Auto merge of #58081 - Centril:liballoc-2018, r=oli-obk

Transition liballoc to Rust 2018

This transitions liballoc to Rust 2018 edition and applies relevant idiom lints.
I also did a small bit of drive-by cleanup along the way.

r? @oli-obk

I started with liballoc since it seemed easiest. In particular, adding `edition = "2018"` to libcore gave me way too many errors due to stdsimd. Ideally we should be able to continue this crate-by-crate until all crates use 2018.

8 files changed, 32 insertions, 29 deletions

diff --git a/src/liballoc/tests/btree/map.rs b/src/liballoc/tests/btree/map.rs
index 05e0bdffaa8..aaf50407328 100644
--- a/src/liballoc/tests/btree/map.rs
+++ b/src/liballoc/tests/btree/map.rs
@@ -2,8 +2,8 @@ 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::iter::FromIterator;
+
 use super::DeterministicRng;
 
 #[test]
@@ -199,7 +199,7 @@ fn test_range_inclusive() {
 
 #[test]
 fn test_range_inclusive_max_value() {
-    let max = ::std::usize::MAX;
+    let max = std::usize::MAX;
     let map: BTreeMap<_, _> = vec![(max, 0)].into_iter().collect();
 
     assert_eq!(map.range(max..=max).collect::<Vec<_>>(), &[(&max, &0)]);
diff --git a/src/liballoc/tests/btree/set.rs b/src/liballoc/tests/btree/set.rs
index e24c04fd8ac..4f5168f1ce5 100644
--- a/src/liballoc/tests/btree/set.rs
+++ b/src/liballoc/tests/btree/set.rs
@@ -1,6 +1,6 @@
 use std::collections::BTreeSet;
-
 use std::iter::FromIterator;
+
 use super::DeterministicRng;
 
 #[test]
@@ -15,6 +15,8 @@ fn test_clone_eq() {
 
 #[test]
 fn test_hash() {
+    use crate::hash;
+
     let mut x = BTreeSet::new();
     let mut y = BTreeSet::new();
 
@@ -26,7 +28,7 @@ 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)
diff --git a/src/liballoc/tests/linked_list.rs b/src/liballoc/tests/linked_list.rs
index 6e775f9650d..0fbfbdccd45 100644
--- a/src/liballoc/tests/linked_list.rs
+++ b/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]
diff --git a/src/liballoc/tests/slice.rs b/src/liballoc/tests/slice.rs
index 0300bd7f3f6..334466dfb25 100644
--- a/src/liballoc/tests/slice.rs
+++ b/src/liballoc/tests/slice.rs
@@ -1,14 +1,13 @@
 use std::cell::Cell;
-use std::cmp::Ordering::{Equal, Greater, Less};
-use std::cmp::Ordering;
+use std::cmp::Ordering::{self, Equal, Greater, Less};
 use std::mem;
 use std::panic;
 use std::rc::Rc;
-use std::sync::atomic::Ordering::Relaxed;
-use std::sync::atomic::AtomicUsize;
+use std::sync::atomic::{Ordering::Relaxed, AtomicUsize};
 use std::thread;
 
-use rand::{Rng, RngCore, thread_rng, seq::SliceRandom};
+use rand::{Rng, RngCore, thread_rng};
+use rand::seq::SliceRandom;
 use rand::distributions::Standard;
 
 fn square(n: usize) -> usize {
@@ -476,7 +475,7 @@ 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;
diff --git a/src/liballoc/tests/str.rs b/src/liballoc/tests/str.rs
index 66a1b947a7d..1bc1bd8d78c 100644
--- a/src/liballoc/tests/str.rs
+++ b/src/liballoc/tests/str.rs
@@ -584,7 +584,7 @@ mod slice_index {
     }
 
     mod boundary {
-        const DATA: &'static str = "abcαβγ";
+        const DATA: &str = "abcαβγ";
 
         const BAD_START: usize = 4;
         const GOOD_START: usize = 3;
@@ -648,7 +648,7 @@ mod slice_index {
         }
     }
 
