Auto merge of #49163 - SimonSapin:range-bounds, r=alexcrichton

Rename RangeArgument to RangeBounds, move it and Bound to libcore

As proposed in the tracking issue: https://github.com/rust-lang/rust/issues/30877

Changes to *stable* items:

* `core::ops::Bound` / `std::ops::Bound` is new
* `std::collections::Bound` is a deprecated reexport of it (does this actually cause a warning?)

Changes to *unstable* items

* `alloc::Bound` is gone
* `alloc::range::RangeArgument` is moved to `core::ops::RangeBounds` / `std::ops::RangeBounds`
* `alloc::range` is gone
* `std::collections::range::RangeArgument` is deprecated reexport, to be removed later
* `std::collections::range` is deprecated, to be removed later
* `impl RangeBounds<T> for Range{,From,To,Inclusive,ToInclusive}<&T>` are added

The idea of replacing this trait with a type to be used with `Into<_>` is left for future consideration / work.

(Fixes https://github.com/rust-lang-nursery/rust-clippy/issues/2552.)

8 files changed, 22 insertions, 229 deletions

diff --git a/src/liballoc/btree/map.rs b/src/liballoc/btree/map.rs
index cada190032a..c604df7049e 100644
--- a/src/liballoc/btree/map.rs
+++ b/src/liballoc/btree/map.rs
@@ -13,12 +13,12 @@ use core::fmt::Debug;
 use core::hash::{Hash, Hasher};
 use core::iter::{FromIterator, Peekable, FusedIterator};
 use core::marker::PhantomData;
+use core::ops::Bound::{Excluded, Included, Unbounded};
 use core::ops::Index;
+use core::ops::RangeBounds;
 use core::{fmt, intrinsics, mem, ptr};
 
 use borrow::Borrow;
-use Bound::{Excluded, Included, Unbounded};
-use range::RangeArgument;
 
 use super::node::{self, Handle, NodeRef, marker};
 use super::search;
@@ -804,7 +804,7 @@ impl<K: Ord, V> BTreeMap<K, V> {
     ///
     /// ```
     /// use std::collections::BTreeMap;
-    /// use std::collections::Bound::Included;
+    /// use std::ops::Bound::Included;
     ///
     /// let mut map = BTreeMap::new();
     /// map.insert(3, "a");
@@ -817,7 +817,7 @@ impl<K: Ord, V> BTreeMap<K, V> {
     /// ```
     #[stable(feature = "btree_range", since = "1.17.0")]
     pub fn range<T: ?Sized, R>(&self, range: R) -> Range<K, V>
-        where T: Ord, K: Borrow<T>, R: RangeArgument<T>
+        where T: Ord, K: Borrow<T>, R: RangeBounds<T>
     {
         let root1 = self.root.as_ref();
         let root2 = self.root.as_ref();
@@ -857,7 +857,7 @@ impl<K: Ord, V> BTreeMap<K, V> {
     /// ```
     #[stable(feature = "btree_range", since = "1.17.0")]
     pub fn range_mut<T: ?Sized, R>(&mut self, range: R) -> RangeMut<K, V>
-        where T: Ord, K: Borrow<T>, R: RangeArgument<T>
+        where T: Ord, K: Borrow<T>, R: RangeBounds<T>
     {
         let root1 = self.root.as_mut();
         let root2 = unsafe { ptr::read(&root1) };
@@ -1812,7 +1812,7 @@ fn last_leaf_edge<BorrowType, K, V>
     }
 }
 
-fn range_search<BorrowType, K, V, Q: ?Sized, R: RangeArgument<Q>>(
+fn range_search<BorrowType, K, V, Q: ?Sized, R: RangeBounds<Q>>(
     root1: NodeRef<BorrowType, K, V, marker::LeafOrInternal>,
     root2: NodeRef<BorrowType, K, V, marker::LeafOrInternal>,
     range: R
diff --git a/src/liballoc/btree/set.rs b/src/liballoc/btree/set.rs
index 2e3157147a0..2aad476d315 100644
--- a/src/liballoc/btree/set.rs
+++ b/src/liballoc/btree/set.rs
@@ -16,12 +16,11 @@ use core::cmp::{min, max};
 use core::fmt::Debug;
 use core::fmt;
 use core::iter::{Peekable, FromIterator, FusedIterator};
-use core::ops::{BitOr, BitAnd, BitXor, Sub};
+use core::ops::{BitOr, BitAnd, BitXor, Sub, RangeBounds};
 
 use borrow::Borrow;
 use btree_map::{BTreeMap, Keys};
 use super::Recover;
-use range::RangeArgument;
 
