Improve hygiene of `newtype_index`

Also add unit tests

13 files changed, 80 insertions, 52 deletions

diff --git a/src/librustc/dep_graph/serialized.rs b/src/librustc/dep_graph/serialized.rs
index 640877d3d55..45ef52dbf39 100644
--- a/src/librustc/dep_graph/serialized.rs
+++ b/src/librustc/dep_graph/serialized.rs
@@ -2,7 +2,7 @@
 
 use crate::dep_graph::DepNode;
 use crate::ich::Fingerprint;
-use rustc_index::vec::{Idx, IndexVec};
+use rustc_index::vec::IndexVec;
 
 rustc_index::newtype_index! {
     pub struct SerializedDepNodeIndex { .. }
diff --git a/src/librustc/middle/region.rs b/src/librustc/middle/region.rs
index b2a5efca92d..9e9c8bd8464 100644
--- a/src/librustc/middle/region.rs
+++ b/src/librustc/middle/region.rs
@@ -14,7 +14,6 @@ use rustc_hir::Node;
 
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
-use rustc_index::vec::Idx;
 use rustc_macros::HashStable;
 use rustc_span::{Span, DUMMY_SP};
 
diff --git a/src/librustc_hir/hir_id.rs b/src/librustc_hir/hir_id.rs
index 46294641171..6d2ec445763 100644
--- a/src/librustc_hir/hir_id.rs
+++ b/src/librustc_hir/hir_id.rs
@@ -56,7 +56,6 @@ impl fmt::Display for HirId {
 rustc_data_structures::define_id_collections!(HirIdMap, HirIdSet, HirId);
 rustc_data_structures::define_id_collections!(ItemLocalMap, ItemLocalSet, ItemLocalId);
 
-use rustc_index::vec::Idx;
 rustc_index::newtype_index! {
     /// An `ItemLocalId` uniquely identifies something within a given "item-like";
     /// that is, within a `hir::Item`, `hir::TraitItem`, or `hir::ImplItem`. There is no
diff --git a/src/librustc_index/vec.rs b/src/librustc_index/vec.rs
index 1f6a330cdc2..d14bafb44fd 100644
--- a/src/librustc_index/vec.rs
+++ b/src/librustc_index/vec.rs
@@ -120,13 +120,13 @@ macro_rules! newtype_index {
         impl $type {
             $v const MAX_AS_U32: u32 = $max;
 
-            $v const MAX: $type = $type::from_u32_const($max);
+            $v const MAX: Self = Self::from_u32_const($max);
 
             #[inline]
             $v fn from_usize(value: usize) -> Self {
                 assert!(value <= ($max as usize));
                 unsafe {
-                    $type::from_u32_unchecked(value as u32)
+                    Self::from_u32_unchecked(value as u32)
                 }
             }
 
@@ -134,7 +134,7 @@ macro_rules! newtype_index {
             $v fn from_u32(value: u32) -> Self {
                 assert!(value <= $max);
                 unsafe {
-                    $type::from_u32_unchecked(value)
+                    Self::from_u32_unchecked(value)
                 }
             }
 
@@ -152,13 +152,13 @@ macro_rules! newtype_index {
                 ];
 
                 unsafe {
-                    $type { private: value }
+                    Self { private: value }
                 }
             }
 
             #[inline]
             $v const unsafe fn from_u32_unchecked(value: u32) -> Self {
-                $type { private: value }
+                Self { private: value }
             }
 
             /// Extracts the value of this index as an integer.
@@ -184,14 +184,14 @@ macro_rules! newtype_index {
             type Output = Self;
 
             fn add(self, other: usize) -> Self {
-                Self::new(self.index() + other)
+                Self::from_usize(self.index() + other)
             }
         }
 
-        impl Idx for $type {
+        impl $crate::vec::Idx for $type {
             #[inline]
             fn new(value: usize) -> Self {
-                Self::from(value)
+                Self::from_usize(value)
             }
 
             #[inline]
@@ -204,39 +204,39 @@ macro_rules! newtype_index {
             #[inline]
             fn steps_between(start: &Self, end: &Self) -> Option<usize> {
                 <usize as ::std::iter::Step>::steps_between(
-                    &Idx::index(*start),
-                    &Idx::index(*end),
+                    &Self::index(*start),
+                    &Self::index(*end),
                 )
             }
 
             #[inline]
             fn replace_one(&mut self) -> Self {
-                ::std::mem::replace(self, Self::new(1))
+                ::std::mem::replace(self, Self::from_u32(1))
             }
 
