mv compiler to compiler/

compiler/rustc_index/src/bit_set/tests.rs

@@ -0,0 +1,366 @@
+use super::*;
+
+extern crate test;
+use test::Bencher;
+
+#[test]
+fn test_new_filled() {
+    for i in 0..128 {
+        let idx_buf = BitSet::new_filled(i);
+        let elems: Vec<usize> = idx_buf.iter().collect();
+        let expected: Vec<usize> = (0..i).collect();
+        assert_eq!(elems, expected);
+    }
+}
+
+#[test]
+fn bitset_iter_works() {
+    let mut bitset: BitSet<usize> = BitSet::new_empty(100);
+    bitset.insert(1);
+    bitset.insert(10);
+    bitset.insert(19);
+    bitset.insert(62);
+    bitset.insert(63);
+    bitset.insert(64);
+    bitset.insert(65);
+    bitset.insert(66);
+    bitset.insert(99);
+    assert_eq!(bitset.iter().collect::<Vec<_>>(), [1, 10, 19, 62, 63, 64, 65, 66, 99]);
+}
+
+#[test]
+fn bitset_iter_works_2() {
+    let mut bitset: BitSet<usize> = BitSet::new_empty(320);
+    bitset.insert(0);
+    bitset.insert(127);
+    bitset.insert(191);
+    bitset.insert(255);
+    bitset.insert(319);
+    assert_eq!(bitset.iter().collect::<Vec<_>>(), [0, 127, 191, 255, 319]);
+}
+
+#[test]
+fn union_two_sets() {
+    let mut set1: BitSet<usize> = BitSet::new_empty(65);
+    let mut set2: BitSet<usize> = BitSet::new_empty(65);
+    assert!(set1.insert(3));
+    assert!(!set1.insert(3));
+    assert!(set2.insert(5));
+    assert!(set2.insert(64));
+    assert!(set1.union(&set2));
+    assert!(!set1.union(&set2));
+    assert!(set1.contains(3));
+    assert!(!set1.contains(4));
+    assert!(set1.contains(5));
+    assert!(!set1.contains(63));
+    assert!(set1.contains(64));
+}
+
+#[test]
+fn hybrid_bitset() {
+    let mut sparse038: HybridBitSet<usize> = HybridBitSet::new_empty(256);
+    assert!(sparse038.is_empty());
+    assert!(sparse038.insert(0));
+    assert!(sparse038.insert(1));
+    assert!(sparse038.insert(8));
+    assert!(sparse038.insert(3));
+    assert!(!sparse038.insert(3));
+    assert!(sparse038.remove(1));
+    assert!(!sparse038.is_empty());
+    assert_eq!(sparse038.iter().collect::<Vec<_>>(), [0, 3, 8]);
+
+    for i in 0..256 {
+        if i == 0 || i == 3 || i == 8 {
+            assert!(sparse038.contains(i));
+        } else {
+            assert!(!sparse038.contains(i));
+        }
+    }
+
+    let mut sparse01358 = sparse038.clone();
+    assert!(sparse01358.insert(1));
+    assert!(sparse01358.insert(5));
+    assert_eq!(sparse01358.iter().collect::<Vec<_>>(), [0, 1, 3, 5, 8]);
+
+    let mut dense10 = HybridBitSet::new_empty(256);
+    for i in 0..10 {
+        assert!(dense10.insert(i));
+    }
+    assert!(!dense10.is_empty());
+    assert_eq!(dense10.iter().collect::<Vec<_>>(), [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);
+
+    let mut dense256 = HybridBitSet::new_empty(256);
+    assert!(dense256.is_empty());
+    dense256.insert_all();
+    assert!(!dense256.is_empty());
+    for i in 0..256 {
+        assert!(dense256.contains(i));
+    }
+
+    assert!(sparse038.superset(&sparse038)); // sparse + sparse (self)
+    assert!(sparse01358.superset(&sparse038)); // sparse + sparse
+    assert!(dense10.superset(&sparse038)); // dense + sparse
+    assert!(dense10.superset(&dense10)); // dense + dense (self)
+    assert!(dense256.superset(&dense10)); // dense + dense
+
+    let mut hybrid = sparse038;
+    assert!(!sparse01358.union(&hybrid)); // no change
+    assert!(hybrid.union(&sparse01358));
+    assert!(hybrid.superset(&sparse01358) && sparse01358.superset(&hybrid));
+    assert!(!dense10.union(&sparse01358));
+    assert!(!dense256.union(&dense10));
+    let mut dense = dense10;
+    assert!(dense.union(&dense256));
+    assert!(dense.superset(&dense256) && dense256.superset(&dense));
+    assert!(hybrid.union(&dense256));
+    assert!(hybrid.superset(&dense256) && dense256.superset(&hybrid));
+
+    assert_eq!(dense256.iter().count(), 256);
+    let mut dense0 = dense256;
+    for i in 0..256 {
+        assert!(dense0.remove(i));
+    }
+    assert!(!dense0.remove(0));
+    assert!(dense0.is_empty());
+}
+
+#[test]
+fn grow() {
+    let mut set: GrowableBitSet<usize> = GrowableBitSet::with_capacity(65);
+    for index in 0..65 {
+        assert!(set.insert(index));
+        assert!(!set.insert(index));
+    }
+    set.ensure(128);
+
+    // Check if the bits set before growing are still set
+    for index in 0..65 {
+        assert!(set.contains(index));
+    }
+
+    // Check if the new bits are all un-set
+    for index in 65..128 {
+        assert!(!set.contains(index));
+    }
+
+    // Check that we can set all new bits without running out of bounds
+    for index in 65..128 {
+        assert!(set.insert(index));
+        assert!(!set.insert(index));
+    }
+}
+
+#[test]
+fn matrix_intersection() {
+    let mut matrix: BitMatrix<usize, usize> = BitMatrix::new(200, 200);
+
+    // (*) Elements reachable from both 2 and 65.