 // FIXME(conventions): implement bounded iterators
 
@@ -240,7 +239,7 @@ impl<T: Ord> BTreeSet<T> {
     ///
     /// ```
     /// use std::collections::BTreeSet;
-    /// use std::collections::Bound::Included;
+    /// use std::ops::Bound::Included;
     ///
     /// let mut set = BTreeSet::new();
     /// set.insert(3);
@@ -253,7 +252,7 @@ impl<T: Ord> BTreeSet<T> {
     /// ```
     #[stable(feature = "btree_range", since = "1.17.0")]
     pub fn range<K: ?Sized, R>(&self, range: R) -> Range<T>
-        where K: Ord, T: Borrow<K>, R: RangeArgument<K>
+        where K: Ord, T: Borrow<K>, R: RangeBounds<K>
     {
         Range { iter: self.map.range(range) }
     }
diff --git a/src/liballoc/lib.rs b/src/liballoc/lib.rs
index 19d64d8fea9..e98b58994bf 100644
--- a/src/liballoc/lib.rs
+++ b/src/liballoc/lib.rs
@@ -88,6 +88,7 @@
 #![feature(box_syntax)]
 #![feature(cfg_target_has_atomic)]
 #![feature(coerce_unsized)]
+#![feature(collections_range)]
 #![feature(const_fn)]
 #![feature(core_intrinsics)]
 #![feature(custom_attribute)]
@@ -178,7 +179,6 @@ mod btree;
 pub mod borrow;
 pub mod fmt;
 pub mod linked_list;
-pub mod range;
 pub mod slice;
 pub mod str;
 pub mod string;
@@ -204,57 +204,6 @@ mod std {
     pub use core::ops;      // RangeFull
 }
 
