]
+    pub(crate) fn do_alloc<A: Allocator>(alloc: &A, layout: Layout) -> Result<NonNull<[u8]>, ()> {
+        match alloc.allocate(layout) {
+            Ok(ptr) => Ok(ptr),
+            Err(_) => Err(()),
+        }
+    }
+}
+
+// No-defaults case.
+// When building with default-features turned off and
+// neither `nightly` nor `allocator-api2` is enabled,
+// this will be used.
+// Making it impossible to use any custom allocator with collections defined
+// in this crate.
+// Any crate in build-tree can enable `allocator-api2`,
+// or `nightly` without disturbing users that don't want to use it.
+#[cfg(not(any(feature = "nightly", feature = "allocator-api2")))]
+mod inner {
+    use crate::alloc::alloc::{alloc, dealloc, Layout};
+    use core::ptr::NonNull;
+
+    #[allow(clippy::missing_safety_doc)] // not exposed outside of this crate
+    pub unsafe trait Allocator {
+        fn allocate(&self, layout: Layout) -> Result<NonNull<[u8]>, ()>;
+        unsafe fn deallocate(&self, ptr: NonNull<u8>, layout: Layout);
+    }
+
+    #[derive(Copy, Clone)]
+    pub struct Global;
+
+    unsafe impl Allocator for Global {
+        #[inline]
+        fn allocate(&self, layout: Layout) -> Result<NonNull<[u8]>, ()> {
+            match unsafe { NonNull::new(alloc(layout)) } {
+                Some(data) => {
+                    // SAFETY: this is NonNull::slice_from_raw_parts.
+                    Ok(unsafe {
+                        NonNull::new_unchecked(core::ptr::slice_from_raw_parts_mut(
+                            data.as_ptr(),
+                            layout.size(),
+                        ))
+                    })
+                }
+                None => Err(()),
+            }
+        }
+        #[inline]
+        unsafe fn deallocate(&self, ptr: NonNull<u8>, layout: Layout) {
+            dealloc(ptr.as_ptr(), layout);
+        }
+    }
+
+    impl Default for Global {
+        #[inline]
+        fn default() -> Self {
+            Global
+        }
+    }
+
+    pub(crate) fn do_alloc<A: Allocator>(alloc: &A, layout: Layout) -> Result<NonNull<[u8]>, ()> {
+        alloc.allocate(layout)
+    }
+}

vendor/hashbrown/src/rustc_entry.rs

@@ -0,0 +1,567 @@
+use self::RustcEntry::*;
+use crate::map::{make_hash, Drain, HashMap, IntoIter, Iter, IterMut};
+use crate::raw::{Allocator, Bucket, Global, RawTable};
+use core::fmt::{self, Debug};
+use core::hash::{BuildHasher, Hash};
+use core::mem;
+
+impl<K, V, S, A> HashMap<K, V, S, A>
+where
+    K: Eq + Hash,
+    S: BuildHasher,
+    A: Allocator,
+{
+    /// Gets the given key's corresponding entry in the map for in-place manipulation.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut letters = HashMap::new();
+    ///
+    /// for ch in "a short treatise on fungi".chars() {
+    ///     let counter = letters.rustc_entry(ch).or_insert(0);
+    ///     *counter += 1;
+    /// }
+    ///
+    /// assert_eq!(letters[&'s'], 2);
+    /// assert_eq!(letters[&'t'], 3);
+    /// assert_eq!(letters[&'u'], 1);
+    /// assert_eq!(letters.get(&'y'), None);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn rustc_entry(&mut self, key: K) -> RustcEntry<'_, K, V, A> {
+        let hash = make_hash(&self.hash_builder, &key);
+        if let Some(elem) = self.table.find(hash, |q| q.0.eq(&key)) {
+            RustcEntry::Occupied(RustcOccupiedEntry {
+                elem,
+                table: &mut self.table,
+            })
+        } else {
+            // Ideally we would put this in VacantEntry::insert, but Entry is not
+            // generic over the BuildHasher and adding a generic parameter would be
+            // a breaking change.