+
+    matrix.insert(2, 3);
+    matrix.insert(2, 6);
+    matrix.insert(2, 10); // (*)
+    matrix.insert(2, 64); // (*)
+    matrix.insert(2, 65);
+    matrix.insert(2, 130);
+    matrix.insert(2, 160); // (*)
+
+    matrix.insert(64, 133);
+
+    matrix.insert(65, 2);
+    matrix.insert(65, 8);
+    matrix.insert(65, 10); // (*)
+    matrix.insert(65, 64); // (*)
+    matrix.insert(65, 68);
+    matrix.insert(65, 133);
+    matrix.insert(65, 160); // (*)
+
+    let intersection = matrix.intersect_rows(2, 64);
+    assert!(intersection.is_empty());
+
+    let intersection = matrix.intersect_rows(2, 65);
+    assert_eq!(intersection, &[10, 64, 160]);
+}
+
+#[test]
+fn matrix_iter() {
+    let mut matrix: BitMatrix<usize, usize> = BitMatrix::new(64, 100);
+    matrix.insert(3, 22);
+    matrix.insert(3, 75);
+    matrix.insert(2, 99);
+    matrix.insert(4, 0);
+    matrix.union_rows(3, 5);
+    matrix.insert_all_into_row(6);
+
+    let expected = [99];
+    let mut iter = expected.iter();
+    for i in matrix.iter(2) {
+        let j = *iter.next().unwrap();
+        assert_eq!(i, j);
+    }
+    assert!(iter.next().is_none());
+
+    let expected = [22, 75];
+    let mut iter = expected.iter();
+    assert_eq!(matrix.count(3), expected.len());
+    for i in matrix.iter(3) {
+        let j = *iter.next().unwrap();
+        assert_eq!(i, j);
+    }
+    assert!(iter.next().is_none());
+
+    let expected = [0];
+    let mut iter = expected.iter();
+    assert_eq!(matrix.count(4), expected.len());
+    for i in matrix.iter(4) {
+        let j = *iter.next().unwrap();
+        assert_eq!(i, j);
+    }
+    assert!(iter.next().is_none());
+
+    let expected = [22, 75];
+    let mut iter = expected.iter();
+    assert_eq!(matrix.count(5), expected.len());
+    for i in matrix.iter(5) {
+        let j = *iter.next().unwrap();
+        assert_eq!(i, j);
+    }
+    assert!(iter.next().is_none());
+
+    assert_eq!(matrix.count(6), 100);
+    let mut count = 0;
+    for (idx, i) in matrix.iter(6).enumerate() {
+        assert_eq!(idx, i);
+        count += 1;
+    }
+    assert_eq!(count, 100);
+
+    if let Some(i) = matrix.iter(7).next() {
+        panic!("expected no elements in row, but contains element {:?}", i);
+    }
+}
+
+#[test]
+fn sparse_matrix_iter() {
+    let mut matrix: SparseBitMatrix<usize, usize> = SparseBitMatrix::new(100);
+    matrix.insert(3, 22);
+    matrix.insert(3, 75);
+    matrix.insert(2, 99);
+    matrix.insert(4, 0);
+    matrix.union_rows(3, 5);
+
+    let expected = [99];
+    let mut iter = expected.iter();
+    for i in matrix.iter(2) {
+        let j = *iter.next().unwrap();
+        assert_eq!(i, j);
+    }
+    assert!(iter.next().is_none());
+
+    let expected = [22, 75];
+    let mut iter = expected.iter();
+    for i in matrix.iter(3) {
+        let j = *iter.next().unwrap();
+        assert_eq!(i, j);
+    }
+    assert!(iter.next().is_none());
+
+    let expected = [0];
+    let mut iter = expected.iter();
+    for i in matrix.iter(4) {
+        let j = *iter.next().unwrap();
+        assert_eq!(i, j);
+    }
+    assert!(iter.next().is_none());
+
+    let expected = [22, 75];
+    let mut iter = expected.iter();
+    for i in matrix.iter(5) {
+        let j = *iter.next().unwrap();
+        assert_eq!(i, j);
+    }
+    assert!(iter.next().is_none());
+}
+
+/// Merge dense hybrid set into empty sparse hybrid set.
+#[bench]
+fn union_hybrid_sparse_empty_to_dense(b: &mut Bencher) {
+    let mut pre_dense: HybridBitSet<usize> = HybridBitSet::new_empty(256);
+    for i in 0..10 {
+        assert!(pre_dense.insert(i));
+    }
+    let pre_sparse: HybridBitSet<usize> = HybridBitSet::new_empty(256);
+    b.iter(|| {
+        let dense = pre_dense.clone();
+        let mut sparse = pre_sparse.clone();
+        sparse.union(&dense);
+    })
+}
+
+/// Merge dense hybrid set into full hybrid set with same indices.
+#[bench]
+fn union_hybrid_sparse_full_to_dense(b: &mut Bencher) {
+    let mut pre_dense: HybridBitSet<usize> = HybridBitSet::new_empty(256);
+    for i in 0..10 {
+        assert!(pre_dense.insert(i));
+    }
+    let mut pre_sparse: HybridBitSet<usize> = HybridBitSet::new_empty(256);
+    for i in 0..SPARSE_MAX {
+        assert!(pre_sparse.insert(i));
+    }
+    b.iter(|| {
+        let dense = pre_dense.clone();
+        let mut sparse = pre_sparse.clone();
+        sparse.union(&dense);
+    })
+}
+
+/// Merge dense hybrid set into full hybrid set with indices over the whole domain.
