Auto merge of #35666 - eddyb:rollup, r=eddyb

Rollup of 30 pull requests

- Successful merges: #34941, #35392, #35444, #35447, #35491, #35533, #35539, #35558, #35573, #35574, #35577, #35586, #35588, #35594, #35596, #35597, #35598, #35606, #35611, #35615, #35616, #35620, #35622, #35640, #35643, #35644, #35646, #35647, #35648, #35661
- Failed merges: #35395, #35415

Author: bors

Diff for: configure

@@ -1013,7 +1013,7 @@ then
     LLVM_VERSION=$($LLVM_CONFIG --version)
 
     case $LLVM_VERSION in
-        (3.[7-8]*)
+        (3.[7-9]*)
             msg "found ok version of LLVM: $LLVM_VERSION"
             ;;
         (*)

Diff for: mk/cfg/i586-unknown-linux-gnu.mk

@@ -7,8 +7,8 @@ CFG_LIB_NAME_i586-unknown-linux-gnu=lib$(1).so
 CFG_STATIC_LIB_NAME_i586-unknown-linux-gnu=lib$(1).a
 CFG_LIB_GLOB_i586-unknown-linux-gnu=lib$(1)-*.so
 CFG_LIB_DSYM_GLOB_i586-unknown-linux-gnu=lib$(1)-*.dylib.dSYM
-CFG_JEMALLOC_CFLAGS_i586-unknown-linux-gnu := -m32 $(CFLAGS) -march=pentium
-CFG_GCCISH_CFLAGS_i586-unknown-linux-gnu :=  -g -fPIC -m32 $(CFLAGS) -march=pentium
+CFG_JEMALLOC_CFLAGS_i586-unknown-linux-gnu := -m32 $(CFLAGS) -march=pentium -Wa,-mrelax-relocations=no
+CFG_GCCISH_CFLAGS_i586-unknown-linux-gnu :=  -g -fPIC -m32 $(CFLAGS) -march=pentium -Wa,-mrelax-relocations=no
 CFG_GCCISH_CXXFLAGS_i586-unknown-linux-gnu := -fno-rtti $(CXXFLAGS) -march=pentium
 CFG_GCCISH_LINK_FLAGS_i586-unknown-linux-gnu := -shared -fPIC -ldl -pthread  -lrt -g -m32
 CFG_GCCISH_DEF_FLAG_i586-unknown-linux-gnu := -Wl,--export-dynamic,--dynamic-list=

Diff for: mk/cfg/i686-unknown-linux-musl.mk

@@ -7,8 +7,8 @@ CFG_INSTALL_ONLY_RLIB_i686-unknown-linux-musl = 1
 CFG_LIB_NAME_i686-unknown-linux-musl=lib$(1).so
 CFG_STATIC_LIB_NAME_i686-unknown-linux-musl=lib$(1).a
 CFG_LIB_GLOB_i686-unknown-linux-musl=lib$(1)-*.so
-CFG_JEMALLOC_CFLAGS_i686-unknown-linux-musl := -m32 -Wl,-melf_i386
-CFG_GCCISH_CFLAGS_i686-unknown-linux-musl :=  -g -fPIC -m32 -Wl,-melf_i386
+CFG_JEMALLOC_CFLAGS_i686-unknown-linux-musl := -m32 -Wl,-melf_i386 -Wa,-mrelax-relocations=no
+CFG_GCCISH_CFLAGS_i686-unknown-linux-musl :=  -g -fPIC -m32 -Wl,-melf_i386 -Wa,-mrelax-relocations=no
 CFG_GCCISH_CXXFLAGS_i686-unknown-linux-musl :=
 CFG_GCCISH_LINK_FLAGS_i686-unknown-linux-musl :=
 CFG_GCCISH_DEF_FLAG_i686-unknown-linux-musl :=