-    const LOREM_PARAGRAPH: &'static str = "\
+    const LOREM_PARAGRAPH: &str = "\
     Lorem ipsum dolor sit amet, consectetur adipiscing elit. Suspendisse quis lorem \
     sit amet dolor ultricies condimentum. Praesent iaculis purus elit, ac malesuada \
     quam malesuada in. Duis sed orci eros. Suspendisse sit amet magna mollis, mollis \
@@ -1068,7 +1068,7 @@ fn test_rev_iterator() {
 #[test]
 fn test_chars_decoding() {
     let mut bytes = [0; 4];
-    for c in (0..0x110000).filter_map(::std::char::from_u32) {
+    for c in (0..0x110000).filter_map(std::char::from_u32) {
         let s = c.encode_utf8(&mut bytes);
         if Some(c) != s.chars().next() {
             panic!("character {:x}={} does not decode correctly", c as u32, c);
@@ -1079,7 +1079,7 @@ fn test_chars_decoding() {
 #[test]
 fn test_chars_rev_decoding() {
     let mut bytes = [0; 4];
-    for c in (0..0x110000).filter_map(::std::char::from_u32) {
+    for c in (0..0x110000).filter_map(std::char::from_u32) {
         let s = c.encode_utf8(&mut bytes);
         if Some(c) != s.chars().rev().next() {
             panic!("character {:x}={} does not decode correctly", c as u32, c);
@@ -1599,8 +1599,7 @@ fn test_repeat() {
 }
 
 mod pattern {
-    use std::str::pattern::Pattern;
-    use std::str::pattern::{Searcher, ReverseSearcher};
+    use std::str::pattern::{Pattern, Searcher, ReverseSearcher};
     use std::str::pattern::SearchStep::{self, Match, Reject, Done};
 
     macro_rules! make_test {
diff --git a/src/liballoc/tests/string.rs b/src/liballoc/tests/string.rs
index 8a5bfca8b7d..e5ce51a36ee 100644
--- a/src/liballoc/tests/string.rs
+++ b/src/liballoc/tests/string.rs
@@ -21,7 +21,7 @@ impl<'a> IntoCow<'a, str> for &'a str {
 
 #[test]
 fn test_from_str() {
-    let owned: Option<::std::string::String> = "string".parse().ok();
+    let owned: Option<std::string::String> = "string".parse().ok();
     assert_eq!(owned.as_ref().map(|s| &**s), Some("string"));
 }
 
@@ -122,7 +122,7 @@ fn test_from_utf16() {
         let s_as_utf16 = s.encode_utf16().collect::<Vec<u16>>();
         let u_as_string = String::from_utf16(&u).unwrap();
 
-        assert!(::core::char::decode_utf16(u.iter().cloned()).all(|r| r.is_ok()));
+        assert!(core::char::decode_utf16(u.iter().cloned()).all(|r| r.is_ok()));
         assert_eq!(s_as_utf16, u);
 
         assert_eq!(u_as_string, s);
diff --git a/src/liballoc/tests/vec.rs b/src/liballoc/tests/vec.rs
index 0fdcf34c783..89f2e0a046d 100644
--- a/src/liballoc/tests/vec.rs
+++ b/src/liballoc/tests/vec.rs
@@ -8,7 +8,7 @@ struct DropCounter<'a> {
     count: &'a mut u32,
 }
 
-impl<'a> Drop for DropCounter<'a> {
+impl Drop for DropCounter<'_> {
     fn drop(&mut self) {
         *self.count += 1;
     }
@@ -638,7 +638,7 @@ fn test_splice_unbounded() {
 fn test_splice_forget() {
     let mut v = vec![1, 2, 3, 4, 5];
     let a = [10, 11, 12];
-    ::std::mem::forget(v.splice(2..4, a.iter().cloned()));
+    std::mem::forget(v.splice(2..4, a.iter().cloned()));
     assert_eq!(v, &[1, 2]);
 }
 
diff --git a/src/liballoc/tests/vec_deque.rs b/src/liballoc/tests/vec_deque.rs
index c9d16a06b47..aa49bdb0090 100644
--- a/src/liballoc/tests/vec_deque.rs
+++ b/src/liballoc/tests/vec_deque.rs
@@ -1,12 +1,13 @@
-use std::collections::VecDeque;
 use std::fmt::Debug;
-use std::collections::vec_deque::{Drain};
+use std::collections::{VecDeque, vec_deque::Drain};
 use std::collections::CollectionAllocErr::*;
 use std::mem::size_of;
 use std::{usize, isize};
 
-use self::Taggy::*;
-use self::Taggypar::*;
+use crate::hash;
+
+use Taggy::*;
+use Taggypar::*;
 
 #[test]
 fn test_simple() {
@@ -583,7 +584,7 @@ fn test_hash() {
     y.push_back(2);
     y.push_back(3);
 
-    assert!(::hash(&x) == ::hash(&y));
+    assert!(hash(&x) == hash(&y));
 }
 
 #[test]
@@ -599,7 +600,7 @@ 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);
     }
@@ -998,7 +999,7 @@ struct DropCounter<'a> {
     count: &'a mut u32,
 }
 
-impl<'a> Drop for DropCounter<'a> {
+impl Drop for DropCounter<'_> {
     fn drop(&mut self) {
         *self.count += 1;
     }