---

yaml
---
r: 235257
b: refs/heads/stable
c: 80f9d93
h: refs/heads/master
i:
  235255: fe59a62
v: v3

Author: steveklabnik

[refs]

@@ -29,7 +29,7 @@ refs/heads/tmp: afae2ff723393b3ab4ccffef6ac7c6d1809e2da0
 refs/tags/1.0.0-alpha.2: 4c705f6bc559886632d3871b04f58aab093bfa2f
 refs/tags/homu-tmp: f859507de8c410b648d934d8f5ec1c52daac971d
 refs/tags/1.0.0-beta: 8cbb92b53468ee2b0c2d3eeb8567005953d40828
-refs/heads/stable: 8d9f1bab756720fce7337d3d8cc5960b036a266e
+refs/heads/stable: 80f9d935859a8ae783fdc85656fe498a59e8ebc2
 refs/tags/1.0.0: 55bd4f8ff2b323f317ae89e254ce87162d52a375
 refs/tags/1.1.0: bc3c16f09287e5545c1d3f76b7abd54f2eca868b
 refs/tags/1.2.0: f557861f822c34f07270347b94b5280de20a597e

branches/stable/src/doc/complement-design-faq.md

@@ -99,7 +99,7 @@ Second, it makes cost explicit. In general, the only safe way to have a
 non-exhaustive match would be to panic the thread if nothing is matched, though
 it could fall through if the type of the `match` expression is `()`. This sort
 of hidden cost and special casing is against the language's philosophy. It's
-easy to ignore certain cases by using the `_` wildcard:
+easy to ignore all unspecified cases by using the `_` wildcard:
 
 ```rust,ignore
 match val.do_something() {

branches/stable/src/doc/trpl/concurrency.md

@@ -10,11 +10,12 @@ system is up to the task, and gives you powerful ways to reason about
 concurrent code at compile time.
 
 Before we talk about the concurrency features that come with Rust, it's important
-to understand something: Rust is low-level enough that all of this is provided
-by the standard library, not by the language. This means that if you don't like
-some aspect of the way Rust handles concurrency, you can implement an alternative
-way of doing things. [mio](https://github.com/carllerche/mio) is a real-world
-example of this principle in action.
+to understand something: Rust is low-level enough that the vast majority of
+this is provided by the standard library, not by the language. This means that
+if you don't like some aspect of the way Rust handles concurrency, you can
+implement an alternative way of doing things.
+[mio](https://github.com/carllerche/mio) is a real-world example of this
+principle in action.
 
 ## Background: `Send` and `Sync`
 

branches/stable/src/doc/trpl/lifetimes.md

@@ -101,6 +101,8 @@ the lifetime `'a` has snuck in between the `&` and the `mut i32`. We read `&mut
 i32` as ‘a mutable reference to an i32’ and `&'a mut i32` as ‘a mutable
 reference to an `i32` with the lifetime `'a`’.
 
+# In `struct`s
+
 You’ll also need explicit lifetimes when working with [`struct`][structs]s:
 
 ```rust
@@ -137,6 +139,33 @@ x: &'a i32,
 uses it. So why do we need a lifetime here? We need to ensure that any reference
 to a `Foo` cannot outlive the reference to an `i32` it contains.
 
+## `impl` blocks
+
+Let’s implement a method on `Foo`:
+
+```rust
+struct Foo<'a> {
+    x: &'a i32,
+}
+
+impl<'a> Foo<'a> {
+    fn x(&self) -> &'a i32 { self.x }
+}
+
+fn main() {
+    let y = &5; // this is the same as `let _y = 5; let y = &_y;`
+    let f = Foo { x: y };
+
+    println!("x is: {}", f.x());
+}
+```
+
+As you can see, we need to declare a lifetime for `Foo` in the `impl` line. We repeat
+`'a` twice, just like on functions: `impl<'a>` defines a lifetime `'a`, and `Foo<'a>`
+uses it.
+
+## Multiple lifetimes
+
 If you have multiple references, you can use the same lifetime multiple times:
 
 ```rust

branches/stable/src/doc/trpl/unsafe.md

@@ -8,7 +8,7 @@ this, Rust has a keyword, `unsafe`. Code using `unsafe` has less restrictions
 than normal code does.
 
 Let’s go over the syntax, and then we’ll talk semantics. `unsafe` is used in
-two contexts. The first one is to mark a function as unsafe:
+four contexts. The first one is to mark a function as unsafe:
 
