Merge remote-tracking branch 'origin/master' into miri

Author: oli-obk

.gitattributes

@@ -7,3 +7,4 @@
 src/etc/installer/gfx/* binary
 *.woff binary
 src/vendor/** -text
+Cargo.lock -merge

CONTRIBUTING.md

@@ -336,7 +336,7 @@ will run all the tests on every platform we support. If it all works out,
 
 Speaking of tests, Rust has a comprehensive test suite. More information about
 it can be found
-[here](https://github.com/rust-lang/rust-wiki-backup/blob/master/Note-testsuite.md).
+[here](https://github.com/rust-lang/rust/blob/master/src/test/COMPILER_TESTS.md).
 
 ### External Dependencies
 [external-dependencies]: #external-dependencies

src/doc/not_found.md

@@ -13,20 +13,20 @@ Some things that might be helpful to you though:
 
 # Search
 
-* <form action="https://duckduckgo.com/">
+<form action="https://duckduckgo.com/">
     <input type="text" id="site-search" name="q" size="80"></input>
-    <input type="submit" value="Search DuckDuckGo">
-</form>
-* Rust doc search: <span id="core-search"></span>
+    <input type="submit" value="Search DuckDuckGo"></form>
+
+Rust doc search: <span id="core-search"></span>
 
 # Reference
 
-* [The Rust official site](https://www.rust-lang.org)
-* [The Rust reference](https://doc.rust-lang.org/reference/index.html)
+ * [The Rust official site](https://www.rust-lang.org)
+ * [The Rust reference](https://doc.rust-lang.org/reference/index.html)
 
 # Docs
 
-* [The standard library](https://doc.rust-lang.org/std/)
+[The standard library](https://doc.rust-lang.org/std/)
 
 <script>
 function get_url_fragments() {

src/liballoc/allocator.rs

@@ -217,14 +217,8 @@ impl Layout {
     /// On arithmetic overflow, returns `None`.
     #[inline]
     pub fn repeat(&self, n: usize) -> Option<(Self, usize)> {
-        let padded_size = match self.size.checked_add(self.padding_needed_for(self.align)) {
-            None => return None,
-            Some(padded_size) => padded_size,
-        };
-        let alloc_size = match padded_size.checked_mul(n) {
-            None => return None,
-            Some(alloc_size) => alloc_size,
-        };
+        let padded_size = self.size.checked_add(self.padding_needed_for(self.align))?;
+        let alloc_size = padded_size.checked_mul(n)?;
 
         // We can assume that `self.align` is a power-of-two that does
         // not exceed 2<sup>31</sup>. Furthermore, `alloc_size` has already been
@@ -246,26 +240,14 @@ impl Layout {
     /// On arithmetic overflow, returns `None`.
     pub fn extend(&self, next: Self) -> Option<(Self, usize)> {
         let new_align = cmp::max(self.align, next.align);
-        let realigned = match Layout::from_size_align(self.size, new_align) {
-            None => return None,
-            Some(l) => l,
-        };
+        let realigned = Layout::from_size_align(self.size, new_align)?;
 
         let pad = realigned.padding_needed_for(next.align);
 
-        let offset = match self.size.checked_add(pad) {
-            None => return None,
-            Some(offset) => offset,
-        };
-        let new_size = match offset.checked_add(next.size) {
-            None => return None,
-            Some(new_size) => new_size,
-        };
+        let offset = self.size.checked_add(pad)?;
+        let new_size = offset.checked_add(next.size)?;
 
-        let layout = match Layout::from_size_align(new_size, new_align) {
-            None => return None,
-            Some(l) => l,
-        };
+        let layout = Layout::from_size_align(new_size, new_align)?;
         Some((layout, offset))
     }
 
@@ -282,11 +264,7 @@ impl Layout {
     ///
     /// On arithmetic overflow, returns `None`.
     pub fn repeat_packed(&self, n: usize) -> Option<Self> {
-        let size = match self.size().checked_mul(n) {
-            None => return None,
-            Some(scaled) => scaled,
-        };
-
+        let size = self.size().checked_mul(n)?;
         Layout::from_size_align(size, self.align)
     }
 