+            self.reserve(1);
+
+            RustcEntry::Vacant(RustcVacantEntry {
+                hash,
+                key,
+                table: &mut self.table,
+            })
+        }
+    }
+}
+
+/// A view into a single entry in a map, which may either be vacant or occupied.
+///
+/// This `enum` is constructed from the [`rustc_entry`] method on [`HashMap`].
+///
+/// [`HashMap`]: struct.HashMap.html
+/// [`rustc_entry`]: struct.HashMap.html#method.rustc_entry
+pub enum RustcEntry<'a, K, V, A = Global>
+where
+    A: Allocator,
+{
+    /// An occupied entry.
+    Occupied(RustcOccupiedEntry<'a, K, V, A>),
+
+    /// A vacant entry.
+    Vacant(RustcVacantEntry<'a, K, V, A>),
+}
+
+impl<K: Debug, V: Debug, A: Allocator> Debug for RustcEntry<'_, K, V, A> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match *self {
+            Vacant(ref v) => f.debug_tuple("Entry").field(v).finish(),
+            Occupied(ref o) => f.debug_tuple("Entry").field(o).finish(),
+        }
+    }
+}
+
+/// A view into an occupied entry in a `HashMap`.
+/// It is part of the [`RustcEntry`] enum.
+///
+/// [`RustcEntry`]: enum.RustcEntry.html
+pub struct RustcOccupiedEntry<'a, K, V, A = Global>
+where
+    A: Allocator,
+{
+    elem: Bucket<(K, V)>,
+    table: &'a mut RawTable<(K, V), A>,
+}
+
+unsafe impl<K, V, A> Send for RustcOccupiedEntry<'_, K, V, A>
+where
+    K: Send,
+    V: Send,
+    A: Allocator + Send,
+{
+}
+unsafe impl<K, V, A> Sync for RustcOccupiedEntry<'_, K, V, A>
+where
+    K: Sync,
+    V: Sync,
+    A: Allocator + Sync,
+{
+}
+
+impl<K: Debug, V: Debug, A: Allocator> Debug for RustcOccupiedEntry<'_, K, V, A> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("OccupiedEntry")
+            .field("key", self.key())
+            .field("value", self.get())
+            .finish()
+    }
+}
+
+/// A view into a vacant entry in a `HashMap`.
+/// It is part of the [`RustcEntry`] enum.
+///
+/// [`RustcEntry`]: enum.RustcEntry.html
+pub struct RustcVacantEntry<'a, K, V, A = Global>
+where
+    A: Allocator,
+{
+    hash: u64,
+    key: K,
+    table: &'a mut RawTable<(K, V), A>,
+}
+
+impl<K: Debug, V, A: Allocator> Debug for RustcVacantEntry<'_, K, V, A> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_tuple("VacantEntry").field(self.key()).finish()
+    }
+}
+
+impl<'a, K, V, A: Allocator> RustcEntry<'a, K, V, A> {
+    /// Sets the value of the entry, and returns a RustcOccupiedEntry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    /// let entry = map.rustc_entry("horseyland").insert(37);
+    ///
+    /// assert_eq!(entry.key(), &"horseyland");
+    /// ```
+    pub fn insert(self, value: V) -> RustcOccupiedEntry<'a, K, V, A> {
+        match self {
+            Vacant(entry) => entry.insert_entry(value),
+            Occupied(mut entry) => {
+                entry.insert(value);
+                entry
+            }
+        }
+    }
+
+    /// Ensures a value is in the entry by inserting the default if empty, and returns
+    /// a mutable reference to the value in the entry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    ///
+    /// map.rustc_entry("poneyland").or_insert(3);
+    /// assert_eq!(map["poneyland"], 3);
+    ///
+    /// *map.rustc_entry("poneyland").or_insert(10) *= 2;
+    /// assert_eq!(map["poneyland"], 6);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn or_insert(self, default: V) -> &'a mut V
+    where
+        K: Hash,
+    {
+        match self {
+            Occupied(entry) => entry.into_mut(),
+            Vacant(entry) => entry.insert(default),
+        }
+    }
+
+    /// Ensures a value is in the entry by inserting the result of the default function if empty,
+    /// and returns a mutable reference to the value in the entry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map: HashMap<&str, String> = HashMap::new();
+    /// let s = "hoho".to_string();
+    ///
+    /// map.rustc_entry("poneyland").or_insert_with(|| s);
+    ///
+    /// assert_eq!(map["poneyland"], "hoho".to_string());