 ```rust
 unsafe fn danger_will_robinson() {
@@ -27,15 +27,40 @@ unsafe {
 }
 ```
 
+The third is for unsafe traits:
+
+```rust
+unsafe trait Scary { }
+```
+
+And the fourth is for `impl`ementing one of those traits:
+
+```rust
+# unsafe trait Scary { }
+unsafe impl Scary for i32 {}
+```
+
 It’s important to be able to explicitly delineate code that may have bugs that
 cause big problems. If a Rust program segfaults, you can be sure it’s somewhere
 in the sections marked `unsafe`.
 
 # What does ‘safe’ mean?
 
-Safe, in the context of Rust, means “doesn’t do anything unsafe.” Easy!
+Safe, in the context of Rust, means ‘doesn’t do anything unsafe’. It’s also
+important to know that there are certain behaviors that are probably not
+desirable in your code, but are expressly _not_ unsafe:
 
-Okay, let’s try again: what is not safe to do? Here’s a list:
+* Deadlocks
+* Leaks of memory or other resources
+* Exiting without calling destructors
+* Integer overflow
+
+Rust cannot prevent all kinds of software problems. Buggy code can and will be
+written in Rust. These things aren’t great, but they don’t qualify as `unsafe`
+specifically.
+
+In addition, the following are all undefined behaviors in Rust, and must be
+avoided, even when writing `unsafe` code:
 
 * Data races
 * Dereferencing a null/dangling raw pointer
@@ -64,18 +89,6 @@ Okay, let’s try again: what is not safe to do? Here’s a list:
 [undef]: http://llvm.org/docs/LangRef.html#undefined-values
 [aliasing]: http://llvm.org/docs/LangRef.html#pointer-aliasing-rules
 
-Whew! That’s a bunch of stuff. It’s also important to notice all kinds of
-behaviors that are certainly bad, but are expressly _not_ unsafe:
-
-* Deadlocks
-* Leaks of memory or other resources
-* Exiting without calling destructors
-* Integer overflow
-
-Rust cannot prevent all kinds of software problems. Buggy code can and will be
-written in Rust. These things aren’t great, but they don’t qualify as `unsafe`
-specifically.
-
 # Unsafe Superpowers
 
 In both unsafe functions and unsafe blocks, Rust will let you do three things

branches/stable/src/libcore/fmt/mod.rs

@@ -273,6 +273,8 @@ impl<'a> Display for Arguments<'a> {
 ///
 /// Generally speaking, you should just `derive` a `Debug` implementation.
 ///
+/// When used with the alternate format specifier `#?`, the output is pretty-printed.
+///
 /// For more information on formatters, see [the module-level documentation][module].
 ///
 /// [module]: ../index.html
@@ -314,13 +316,42 @@ impl<'a> Display for Arguments<'a> {
 /// println!("The origin is: {:?}", origin);
 /// ```
 ///
+/// This outputs:
+///
+/// ```text
+/// The origin is: Point { x: 0, y: 0 }
+/// ```
+///
 /// There are a number of `debug_*` methods on `Formatter` to help you with manual
 /// implementations, such as [`debug_struct`][debug_struct].
 ///
 /// `Debug` implementations using either `derive` or the debug builder API
 /// on `Formatter` support pretty printing using the alternate flag: `{:#?}`.
 ///
 /// [debug_struct]: ../std/fmt/struct.Formatter.html#method.debug_struct
+///
+/// Pretty printing with `#?`:
+///
+/// ```
+/// #[derive(Debug)]
+/// struct Point {
+///     x: i32,
+///     y: i32,
+/// }
+///
+/// let origin = Point { x: 0, y: 0 };
+///
+/// println!("The origin is: {:#?}", origin);
+/// ```
+///
+/// This outputs:
+///
+/// ```text
+/// The origin is: Point {
+///     x: 0,
+///     y: 0
+/// }
+/// ```
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_on_unimplemented = "`{Self}` cannot be formatted using `:?`; if it is \