+#[bench]
+fn union_hybrid_sparse_domain_to_dense(b: &mut Bencher) {
+    let mut pre_dense: HybridBitSet<usize> = HybridBitSet::new_empty(SPARSE_MAX * 64);
+    for i in 0..10 {
+        assert!(pre_dense.insert(i));
+    }
+    let mut pre_sparse: HybridBitSet<usize> = HybridBitSet::new_empty(SPARSE_MAX * 64);
+    for i in 0..SPARSE_MAX {
+        assert!(pre_sparse.insert(i * 64));
+    }
+    b.iter(|| {
+        let dense = pre_dense.clone();
+        let mut sparse = pre_sparse.clone();
+        sparse.union(&dense);
+    })
+}
+
+/// Merge dense hybrid set into empty hybrid set where the domain is very small.
+#[bench]
+fn union_hybrid_sparse_empty_small_domain(b: &mut Bencher) {
+    let mut pre_dense: HybridBitSet<usize> = HybridBitSet::new_empty(SPARSE_MAX);
+    for i in 0..SPARSE_MAX {
+        assert!(pre_dense.insert(i));
+    }
+    let pre_sparse: HybridBitSet<usize> = HybridBitSet::new_empty(SPARSE_MAX);
+    b.iter(|| {
+        let dense = pre_dense.clone();
+        let mut sparse = pre_sparse.clone();
+        sparse.union(&dense);
+    })
+}
+
+/// Merge dense hybrid set into full hybrid set where the domain is very small.
+#[bench]
+fn union_hybrid_sparse_full_small_domain(b: &mut Bencher) {
+    let mut pre_dense: HybridBitSet<usize> = HybridBitSet::new_empty(SPARSE_MAX);
+    for i in 0..SPARSE_MAX {
+        assert!(pre_dense.insert(i));
+    }
+    let mut pre_sparse: HybridBitSet<usize> = HybridBitSet::new_empty(SPARSE_MAX);
+    for i in 0..SPARSE_MAX {
+        assert!(pre_sparse.insert(i));
+    }
+    b.iter(|| {
+        let dense = pre_dense.clone();
+        let mut sparse = pre_sparse.clone();
+        sparse.union(&dense);
+    })
+}

compiler/rustc_index/src/lib.rs

@@ -0,0 +1,11 @@
+#![feature(allow_internal_unstable)]
+#![feature(bool_to_option)]
+#![feature(const_fn)]
+#![feature(const_panic)]
+#![feature(extend_one)]
+#![feature(unboxed_closures)]
+#![feature(test)]
+#![feature(fn_traits)]
+
+pub mod bit_set;
+pub mod vec;

compiler/rustc_index/src/vec.rs

@@ -0,0 +1,846 @@
+use rustc_serialize::{Decodable, Decoder, Encodable, Encoder};
+
+use std::fmt;
+use std::fmt::Debug;
+use std::hash::Hash;
+use std::iter::{self, FromIterator};
+use std::marker::PhantomData;
+use std::ops::{Index, IndexMut, Range, RangeBounds};
+use std::slice;
+use std::vec;
+
+/// Represents some newtyped `usize` wrapper.
+///
+/// Purpose: avoid mixing indexes for different bitvector domains.
+pub trait Idx: Copy + 'static + Ord + Debug + Hash {
+    fn new(idx: usize) -> Self;
+
+    fn index(self) -> usize;
+
+    fn increment_by(&mut self, amount: usize) {
+        *self = self.plus(amount);
+    }
+
+    fn plus(self, amount: usize) -> Self {
+        Self::new(self.index() + amount)
+    }
+}
+
+impl Idx for usize {
+    #[inline]
+    fn new(idx: usize) -> Self {
+        idx
+    }
+    #[inline]
+    fn index(self) -> usize {
+        self
+    }
+}
+
+impl Idx for u32 {
+    #[inline]
+    fn new(idx: usize) -> Self {
+        assert!(idx <= u32::MAX as usize);
+        idx as u32
+    }
+    #[inline]
+    fn index(self) -> usize {
+        self as usize
+    }
+}
+
+/// Creates a struct type `S` that can be used as an index with
+/// `IndexVec` and so on.
+///
+/// There are two ways of interacting with these indices:
+///
+/// - The `From` impls are the preferred way. So you can do
+///   `S::from(v)` with a `usize` or `u32`. And you can convert back
+///   to an integer with `u32::from(s)`.
+///
+/// - Alternatively, you can use the methods `S::new(v)` and `s.index()`
+///   to create/return a value.
+///
+/// Internally, the index uses a u32, so the index must not exceed
+/// `u32::MAX`. You can also customize things like the `Debug` impl,
+/// what traits are derived, and so forth via the macro.
