liballoc: refactor & fix some imports.

src/liballoc/alloc.rs

@@ -2,9 +2,11 @@
 
 #![stable(feature = "alloc_module", since = "1.28.0")]
 
-use core::intrinsics::{min_align_of_val, size_of_val};
-use core::ptr::{NonNull, Unique};
-use core::usize;
+use core::{
+    intrinsics::{min_align_of_val, size_of_val},
+    ptr::{NonNull, Unique},
+    usize,
+};
 
 #[stable(feature = "alloc_module", since = "1.28.0")]
 #[doc(inline)]
@@ -228,8 +230,10 @@ pub fn handle_alloc_error(layout: Layout) -> ! {
 mod tests {
     extern crate test;
     use self::test::Bencher;
-    use boxed::Box;
-    use alloc::{Global, Alloc, Layout, handle_alloc_error};
+    use crate::{
+        boxed::Box,
+        alloc::{Global, Alloc, Layout, handle_alloc_error},
+    };
 
     #[test]
     fn allocate_zeroed() {

src/liballoc/benches/btree/map.rs

@@ -1,6 +1,8 @@
-use std::iter::Iterator;
-use std::vec::Vec;
-use std::collections::BTreeMap;
+use std::{
+    iter::Iterator,
+    vec::Vec,
+    collections::BTreeMap,
+};
 use rand::{Rng, seq::SliceRandom, thread_rng};
 use test::{Bencher, black_box};
 

src/liballoc/benches/slice.rs

@@ -1,9 +1,8 @@
-use rand::{thread_rng};
-use std::mem;
-use std::ptr;
-
-use rand::{Rng, SeedableRng};
-use rand::distributions::{Standard, Alphanumeric};
+use std::{mem, ptr};
+use rand::{
+    thread_rng, Rng, SeedableRng,
+    distributions::{Standard, Alphanumeric},
+};
 use rand_xorshift::XorShiftRng;
 use test::{Bencher, black_box};
 

src/liballoc/borrow.rs

@@ -2,12 +2,13 @@
 
 #![stable(feature = "rust1", since = "1.0.0")]
 
-use core::cmp::Ordering;
-use core::hash::{Hash, Hasher};
-use core::ops::{Add, AddAssign, Deref};
+use core::{
+    cmp::Ordering,
+    hash::{Hash, Hasher},
+    ops::{Add, AddAssign, Deref},
+};
 
-use crate::fmt;
-use crate::string::String;
+use crate::{fmt, string::String};
 
 use self::Cow::*;
 

src/liballoc/boxed.rs

@@ -56,26 +56,28 @@
 
 #![stable(feature = "rust1", since = "1.0.0")]
 
-use core::any::Any;
-use core::borrow;
-use core::cmp::Ordering;
-use core::convert::From;
-use core::fmt;
-use core::future::Future;
-use core::hash::{Hash, Hasher};
-use core::iter::{Iterator, FromIterator, FusedIterator};
-use core::marker::{Unpin, Unsize};
-use core::mem;
-use core::pin::Pin;
-use core::ops::{
-    CoerceUnsized, DispatchFromDyn, Deref, DerefMut, Receiver, Generator, GeneratorState
+use core::{
+    any::Any,
+    borrow,
+    cmp::Ordering,
+    convert::From,
+    fmt,
+    future::Future,
+    hash::{Hash, Hasher},
+    iter::{Iterator, FromIterator, FusedIterator},
+    marker::{Unpin, Unsize},
+    mem,
+    pin::Pin,
+    ops::{CoerceUnsized, DispatchFromDyn, Deref, DerefMut, Receiver, Generator, GeneratorState},
+    ptr::{self, NonNull, Unique},
+    task::{LocalWaker, Poll},
 };
-use core::ptr::{self, NonNull, Unique};
-use core::task::{LocalWaker, Poll};
 
-use crate::vec::Vec;
-use crate::raw_vec::RawVec;
-use crate::str::from_boxed_utf8_unchecked;
+use crate::{
+    vec::Vec,
+    raw_vec::RawVec,
+    str::from_boxed_utf8_unchecked,
+};
 
 /// A pointer type for heap allocation.
 ///

src/liballoc/boxed_test.rs

@@ -1,11 +1,13 @@
 //! Test for `boxed` mod.
 
