Auto merge of #39180 - GuillaumeGomez:rollup, r=GuillaumeGomez

Rollup of 11 pull requests

- Successful merges: #38457, #38922, #38970, #39039, #39091, #39115, #39121, #39149, #39150, #39151, #39165
- Failed merges:

RELEASES.md

@@ -3371,7 +3371,7 @@ Version 1.0.0-alpha (2015-01-09)
       platforms.
     * Rust comes with rust-gdb and rust-lldb scripts that launch their
       respective debuggers with Rust-appropriate pretty-printing.
-    * The Windows installation of Rust is distributed with the the
+    * The Windows installation of Rust is distributed with the
       MinGW components currently required to link binaries on that
       platform.
 

src/libcollections/slice.rs

@@ -181,7 +181,7 @@ impl<T> [T] {
         core_slice::SliceExt::len(self)
     }
 
-    /// Returns true if the slice has a length of 0.
+    /// Returns `true` if the slice has a length of 0.
     ///
     /// # Example
     ///
@@ -342,15 +342,22 @@ impl<T> [T] {
         core_slice::SliceExt::last_mut(self)
     }
 
-    /// Returns the element of a slice at the given index, or `None` if the
-    /// index is out of bounds.
+    /// Returns a reference to an element or subslice depending on the type of
+    /// index.
+    ///
+    /// - If given a position, returns a reference to the element at that
+    ///   position or `None` if out of bounds.
+    /// - If given a range, returns the subslice corresponding to that range,
+    ///   or `None` if out of bounds.
     ///
     /// # Examples
     ///
     /// ```
     /// let v = [10, 40, 30];
     /// assert_eq!(Some(&40), v.get(1));
+    /// assert_eq!(Some(&[10, 40][..]), v.get(0..2));
     /// assert_eq!(None, v.get(3));
+    /// assert_eq!(None, v.get(0..4));
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
@@ -360,7 +367,10 @@ impl<T> [T] {
         core_slice::SliceExt::get(self, index)
     }
 
-    /// Returns a mutable reference to the element at the given index.
+    /// Returns a mutable reference to an element or subslice depending on the
+    /// type of index (see [`get()`]) or `None` if the index is out of bounds.
+    ///
+    /// [`get()`]: #method.get
     ///
     /// # Examples
     ///
@@ -372,7 +382,6 @@ impl<T> [T] {
     /// }
     /// assert_eq!(x, &[0, 42, 2]);
     /// ```
-    /// or `None` if the index is out of bounds
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn get_mut<I>(&mut self, index: I) -> Option<&mut I::Output>
@@ -381,8 +390,8 @@ impl<T> [T] {
         core_slice::SliceExt::get_mut(self, index)
     }
 
-    /// Returns a pointer to the element at the given index, without doing
-    /// bounds checking. So use it very carefully!
+    /// Returns a reference to an element or subslice, without doing bounds
+    /// checking. So use it very carefully!
     ///
     /// # Examples
     ///
@@ -401,8 +410,8 @@ impl<T> [T] {
         core_slice::SliceExt::get_unchecked(self, index)
     }
 
-    /// Returns an unsafe mutable pointer to the element in index. So use it
-    /// very carefully!
+    /// Returns a mutable reference to an element or subslice, without doing
+    /// bounds checking. So use it very carefully!
     ///
     /// # Examples
     ///
@@ -540,12 +549,8 @@ impl<T> [T] {
     ///
     /// ```
     /// let x = &mut [1, 2, 4];
-    /// {
-    ///     let iterator = x.iter_mut();
-    ///
-    ///     for elem in iterator {
-    ///         *elem += 2;
-    ///     }
+    /// for elem in x.iter_mut() {
+    ///     *elem += 2;
     /// }
     /// assert_eq!(x, &[3, 4, 6]);
     /// ```
@@ -880,7 +885,7 @@ impl<T> [T] {
         core_slice::SliceExt::rsplitn_mut(self, n, pred)
     }
 
-    /// Returns true if the slice contains an element with the given value.
+    /// Returns `true` if the slice contains an element with the given value.
     ///
     /// # Examples
     ///
@@ -896,7 +901,7 @@ impl<T> [T] {
         core_slice::SliceExt::contains(self, x)
     }
 
-    /// Returns true if `needle` is a prefix of the slice.
+    /// Returns `true` if `needle` is a prefix of the slice.
     ///
     /// # Examples
     ///
@@ -907,14 +912,23 @@ impl<T> [T] {
     /// assert!(!v.starts_with(&[50]));
     /// assert!(!v.starts_with(&[10, 50]));
     /// ```
+    ///
+    /// Always returns `true` if `needle` is an empty slice:
+    ///
+    /// ```
+    /// let v = &[10, 40, 30];
+    /// assert!(v.starts_with(&[]));
+    /// let v: &[u8] = &[];
+    /// assert!(v.starts_with(&[]));
+    /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn starts_with(&self, needle: &[T]) -> bool
         where T: PartialEq
     {
         core_slice::SliceExt::starts_with(self, needle)
     }
 