-/// An endpoint of a range of keys.
-///
-/// # Examples
-///
-/// `Bound`s are range endpoints:
-///
-/// ```
-/// #![feature(collections_range)]
-///
-/// use std::collections::range::RangeArgument;
-/// use std::collections::Bound::*;
-///
-/// assert_eq!((..100).start(), Unbounded);
-/// assert_eq!((1..12).start(), Included(&1));
-/// assert_eq!((1..12).end(), Excluded(&12));
-/// ```
-///
-/// Using a tuple of `Bound`s as an argument to [`BTreeMap::range`].
-/// Note that in most cases, it's better to use range syntax (`1..5`) instead.
-///
-/// ```
-/// use std::collections::BTreeMap;
-/// use std::collections::Bound::{Excluded, Included, Unbounded};
-///
-/// let mut map = BTreeMap::new();
-/// map.insert(3, "a");
-/// map.insert(5, "b");
-/// map.insert(8, "c");
-///
-/// for (key, value) in map.range((Excluded(3), Included(8))) {
-///     println!("{}: {}", key, value);
-/// }
-///
-/// assert_eq!(Some((&3, &"a")), map.range((Unbounded, Included(5))).next());
-/// ```
-///
-/// [`BTreeMap::range`]: btree_map/struct.BTreeMap.html#method.range
-#[stable(feature = "collections_bound", since = "1.17.0")]
-#[derive(Clone, Copy, Debug, Hash, PartialEq, Eq)]
-pub enum Bound<T> {
-    /// An inclusive bound.
-    #[stable(feature = "collections_bound", since = "1.17.0")]
-    Included(#[stable(feature = "collections_bound", since = "1.17.0")] T),
-    /// An exclusive bound.
-    #[stable(feature = "collections_bound", since = "1.17.0")]
-    Excluded(#[stable(feature = "collections_bound", since = "1.17.0")] T),
-    /// An infinite endpoint. Indicates that there is no bound in this direction.
-    #[stable(feature = "collections_bound", since = "1.17.0")]
-    Unbounded,
-}
-
 /// An intermediate trait for specialization of `Extend`.
 #[doc(hidden)]
 trait SpecExtend<I: IntoIterator> {
diff --git a/src/liballoc/range.rs b/src/liballoc/range.rs
deleted file mode 100644
index b03abc85180..00000000000
--- a/src/liballoc/range.rs
+++ /dev/null
@@ -1,152 +0,0 @@
-// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
-// file at the top-level directory of this distribution and at
-// http://rust-lang.org/COPYRIGHT.
-//
-// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
-// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
-// option. This file may not be copied, modified, or distributed
-// except according to those terms.
-
-#![unstable(feature = "collections_range",
-            reason = "waiting for dust to settle on inclusive ranges",
-            issue = "30877")]
-
-//! Range syntax.
-
-use core::ops::{RangeFull, Range, RangeTo, RangeFrom, RangeInclusive, RangeToInclusive};
-use Bound::{self, Excluded, Included, Unbounded};
-
-/// `RangeArgument` is implemented by Rust's built-in range types, produced
-/// by range syntax like `..`, `a..`, `..b` or `c..d`.
-pub trait RangeArgument<T: ?Sized> {
-    /// Start index bound.
-    ///
-    /// Returns the start value as a `Bound`.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(alloc)]
-    /// #![feature(collections_range)]
-    ///
-    /// extern crate alloc;
-    ///
-    /// # fn main() {
-    /// use alloc::range::RangeArgument;
-    /// use alloc::Bound::*;
-    ///
-    /// assert_eq!((..10).start(), Unbounded);
-    /// assert_eq!((3..10).start(), Included(&3));
-    /// # }
-    /// ```
-    fn start(&self) -> Bound<&T>;
-
-    /// End index bound.
-    ///
-    /// Returns the end value as a `Bound`.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(alloc)]
-    /// #![feature(collections_range)]
-    ///
-    /// extern crate alloc;
-    ///
-    /// # fn main() {
-    /// use alloc::range::RangeArgument;
-    /// use alloc::Bound::*;
-    ///
-    /// assert_eq!((3..).end(), Unbounded);
-    /// assert_eq!((3..10).end(), Excluded(&10));
-    /// # }
-    /// ```
-    fn end(&self) -> Bound<&T>;
-}
-
-// FIXME add inclusive ranges to RangeArgument
-
-impl<T: ?Sized> RangeArgument<T> for RangeFull {
-    fn start(&self) -> Bound<&T> {
-        Unbounded
-    }
-    fn end(&self) -> Bound<&T> {
-        Unbounded
-    }
-}
-
-impl<T> RangeArgument<T> for RangeFrom<T> {
-    fn start(&self) -> Bound<&T> {
-        Included(&self.start)
-    }
-    fn end(&self) -> Bound<&T> {
-        Unbounded
-    }
-}
-
-impl<T> RangeArgument<T> for RangeTo<T> {
-    fn start(&self) -> Bound<&T> {
-        Unbounded
-    }
-    fn end(&self) -> Bound<&T> {
-        Excluded(&self.end)
-    }
-}
-
-impl<T> RangeArgument<T> for Range<T> {
-    fn start(&self) -> Bound<&T> {
-        Included(&self.start)
-    }
-    fn end(&self) -> Bound<&T> {
-        Excluded(&self.end)
-    }
-}
-
-#[stable(feature = "inclusive_range", since = "1.26.0")]
-impl<T> RangeArgument<T> for RangeInclusive<T> {
-    fn start(&self) -> Bound<&T> {
-        Included(&self.start)
-    }
-    fn end(&self) -> Bound<&T> {
-        Included(&self.end)
-    }
-}
-
-#[stable(feature = "inclusive_range", since = "1.26.0")]
-impl<T> RangeArgument<T> for RangeToInclusive<T> {
-    fn start(&self) -> Bound<&T> {
-        Unbounded
-    }
-    fn end(&self) -> Bound<&T> {
-        Included(&self.end)
-    }
-}
-
-impl<T> RangeArgument<T> for (Bound<T>, Bound<T>) {
-    fn start(&self) -> Bound<&T> {
-        match *self {
-            (Included(ref start), _) => Included(start),
-            (Excluded(ref start), _) => Excluded(start),
-            (Unbounded, _)           => Unbounded,
-        }
-    }
-
-    fn end(&self) -> Bound<&T> {
-        match *self {
-            (_, Included(ref end)) => Included(end),
-            (_, Excluded(ref end)) => Excluded(end),
-            (_, Unbounded)         => Unbounded,
-        }
-    }
-}
-
-impl<'a, T: ?Sized + 'a> RangeArgument<T> for (Bound<&'a T>, Bound<&'a T>) {
-    fn start(&self) -> Bound<&T> {
-        self.0
-    }
-
-    fn end(&self) -> Bound<&T> {
-        self.1
-    }
-}
diff --git a/src/liballoc/string.rs b/src/liballoc/string.rs
index 23c12bef3aa..aa202e23628 100644
--- a/src/liballoc/string.rs
+++ b/src/liballoc/string.rs
@@ -59,15 +59,14 @@
 use core::fmt;
 use core::hash;
 use core::iter::{FromIterator, FusedIterator};
-use core::ops::{self, Add, AddAssign, Index, IndexMut};
+use core::ops::Bound::{Excluded, Included, Unbounded};
+use core::ops::{self, Add, AddAssign, Index, IndexMut, RangeBounds};
 use core::ptr;
 use core::str::pattern::Pattern;
 use std_unicode::lossy;
 use std_unicode::char::{decode_utf16, REPLACEMENT_CHARACTER};
 