Diff for: src/bootstrap/lib.rs

@@ -870,8 +870,13 @@ impl Build {
         // This is a hack, because newer binutils broke things on some vms/distros
         // (i.e., linking against unknown relocs disabled by the following flag)
         // See: https://github.com/rust-lang/rust/issues/34978
-        if target == "x86_64-unknown-linux-musl" {
-            base.push("-Wa,-mrelax-relocations=no".into());
+        match target {
+            "i586-unknown-linux-gnu" |
+            "i686-unknown-linux-musl" |
+            "x86_64-unknown-linux-musl" => {
+                base.push("-Wa,-mrelax-relocations=no".into());
+            },
+            _ => {},
         }
         return base
     }

Diff for: src/bootstrap/sanity.rs

@@ -98,7 +98,8 @@ pub fn check(build: &mut Build) {
         if target.contains("rumprun") ||
            target.contains("bitrig") ||
            target.contains("openbsd") ||
-           target.contains("msvc") {
+           target.contains("msvc") ||
+           target.contains("emscripten") {
             build.config.use_jemalloc = false;
         }
 

Diff for: src/doc/book/error-handling.md

@@ -166,7 +166,7 @@ story. The other half is *using* the `find` function we've written. Let's try
 to use it to find the extension in a file name.
 
 ```rust
-# fn find(_: &str, _: char) -> Option<usize> { None }
+# fn find(haystack: &str, needle: char) -> Option<usize> { haystack.find(needle) }
 fn main() {
     let file_name = "foobar.rs";
     match find(file_name, '.') {
@@ -223,7 +223,7 @@ Getting the extension of a file name is a pretty common operation, so it makes
 sense to put it into a function:
 
 ```rust
-# fn find(_: &str, _: char) -> Option<usize> { None }
+# fn find(haystack: &str, needle: char) -> Option<usize> { haystack.find(needle) }
 // Returns the extension of the given file name, where the extension is defined
 // as all characters following the first `.`.
 // If `file_name` has no `.`, then `None` is returned.
@@ -272,7 +272,7 @@ Armed with our new combinator, we can rewrite our `extension_explicit` method
 to get rid of the case analysis:
 
 ```rust
-# fn find(_: &str, _: char) -> Option<usize> { None }
+# fn find(haystack: &str, needle: char) -> Option<usize> { haystack.find(needle) }
 // Returns the extension of the given file name, where the extension is defined
 // as all characters following the first `.`.
 // If `file_name` has no `.`, then `None` is returned.

Diff for: src/doc/book/variable-bindings.md

@@ -125,7 +125,7 @@ warning, but it will still print "Hello, world!":
 
 ```text
    Compiling hello_world v0.0.1 (file:///home/you/projects/hello_world)
-src/main.rs:2:9: 2:10 warning: unused variable: `x`, #[warn(unused_variable)]
+src/main.rs:2:9: 2:10 warning: unused variable: `x`, #[warn(unused_variables)]
    on by default
 src/main.rs:2     let x: i32;
                       ^

Diff for: src/liballoc/raw_vec.rs

@@ -17,7 +17,7 @@ use super::boxed::Box;
 use core::ops::Drop;
 use core::cmp;
 
-/// A low-level utility for more ergonomically allocating, reallocating, and deallocating a
+/// 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
 /// involved. This type is excellent for building your own data structures like Vec and VecDeque.
 /// In particular:
@@ -534,8 +534,8 @@ impl<T> RawVec<T> {
     /// Converts the entire buffer into `Box<[T]>`.
     ///
     /// While it is not *strictly* Undefined Behavior to call
-    /// this procedure while some of the RawVec is unintialized,
-    /// it cetainly makes it trivial to trigger it.
+    /// this procedure while some of the RawVec is uninitialized,
+    /// it certainly makes it trivial to trigger it.
     ///
     /// Note that this will correctly reconstitute any `cap` changes
     /// that may have been performed. (see description of type for details)