@@ -306,14 +284,8 @@ impl Layout {
     ///
     /// On arithmetic overflow, returns `None`.
     pub fn extend_packed(&self, next: Self) -> Option<(Self, usize)> {
-        let new_size = match self.size().checked_add(next.size()) {
-            None => return None,
-            Some(new_size) => new_size,
-        };
-        let layout = match Layout::from_size_align(new_size, self.align) {
-            None => return None,
-            Some(l) => l,
-        };
+        let new_size = self.size().checked_add(next.size())?;
+        let layout = Layout::from_size_align(new_size, self.align)?;
         Some((layout, self.size()))
     }
 

src/liballoc/benches/btree/map.rs

@@ -12,7 +12,7 @@
 use std::iter::Iterator;
 use std::vec::Vec;
 use std::collections::BTreeMap;
-use std::__rand::{Rng, thread_rng};
+use rand::{Rng, thread_rng};
 use test::{Bencher, black_box};
 
 macro_rules! map_insert_rand_bench {

src/liballoc/benches/slice.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use std::__rand::{thread_rng};
+use rand::{thread_rng};
 use std::mem;
 use std::ptr;
 

src/liballoc/btree/set.rs

@@ -1067,21 +1067,15 @@ impl<'a, T: Ord> Iterator for Intersection<'a, T> {
 
     fn next(&mut self) -> Option<&'a T> {
         loop {
-            let o_cmp = match (self.a.peek(), self.b.peek()) {
-                (None, _) => None,
-                (_, None) => None,
-                (Some(a1), Some(b1)) => Some(a1.cmp(b1)),
-            };
-            match o_cmp {
-                None => return None,
-                Some(Less) => {
+            match Ord::cmp(self.a.peek()?, self.b.peek()?) {
+                Less => {
                     self.a.next();
                 }
-                Some(Equal) => {
+                Equal => {
                     self.b.next();
                     return self.a.next();
                 }
-                Some(Greater) => {
+                Greater => {
                     self.b.next();
                 }
             }

src/liballoc/linked_list.rs

@@ -1071,6 +1071,15 @@ impl<'a, T, F> Iterator for DrainFilter<'a, T, F>
     }
 }
 
+#[unstable(feature = "drain_filter", reason = "recently added", issue = "43244")]
+impl<'a, T, F> Drop for DrainFilter<'a, T, F>
+    where F: FnMut(&mut T) -> bool,
+{
+    fn drop(&mut self) {
+        for _ in self { }
+    }
+}
+
 #[unstable(feature = "drain_filter", reason = "recently added", issue = "43244")]
 impl<'a, T: 'a + fmt::Debug, F> fmt::Debug for DrainFilter<'a, T, F>
     where F: FnMut(&mut T) -> bool

src/liballoc/string.rs

@@ -1044,10 +1044,7 @@ impl String {
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn pop(&mut self) -> Option<char> {
-        let ch = match self.chars().rev().next() {
-            Some(ch) => ch,
-            None => return None,
-        };
+        let ch = self.chars().rev().next()?;
         let newlen = self.len() - ch.len_utf8();
         unsafe {
             self.vec.set_len(newlen);

src/liballoc/vec.rs

@@ -1423,10 +1423,7 @@ impl<T: PartialEq> Vec<T> {
     /// ```
     #[unstable(feature = "vec_remove_item", reason = "recently added", issue = "40062")]
     pub fn remove_item(&mut self, item: &T) -> Option<T> {
-        let pos = match self.iter().position(|x| *x == *item) {
-            Some(x) => x,
-            None => return None,
-        };
+        let pos = self.iter().position(|x| *x == *item)?;
         Some(self.remove(pos))
     }
 }

src/libcore/cell.rs

@@ -1084,9 +1084,11 @@ impl<'b, T: ?Sized> RefMut<'b, T> {
     pub fn map<U: ?Sized, F>(orig: RefMut<'b, T>, f: F) -> RefMut<'b, U>
         where F: FnOnce(&mut T) -> &mut U
     {
+        // FIXME(nll-rfc#40): fix borrow-check
+        let RefMut { value, borrow } = orig;
         RefMut {
-            value: f(orig.value),
-            borrow: orig.borrow,
+            value: f(value),
+            borrow: borrow,
         }
     }
 }

src/libcore/iter/mod.rs

@@ -1776,12 +1776,18 @@ impl<I: Iterator> Iterator for Peekable<I> {
 
     #[inline]
     fn nth(&mut self, n: usize) -> Option<I::Item> {
-        match self.peeked.take() {
-            // the .take() below is just to avoid "move into pattern guard"
-            Some(ref mut v) if n == 0 => v.take(),
-            Some(None) => None,
-            Some(Some(_)) => self.iter.nth(n - 1),
-            None => self.iter.nth(n),
+        // FIXME(#6393): merge these when borrow-checking gets better.
+        if n == 0 {
+            match self.peeked.take() {
+                Some(v) => v,
+                None => self.iter.nth(n),
+            }
+        } else {
+            match self.peeked.take() {
+                Some(None) => None,
+                Some(Some(_)) => self.iter.nth(n - 1),
+                None => self.iter.nth(n),
+            }
         }
     }
 