+#[macro_export]
+#[allow_internal_unstable(step_trait, step_trait_ext, rustc_attrs)]
+macro_rules! newtype_index {
+    // ---- public rules ----
+
+    // Use default constants
+    ($(#[$attrs:meta])* $v:vis struct $name:ident { .. }) => (
+        $crate::newtype_index!(
+            // Leave out derives marker so we can use its absence to ensure it comes first
+            @attrs        [$(#[$attrs])*]
+            @type         [$name]
+            // shave off 256 indices at the end to allow space for packing these indices into enums
+            @max          [0xFFFF_FF00]
+            @vis          [$v]
+            @debug_format ["{}"]);
+    );
+
+    // Define any constants
+    ($(#[$attrs:meta])* $v:vis struct $name:ident { $($tokens:tt)+ }) => (
+        $crate::newtype_index!(
+            // Leave out derives marker so we can use its absence to ensure it comes first
+            @attrs        [$(#[$attrs])*]
+            @type         [$name]
+            // shave off 256 indices at the end to allow space for packing these indices into enums
+            @max          [0xFFFF_FF00]
+            @vis          [$v]
+            @debug_format ["{}"]
+                          $($tokens)+);
+    );
+
+    // ---- private rules ----
+
+    // Base case, user-defined constants (if any) have already been defined
+    (@derives      [$($derives:ident,)*]
+     @attrs        [$(#[$attrs:meta])*]
+     @type         [$type:ident]
+     @max          [$max:expr]
+     @vis          [$v:vis]
+     @debug_format [$debug_format:tt]) => (
+        $(#[$attrs])*
+        #[derive(Copy, PartialEq, Eq, Hash, PartialOrd, Ord, $($derives),*)]
+        #[rustc_layout_scalar_valid_range_end($max)]
+        $v struct $type {
+            private: u32
+        }
+
+        impl Clone for $type {
+            fn clone(&self) -> Self {
+                *self
+            }
+        }
+
+        impl $type {
+            $v const MAX_AS_U32: u32 = $max;
+
+            $v const MAX: Self = Self::from_u32($max);
+
+            #[inline]
+            $v const fn from_usize(value: usize) -> Self {
+                assert!(value <= ($max as usize));
+                unsafe {
+                    Self::from_u32_unchecked(value as u32)
+                }
+            }
+
+            #[inline]
+            $v const fn from_u32(value: u32) -> Self {
+                assert!(value <= $max);
+                unsafe {
+                    Self::from_u32_unchecked(value)
+                }
+            }
+
+            #[inline]
+            $v const unsafe fn from_u32_unchecked(value: u32) -> Self {
+                Self { private: value }
+            }
+
+            /// Extracts the value of this index as an integer.
+            #[inline]
+            $v const fn index(self) -> usize {
+                self.as_usize()
+            }
+
+            /// Extracts the value of this index as a `u32`.
+            #[inline]
+            $v const fn as_u32(self) -> u32 {
+                self.private
+            }
+
+            /// Extracts the value of this index as a `usize`.
+            #[inline]
+            $v const fn as_usize(self) -> usize {
+                self.as_u32() as usize
+            }
+        }
+
+        impl std::ops::Add<usize> for $type {
+            type Output = Self;
+
+            fn add(self, other: usize) -> Self {
+                Self::from_usize(self.index() + other)
+            }
+        }
+
+        impl $crate::vec::Idx for $type {
+            #[inline]
+            fn new(value: usize) -> Self {
+                Self::from_usize(value)
+            }
+
+            #[inline]
+            fn index(self) -> usize {
+                self.as_usize()
+            }
+        }
+
+        unsafe impl ::std::iter::Step for $type {
+            #[inline]
+            fn steps_between(start: &Self, end: &Self) -> Option<usize> {
+                <usize as ::std::iter::Step>::steps_between(
+                    &Self::index(*start),
+                    &Self::index(*end),
+                )
+            }
+
+            #[inline]
+            fn forward_checked(start: Self, u: usize) -> Option<Self> {
+                Self::index(start).checked_add(u).map(Self::from_usize)
+            }
+
+            #[inline]
+            fn backward_checked(start: Self, u: usize) -> Option<Self> {
+                Self::index(start).checked_sub(u).map(Self::from_usize)
+            }
+        }
+
+        impl From<$type> for u32 {
+            #[inline]
+            fn from(v: $type) -> u32 {
+                v.as_u32()
+            }
+        }
+
+        impl From<$type> for usize {
+            #[inline]
+            fn from(v: $type) -> usize {
+                v.as_usize()
+            }
+        }
+
+        impl From<usize> for $type {
+            #[inline]
+            fn from(value: usize) -> Self {
+                Self::from_usize(value)
+            }
+        }
+
+        impl From<u32> for $type {
+            #[inline]
+            fn from(value: u32) -> Self {
+                Self::from_u32(value)
+            }
+        }
+
+        $crate::newtype_index!(
+            @handle_debug
+            @derives      [$($derives,)*]
+            @type         [$type]
+            @debug_format [$debug_format]);
+    );
+
+    // base case for handle_debug where format is custom. No Debug implementation is emitted.
+    (@handle_debug
+     @derives      [$($_derives:ident,)*]
+     @type         [$type:ident]
+     @debug_format [custom]) => ();
+
+    // base case for handle_debug, no debug overrides found, so use default
+    (@handle_debug
+     @derives      []
+     @type         [$type:ident]
+     @debug_format [$debug_format:tt]) => (
+        impl ::std::fmt::Debug for $type {
+            fn fmt(&self, fmt: &mut ::std::fmt::Formatter<'_>) -> ::std::fmt::Result {
+                write!(fmt, $debug_format, self.as_u32())
+            }
+        }
+    );
+
+    // Debug is requested for derive, don't generate any Debug implementation.
+    (@handle_debug
+     @derives      [Debug, $($derives:ident,)*]
+     @type         [$type:ident]
+     @debug_format [$debug_format:tt]) => ();
+
+    // It's not Debug, so just pop it off the front of the derives stack and check the rest.