Diff for: src/libcollections/string.rs

@@ -1152,7 +1152,7 @@ impl String {
         self.vec.set_len(len + amt);
     }
 
-    /// Inserts a string into this `String` at a byte position.
+    /// Inserts a string slice into this `String` at a byte position.
     ///
     /// This is an `O(n)` operation as it requires copying every element in the
     /// buffer.
@@ -1182,8 +1182,7 @@ impl String {
                reason = "recent addition",
                issue = "35553")]
     pub fn insert_str(&mut self, idx: usize, string: &str) {
-        let len = self.len();
-        assert!(idx <= len);
+        assert!(idx <= self.len());
         assert!(self.is_char_boundary(idx));
 
         unsafe {

Diff for: src/libcollections/vec.rs

@@ -1446,13 +1446,12 @@ impl<T> IntoIterator for Vec<T> {
     #[inline]
     fn into_iter(mut self) -> IntoIter<T> {
         unsafe {
-            let ptr = self.as_mut_ptr();
-            assume(!ptr.is_null());
-            let begin = ptr as *const T;
+            let begin = self.as_mut_ptr();
+            assume(!begin.is_null());
             let end = if mem::size_of::<T>() == 0 {
-                arith_offset(ptr as *const i8, self.len() as isize) as *const T
+                arith_offset(begin as *const i8, self.len() as isize) as *const T
             } else {
-                ptr.offset(self.len() as isize) as *const T
+                begin.offset(self.len() as isize) as *const T
             };
             let buf = ptr::read(&self.buf);
             mem::forget(self);
@@ -1710,10 +1709,52 @@ impl<'a, T> FromIterator<T> for Cow<'a, [T]> where T: Clone {
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct IntoIter<T> {
     _buf: RawVec<T>,
-    ptr: *const T,
+    ptr: *mut T,
     end: *const T,
 }
 
+impl<T> IntoIter<T> {
+    /// Returns the remaining items of this iterator as a slice.
+    ///
+    /// # Examples
+    ///
+    /// ```rust
+    /// # #![feature(vec_into_iter_as_slice)]
+    /// let vec = vec!['a', 'b', 'c'];
+    /// let mut into_iter = vec.into_iter();
+    /// assert_eq!(into_iter.as_slice(), &['a', 'b', 'c']);
+    /// let _ = into_iter.next().unwrap();
+    /// assert_eq!(into_iter.as_slice(), &['b', 'c']);
+    /// ```
+    #[unstable(feature = "vec_into_iter_as_slice", issue = "35601")]
+    pub fn as_slice(&self) -> &[T] {
+        unsafe {
+            slice::from_raw_parts(self.ptr, self.len())
+        }
+    }
+
+    /// Returns the remaining items of this iterator as a mutable slice.
+    ///
+    /// # Examples
+    ///
+    /// ```rust
+    /// # #![feature(vec_into_iter_as_slice)]
+    /// let vec = vec!['a', 'b', 'c'];
+    /// let mut into_iter = vec.into_iter();
+    /// assert_eq!(into_iter.as_slice(), &['a', 'b', 'c']);
+    /// into_iter.as_mut_slice()[2] = 'z';
+    /// assert_eq!(into_iter.next().unwrap(), 'a');
+    /// assert_eq!(into_iter.next().unwrap(), 'b');
+    /// assert_eq!(into_iter.next().unwrap(), 'z');
+    /// ```
+    #[unstable(feature = "vec_into_iter_as_slice", issue = "35601")]
+    pub fn as_mut_slice(&self) -> &mut [T] {
+        unsafe {
+            slice::from_raw_parts_mut(self.ptr, self.len())
+        }
+    }
+}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 unsafe impl<T: Send> Send for IntoIter<T> {}
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -1726,14 +1767,14 @@ impl<T> Iterator for IntoIter<T> {
     #[inline]
     fn next(&mut self) -> Option<T> {
         unsafe {
-            if self.ptr == self.end {
+            if self.ptr as *const _ == self.end {
                 None
             } else {
                 if mem::size_of::<T>() == 0 {
                     // purposefully don't use 'ptr.offset' because for
                     // vectors with 0-size elements this would return the
                     // same pointer.
-                    self.ptr = arith_offset(self.ptr as *const i8, 1) as *const T;
+                    self.ptr = arith_offset(self.ptr as *const i8, 1) as *mut T;
 