             #[inline]
             fn replace_zero(&mut self) -> Self {
-                ::std::mem::replace(self, Self::new(0))
+                ::std::mem::replace(self, Self::from_u32(0))
             }
 
             #[inline]
             fn add_one(&self) -> Self {
-                Self::new(Idx::index(*self) + 1)
+                Self::from_usize(Self::index(*self) + 1)
             }
 
             #[inline]
             fn sub_one(&self) -> Self {
-                Self::new(Idx::index(*self) - 1)
+                Self::from_usize(Self::index(*self) - 1)
             }
 
             #[inline]
             fn add_usize(&self, u: usize) -> Option<Self> {
-                Idx::index(*self).checked_add(u).map(Self::new)
+                Self::index(*self).checked_add(u).map(Self::from_usize)
             }
 
             #[inline]
             fn sub_usize(&self, u: usize) -> Option<Self> {
-                Idx::index(*self).checked_sub(u).map(Self::new)
+                Self::index(*self).checked_sub(u).map(Self::from_usize)
             }
         }
 
@@ -257,14 +257,14 @@ macro_rules! newtype_index {
         impl From<usize> for $type {
             #[inline]
             fn from(value: usize) -> Self {
-                $type::from_usize(value)
+                Self::from_usize(value)
             }
         }
 
         impl From<u32> for $type {
             #[inline]
             fn from(value: u32) -> Self {
-                $type::from_u32(value)
+                Self::from_u32(value)
             }
         }
 
@@ -409,7 +409,7 @@ macro_rules! newtype_index {
     (@decodable $type:ident) => (
         impl ::rustc_serialize::Decodable for $type {
             fn decode<D: ::rustc_serialize::Decoder>(d: &mut D) -> Result<Self, D::Error> {
-                d.read_u32().map(Self::from)
+                d.read_u32().map(Self::from_u32)
             }
         }
     );
@@ -500,7 +500,7 @@ macro_rules! newtype_index {
                    const $name:ident = $constant:expr,
                    $($tokens:tt)*) => (
         $(#[doc = $doc])*
-        pub const $name: $type = $type::from_u32_const($constant);
+        $v const $name: $type = $type::from_u32_const($constant);
         $crate::newtype_index!(
             @derives      [$($derives,)*]
             @attrs        [$(#[$attrs])*]
@@ -839,3 +839,6 @@ impl<I: Idx> FnMut<(usize,)> for IntoIdx<I> {
         I::new(n)
     }
 }
+
+#[cfg(test)]
+mod tests;
diff --git a/src/librustc_index/vec/tests.rs b/src/librustc_index/vec/tests.rs
new file mode 100644
index 00000000000..15c43c72c7b
--- /dev/null
+++ b/src/librustc_index/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)));
+}
diff --git a/src/librustc_mir/borrow_check/constraints/mod.rs b/src/librustc_mir/borrow_check/constraints/mod.rs
index 48defecd28c..ef70b127ac5 100644
--- a/src/librustc_mir/borrow_check/constraints/mod.rs
+++ b/src/librustc_mir/borrow_check/constraints/mod.rs
@@ -1,7 +1,7 @@
 use rustc::mir::ConstraintCategory;
 use rustc::ty::RegionVid;
 use rustc_data_structures::graph::scc::Sccs;
-use rustc_index::vec::{Idx, IndexVec};
+use rustc_index::vec::IndexVec;
 use std::fmt;
 use std::ops::Index;
 
diff --git a/src/librustc_mir/borrow_check/member_constraints.rs b/src/librustc_mir/borrow_check/member_constraints.rs
index 53fa5b12698..c95919685bb 100644
--- a/src/librustc_mir/borrow_check/member_constraints.rs
+++ b/src/librustc_mir/borrow_check/member_constraints.rs
@@ -2,7 +2,7 @@ use crate::rustc::ty::{self, Ty};
 use rustc::infer::region_constraints::MemberConstraint;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_hir::def_id::DefId;
-use rustc_index::vec::{Idx, IndexVec};
+use rustc_index::vec::IndexVec;
 use rustc_span::Span;
 use std::hash::Hash;
 use std::ops::Index;
diff --git a/src/librustc_mir/borrow_check/type_check/liveness/local_use_map.rs b/src/librustc_mir/borrow_check/type_check/liveness/local_use_map.rs
index 7bf355ddbf6..8155aa0ee00 100644
--- a/src/librustc_mir/borrow_check/type_check/liveness/local_use_map.rs
+++ b/src/librustc_mir/borrow_check/type_check/liveness/local_use_map.rs
@@ -1,7 +1,7 @@
 use rustc::mir::visit::{PlaceContext, Visitor};
 use rustc::mir::{Local, Location, ReadOnlyBodyAndCache};
 use rustc_data_structures::vec_linked_list as vll;
-use rustc_index::vec::{Idx, IndexVec};
+use rustc_index::vec::IndexVec;
 