+    (@handle_debug
+     @derives      [$_derive:ident, $($derives:ident,)*]
+     @type         [$type:ident]
+     @debug_format [$debug_format:tt]) => (
+        $crate::newtype_index!(
+            @handle_debug
+            @derives      [$($derives,)*]
+            @type         [$type]
+            @debug_format [$debug_format]);
+    );
+
+    // Append comma to end of derives list if it's missing
+    (@attrs        [$(#[$attrs:meta])*]
+     @type         [$type:ident]
+     @max          [$max:expr]
+     @vis          [$v:vis]
+     @debug_format [$debug_format:tt]
+                   derive [$($derives:ident),*]
+                   $($tokens:tt)*) => (
+        $crate::newtype_index!(
+            @attrs        [$(#[$attrs])*]
+            @type         [$type]
+            @max          [$max]
+            @vis          [$v]
+            @debug_format [$debug_format]
+                          derive [$($derives,)*]
+                          $($tokens)*);
+    );
+
+    // By not including the @derives marker in this list nor in the default args, we can force it
+    // to come first if it exists. When encodable is custom, just use the derives list as-is.
+    (@attrs        [$(#[$attrs:meta])*]
+     @type         [$type:ident]
+     @max          [$max:expr]
+     @vis          [$v:vis]
+     @debug_format [$debug_format:tt]
+                   derive [$($derives:ident,)+]
+                   ENCODABLE = custom
+                   $($tokens:tt)*) => (
+        $crate::newtype_index!(
+            @attrs        [$(#[$attrs])*]
+            @derives      [$($derives,)+]
+            @type         [$type]
+            @max          [$max]
+            @vis          [$v]
+            @debug_format [$debug_format]
+                          $($tokens)*);
+    );
+
+    // By not including the @derives marker in this list nor in the default args, we can force it
+    // to come first if it exists. When encodable isn't custom, add serialization traits by default.
+    (@attrs        [$(#[$attrs:meta])*]
+     @type         [$type:ident]
+     @max          [$max:expr]
+     @vis          [$v:vis]
+     @debug_format [$debug_format:tt]
+                   derive [$($derives:ident,)+]
+                   $($tokens:tt)*) => (
+        $crate::newtype_index!(
+            @derives      [$($derives,)+]
+            @attrs        [$(#[$attrs])*]
+            @type         [$type]
+            @max          [$max]
+            @vis          [$v]
+            @debug_format [$debug_format]
+                          $($tokens)*);
+        $crate::newtype_index!(@serializable $type);
+    );
+
+    // The case where no derives are added, but encodable is overridden. Don't
+    // derive serialization traits
+    (@attrs        [$(#[$attrs:meta])*]
+     @type         [$type:ident]
+     @max          [$max:expr]
+     @vis          [$v:vis]
+     @debug_format [$debug_format:tt]
+                   ENCODABLE = custom
+                   $($tokens:tt)*) => (
+        $crate::newtype_index!(
+            @derives      []
+            @attrs        [$(#[$attrs])*]
+            @type         [$type]
+            @max          [$max]
+            @vis          [$v]
+            @debug_format [$debug_format]
+                          $($tokens)*);
+    );
+
+    // The case where no derives are added, add serialization derives by default
+    (@attrs        [$(#[$attrs:meta])*]
+     @type         [$type:ident]
+     @max          [$max:expr]
+     @vis          [$v:vis]
+     @debug_format [$debug_format:tt]
+                   $($tokens:tt)*) => (
+        $crate::newtype_index!(
+            @derives      []
+            @attrs        [$(#[$attrs])*]
+            @type         [$type]
+            @max          [$max]
+            @vis          [$v]
+            @debug_format [$debug_format]
+                          $($tokens)*);
+        $crate::newtype_index!(@serializable $type);
+    );
+
+    (@serializable $type:ident) => (
+        impl<D: ::rustc_serialize::Decoder> ::rustc_serialize::Decodable<D> for $type {
+            fn decode(d: &mut D) -> Result<Self, D::Error> {
+                d.read_u32().map(Self::from_u32)
+            }
+        }
+        impl<E: ::rustc_serialize::Encoder> ::rustc_serialize::Encodable<E> for $type {
+            fn encode(&self, e: &mut E) -> Result<(), E::Error> {
+                e.emit_u32(self.private)
+            }
+        }
+    );
+
+    // Rewrite final without comma to one that includes comma
+    (@derives      [$($derives:ident,)*]
+     @attrs        [$(#[$attrs:meta])*]
+     @type         [$type:ident]
+     @max          [$max:expr]
+     @vis          [$v:vis]
+     @debug_format [$debug_format:tt]
+                   $name:ident = $constant:expr) => (
+        $crate::newtype_index!(
+            @derives      [$($derives,)*]
+            @attrs        [$(#[$attrs])*]
+            @type         [$type]
+            @max          [$max]
+            @vis          [$v]
+            @debug_format [$debug_format]
+                          $name = $constant,);
+    );
+
+    // Rewrite final const without comma to one that includes comma
+    (@derives      [$($derives:ident,)*]
+     @attrs        [$(#[$attrs:meta])*]
+     @type         [$type:ident]
+     @max          [$max:expr]