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn or_insert_with<F: FnOnce() -> V>(self, default: F) -> &'a mut V
+    where
+        K: Hash,
+    {
+        match self {
+            Occupied(entry) => entry.into_mut(),
+            Vacant(entry) => entry.insert(default()),
+        }
+    }
+
+    /// Returns a reference to this entry's key.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    /// assert_eq!(map.rustc_entry("poneyland").key(), &"poneyland");
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn key(&self) -> &K {
+        match *self {
+            Occupied(ref entry) => entry.key(),
+            Vacant(ref entry) => entry.key(),
+        }
+    }
+
+    /// Provides in-place mutable access to an occupied entry before any
+    /// potential inserts into the map.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    ///
+    /// map.rustc_entry("poneyland")
+    ///    .and_modify(|e| { *e += 1 })
+    ///    .or_insert(42);
+    /// assert_eq!(map["poneyland"], 42);
+    ///
+    /// map.rustc_entry("poneyland")
+    ///    .and_modify(|e| { *e += 1 })
+    ///    .or_insert(42);
+    /// assert_eq!(map["poneyland"], 43);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn and_modify<F>(self, f: F) -> Self
+    where
+        F: FnOnce(&mut V),
+    {
+        match self {
+            Occupied(mut entry) => {
+                f(entry.get_mut());
+                Occupied(entry)
+            }
+            Vacant(entry) => Vacant(entry),
+        }
+    }
+}
+
+impl<'a, K, V: Default, A: Allocator> RustcEntry<'a, K, V, A> {
+    /// Ensures a value is in the entry by inserting the default value if empty,
+    /// and returns a mutable reference to the value in the entry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # fn main() {
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map: HashMap<&str, Option<u32>> = HashMap::new();
+    /// map.rustc_entry("poneyland").or_default();
+    ///
+    /// assert_eq!(map["poneyland"], None);
+    /// # }
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn or_default(self) -> &'a mut V
+    where
+        K: Hash,
+    {
+        match self {
+            Occupied(entry) => entry.into_mut(),
+            Vacant(entry) => entry.insert(Default::default()),
+        }
+    }
+}
+
+impl<'a, K, V, A: Allocator> RustcOccupiedEntry<'a, K, V, A> {
+    /// Gets a reference to the key in the entry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    /// map.rustc_entry("poneyland").or_insert(12);
+    /// assert_eq!(map.rustc_entry("poneyland").key(), &"poneyland");
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn key(&self) -> &K {
+        unsafe { &self.elem.as_ref().0 }
+    }
+
+    /// Take the ownership of the key and value from the map.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// use hashbrown::hash_map::RustcEntry;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    /// map.rustc_entry("poneyland").or_insert(12);
+    ///
+    /// if let RustcEntry::Occupied(o) = map.rustc_entry("poneyland") {
+    ///     // We delete the entry from the map.
+    ///     o.remove_entry();
+    /// }
+    ///
+    /// assert_eq!(map.contains_key("poneyland"), false);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn remove_entry(self) -> (K, V) {
+        unsafe { self.table.remove(self.elem).0 }
+    }
+
+    /// Gets a reference to the value in the entry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// use hashbrown::hash_map::RustcEntry;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    /// map.rustc_entry("poneyland").or_insert(12);
+    ///
+    /// if let RustcEntry::Occupied(o) = map.rustc_entry("poneyland") {
+    ///     assert_eq!(o.get(), &12);
+    /// }
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn get(&self) -> &V {
+        unsafe { &self.elem.as_ref().1 }
+    }
+
+    /// Gets a mutable reference to the value in the entry.
+    ///
+    /// If you need a reference to the `RustcOccupiedEntry` which may outlive the
+    /// destruction of the `RustcEntry` value, see [`into_mut`].