-use core::any::Any;
-use core::ops::Deref;
-use core::result::Result::{Err, Ok};
-use core::clone::Clone;
-use core::f64;
-use core::i64;
+use core::{
+    any::Any,
+    ops::Deref,
+    result::Result::{Err, Ok},
+    clone::Clone,
+    f64,
+    i64,
+};
 
 use std::boxed::Box;
 

src/liballoc/collections/binary_heap.rs

@@ -145,14 +145,18 @@
 #![allow(missing_docs)]
 #![stable(feature = "rust1", since = "1.0.0")]
 
-use core::ops::{Deref, DerefMut};
-use core::iter::{FromIterator, FusedIterator};
-use core::mem::{swap, size_of, ManuallyDrop};
-use core::ptr;
-use core::fmt;
+use core::{
+    ops::{Deref, DerefMut},
+    iter::{FromIterator, FusedIterator},
+    mem::{swap, size_of, ManuallyDrop},
+    ptr,
+    fmt,
+};
 
-use crate::slice;
-use crate::vec::{self, Vec};
+use crate::{
+    slice,
+    vec::{self, Vec},
+};
 
 use super::SpecExtend;
 

src/liballoc/collections/btree/map.rs

@@ -1,23 +1,24 @@
-use core::cmp::Ordering;
-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 core::{
+    cmp::Ordering,
+    fmt::Debug,
+    hash::{Hash, Hasher},
+    iter::{FromIterator, Peekable, FusedIterator},
+    marker::PhantomData,
+    ops::{
+        Bound::{Excluded, Included, Unbounded},
+        Index, RangeBounds,
+    },
+    fmt, intrinsics, mem, ptr,
+};
 
 use crate::borrow::Borrow;
 
-use super::node::{self, Handle, NodeRef, marker};
-use super::search;
+use super::{
+    node::{self, Handle, NodeRef, marker, InsertResult::*, ForceResult::*},
+    search::{self, SearchResult::*},
+};
 
-use super::node::InsertResult::*;
-use super::node::ForceResult::*;
-use super::search::SearchResult::*;
-use self::UnderflowResult::*;
-use self::Entry::*;
+use self::{UnderflowResult::*, Entry::*};
 
 /// A map based on a B-Tree.
 ///

src/liballoc/collections/btree/node.rs

@@ -31,13 +31,17 @@
 // - A node of length `n` has `n` keys, `n` values, and (in an internal node) `n + 1` edges.
 //   This implies that even an empty internal node has at least one edge.
 
-use core::marker::PhantomData;
-use core::mem::{self, MaybeUninit};
-use core::ptr::{self, Unique, NonNull};
-use core::slice;
+use core::{
+    marker::PhantomData,
+    mem::{self, MaybeUninit},
+    ptr::{self, Unique, NonNull},
+    slice,
+};
 
-use crate::alloc::{Global, Alloc, Layout};
-use crate::boxed::Box;
+use crate::{
+    alloc::{Global, Alloc, Layout},
+    boxed::Box,
+};
 
 const B: usize = 6;
 pub const MIN_LEN: usize = B - 1;

src/liballoc/collections/btree/search.rs

@@ -2,9 +2,8 @@
 
 use crate::borrow::Borrow;
 
-use super::node::{Handle, NodeRef, marker};
+use super::node::{Handle, NodeRef, marker, ForceResult::*};
 
-use super::node::ForceResult::*;
 use self::SearchResult::*;
 
 pub enum SearchResult<BorrowType, K, V, FoundType, GoDownType> {

src/liballoc/collections/btree/set.rs

@@ -1,15 +1,20 @@
 // This is pretty much entirely stolen from TreeSet, since BTreeMap has an identical interface
 // to TreeMap
 
-use core::cmp::Ordering::{self, Less, Greater, Equal};
-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, RangeBounds};
+use core::{
+    cmp::{
+        Ordering::{self, Less, Greater, Equal},
+        min, max,
+    },
+    fmt::{self, Debug},
+    iter::{Peekable, FromIterator, FusedIterator},
+    ops::{BitOr, BitAnd, BitXor, Sub, RangeBounds},
+};
 
-use crate::borrow::Borrow;
-use crate::collections::btree_map::{self, BTreeMap, Keys};
+use crate::{
+    borrow::Borrow,
+    collections::btree_map::{self, BTreeMap, Keys},
+};
 use super::Recover;
 
 // FIXME(conventions): implement bounded iterators

src/liballoc/collections/linked_list.rs

@@ -12,13 +12,15 @@
 
 #![stable(feature = "rust1", since = "1.0.0")]
 
-use core::cmp::Ordering;
-use core::fmt;
-use core::hash::{Hasher, Hash};
-use core::iter::{FromIterator, FusedIterator};
-use core::marker::PhantomData;
-use core::mem;
-use core::ptr::NonNull;
+use core::{
+    cmp::Ordering,
+    fmt,
+    hash::{Hasher, Hash},
+    iter::{FromIterator, FusedIterator},
+    marker::PhantomData,
+    mem,
+    ptr::NonNull,
+};
 
 use crate::boxed::Box;
 use super::SpecExtend;
@@ -1213,11 +1215,8 @@ unsafe impl<'a, T: Sync> Sync for IterMut<'a, T> {}
 