 use crate::util::liveness::{categorize, DefUse};
 
diff --git a/src/librustc_mir/dataflow/impls/borrows.rs b/src/librustc_mir/dataflow/impls/borrows.rs
index 30eccebd331..8d51cb23912 100644
--- a/src/librustc_mir/dataflow/impls/borrows.rs
+++ b/src/librustc_mir/dataflow/impls/borrows.rs
@@ -4,7 +4,7 @@ use rustc::ty::{self, TyCtxt};
 
 use rustc_data_structures::fx::FxHashMap;
 use rustc_index::bit_set::BitSet;
-use rustc_index::vec::{Idx, IndexVec};
+use rustc_index::vec::IndexVec;
 
 use crate::borrow_check::{
     places_conflict, BorrowData, BorrowSet, PlaceConflictBias, PlaceExt, RegionInferenceContext,
diff --git a/src/librustc_mir/dataflow/move_paths/mod.rs b/src/librustc_mir/dataflow/move_paths/mod.rs
index 6450762d351..e5cddaf6c66 100644
--- a/src/librustc_mir/dataflow/move_paths/mod.rs
+++ b/src/librustc_mir/dataflow/move_paths/mod.rs
@@ -2,7 +2,7 @@ use core::slice::Iter;
 use rustc::mir::*;
 use rustc::ty::{ParamEnv, Ty, TyCtxt};
 use rustc_data_structures::fx::FxHashMap;
-use rustc_index::vec::{Enumerated, Idx, IndexVec};
+use rustc_index::vec::{Enumerated, IndexVec};
 use rustc_span::Span;
 use smallvec::SmallVec;
 
diff --git a/src/librustc_session/node_id.rs b/src/librustc_session/node_id.rs
index 5e51c5a92cc..9fefe908e57 100644
--- a/src/librustc_session/node_id.rs
+++ b/src/librustc_session/node_id.rs
@@ -1,4 +1,3 @@
-use rustc_index::vec::Idx;
 use rustc_serialize::{Decoder, Encoder};
 use rustc_span::ExpnId;
 use std::fmt;
diff --git a/src/librustc_span/symbol.rs b/src/librustc_span/symbol.rs
index fea72744d31..40abc8b2179 100644
--- a/src/librustc_span/symbol.rs
+++ b/src/librustc_span/symbol.rs
@@ -5,7 +5,6 @@
 use arena::DroplessArena;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher, ToStableHashKey};
-use rustc_index::vec::Idx;
 use rustc_macros::{symbols, HashStable_Generic};
 use rustc_serialize::{Decodable, Decoder, Encodable, Encoder};
 use rustc_serialize::{UseSpecializedDecodable, UseSpecializedEncodable};
diff --git a/src/test/ui-fulldeps/newtype_index.rs b/src/test/ui-fulldeps/newtype_index.rs
deleted file mode 100644
index fe68b394e5a..00000000000
--- a/src/test/ui-fulldeps/newtype_index.rs
+++ /dev/null
@@ -1,22 +0,0 @@
-// run-pass
-
-#![feature(rustc_private)]
-
-extern crate rustc_index;
-extern crate serialize as rustc_serialize;
-
-use rustc_index::{newtype_index, vec::Idx};
-
-newtype_index!(struct MyIdx { MAX = 0xFFFF_FFFA });
-
-use std::mem::size_of;
-
-fn main() {
-    assert_eq!(size_of::<MyIdx>(), 4);
-    assert_eq!(size_of::<Option<MyIdx>>(), 4);
-    assert_eq!(size_of::<Option<Option<MyIdx>>>(), 4);
-    assert_eq!(size_of::<Option<Option<Option<MyIdx>>>>(), 4);
-    assert_eq!(size_of::<Option<Option<Option<Option<MyIdx>>>>>(), 4);
-    assert_eq!(size_of::<Option<Option<Option<Option<Option<MyIdx>>>>>>(), 4);
-    assert_eq!(size_of::<Option<Option<Option<Option<Option<Option<MyIdx>>>>>>>(), 8);
-}