src/libcore/macros.rs

@@ -596,9 +596,9 @@ mod builtin {
 
     /// Unconditionally causes compilation to fail with the given error message when encountered.
     ///
-    /// For more information, see the [RFC].
+    /// For more information, see the documentation for [`std::compile_error!`].
     ///
-    /// [RFC]: https://github.com/rust-lang/rfcs/blob/master/text/1695-add-error-macro.md
+    /// [`std::compile_error!`]: ../std/macro.compile_error.html
     #[stable(feature = "compile_error_macro", since = "1.20.0")]
     #[macro_export]
     #[cfg(dox)]
@@ -736,7 +736,7 @@ mod builtin {
     #[cfg(dox)]
     macro_rules! module_path { () => ({ /* compiler built-in */ }) }
 
-    /// Boolean evaluation of configuration flags.
+    /// Boolean evaluation of configuration flags, at compile-time.
     ///
     /// For more information, see the documentation for [`std::cfg!`].
     ///

src/libcore/option.rs

@@ -338,6 +338,12 @@ impl<T> Option<T> {
 
     /// Returns the contained value or a default.
     ///
+    /// Arguments passed to `unwrap_or` are eagerly evaluated; if you are passing
+    /// the result of a function call, it is recommended to use [`unwrap_or_else`],
+    /// which is lazily evaluated.
+    ///
+    /// [`unwrap_or_else`]: #method.unwrap_or_else
+    ///
     /// # Examples
     ///
     /// ```
@@ -451,11 +457,16 @@ impl<T> Option<T> {
     /// Transforms the `Option<T>` into a [`Result<T, E>`], mapping [`Some(v)`] to
     /// [`Ok(v)`] and [`None`] to [`Err(err)`].
     ///
+    /// Arguments passed to `ok_or` are eagerly evaluated; if you are passing the
+    /// result of a function call, it is recommended to use [`ok_or_else`], which is
+    /// lazily evaluated.
+    ///
     /// [`Result<T, E>`]: ../../std/result/enum.Result.html
     /// [`Ok(v)`]: ../../std/result/enum.Result.html#variant.Ok
     /// [`Err(err)`]: ../../std/result/enum.Result.html#variant.Err
     /// [`None`]: #variant.None
     /// [`Some(v)`]: #variant.Some
+    /// [`ok_or_else`]: #method.ok_or_else
     ///
     /// # Examples
     ///
@@ -644,6 +655,12 @@ impl<T> Option<T> {
 
     /// Returns the option if it contains a value, otherwise returns `optb`.
     ///
+    /// Arguments passed to `or` are eagerly evaluated; if you are passing the
+    /// result of a function call, it is recommended to use [`or_else`], which is
+    /// lazily evaluated.
+    ///
+    /// [`or_else`]: #method.or_else
+    ///
     /// # Examples
     ///
     /// ```

src/libcore/ptr.rs

@@ -91,15 +91,53 @@ pub const fn null<T>() -> *const T { 0 as *const T }
 pub const fn null_mut<T>() -> *mut T { 0 as *mut T }
 
 /// Swaps the values at two mutable locations of the same type, without
-/// deinitializing either. They may overlap, unlike `mem::swap` which is
-/// otherwise equivalent.
+/// deinitializing either.
+///
+/// The values pointed at by `x` and `y` may overlap, unlike `mem::swap` which
+/// is otherwise equivalent. If the values do overlap, then the overlapping
+/// region of memory from `x` will be used. This is demonstrated in the
+/// examples section below.
 ///
 /// # Safety
 ///
 /// This function copies the memory through the raw pointers passed to it
 /// as arguments.
 ///
 /// Ensure that these pointers are valid before calling `swap`.
+///
+/// # Examples
+///
+/// Swapping two non-overlapping regions:
+///
+/// ```
+/// use std::ptr;
+///
+/// let mut array = [0, 1, 2, 3];
+///
+/// let x = array[0..].as_mut_ptr() as *mut [u32; 2];
+/// let y = array[2..].as_mut_ptr() as *mut [u32; 2];
+///
+/// unsafe {
+///     ptr::swap(x, y);
+///     assert_eq!([2, 3, 0, 1], array);
+/// }
+/// ```
+///
+/// Swapping two overlapping regions:
+///
+/// ```
+/// use std::ptr;
+///
+/// let mut array = [0, 1, 2, 3];
+///
+/// let x = array[0..].as_mut_ptr() as *mut [u32; 3];
+/// let y = array[1..].as_mut_ptr() as *mut [u32; 3];
+///
+/// unsafe {
+///     ptr::swap(x, y);
+///     assert_eq!([1, 0, 1, 2], array);
+/// }
+/// ```
 #[inline]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub unsafe fn swap<T>(x: *mut T, y: *mut T) {