                     // Use a non-null pointer value
                     Some(ptr::read(EMPTY as *mut T))
@@ -1776,7 +1817,7 @@ impl<T> DoubleEndedIterator for IntoIter<T> {
             } else {
                 if mem::size_of::<T>() == 0 {
                     // See above for why 'ptr.offset' isn't used
-                    self.end = arith_offset(self.end as *const i8, -1) as *const T;
+                    self.end = arith_offset(self.end as *const i8, -1) as *mut T;
 
                     // Use a non-null pointer value
                     Some(ptr::read(EMPTY as *mut T))
@@ -1796,9 +1837,7 @@ impl<T> ExactSizeIterator for IntoIter<T> {}
 #[stable(feature = "vec_into_iter_clone", since = "1.8.0")]
 impl<T: Clone> Clone for IntoIter<T> {
     fn clone(&self) -> IntoIter<T> {
-        unsafe {
-            slice::from_raw_parts(self.ptr, self.len()).to_owned().into_iter()
-        }
+        self.as_slice().to_owned().into_iter()
     }
 }
 

Diff for: src/libcollectionstest/lib.rs

@@ -28,6 +28,7 @@
 #![feature(unboxed_closures)]
 #![feature(unicode)]
 #![feature(vec_deque_contains)]
+#![feature(vec_into_iter_as_slice)]
 
 extern crate collections;
 extern crate test;

Diff for: src/libcollectionstest/vec.rs

@@ -478,6 +478,29 @@ fn test_split_off() {
     assert_eq!(vec2, [5, 6]);
 }
 
+#[test]
+fn test_into_iter_as_slice() {
+    let vec = vec!['a', 'b', 'c'];
+    let mut into_iter = vec.into_iter();
+    assert_eq!(into_iter.as_slice(), &['a', 'b', 'c']);
+    let _ = into_iter.next().unwrap();
+    assert_eq!(into_iter.as_slice(), &['b', 'c']);
+    let _ = into_iter.next().unwrap();
+    let _ = into_iter.next().unwrap();
+    assert_eq!(into_iter.as_slice(), &[]);
+}
+
+#[test]
+fn test_into_iter_as_mut_slice() {
+    let vec = vec!['a', 'b', 'c'];
+    let mut into_iter = vec.into_iter();
+    assert_eq!(into_iter.as_slice(), &['a', 'b', 'c']);
+    into_iter.as_mut_slice()[0] = 'x';
+    into_iter.as_mut_slice()[1] = 'y';
+    assert_eq!(into_iter.next().unwrap(), 'x');
+    assert_eq!(into_iter.as_slice(), &['y', 'c']);
+}
+
 #[test]
 fn test_into_iter_count() {
     assert_eq!(vec![1, 2, 3].into_iter().count(), 3);

Diff for: src/libcore/cell.rs

@@ -146,6 +146,7 @@
 
 use clone::Clone;
 use cmp::{PartialEq, Eq, PartialOrd, Ord, Ordering};
+use convert::From;
 use default::Default;
 use fmt::{self, Debug, Display};
 use marker::{Copy, PhantomData, Send, Sync, Sized, Unsize};
@@ -329,6 +330,13 @@ impl<T:Ord + Copy> Ord for Cell<T> {
     }
 }
 
+#[stable(feature = "cell_from", since = "1.12.0")]
+impl<T: Copy> From<T> for Cell<T> {
+    fn from(t: T) -> Cell<T> {
+        Cell::new(t)
+    }
+}
+
 /// A mutable memory location with dynamically checked borrow rules
 ///
 /// See the [module-level documentation](index.html) for more.
@@ -742,6 +750,13 @@ impl<T: ?Sized + Ord> Ord for RefCell<T> {
     }
 }
 
+#[stable(feature = "cell_from", since = "1.12.0")]
+impl<T> From<T> for RefCell<T> {
+    fn from(t: T) -> RefCell<T> {
+        RefCell::new(t)
+    }
+}
+
 struct BorrowRef<'b> {
     borrow: &'b Cell<BorrowFlag>,
 }
@@ -1064,3 +1079,10 @@ impl<T: Default> Default for UnsafeCell<T> {
         UnsafeCell::new(Default::default())
     }
 }
+
+#[stable(feature = "cell_from", since = "1.12.0")]
+impl<T> From<T> for UnsafeCell<T> {
+    fn from(t: T) -> UnsafeCell<T> {
+        UnsafeCell::new(t)
+    }
+}