+     @vis          [$v:vis]
+     @debug_format [$debug_format:tt]
+                   $(#[doc = $doc:expr])*
+                   const $name:ident = $constant:expr) => (
+        $crate::newtype_index!(
+            @derives      [$($derives,)*]
+            @attrs        [$(#[$attrs])*]
+            @type         [$type]
+            @max          [$max]
+            @vis          [$v]
+            @debug_format [$debug_format]
+                          $(#[doc = $doc])* const $name = $constant,);
+    );
+
+    // Replace existing default for max
+    (@derives      [$($derives:ident,)*]
+     @attrs        [$(#[$attrs:meta])*]
+     @type         [$type:ident]
+     @max          [$_max:expr]
+     @vis          [$v:vis]
+     @debug_format [$debug_format:tt]
+                   MAX = $max:expr,
+                   $($tokens:tt)*) => (
+        $crate::newtype_index!(
+            @derives      [$($derives,)*]
+            @attrs        [$(#[$attrs])*]
+            @type         [$type]
+            @max          [$max]
+            @vis          [$v]
+            @debug_format [$debug_format]
+                          $($tokens)*);
+    );
+
+    // Replace existing default for debug_format
+    (@derives      [$($derives:ident,)*]
+     @attrs        [$(#[$attrs:meta])*]
+     @type         [$type:ident]
+     @max          [$max:expr]
+     @vis          [$v:vis]
+     @debug_format [$_debug_format:tt]
+                   DEBUG_FORMAT = $debug_format:tt,
+                   $($tokens:tt)*) => (
+        $crate::newtype_index!(
+            @derives      [$($derives,)*]
+            @attrs        [$(#[$attrs])*]
+            @type         [$type]
+            @max          [$max]
+            @vis          [$v]
+            @debug_format [$debug_format]
+                          $($tokens)*);
+    );
+
+    // Assign a user-defined constant
+    (@derives      [$($derives:ident,)*]
+     @attrs        [$(#[$attrs:meta])*]
+     @type         [$type:ident]
+     @max          [$max:expr]
+     @vis          [$v:vis]
+     @debug_format [$debug_format:tt]
+                   $(#[doc = $doc:expr])*
+                   const $name:ident = $constant:expr,
+                   $($tokens:tt)*) => (
+        $(#[doc = $doc])*
+        $v const $name: $type = $type::from_u32($constant);
+        $crate::newtype_index!(
+            @derives      [$($derives,)*]
+            @attrs        [$(#[$attrs])*]
+            @type         [$type]
+            @max          [$max]
+            @vis          [$v]
+            @debug_format [$debug_format]
+                          $($tokens)*);
+    );
+}
+
+#[derive(Clone, PartialEq, Eq, Hash)]
+pub struct IndexVec<I: Idx, T> {
+    pub raw: Vec<T>,
+    _marker: PhantomData<fn(&I)>,
+}
+
+// Whether `IndexVec` is `Send` depends only on the data,
+// not the phantom data.
+unsafe impl<I: Idx, T> Send for IndexVec<I, T> where T: Send {}
+
+impl<S: Encoder, I: Idx, T: Encodable<S>> Encodable<S> for IndexVec<I, T> {
+    fn encode(&self, s: &mut S) -> Result<(), S::Error> {
+        Encodable::encode(&self.raw, s)
+    }
+}
+
+impl<S: Encoder, I: Idx, T: Encodable<S>> Encodable<S> for &IndexVec<I, T> {
+    fn encode(&self, s: &mut S) -> Result<(), S::Error> {
+        Encodable::encode(&self.raw, s)
+    }
+}
+
+impl<D: Decoder, I: Idx, T: Decodable<D>> Decodable<D> for IndexVec<I, T> {
+    fn decode(d: &mut D) -> Result<Self, D::Error> {
+        Decodable::decode(d).map(|v| IndexVec { raw: v, _marker: PhantomData })
+    }
+}
+
+impl<I: Idx, T: fmt::Debug> fmt::Debug for IndexVec<I, T> {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Debug::fmt(&self.raw, fmt)
+    }
+}
+
+pub type Enumerated<I, J> = iter::Map<iter::Enumerate<J>, IntoIdx<I>>;
+
+impl<I: Idx, T> IndexVec<I, T> {
+    #[inline]
+    pub fn new() -> Self {
+        IndexVec { raw: Vec::new(), _marker: PhantomData }
+    }
+
+    #[inline]
+    pub fn from_raw(raw: Vec<T>) -> Self {
+        IndexVec { raw, _marker: PhantomData }
+    }
+
+    #[inline]
+    pub fn with_capacity(capacity: usize) -> Self {
+        IndexVec { raw: Vec::with_capacity(capacity), _marker: PhantomData }
+    }
+
+    #[inline]
+    pub fn from_elem<S>(elem: T, universe: &IndexVec<I, S>) -> Self
+    where
+        T: Clone,
+    {
+        IndexVec { raw: vec![elem; universe.len()], _marker: PhantomData }
+    }
+
+    #[inline]
+    pub fn from_elem_n(elem: T, n: usize) -> Self
+    where
+        T: Clone,
+    {
+        IndexVec { raw: vec![elem; n], _marker: PhantomData }
+    }
+
+    /// Create an `IndexVec` with `n` elements, where the value of each
+    /// element is the result of `func(i)`. (The underlying vector will
+    /// be allocated only once, with a capacity of at least `n`.)
+    #[inline]
+    pub fn from_fn_n(func: impl FnMut(I) -> T, n: usize) -> Self {
+        let indices = (0..n).map(I::new);
+        Self::from_raw(indices.map(func).collect())
+    }
+
+    #[inline]
+    pub fn push(&mut self, d: T) -> I {
+        let idx = I::new(self.len());
+        self.raw.push(d);
+        idx
+    }
+
+    #[inline]
+    pub fn pop(&mut self) -> Option<T> {
+        self.raw.pop()
+    }
+
+    #[inline]
+    pub fn len(&self) -> usize {
+        self.raw.len()
+    }
+
+    /// Gives the next index that will be assigned when `push` is
+    /// called.