-    /// Returns true if `needle` is a suffix of the slice.
+    /// Returns `true` if `needle` is a suffix of the slice.
     ///
     /// # Examples
     ///
@@ -925,6 +939,15 @@ impl<T> [T] {
     /// assert!(!v.ends_with(&[50]));
     /// assert!(!v.ends_with(&[50, 30]));
     /// ```
+    ///
+    /// Always returns `true` if `needle` is an empty slice:
+    ///
+    /// ```
+    /// let v = &[10, 40, 30];
+    /// assert!(v.ends_with(&[]));
+    /// let v: &[u8] = &[];
+    /// assert!(v.ends_with(&[]));
+    /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn ends_with(&self, needle: &[T]) -> bool
         where T: PartialEq

src/librustc/dep_graph/thread.rs

@@ -56,7 +56,7 @@ pub struct DepGraphThreadData {
     // current buffer, where we accumulate messages
     messages: VecCell<DepMessage>,
 
-    // whence to receive new buffer when full
+    // where to receive new buffer when full
     swap_in: Receiver<Vec<DepMessage>>,
 
     // where to send buffer when full

src/librustc/diagnostics.rs

@@ -1454,6 +1454,40 @@ struct Prince<'kiss, 'SnowWhite: 'kiss> { // You say here that 'kiss must live
 ```
 "##,
 
+E0491: r##"
+A reference has a longer lifetime than the data it references.
+
+Erroneous code example:
+
+```compile_fail,E0491
+// struct containing a reference requires a lifetime parameter,
+// because the data the reference points to must outlive the struct (see E0106)
+struct Struct<'a> {
+    ref_i32: &'a i32,
+}
+
+// However, a nested struct like this, the signature itself does not tell
+// whether 'a outlives 'b or the other way around.
+// So it could be possible that 'b of reference outlives 'a of the data.
+struct Nested<'a, 'b> {
+    ref_struct: &'b Struct<'a>, // compile error E0491
+}
+```
+
+To fix this issue, you can specify a bound to the lifetime like below:
+
+```
+struct Struct<'a> {
+    ref_i32: &'a i32,
+}
+
+// 'a: 'b means 'a outlives 'b
+struct Nested<'a: 'b, 'b> {
+    ref_struct: &'b Struct<'a>,
+}
+```
+"##,
+
 E0496: r##"
 A lifetime name is shadowing another lifetime name. Erroneous code example:
 
@@ -1697,7 +1731,6 @@ register_diagnostics! {
     E0488, // lifetime of variable does not enclose its declaration
     E0489, // type/lifetime parameter not in scope here
     E0490, // a value of type `..` is borrowed for too long
-    E0491, // in type `..`, reference has a longer lifetime than the data it...
     E0495, // cannot infer an appropriate lifetime due to conflicting requirements
     E0566  // conflicting representation hints
 }

src/librustc/ty/inhabitedness/mod.rs

@@ -190,7 +190,13 @@ impl<'a, 'gcx, 'tcx> TyS<'tcx> {
                     ty.uninhabited_from(visited, tcx)
                 }
             }
-            TyRef(_, ref tm) => tm.ty.uninhabited_from(visited, tcx),
+            TyRef(_, ref tm) => {
+                if tcx.sess.features.borrow().never_type {
+                    tm.ty.uninhabited_from(visited, tcx)
+                } else {
+                    DefIdForest::empty()
+                }
+            }
 
             _ => DefIdForest::empty(),
         }

src/librustc_typeck/collect.rs

@@ -716,6 +716,16 @@ fn ensure_no_ty_param_bounds(ccx: &CrateCtxt,
         }
     }
 
+    for predicate in generics.where_clause.predicates.iter() {
+        match *predicate {
+            hir::WherePredicate::BoundPredicate(..) => {
+                warn = true;
+            }
+            hir::WherePredicate::RegionPredicate(..) => { }
+            hir::WherePredicate::EqPredicate(..) => { }
+        }
+    }
+
     if warn {
         // According to accepted RFC #XXX, we should
         // eventually accept these, but it will not be

src/libstd/fs.rs

@@ -81,7 +81,8 @@ use time::SystemTime;
 /// # }
 /// ```
 ///
-/// [`BufReader`]: ../io/struct.BufReader.html
+/// [`Read`]: ../io/trait.Read.html
+/// [`BufReader<R>`]: ../io/struct.BufReader.html
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct File {
     inner: fs_imp::File,

src/libstd/macros.rs

@@ -458,23 +458,38 @@ pub mod builtin {
 
     /// Parse a file as an expression or an item according to the context.
     ///
-    /// The file is located relative to the current file. (similarly to how