 #[cfg(test)]
 mod tests {
-    use std::thread;
-    use std::vec::Vec;
-
+    use std::{thread, vec::Vec};
     use rand::{thread_rng, RngCore};
-
     use super::{LinkedList, Node};
 
     #[cfg(test)]

src/liballoc/collections/vec_deque.rs

@@ -7,22 +7,25 @@
 
 #![stable(feature = "rust1", since = "1.0.0")]
 
-use core::cmp::Ordering;
-use core::fmt;
-use core::iter::{repeat_with, FromIterator, FusedIterator};
-use core::mem;
-use core::ops::Bound::{Excluded, Included, Unbounded};
-use core::ops::{Index, IndexMut, RangeBounds, Try};
-use core::ptr;
-use core::ptr::NonNull;
-use core::slice;
+use core::{
+    cmp::{self, Ordering},
+    fmt,
+    iter::{repeat_with, FromIterator, FusedIterator},
+    mem,
+    ops::{
+        Bound::{Excluded, Included, Unbounded},
+        Index, IndexMut, RangeBounds, Try,
+    },
+    ptr::{self, NonNull},
+    slice,
+    hash::{Hash, Hasher},
+};
 
-use core::hash::{Hash, Hasher};
-use core::cmp;
-
-use crate::collections::CollectionAllocErr;
-use crate::raw_vec::RawVec;
-use crate::vec::Vec;
+use crate::{
+    collections::CollectionAllocErr,
+    raw_vec::RawVec,
+    vec::Vec,
+};
 
 const INITIAL_CAPACITY: usize = 7; // 2^3 - 1
 const MINIMUM_CAPACITY: usize = 1; // 2 - 1
@@ -2758,7 +2761,7 @@ fn from(other: VecDeque<T>) -> Self {
 
 #[cfg(test)]
 mod tests {
-    use test;
+    use ::test;
 
     use super::VecDeque;
 
@@ -3036,7 +3039,7 @@ fn test_split_off() {
 
     #[test]
     fn test_from_vec() {
-        use vec::Vec;
+        use crate::vec::Vec;
         for cap in 0..35 {
             for len in 0..=cap {
                 let mut vec = Vec::with_capacity(cap);
@@ -3052,7 +3055,7 @@ fn test_from_vec() {
 
     #[test]
     fn test_vec_from_vecdeque() {
-        use vec::Vec;
+        use crate::vec::Vec;
 
         fn create_vec_and_test_convert(cap: usize, offset: usize, len: usize) {
             let mut vd = VecDeque::with_capacity(cap);
@@ -3114,7 +3117,7 @@ fn create_vec_and_test_convert(cap: usize, offset: usize, len: usize) {
 
     #[test]
     fn issue_53529() {
-        use boxed::Box;
+        use crate::boxed::Box;
 
         let mut dst = VecDeque::new();
         dst.push_front(Box::new(1));

src/liballoc/fmt.rs

@@ -509,21 +509,16 @@
 #[unstable(feature = "fmt_internals", issue = "0")]
 pub use core::fmt::rt;
 #[stable(feature = "rust1", since = "1.0.0")]
-pub use core::fmt::{Formatter, Result, Write};
-#[stable(feature = "rust1", since = "1.0.0")]
-pub use core::fmt::{Binary, Octal};
-#[stable(feature = "rust1", since = "1.0.0")]
-pub use core::fmt::{Debug, Display};
-#[stable(feature = "rust1", since = "1.0.0")]
-pub use core::fmt::{LowerHex, Pointer, UpperHex};
-#[stable(feature = "rust1", since = "1.0.0")]
-pub use core::fmt::{LowerExp, UpperExp};
-#[stable(feature = "rust1", since = "1.0.0")]
-pub use core::fmt::Error;
-#[stable(feature = "rust1", since = "1.0.0")]
-pub use core::fmt::{write, ArgumentV1, Arguments};
-#[stable(feature = "rust1", since = "1.0.0")]
-pub use core::fmt::{DebugList, DebugMap, DebugSet, DebugStruct, DebugTuple};
+pub use core::fmt::{
+    Formatter, Result, Write,
+    Binary, Octal,
+    Debug, Display,
+    LowerHex, Pointer, UpperHex,
+    LowerExp, UpperExp,
+    Error,
+    write, ArgumentV1, Arguments,
+    DebugList, DebugMap, DebugSet, DebugStruct, DebugTuple
+};
 #[stable(feature = "fmt_flags_align", since = "1.28.0")]
 pub use core::fmt::{Alignment};
 

src/liballoc/prelude.rs

@@ -12,8 +12,11 @@
 
 #![unstable(feature = "alloc", issue = "27783")]
 