+    ///
+    /// [`into_mut`]: #method.into_mut
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// use hashbrown::hash_map::RustcEntry;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    /// map.rustc_entry("poneyland").or_insert(12);
+    ///
+    /// assert_eq!(map["poneyland"], 12);
+    /// if let RustcEntry::Occupied(mut o) = map.rustc_entry("poneyland") {
+    ///     *o.get_mut() += 10;
+    ///     assert_eq!(*o.get(), 22);
+    ///
+    ///     // We can use the same RustcEntry multiple times.
+    ///     *o.get_mut() += 2;
+    /// }
+    ///
+    /// assert_eq!(map["poneyland"], 24);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn get_mut(&mut self) -> &mut V {
+        unsafe { &mut self.elem.as_mut().1 }
+    }
+
+    /// Converts the RustcOccupiedEntry into a mutable reference to the value in the entry
+    /// with a lifetime bound to the map itself.
+    ///
+    /// If you need multiple references to the `RustcOccupiedEntry`, see [`get_mut`].
+    ///
+    /// [`get_mut`]: #method.get_mut
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// use hashbrown::hash_map::RustcEntry;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    /// map.rustc_entry("poneyland").or_insert(12);
+    ///
+    /// assert_eq!(map["poneyland"], 12);
+    /// if let RustcEntry::Occupied(o) = map.rustc_entry("poneyland") {
+    ///     *o.into_mut() += 10;
+    /// }
+    ///
+    /// assert_eq!(map["poneyland"], 22);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn into_mut(self) -> &'a mut V {
+        unsafe { &mut self.elem.as_mut().1 }
+    }
+
+    /// Sets the value of the entry, and returns the entry's old value.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// use hashbrown::hash_map::RustcEntry;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    /// map.rustc_entry("poneyland").or_insert(12);
+    ///
+    /// if let RustcEntry::Occupied(mut o) = map.rustc_entry("poneyland") {
+    ///     assert_eq!(o.insert(15), 12);
+    /// }
+    ///
+    /// assert_eq!(map["poneyland"], 15);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn insert(&mut self, value: V) -> V {
+        mem::replace(self.get_mut(), value)
+    }
+
+    /// Takes the value out of the entry, and returns it.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// use hashbrown::hash_map::RustcEntry;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    /// map.rustc_entry("poneyland").or_insert(12);
+    ///
+    /// if let RustcEntry::Occupied(o) = map.rustc_entry("poneyland") {
+    ///     assert_eq!(o.remove(), 12);
+    /// }
+    ///
+    /// assert_eq!(map.contains_key("poneyland"), false);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn remove(self) -> V {
+        self.remove_entry().1
+    }
+}
+
+impl<'a, K, V, A: Allocator> RustcVacantEntry<'a, K, V, A> {
+    /// Gets a reference to the key that would be used when inserting a value
+    /// through the `RustcVacantEntry`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    /// assert_eq!(map.rustc_entry("poneyland").key(), &"poneyland");
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn key(&self) -> &K {
+        &self.key
+    }
+
+    /// Take ownership of the key.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// use hashbrown::hash_map::RustcEntry;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    ///
+    /// if let RustcEntry::Vacant(v) = map.rustc_entry("poneyland") {
+    ///     v.into_key();
+    /// }
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn into_key(self) -> K {
+        self.key
+    }
+
+    /// Sets the value of the entry with the RustcVacantEntry's key,
+    /// and returns a mutable reference to it.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// use hashbrown::hash_map::RustcEntry;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    ///
+    /// if let RustcEntry::Vacant(o) = map.rustc_entry("poneyland") {
+    ///     o.insert(37);
+    /// }
+    /// assert_eq!(map["poneyland"], 37);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn insert(self, value: V) -> &'a mut V {