+    #[inline]
+    pub fn next_index(&self) -> I {
+        I::new(self.len())
+    }
+
+    #[inline]
+    pub fn is_empty(&self) -> bool {
+        self.raw.is_empty()
+    }
+
+    #[inline]
+    pub fn into_iter(self) -> vec::IntoIter<T> {
+        self.raw.into_iter()
+    }
+
+    #[inline]
+    pub fn into_iter_enumerated(self) -> Enumerated<I, vec::IntoIter<T>> {
+        self.raw.into_iter().enumerate().map(IntoIdx { _marker: PhantomData })
+    }
+
+    #[inline]
+    pub fn iter(&self) -> slice::Iter<'_, T> {
+        self.raw.iter()
+    }
+
+    #[inline]
+    pub fn iter_enumerated(&self) -> Enumerated<I, slice::Iter<'_, T>> {
+        self.raw.iter().enumerate().map(IntoIdx { _marker: PhantomData })
+    }
+
+    #[inline]
+    pub fn indices(&self) -> iter::Map<Range<usize>, IntoIdx<I>> {
+        (0..self.len()).map(IntoIdx { _marker: PhantomData })
+    }
+
+    #[inline]
+    pub fn iter_mut(&mut self) -> slice::IterMut<'_, T> {
+        self.raw.iter_mut()
+    }
+
+    #[inline]
+    pub fn iter_enumerated_mut(&mut self) -> Enumerated<I, slice::IterMut<'_, T>> {
+        self.raw.iter_mut().enumerate().map(IntoIdx { _marker: PhantomData })
+    }
+
+    #[inline]
+    pub fn drain<'a, R: RangeBounds<usize>>(
+        &'a mut self,
+        range: R,
+    ) -> impl Iterator<Item = T> + 'a {
+        self.raw.drain(range)
+    }
+
+    #[inline]
+    pub fn drain_enumerated<'a, R: RangeBounds<usize>>(
+        &'a mut self,
+        range: R,
+    ) -> impl Iterator<Item = (I, T)> + 'a {
+        self.raw.drain(range).enumerate().map(IntoIdx { _marker: PhantomData })
+    }
+
+    #[inline]
+    pub fn last(&self) -> Option<I> {
+        self.len().checked_sub(1).map(I::new)
+    }
+
+    #[inline]
+    pub fn shrink_to_fit(&mut self) {
+        self.raw.shrink_to_fit()
+    }
+
+    #[inline]
+    pub fn swap(&mut self, a: I, b: I) {
+        self.raw.swap(a.index(), b.index())
+    }
+
+    #[inline]
+    pub fn truncate(&mut self, a: usize) {
+        self.raw.truncate(a)
+    }
+
+    #[inline]
+    pub fn get(&self, index: I) -> Option<&T> {
+        self.raw.get(index.index())
+    }
+
+    #[inline]
+    pub fn get_mut(&mut self, index: I) -> Option<&mut T> {
+        self.raw.get_mut(index.index())
+    }
+
+    /// Returns mutable references to two distinct elements, a and b. Panics if a == b.
+    #[inline]
+    pub fn pick2_mut(&mut self, a: I, b: I) -> (&mut T, &mut T) {
+        let (ai, bi) = (a.index(), b.index());
+        assert!(ai != bi);
+
+        if ai < bi {
+            let (c1, c2) = self.raw.split_at_mut(bi);
+            (&mut c1[ai], &mut c2[0])
+        } else {
+            let (c2, c1) = self.pick2_mut(b, a);
+            (c1, c2)
+        }
+    }
+
+    /// Returns mutable references to three distinct elements or panics otherwise.
+    #[inline]
+    pub fn pick3_mut(&mut self, a: I, b: I, c: I) -> (&mut T, &mut T, &mut T) {
+        let (ai, bi, ci) = (a.index(), b.index(), c.index());
+        assert!(ai != bi && bi != ci && ci != ai);
+        let len = self.raw.len();
+        assert!(ai < len && bi < len && ci < len);
+        let ptr = self.raw.as_mut_ptr();
+        unsafe { (&mut *ptr.add(ai), &mut *ptr.add(bi), &mut *ptr.add(ci)) }
+    }
+
+    pub fn convert_index_type<Ix: Idx>(self) -> IndexVec<Ix, T> {
+        IndexVec { raw: self.raw, _marker: PhantomData }
+    }
+}
+
+impl<I: Idx, T: Clone> IndexVec<I, T> {
+    /// Grows the index vector so that it contains an entry for
+    /// `elem`; if that is already true, then has no
+    /// effect. Otherwise, inserts new values as needed by invoking
+    /// `fill_value`.