                             defined in your crate, add `#[derive(Debug)]` or \
@@ -379,6 +410,8 @@ pub trait Display {
 ///
 /// The `Octal` trait should format its output as a number in base-8.
 ///
+/// The alternate flag, `#`, adds a `0o` in front of the output.
+///
 /// For more information on formatters, see [the module-level documentation][module].
 ///
 /// [module]: ../index.html
@@ -391,6 +424,7 @@ pub trait Display {
 /// let x = 42; // 42 is '52' in octal
 ///
 /// assert_eq!(format!("{:o}", x), "52");
+/// assert_eq!(format!("{:#o}", x), "0o52");
 /// ```
 ///
 /// Implementing `Octal` on a type:
@@ -423,6 +457,8 @@ pub trait Octal {
 ///
 /// The `Binary` trait should format its output as a number in binary.
 ///
+/// The alternate flag, `#`, adds a `0b` in front of the output.
+///
 /// For more information on formatters, see [the module-level documentation][module].
 ///
 /// [module]: ../index.html
@@ -435,6 +471,7 @@ pub trait Octal {
 /// let x = 42; // 42 is '101010' in binary
 ///
 /// assert_eq!(format!("{:b}", x), "101010");
+/// assert_eq!(format!("{:#b}", x), "0b101010");
 /// ```
 ///
 /// Implementing `Binary` on a type:
@@ -468,6 +505,8 @@ pub trait Binary {
 /// The `LowerHex` trait should format its output as a number in hexidecimal, with `a` through `f`
 /// in lower case.
 ///
+/// The alternate flag, `#`, adds a `0x` in front of the output.
+///
 /// For more information on formatters, see [the module-level documentation][module].
 ///
 /// [module]: ../index.html
@@ -480,6 +519,7 @@ pub trait Binary {
 /// let x = 42; // 42 is '2a' in hex
 ///
 /// assert_eq!(format!("{:x}", x), "2a");
+/// assert_eq!(format!("{:#x}", x), "0x2a");
 /// ```
 ///
 /// Implementing `LowerHex` on a type:
@@ -513,6 +553,8 @@ pub trait LowerHex {
 /// The `UpperHex` trait should format its output as a number in hexidecimal, with `A` through `F`
 /// in upper case.
 ///
+/// The alternate flag, `#`, adds a `0x` in front of the output.
+///
 /// For more information on formatters, see [the module-level documentation][module].
 ///
 /// [module]: ../index.html
@@ -525,6 +567,7 @@ pub trait LowerHex {
 /// let x = 42; // 42 is '2A' in hex
 ///
 /// assert_eq!(format!("{:X}", x), "2A");
+/// assert_eq!(format!("{:#X}", x), "0x2A");
 /// ```
 ///
 /// Implementing `UpperHex` on a type:

branches/stable/src/librustc/diagnostics.rs

@@ -1237,5 +1237,6 @@ register_diagnostics! {
     E0314, // closure outlives stack frame
     E0315, // cannot invoke closure outside of its lifetime
     E0316, // nested quantification of lifetimes
-    E0370  // discriminant overflow
+    E0370, // discriminant overflow
+    E0400  // overloaded derefs are not allowed in constants
 }

branches/stable/src/librustc/middle/cfg/construct.rs

@@ -332,7 +332,7 @@ impl<'a, 'tcx> CFGBuilder<'a, 'tcx> {
             }
 
             ast::ExprIndex(ref l, ref r) |
-            ast::ExprBinary(_, ref l, ref r) if self.is_method_call(expr) => {
+            ast::ExprBinary(_, ref l, ref r) if self.tcx.is_method_call(expr.id) => {
                 self.call(expr, pred, &**l, Some(&**r).into_iter())
             }
 
@@ -342,7 +342,7 @@ impl<'a, 'tcx> CFGBuilder<'a, 'tcx> {
                 self.straightline(expr, pred, fields)
             }
 
-            ast::ExprUnary(_, ref e) if self.is_method_call(expr) => {
+            ast::ExprUnary(_, ref e) if self.tcx.is_method_call(expr.id) => {