-#[unstable(feature = "alloc", issue = "27783")] pub use crate::borrow::ToOwned;
-#[unstable(feature = "alloc", issue = "27783")] pub use crate::boxed::Box;
-#[unstable(feature = "alloc", issue = "27783")] pub use crate::slice::SliceConcatExt;
-#[unstable(feature = "alloc", issue = "27783")] pub use crate::string::{String, ToString};
-#[unstable(feature = "alloc", issue = "27783")] pub use crate::vec::Vec;
+#[unstable(feature = "alloc", issue = "27783")]
+pub use crate::{
+    borrow::ToOwned,
+    boxed::Box,
+    slice::SliceConcatExt,
+    string::{String, ToString},
+    vec::Vec,
+};

src/liballoc/raw_vec.rs

@@ -1,16 +1,19 @@
 #![unstable(feature = "raw_vec_internals", reason = "implementation detail", issue = "0")]
 #![doc(hidden)]
 
-use core::cmp;
-use core::mem;
-use core::ops::Drop;
-use core::ptr::{self, NonNull, Unique};
-use core::slice;
+use core::{
+    cmp,
+    mem,
+    ops::Drop,
+    ptr::{self, NonNull, Unique},
+    slice,
+};
 
-use crate::alloc::{Alloc, Layout, Global, handle_alloc_error};
-use crate::collections::CollectionAllocErr;
-use crate::collections::CollectionAllocErr::*;
-use crate::boxed::Box;
+use crate::{
+    alloc::{Alloc, Layout, Global, handle_alloc_error},
+    collections::CollectionAllocErr::{self, *},
+    boxed::Box,
+};
 
 /// A low-level utility for more ergonomically allocating, reallocating, and deallocating
 /// a buffer of memory on the heap without having to worry about all the corner cases
@@ -753,7 +756,7 @@ mod tests {
 
     #[test]
     fn allocator_param() {
-        use alloc::AllocErr;
+        use crate::alloc::AllocErr;
 
         // Writing a test of integration between third-party
         // allocators and RawVec is a little tricky because the RawVec

src/liballoc/rc.rs

@@ -231,26 +231,28 @@
 #[cfg(test)]
 use std::boxed::Box;
 
-use core::any::Any;
-use core::borrow;
-use core::cell::Cell;
-use core::cmp::Ordering;
-use core::fmt;
-use core::hash::{Hash, Hasher};
-use core::intrinsics::abort;
-use core::marker;
-use core::marker::{Unpin, Unsize, PhantomData};
-use core::mem::{self, align_of_val, forget, size_of_val};
-use core::ops::{Deref, Receiver};
-use core::ops::{CoerceUnsized, DispatchFromDyn};
-use core::pin::Pin;
-use core::ptr::{self, NonNull};
-use core::convert::From;
-use core::usize;
+use core::{
+    any::Any,
+    borrow,
+    cell::Cell,
+    cmp::Ordering,
+    fmt,
+    hash::{Hash, Hasher},
+    intrinsics::abort,
+    marker::{self, Unpin, Unsize, PhantomData},
+    mem::{self, align_of_val, forget, size_of_val},
+    ops::{Deref, Receiver, CoerceUnsized, DispatchFromDyn},
+    pin::Pin,
+    ptr::{self, NonNull},
+    convert::From,
+    usize,
+};
 
-use crate::alloc::{Global, Alloc, Layout, box_free, handle_alloc_error};
-use crate::string::String;
-use crate::vec::Vec;
+use crate::{
+    alloc::{Global, Alloc, Layout, box_free, handle_alloc_error},
+    string::String,
+    vec::Vec,
+};
 
 struct RcBox<T: ?Sized> {
     strong: Cell<usize>,
@@ -1562,14 +1564,15 @@ fn inner(&self) -> &RcBox<T> {
 #[cfg(test)]
 mod tests {
     use super::{Rc, Weak};
-    use std::boxed::Box;
-    use std::cell::RefCell;
-    use std::option::Option;
-    use std::option::Option::{None, Some};
-    use std::result::Result::{Err, Ok};
-    use std::mem::drop;
-    use std::clone::Clone;
-    use std::convert::From;
+    use std::{
+        boxed::Box,
+        cell::RefCell,
+        option::Option::{self, None, Some},
+        result::Result::{Err, Ok},
+        mem::drop,
+        clone::Clone,
+        convert::From,
+    };
 
     #[test]
     fn test_clone() {
@@ -1733,8 +1736,7 @@ fn into_from_raw() {
 
     #[test]
     fn test_into_from_raw_unsized() {
-        use std::fmt::Display;
-        use std::string::ToString;
+        use std::{fmt::Display, string::ToString};
 
         let rc: Rc<str> = Rc::from("foo");
 