-    /// modules are found)
+    /// The file is located relative to the current file (similarly to how
+    /// modules are found).
     ///
     /// Using this macro is often a bad idea, because if the file is
     /// parsed as an expression, it is going to be placed in the
-    /// surrounding code unhygenically. This could result in variables
+    /// surrounding code unhygienically. This could result in variables
     /// or functions being different from what the file expected if
     /// there are variables or functions that have the same name in
     /// the current file.
     ///
     /// # Examples
     ///
+    /// Assume there are two files in the same directory with the following
+    /// contents:
+    ///
+    /// File 'my_str.in':
+    ///
     /// ```ignore
-    /// fn foo() {
-    ///     include!("/path/to/a/file")
+    /// "Hello World!"
+    /// ```
+    ///
+    /// File 'main.rs':
+    ///
+    /// ```ignore
+    /// fn main() {
+    ///     let my_str = include!("my_str.in");
+    ///     println!("{}", my_str);
     /// }
     /// ```
+    ///
+    /// Compiling 'main.rs' and running the resulting binary will print "Hello
+    /// World!".
     #[stable(feature = "rust1", since = "1.0.0")]
     #[macro_export]
     macro_rules! include { ($file:expr) => ({ /* compiler built-in */ }) }

src/libsyntax/feature_gate.rs

@@ -689,10 +689,10 @@ pub const BUILTIN_ATTRIBUTES: &'static [(&'static str, AttributeType, AttributeG
                                                        cfg_fn!(omit_gdb_pretty_printer_section))),
     ("unsafe_destructor_blind_to_params",
      Normal,
-     Gated(Stability::Unstable,
+     Gated(Stability::Deprecated("https://github.com/rust-lang/rust/issues/34761"),
            "dropck_parametricity",
-           "unsafe_destructor_blind_to_params has unstable semantics \
-            and may be removed in the future",
+           "unsafe_destructor_blind_to_params has been replaced by \
+            may_dangle and will be removed in the future",
            cfg_fn!(dropck_parametricity))),
     ("may_dangle",
      Normal,

src/test/compile-fail/feature-gate-dropck-ugeh-2.rs

@@ -0,0 +1,22 @@
+// Copyright 2016 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.
+
+#![deny(deprecated)]
+#![feature(dropck_parametricity)]
+
+struct Foo;
+
+impl Drop for Foo {
+    #[unsafe_destructor_blind_to_params]
+    //~^ ERROR use of deprecated attribute `dropck_parametricity`
+    fn drop(&mut self) {}
+}
+
+fn main() {}

src/test/compile-fail/feature-gate-dropck-ugeh.rs

@@ -27,7 +27,7 @@ struct Foo<T> { data: Vec<T> }
 
 impl<T> Drop for Foo<T> {
     #[unsafe_destructor_blind_to_params] // This is the UGEH attribute
-    //~^ ERROR unsafe_destructor_blind_to_params has unstable semantics
+    //~^ ERROR unsafe_destructor_blind_to_params has been replaced
     fn drop(&mut self) { }
 }
 

src/test/compile-fail/issue-17994.rs

@@ -9,5 +9,6 @@
 // except according to those terms.
 
 trait Tr {}
-type Huh<T> where T: Tr = isize; //~ ERROR type parameter `T` is unused
+type Huh<T> where T: Tr = isize; //~  ERROR type parameter `T` is unused
+                                 //~| WARNING E0122
 fn main() {}

src/test/compile-fail/issue-39122.rs

@@ -0,0 +1,13 @@
+// Copyright 2017 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.
+
+type Foo<T: std::ops::Add> = T; //~ WARNING E0122
+
+type Bar<T> where T: std::ops::Add = T; //~ WARNING E0122

src/test/compile-fail/private-in-public-warn.rs

@@ -89,6 +89,7 @@ mod traits_where {
     pub type Alias<T> where T: PrivTr = T;
         //~^ ERROR private trait `traits_where::PrivTr` in public interface
         //~| WARNING hard error
+        //~| WARNING E0122
     pub trait Tr2<T> where T: PrivTr {}
         //~^ ERROR private trait `traits_where::PrivTr` in public interface
         //~| WARNING hard error

src/test/compile-fail/uninhabited-reference-type-feature-gated.rs

@@ -0,0 +1,19 @@
+// Copyright 2016 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.
+
+enum Void {}
+
+fn main() {
+    let x: Result<u32, &'static Void> = Ok(23);
+    let _ = match x {   //~ ERROR non-exhaustive
+        Ok(n) => n,
+    };
+}
+