 use borrow::{Cow, ToOwned};
-use range::RangeArgument;
-use Bound::{Excluded, Included, Unbounded};
 use str::{self, from_boxed_utf8_unchecked, FromStr, Utf8Error, Chars};
 use vec::Vec;
 use boxed::Box;
@@ -1484,7 +1483,7 @@ impl String {
     /// ```
     #[stable(feature = "drain", since = "1.6.0")]
     pub fn drain<R>(&mut self, range: R) -> Drain
-        where R: RangeArgument<usize>
+        where R: RangeBounds<usize>
     {
         // Memory safety
         //
@@ -1548,7 +1547,7 @@ impl String {
     /// ```
     #[unstable(feature = "splice", reason = "recently added", issue = "44643")]
     pub fn splice<R>(&mut self, range: R, replace_with: &str)
-        where R: RangeArgument<usize>
+        where R: RangeBounds<usize>
     {
         // Memory safety
         //
diff --git a/src/liballoc/tests/btree/map.rs b/src/liballoc/tests/btree/map.rs
index 2393101040d..6ebdb86cc4a 100644
--- a/src/liballoc/tests/btree/map.rs
+++ b/src/liballoc/tests/btree/map.rs
@@ -9,8 +9,8 @@
 // except according to those terms.
 
 use std::collections::BTreeMap;
-use std::collections::Bound::{self, Excluded, Included, Unbounded};
 use std::collections::btree_map::Entry::{Occupied, Vacant};
+use std::ops::Bound::{self, Excluded, Included, Unbounded};
 use std::rc::Rc;
 
 use std::iter::FromIterator;
diff --git a/src/liballoc/vec.rs b/src/liballoc/vec.rs
index bcc999d7386..df08e46fe25 100644
--- a/src/liballoc/vec.rs
+++ b/src/liballoc/vec.rs
@@ -75,7 +75,8 @@ use core::marker::PhantomData;
 use core::mem;
 #[cfg(not(test))]
 use core::num::Float;
-use core::ops::{InPlace, Index, IndexMut, Place, Placer};
+use core::ops::Bound::{Excluded, Included, Unbounded};
+use core::ops::{InPlace, Index, IndexMut, Place, Placer, RangeBounds};
 use core::ops;
 use core::ptr;
 use core::ptr::NonNull;
@@ -85,9 +86,7 @@ use borrow::ToOwned;
 use borrow::Cow;
 use boxed::Box;
 use raw_vec::RawVec;
-use super::range::RangeArgument;
 use super::allocator::CollectionAllocErr;
-use Bound::{Excluded, Included, Unbounded};
 
 /// A contiguous growable array type, written `Vec<T>` but pronounced 'vector'.
 ///
@@ -1176,7 +1175,7 @@ impl<T> Vec<T> {
     /// ```
     #[stable(feature = "drain", since = "1.6.0")]
     pub fn drain<R>(&mut self, range: R) -> Drain<T>
-        where R: RangeArgument<usize>
+        where R: RangeBounds<usize>
     {
         // Memory safety
         //
@@ -1950,7 +1949,7 @@ impl<T> Vec<T> {
     #[inline]
     #[stable(feature = "vec_splice", since = "1.21.0")]
     pub fn splice<R, I>(&mut self, range: R, replace_with: I) -> Splice<I::IntoIter>
-        where R: RangeArgument<usize>, I: IntoIterator<Item=T>
+        where R: RangeBounds<usize>, I: IntoIterator<Item=T>
     {
         Splice {
             drain: self.drain(range),
diff --git a/src/liballoc/vec_deque.rs b/src/liballoc/vec_deque.rs
index be6e8d0f22f..94d042a45aa 100644
--- a/src/liballoc/vec_deque.rs
+++ b/src/liballoc/vec_deque.rs
@@ -21,7 +21,8 @@ use core::cmp::Ordering;
 use core::fmt;
 use core::iter::{repeat, FromIterator, FusedIterator};
 use core::mem;
-use core::ops::{Index, IndexMut, Place, Placer, InPlace};
+use core::ops::Bound::{Excluded, Included, Unbounded};
+use core::ops::{Index, IndexMut, Place, Placer, InPlace, RangeBounds};
 use core::ptr;
 use core::ptr::NonNull;
 use core::slice;
@@ -32,8 +33,6 @@ use core::cmp;
 use raw_vec::RawVec;
 
 use super::allocator::CollectionAllocErr;
-use super::range::RangeArgument;
-use Bound::{Excluded, Included, Unbounded};
 use super::vec::Vec;
 
 const INITIAL_CAPACITY: usize = 7; // 2^3 - 1
@@ -969,7 +968,7 @@ impl<T> VecDeque<T> {
     #[inline]
     #[stable(feature = "drain", since = "1.6.0")]
     pub fn drain<R>(&mut self, range: R) -> Drain<T>
-        where R: RangeArgument<usize>
+        where R: RangeBounds<usize>
     {
         // Memory safety
         //