@@ -1942,8 +1944,7 @@ fn test_from_box_slice() {
 
     #[test]
     fn test_from_box_trait() {
-        use std::fmt::Display;
-        use std::string::ToString;
+        use std::{fmt::Display, string::ToString};
 
         let b: Box<dyn Display> = box 123;
         let r: Rc<dyn Display> = Rc::from(b);

src/liballoc/slice.rs

@@ -87,15 +87,18 @@
 // It's cleaner to just turn off the unused_imports warning than to fix them.
 #![cfg_attr(test, allow(unused_imports, dead_code))]
 
-use core::cmp::Ordering::{self, Less};
-use core::mem::size_of;
-use core::mem;
-use core::ptr;
-use core::{u8, u16, u32};
+use core::{
+    cmp::Ordering::{self, Less},
+    mem::{self, size_of},
+    ptr,
+    u8, u16, u32,
+};
 
-use crate::borrow::{Borrow, BorrowMut, ToOwned};
-use crate::boxed::Box;
-use crate::vec::Vec;
+use crate::{
+    borrow::{Borrow, BorrowMut, ToOwned},
+    boxed::Box,
+    vec::Vec,
+};
 
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use core::slice::{Chunks, Windows};

src/liballoc/str.rs

@@ -28,20 +28,25 @@
 // It's cleaner to just turn off the unused_imports warning than to fix them.
 #![allow(unused_imports)]
 
-use core::fmt;
-use core::str as core_str;
-use core::str::pattern::Pattern;
-use core::str::pattern::{Searcher, ReverseSearcher, DoubleEndedSearcher};
-use core::mem;
-use core::ptr;
-use core::iter::FusedIterator;
-use core::unicode::conversions;
+use core::{
+    fmt,
+    str::{
+        self as core_str,
+        pattern::{Pattern, Searcher, ReverseSearcher, DoubleEndedSearcher},
+    },
+    mem,
+    ptr,
+    iter::FusedIterator,
+    unicode::conversions,
+};
 
-use crate::borrow::{Borrow, ToOwned};
-use crate::boxed::Box;
-use crate::slice::{SliceConcatExt, SliceIndex};
-use crate::string::String;
-use crate::vec::Vec;
+use crate::{
+    borrow::{Borrow, ToOwned},
+    boxed::Box,
+    slice::{SliceConcatExt, SliceIndex},
+    string::String,
+    vec::Vec,
+};
 
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use core::str::{FromStr, Utf8Error};

src/liballoc/string.rs

@@ -46,21 +46,30 @@
 
 #![stable(feature = "rust1", since = "1.0.0")]
 
-use core::char::{decode_utf16, REPLACEMENT_CHARACTER};
-use core::fmt;
-use core::hash;
-use core::iter::{FromIterator, FusedIterator};
-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 core::str::lossy;
+use core::{
+    char::{decode_utf16, REPLACEMENT_CHARACTER},
+    fmt,
+    hash,
+    iter::{FromIterator, FusedIterator},
+    ops::{
+        self,
+        Bound::{Excluded, Included, Unbounded},
+        Add, AddAssign, Index, IndexMut, RangeBounds,
+    },
+    ptr,
+    str::{
+        pattern::Pattern,
+        lossy,
+    }
+};
 
-use crate::collections::CollectionAllocErr;
-use crate::borrow::{Cow, ToOwned};
-use crate::boxed::Box;
-use crate::str::{self, from_boxed_utf8_unchecked, FromStr, Utf8Error, Chars};
-use crate::vec::Vec;
+use crate::{
+    collections::CollectionAllocErr,
+    borrow::{Cow, ToOwned},
+    boxed::Box,
+    str::{self, from_boxed_utf8_unchecked, FromStr, Utf8Error, Chars},
+    vec::Vec,
+};
 
 /// A UTF-8 encoded, growable string.
 ///

src/liballoc/sync.rs

@@ -6,28 +6,33 @@
 //!
 //! [arc]: struct.Arc.html
 
-use core::any::Any;
-use core::sync::atomic;
-use core::sync::atomic::Ordering::{Acquire, Relaxed, Release, SeqCst};
-use core::borrow;
-use core::fmt;
-use core::cmp::{self, Ordering};
-use core::intrinsics::abort;
-use core::mem::{self, align_of_val, size_of_val};
-use core::ops::{Deref, Receiver};
-use core::ops::{CoerceUnsized, DispatchFromDyn};
-use core::pin::Pin;
-use core::ptr::{self, NonNull};
-use core::marker::{Unpin, Unsize, PhantomData};
-use core::hash::{Hash, Hasher};
-use core::{isize, usize};
-use core::convert::From;
+use core::{
+    any::Any,
+    sync::atomic::{
+        self,
+        Ordering::{Acquire, Relaxed, Release, SeqCst}
+    },
+    borrow,
+    fmt,
+    cmp::{self, Ordering},
+    intrinsics::abort,
+    mem::{self, align_of_val, size_of_val},
+    ops::{Deref, Receiver, CoerceUnsized, DispatchFromDyn},
+    pin::Pin,
+    ptr::{self, NonNull},
+    marker::{Unpin, Unsize, PhantomData},
+    hash::{Hash, Hasher},
+    isize, usize,
+    convert::From,
+};
 