+        unsafe {
+            let bucket = self.table.insert_no_grow(self.hash, (self.key, value));
+            &mut bucket.as_mut().1
+        }
+    }
+
+    /// Sets the value of the entry with the RustcVacantEntry's key,
+    /// and returns a RustcOccupiedEntry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// use hashbrown::hash_map::RustcEntry;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    ///
+    /// if let RustcEntry::Vacant(v) = map.rustc_entry("poneyland") {
+    ///     let o = v.insert_entry(37);
+    ///     assert_eq!(o.get(), &37);
+    /// }
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn insert_entry(self, value: V) -> RustcOccupiedEntry<'a, K, V, A> {
+        let bucket = unsafe { self.table.insert_no_grow(self.hash, (self.key, value)) };
+        RustcOccupiedEntry {
+            elem: bucket,
+            table: self.table,
+        }
+    }
+}
+
+impl<K, V> IterMut<'_, K, V> {
+    /// Returns a iterator of references over the remaining items.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn rustc_iter(&self) -> Iter<'_, K, V> {
+        self.iter()
+    }
+}
+
+impl<K, V, A: Allocator> IntoIter<K, V, A> {
+    /// Returns a iterator of references over the remaining items.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn rustc_iter(&self) -> Iter<'_, K, V> {
+        self.iter()
+    }
+}
+
+impl<K, V, A: Allocator> Drain<'_, K, V, A> {
+    /// Returns a iterator of references over the remaining items.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn rustc_iter(&self) -> Iter<'_, K, V> {
+        self.iter()
+    }
+}

vendor/hashbrown/src/scopeguard.rs

@@ -0,0 +1,72 @@
+// Extracted from the scopeguard crate
+use core::{
+    mem::ManuallyDrop,
+    ops::{Deref, DerefMut},
+    ptr,
+};
+
+pub struct ScopeGuard<T, F>
+where
+    F: FnMut(&mut T),
+{
+    dropfn: F,
+    value: T,
+}
+
+#[inline]
+pub fn guard<T, F>(value: T, dropfn: F) -> ScopeGuard<T, F>
+where
+    F: FnMut(&mut T),
+{
+    ScopeGuard { dropfn, value }
+}
+
+impl<T, F> ScopeGuard<T, F>
+where
+    F: FnMut(&mut T),
+{
+    #[inline]
+    pub fn into_inner(guard: Self) -> T {
+        // Cannot move out of Drop-implementing types, so
+        // ptr::read the value out of a ManuallyDrop<Self>
+        // Don't use mem::forget as that might invalidate value
+        let guard = ManuallyDrop::new(guard);
+        unsafe {
+            let value = ptr::read(&guard.value);
+            // read the closure so that it is dropped
+            let _ = ptr::read(&guard.dropfn);
+            value
+        }
+    }
+}
+
+impl<T, F> Deref for ScopeGuard<T, F>
+where
+    F: FnMut(&mut T),
+{
+    type Target = T;
+    #[inline]
+    fn deref(&self) -> &T {
+        &self.value
+    }
+}
+
+impl<T, F> DerefMut for ScopeGuard<T, F>
+where
+    F: FnMut(&mut T),
+{
+    #[inline]
+    fn deref_mut(&mut self) -> &mut T {
+        &mut self.value
+    }
+}
+
+impl<T, F> Drop for ScopeGuard<T, F>
+where
+    F: FnMut(&mut T),
+{
+    #[inline]
+    fn drop(&mut self) {
+        (self.dropfn)(&mut self.value);
+    }
+}

vendor/hashbrown/src/util.rs

@@ -0,0 +1,38 @@
+// FIXME: Replace with `core::hint::{likely, unlikely}` once they are stable.
+#[cfg(feature = "nightly")]
+pub(crate) use core::intrinsics::{likely, unlikely};
+
+#[cfg(not(feature = "nightly"))]
+#[inline(always)]
+#[cold]
+fn cold_path() {}
+
+#[cfg(not(feature = "nightly"))]
+#[inline(always)]
+pub(crate) fn likely(b: bool) -> bool {
+    if b {
+        true
+    } else {
+        cold_path();
+        false
+    }
+}
+
+#[cfg(not(feature = "nightly"))]
+#[inline(always)]
+pub(crate) fn unlikely(b: bool) -> bool {
+    if b {
+        cold_path();
+        true
+    } else {
+        false
+    }
+}
+
+// FIXME: use strict provenance functions once they are stable.
+// Implement it with a transmute for now.
+#[inline(always)]
+#[allow(clippy::useless_transmute)] // clippy is wrong, cast and transmute are different here
+pub(crate) fn invalid_mut<T>(addr: usize) -> *mut T {
+    unsafe { core::mem::transmute(addr) }
+}