+    #[inline]
+    pub fn ensure_contains_elem(&mut self, elem: I, fill_value: impl FnMut() -> T) {
+        let min_new_len = elem.index() + 1;
+        if self.len() < min_new_len {
+            self.raw.resize_with(min_new_len, fill_value);
+        }
+    }
+
+    #[inline]
+    pub fn resize(&mut self, new_len: usize, value: T) {
+        self.raw.resize(new_len, value)
+    }
+
+    #[inline]
+    pub fn resize_to_elem(&mut self, elem: I, fill_value: impl FnMut() -> T) {
+        let min_new_len = elem.index() + 1;
+        self.raw.resize_with(min_new_len, fill_value);
+    }
+}
+
+impl<I: Idx, T: Ord> IndexVec<I, T> {
+    #[inline]
+    pub fn binary_search(&self, value: &T) -> Result<I, I> {
+        match self.raw.binary_search(value) {
+            Ok(i) => Ok(Idx::new(i)),
+            Err(i) => Err(Idx::new(i)),
+        }
+    }
+}
+
+impl<I: Idx, T> Index<I> for IndexVec<I, T> {
+    type Output = T;
+
+    #[inline]
+    fn index(&self, index: I) -> &T {
+        &self.raw[index.index()]
+    }
+}
+
+impl<I: Idx, T> IndexMut<I> for IndexVec<I, T> {
+    #[inline]
+    fn index_mut(&mut self, index: I) -> &mut T {
+        &mut self.raw[index.index()]
+    }
+}
+
+impl<I: Idx, T> Default for IndexVec<I, T> {
+    #[inline]
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl<I: Idx, T> Extend<T> for IndexVec<I, T> {
+    #[inline]
+    fn extend<J: IntoIterator<Item = T>>(&mut self, iter: J) {
+        self.raw.extend(iter);
+    }
+
+    #[inline]
+    fn extend_one(&mut self, item: T) {
+        self.raw.push(item);
+    }
+
+    #[inline]
+    fn extend_reserve(&mut self, additional: usize) {
+        self.raw.reserve(additional);
+    }
+}
+
+impl<I: Idx, T> FromIterator<T> for IndexVec<I, T> {
+    #[inline]
+    fn from_iter<J>(iter: J) -> Self
+    where
+        J: IntoIterator<Item = T>,
+    {
+        IndexVec { raw: FromIterator::from_iter(iter), _marker: PhantomData }
+    }
+}
+
+impl<I: Idx, T> IntoIterator for IndexVec<I, T> {
+    type Item = T;
+    type IntoIter = vec::IntoIter<T>;
+
+    #[inline]
+    fn into_iter(self) -> vec::IntoIter<T> {
+        self.raw.into_iter()
+    }
+}
+
+impl<'a, I: Idx, T> IntoIterator for &'a IndexVec<I, T> {
+    type Item = &'a T;
+    type IntoIter = slice::Iter<'a, T>;
+
+    #[inline]
+    fn into_iter(self) -> slice::Iter<'a, T> {
+        self.raw.iter()
+    }
+}
+
+impl<'a, I: Idx, T> IntoIterator for &'a mut IndexVec<I, T> {
+    type Item = &'a mut T;
+    type IntoIter = slice::IterMut<'a, T>;
+
+    #[inline]
+    fn into_iter(self) -> slice::IterMut<'a, T> {
+        self.raw.iter_mut()
+    }
+}
+
+pub struct IntoIdx<I: Idx> {
+    _marker: PhantomData<fn(&I)>,
+}
+impl<I: Idx, T> FnOnce<((usize, T),)> for IntoIdx<I> {
+    type Output = (I, T);
+
+    extern "rust-call" fn call_once(self, ((n, t),): ((usize, T),)) -> Self::Output {
+        (I::new(n), t)
+    }
+}
+
+impl<I: Idx, T> FnMut<((usize, T),)> for IntoIdx<I> {
+    extern "rust-call" fn call_mut(&mut self, ((n, t),): ((usize, T),)) -> Self::Output {
+        (I::new(n), t)
+    }
+}
+
+impl<I: Idx> FnOnce<(usize,)> for IntoIdx<I> {
+    type Output = I;
+
+    extern "rust-call" fn call_once(self, (n,): (usize,)) -> Self::Output {
+        I::new(n)
+    }
+}
+
+impl<I: Idx> FnMut<(usize,)> for IntoIdx<I> {
+    extern "rust-call" fn call_mut(&mut self, (n,): (usize,)) -> Self::Output {
+        I::new(n)
+    }
+}
+
+#[cfg(test)]
+mod tests;

compiler/rustc_index/src/vec/tests.rs

@@ -0,0 +1,51 @@
+#![allow(dead_code)]
+newtype_index!(struct MyIdx { MAX = 0xFFFF_FFFA });
+
+#[test]
+fn index_size_is_optimized() {
+    use std::mem::size_of;
+
+    assert_eq!(size_of::<MyIdx>(), 4);
+    // Uses 0xFFFF_FFFB
+    assert_eq!(size_of::<Option<MyIdx>>(), 4);
+    // Uses 0xFFFF_FFFC
+    assert_eq!(size_of::<Option<Option<MyIdx>>>(), 4);
+    // Uses 0xFFFF_FFFD
+    assert_eq!(size_of::<Option<Option<Option<MyIdx>>>>(), 4);
+    // Uses 0xFFFF_FFFE
+    assert_eq!(size_of::<Option<Option<Option<Option<MyIdx>>>>>(), 4);
+    // Uses 0xFFFF_FFFF
+    assert_eq!(size_of::<Option<Option<Option<Option<Option<MyIdx>>>>>>(), 4);
+    // Uses a tag
+    assert_eq!(size_of::<Option<Option<Option<Option<Option<Option<MyIdx>>>>>>>(), 8);
+}
+
+#[test]
+fn range_iterator_iterates_forwards() {
+    let range = MyIdx::from_u32(1)..MyIdx::from_u32(4);
+    assert_eq!(
+        range.collect::<Vec<_>>(),
+        [MyIdx::from_u32(1), MyIdx::from_u32(2), MyIdx::from_u32(3)]
+    );
+}
+
+#[test]
+fn range_iterator_iterates_backwards() {
+    let range = MyIdx::from_u32(1)..MyIdx::from_u32(4);
+    assert_eq!(
+        range.rev().collect::<Vec<_>>(),
+        [MyIdx::from_u32(3), MyIdx::from_u32(2), MyIdx::from_u32(1)]
+    );
+}
+
+#[test]
+fn range_count_is_correct() {
+    let range = MyIdx::from_u32(1)..MyIdx::from_u32(4);
+    assert_eq!(range.count(), 3);
+}
+
+#[test]
+fn range_size_hint_is_correct() {
+    let range = MyIdx::from_u32(1)..MyIdx::from_u32(4);
+    assert_eq!(range.size_hint(), (3, Some(3)));
+}