-use crate::alloc::{Global, Alloc, Layout, box_free, handle_alloc_error};
-use crate::boxed::Box;
-use crate::rc::is_dangling;
-use crate::string::String;
-use crate::vec::Vec;
+use crate::{
+    alloc::{Global, Alloc, Layout, box_free, handle_alloc_error},
+    boxed::Box,
+    rc::is_dangling,
+    string::String,
+    vec::Vec,
+};
 
 /// A soft limit on the amount of references that may be made to an `Arc`.
 ///
@@ -1650,21 +1655,21 @@ fn from(mut v: Vec<T>) -> Arc<[T]> {
 
 #[cfg(test)]
 mod tests {
-    use std::boxed::Box;
-    use std::clone::Clone;
-    use std::sync::mpsc::channel;
-    use std::mem::drop;
-    use std::ops::Drop;
-    use std::option::Option;
-    use std::option::Option::{None, Some};
-    use std::sync::atomic;
-    use std::sync::atomic::Ordering::{Acquire, SeqCst};
-    use std::thread;
-    use std::sync::Mutex;
-    use std::convert::From;
+    use std::{
+        boxed::Box,
+        clone::Clone,
+        sync::mpsc::channel,
+        mem::drop,
+        ops::Drop,
+        option::Option::{self, None, Some},
+        sync::atomic::{self, Ordering::{Acquire, SeqCst}},
+        thread,
+        sync::Mutex,
+        convert::From,
+    };
 
     use super::{Arc, Weak};
-    use vec::Vec;
+    use crate::vec::Vec;
 
     struct Canary(*mut atomic::AtomicUsize);
 
@@ -1770,8 +1775,7 @@ fn into_from_raw() {
 
     #[test]
     fn test_into_from_raw_unsized() {
-        use std::fmt::Display;
-        use std::string::ToString;
+        use std::{fmt::Display, string::ToString};
 
         let arc: Arc<str> = Arc::from("foo");
 
@@ -2083,8 +2087,7 @@ fn test_from_box_slice() {
 
     #[test]
     fn test_from_box_trait() {
-        use std::fmt::Display;
-        use std::string::ToString;
+        use std::{fmt::Display, string::ToString};
 
         let b: Box<dyn Display> = box 123;
         let r: Arc<dyn Display> = Arc::from(b);

src/liballoc/task.rs

@@ -8,9 +8,11 @@
 #[cfg(all(target_has_atomic = "ptr", target_has_atomic = "cas"))]
 mod if_arc {
     use super::*;
-    use core::marker::PhantomData;
-    use core::mem;
-    use core::ptr::{self, NonNull};
+    use core::{
+        marker::PhantomData,
+        mem,
+        ptr::{self, NonNull},
+    };
     use crate::sync::Arc;
 
     /// A way of waking up a specific task.

src/liballoc/tests/arc.rs

@@ -1,7 +1,9 @@
-use std::any::Any;
-use std::sync::{Arc, Weak};
-use std::cell::RefCell;
-use std::cmp::PartialEq;
+use std::{
+    any::Any,
+    sync::{Arc, Weak},
+    cell::RefCell,
+    cmp::PartialEq,
+};
 
 #[test]
 fn uninhabited() {

src/liballoc/tests/binary_heap.rs

@@ -1,8 +1,9 @@
-use std::cmp;
-use std::collections::BinaryHeap;
-use std::collections::binary_heap::{Drain, PeekMut};
-use std::panic::{self, AssertUnwindSafe};
-use std::sync::atomic::{AtomicUsize, Ordering};
+use std::{
+    cmp,
+    collections::{BinaryHeap, binary_heap::{Drain, PeekMut}},
+    panic::{self, AssertUnwindSafe},
+    sync::atomic::{AtomicUsize, Ordering},
+};
 
 use rand::{thread_rng, seq::SliceRandom};
 

src/liballoc/tests/btree/map.rs

@@ -1,9 +1,10 @@
-use std::collections::BTreeMap;
-use std::collections::btree_map::Entry::{Occupied, Vacant};
-use std::ops::Bound::{self, Excluded, Included, Unbounded};
-use std::rc::Rc;
+use std::{
+    collections::{BTreeMap, btree_map::Entry::{Occupied, Vacant}},
+    ops::Bound::{self, Excluded, Included, Unbounded},
+    rc::Rc,
+    iter::FromIterator,
+};
 
-use std::iter::FromIterator;
 use super::DeterministicRng;
 