Diff for: src/libcore/convert.rs

@@ -71,8 +71,8 @@ use result::Result;
 ///
 /// # Generic Impls
 ///
-/// - `AsRef` auto-dereference if the inner type is a reference or a mutable
-/// reference (eg: `foo.as_ref()` will work the same if `foo` has type `&mut Foo` or `&&mut Foo`)
+/// - `AsRef` auto-dereferences if the inner type is a reference or a mutable
+/// reference (e.g.: `foo.as_ref()` will work the same if `foo` has type `&mut Foo` or `&&mut Foo`)
 ///
 #[stable(feature = "rust1", since = "1.0.0")]
 pub trait AsRef<T: ?Sized> {
@@ -88,8 +88,8 @@ pub trait AsRef<T: ?Sized> {
 ///
 /// # Generic Impls
 ///
-/// - `AsMut` auto-dereference if the inner type is a reference or a mutable
-/// reference (eg: `foo.as_ref()` will work the same if `foo` has type `&mut Foo` or `&&mut Foo`)
+/// - `AsMut` auto-dereferences if the inner type is a reference or a mutable
+/// reference (e.g.: `foo.as_ref()` will work the same if `foo` has type `&mut Foo` or `&&mut Foo`)
 ///
 #[stable(feature = "rust1", since = "1.0.0")]
 pub trait AsMut<T: ?Sized> {

Diff for: src/libcore/sync/atomic.rs

@@ -32,7 +32,7 @@
 //! atomically-reference-counted shared pointer).
 //!
 //! Most atomic types may be stored in static variables, initialized using
-//! the provided static initializers like `INIT_ATOMIC_BOOL`. Atomic statics
+//! the provided static initializers like `ATOMIC_BOOL_INIT`. Atomic statics
 //! are often used for lazy global initialization.
 //!
 //!

Diff for: src/librustc/middle/entry.rs

@@ -132,8 +132,13 @@ fn find_item(item: &Item, ctxt: &mut EntryContext, at_root: bool) {
             if ctxt.start_fn.is_none() {
                 ctxt.start_fn = Some((item.id, item.span));
             } else {
-                span_err!(ctxt.session, item.span, E0138,
-                          "multiple 'start' functions");
+                struct_span_err!(
+                    ctxt.session, item.span, E0138,
+                    "multiple 'start' functions")
+                    .span_label(ctxt.start_fn.unwrap().1,
+                                &format!("previous `start` function here"))
+                    .span_label(item.span, &format!("multiple `start` functions"))
+                    .emit();
             }
         },
         EntryPointType::None => ()

Diff for: src/librustc/ty/error.rs

@@ -222,7 +222,24 @@ impl<'a, 'gcx, 'lcx, 'tcx> ty::TyS<'tcx> {
             ty::TyArray(_, n) => format!("array of {} elements", n),
             ty::TySlice(_) => "slice".to_string(),
             ty::TyRawPtr(_) => "*-ptr".to_string(),
-            ty::TyRef(_, _) => "&-ptr".to_string(),
+            ty::TyRef(region, tymut) => {
+                let tymut_string = tymut.to_string();
+                if tymut_string == "_" ||         //unknown type name,
+                   tymut_string.len() > 10 ||     //name longer than saying "reference",
+                   region.to_string() != ""       //... or a complex type
+                {
+                    match tymut {
+                        ty::TypeAndMut{mutbl, ..} => {
+                            format!("{}reference", match mutbl {
+                                hir::Mutability::MutMutable => "mutable ",
+                                _ => ""
+                            })
+                        }
+                    }
+                } else {
+                    format!("&{}", tymut_string)
+                }
+            }
             ty::TyFnDef(..) => format!("fn item"),
             ty::TyFnPtr(_) => "fn pointer".to_string(),
             ty::TyTrait(ref inner) => {