 #[test]

src/liballoc/tests/btree/set.rs

@@ -1,6 +1,7 @@
-use std::collections::BTreeSet;
-
-use std::iter::FromIterator;
+use std::{
+    collections::BTreeSet,
+    iter::FromIterator
+};
 use super::DeterministicRng;
 
 #[test]
@@ -15,6 +16,8 @@ fn test_clone_eq() {
 
 #[test]
 fn test_hash() {
+    use crate::hash;
+
     let mut x = BTreeSet::new();
     let mut y = BTreeSet::new();
 
@@ -26,7 +29,7 @@ fn test_hash() {
     y.insert(2);
     y.insert(1);
 
-    assert!(::hash(&x) == ::hash(&y));
+    assert!(hash(&x) == hash(&y));
 }
 
 fn check<F>(a: &[i32], b: &[i32], expected: &[i32], f: F)

src/liballoc/tests/lib.rs

@@ -13,8 +13,10 @@
 extern crate core;
 extern crate rand;
 
-use std::hash::{Hash, Hasher};
-use std::collections::hash_map::DefaultHasher;
+use std::{
+    hash::{Hash, Hasher},
+    collections::hash_map::DefaultHasher,
+};
 
 mod arc;
 mod binary_heap;

src/liballoc/tests/linked_list.rs

@@ -241,10 +241,12 @@ fn test_eq() {
 
 #[test]
 fn test_hash() {
+    use crate::hash;
+
     let mut x = LinkedList::new();
     let mut y = LinkedList::new();
 
-    assert!(::hash(&x) == ::hash(&y));
+    assert!(hash(&x) == hash(&y));
 
     x.push_back(1);
     x.push_back(2);
@@ -254,7 +256,7 @@ fn test_hash() {
     y.push_front(2);
     y.push_front(1);
 
-    assert!(::hash(&x) == ::hash(&y));
+    assert!(hash(&x) == hash(&y));
 }
 
 #[test]

src/liballoc/tests/rc.rs

@@ -1,7 +1,9 @@
-use std::any::Any;
-use std::rc::{Rc, Weak};
-use std::cell::RefCell;
-use std::cmp::PartialEq;
+use std::{
+    any::Any,
+    rc::{Rc, Weak},
+    cell::RefCell,
+    cmp::PartialEq,
+};
 
 #[test]
 fn uninhabited() {

src/liballoc/tests/slice.rs

@@ -1,15 +1,18 @@
-use std::cell::Cell;
-use std::cmp::Ordering::{Equal, Greater, Less};
-use std::cmp::Ordering;
-use std::mem;
-use std::panic;
-use std::rc::Rc;
-use std::sync::atomic::Ordering::Relaxed;
-use std::sync::atomic::AtomicUsize;
-use std::thread;
+use std::{
+    cell::Cell,
+    cmp::Ordering::{self, Equal, Greater, Less},
+    mem,
+    panic,
+    rc::Rc,
+    sync::atomic::{Ordering::Relaxed, AtomicUsize},
+    thread,
+};
 
-use rand::{Rng, RngCore, thread_rng, seq::SliceRandom};
-use rand::distributions::Standard;
+use rand::{
+    Rng, RngCore, thread_rng,
+    seq::SliceRandom,
+    distributions::Standard,
+};
 
 fn square(n: usize) -> usize {
     n * n
@@ -476,7 +479,7 @@ fn test_sort_stability() {
             // the second item represents which occurrence of that
             // number this element is, i.e., the second elements
             // will occur in sorted order.
-            let mut orig: Vec<_> = (0..len)
+            let orig: Vec<_> = (0..len)
                 .map(|_| {
                     let n = thread_rng().gen::<usize>() % 10;
                     counts[n] += 1;

src/liballoc/tests/str.rs

@@ -1,6 +1,8 @@
-use std::borrow::Cow;
-use std::cmp::Ordering::{Equal, Greater, Less};
-use std::str::from_utf8;
+use std::{
+    borrow::Cow,
+    cmp::Ordering::{Equal, Greater, Less},
+    str::from_utf8,
+};
 
 #[test]
 fn test_le() {
@@ -1599,9 +1601,10 @@ fn test_repeat() {
 }
 
 mod pattern {
-    use std::str::pattern::Pattern;
-    use std::str::pattern::{Searcher, ReverseSearcher};
-    use std::str::pattern::SearchStep::{self, Match, Reject, Done};
+    use std::str::pattern::{
+        Pattern, Searcher, ReverseSearcher,
+        SearchStep::{self, Match, Reject, Done},
+    };
 
     macro_rules! make_test {
         ($name:ident, $p:expr, $h:expr, [$($e:expr,)*]) => {

src/liballoc/tests/string.rs

@@ -1,7 +1,9 @@
-use std::borrow::Cow;
-use std::collections::CollectionAllocErr::*;
-use std::mem::size_of;
-use std::{usize, isize};
+use std::{
+    borrow::Cow,
+    collections::CollectionAllocErr::*,
+    mem::size_of,
+    usize, isize,
+};
 
 pub trait IntoCow<'a, B: ?Sized> where B: ToOwned {
     fn into_cow(self) -> Cow<'a, B>;

src/liballoc/tests/vec.rs

@@ -1,8 +1,10 @@
-use std::borrow::Cow;
-use std::mem::size_of;
-use std::{usize, isize};
-use std::vec::{Drain, IntoIter};
-use std::collections::CollectionAllocErr::*;
+use std::{
+    borrow::Cow,
+    mem::size_of,
+    usize, isize,
+    vec::{Drain, IntoIter},
+    collections::CollectionAllocErr::*,
+};
 
 struct DropCounter<'a> {
     count: &'a mut u32,

src/liballoc/tests/vec_deque.rs

@@ -1,9 +1,14 @@
-use std::collections::VecDeque;
-use std::fmt::Debug;
-use std::collections::vec_deque::{Drain};
-use std::collections::CollectionAllocErr::*;
-use std::mem::size_of;
-use std::{usize, isize};
+use std::{
+    fmt::Debug,
+    collections::{
+        VecDeque, vec_deque::Drain,
+        CollectionAllocErr::*,
+    },
+    mem::size_of,
+    usize, isize,
+};
+
+use crate::hash;
 
 use self::Taggy::*;
 use self::Taggypar::*;
@@ -583,7 +588,7 @@ fn test_hash() {
     y.push_back(2);
     y.push_back(3);
 
-    assert!(::hash(&x) == ::hash(&y));
+    assert!(hash(&x) == hash(&y));
 }
 
 #[test]
@@ -599,7 +604,7 @@ fn test_hash_after_rotation() {
             *elt -= 1;
         }
         ring.push_back(len - 1);
-        assert_eq!(::hash(&orig), ::hash(&ring));
+        assert_eq!(hash(&orig), hash(&ring));
         assert_eq!(orig, ring);
         assert_eq!(ring, orig);
     }

src/liballoc/vec.rs

@@ -56,25 +56,30 @@
 
 #![stable(feature = "rust1", since = "1.0.0")]
 
-use core::cmp::{self, Ordering};
-use core::fmt;
-use core::hash::{self, Hash};
-use core::intrinsics::{arith_offset, assume};
-use core::iter::{FromIterator, FusedIterator, TrustedLen};
-use core::marker::PhantomData;
-use core::mem;
-use core::ops::Bound::{Excluded, Included, Unbounded};
-use core::ops::{Index, IndexMut, RangeBounds};
-use core::ops;
-use core::ptr;
-use core::ptr::NonNull;
-use core::slice;
+use core::{
+    cmp::{self, Ordering},
+    fmt,
+    hash::{self, Hash},
+    intrinsics::{arith_offset, assume},
+    iter::{FromIterator, FusedIterator, TrustedLen},
+    marker::PhantomData,
+    mem,
+    ops::{
+        self,
+        Bound::{Excluded, Included, Unbounded},
+        Index, IndexMut, RangeBounds,
+    },
+    ptr::{self, NonNull},
+    slice,
+};
 
-use crate::collections::CollectionAllocErr;
-use crate::borrow::ToOwned;
-use crate::borrow::Cow;
-use crate::boxed::Box;
-use crate::raw_vec::RawVec;
+use crate::{
+    collections::CollectionAllocErr,
+    borrow::ToOwned,
+    borrow::Cow,
+    boxed::Box,
+    raw_vec::RawVec,
+};
 
 /// A contiguous growable array type, written `Vec<T>` but pronounced 'vector'.
 ///
@@ -1646,7 +1651,7 @@ fn clone(&self) -> Vec<T> {
     // NB see the slice::hack module in slice.rs for more information
     #[cfg(test)]
     fn clone(&self) -> Vec<T> {
-        ::slice::to_vec(&**self)
+        crate::slice::to_vec(&**self)
     }
 
     fn clone_from(&mut self, other: &Vec<T>) {
@@ -2193,7 +2198,7 @@ fn from(s: &'a [T]) -> Vec<T> {
     }
     #[cfg(test)]
     fn from(s: &'a [T]) -> Vec<T> {
-        ::slice::to_vec(s)
+        crate::slice::to_vec(s)
     }
 }
 
@@ -2205,7 +2210,7 @@ fn from(s: &'a mut [T]) -> Vec<T> {
     }
     #[cfg(test)]
     fn from(s: &'a mut [T]) -> Vec<T> {
-        ::slice::to_vec(s)
+        crate::slice::to_vec(s)
     }
 }