                 self.call(expr, pred, &**e, None::<ast::Expr>.iter())
             }
 
@@ -631,9 +631,4 @@ impl<'a, 'tcx> CFGBuilder<'a, 'tcx> {
             }
         }
     }
-
-    fn is_method_call(&self, expr: &ast::Expr) -> bool {
-        let method_call = ty::MethodCall::expr(expr.id);
-        self.tcx.tables.borrow().method_map.contains_key(&method_call)
-    }
 }

branches/stable/src/librustc/middle/check_const.rs

@@ -405,6 +405,7 @@ impl<'a, 'tcx, 'v> Visitor<'v> for CheckCrateVisitor<'a, 'tcx> {
 
         let node_ty = self.tcx.node_id_to_type(ex.id);
         check_expr(self, ex, node_ty);
+        check_adjustments(self, ex);
 
         // Special-case some expressions to avoid certain flags bubbling up.
         match ex.node {
@@ -777,6 +778,25 @@ fn check_expr<'a, 'tcx>(v: &mut CheckCrateVisitor<'a, 'tcx>,
     }
 }
 
+/// Check the adjustments of an expression
+fn check_adjustments<'a, 'tcx>(v: &mut CheckCrateVisitor<'a, 'tcx>, e: &ast::Expr) {
+    match v.tcx.tables.borrow().adjustments.get(&e.id) {
+        None | Some(&ty::AdjustReifyFnPointer) | Some(&ty::AdjustUnsafeFnPointer) => {}
+        Some(&ty::AdjustDerefRef(ty::AutoDerefRef { autoderefs, .. })) => {
+            if (0..autoderefs as u32).any(|autoderef| {
+                    v.tcx.is_overloaded_autoderef(e.id, autoderef)
+            }) {
+                v.add_qualif(ConstQualif::NOT_CONST);
+                if v.mode != Mode::Var {
+                    span_err!(v.tcx.sess, e.span, E0400,
+                              "user-defined dereference operators are not allowed in {}s",
+                              v.msg());
+                }
+            }
+        }
+    }
+}
+
 pub fn check_crate(tcx: &ty::ctxt) {
     visit::walk_crate(&mut CheckCrateVisitor {
         tcx: tcx,

branches/stable/src/librustc/middle/stability.rs

@@ -289,15 +289,19 @@ impl<'a, 'tcx> Checker<'a, 'tcx> {
         if !cross_crate { return }
 
         match *stab {
-            Some(&Stability { level: attr::Unstable, ref feature, ref reason, .. }) => {
+            Some(&Stability { level: attr::Unstable, ref feature, ref reason, issue, .. }) => {
                 self.used_features.insert(feature.clone(), attr::Unstable);
 
                 if !self.active_features.contains(feature) {
-                    let msg = match *reason {
+                    let mut msg = match *reason {
                         Some(ref r) => format!("use of unstable library feature '{}': {}",
                                                &feature, &r),
                         None => format!("use of unstable library feature '{}'", &feature)
                     };
+                    if let Some(n) = issue {
+                        use std::fmt::Write;
+                        write!(&mut msg, " (see issue #{})", n).unwrap();
+                    }
 
                     emit_feature_err(&self.tcx.sess.parse_sess.span_diagnostic,
                                       &feature, span, &msg);

branches/stable/src/librustc/middle/ty.rs

@@ -6631,6 +6631,11 @@ impl<'tcx> ctxt<'tcx> {
         self.tables.borrow().method_map.contains_key(&MethodCall::expr(expr_id))
     }
 
+    pub fn is_overloaded_autoderef(&self, expr_id: ast::NodeId, autoderefs: u32) -> bool {
+        self.tables.borrow().method_map.contains_key(&MethodCall::autoderef(expr_id,
+                                                                            autoderefs))
+    }
+
     pub fn upvar_capture(&self, upvar_id: ty::UpvarId) -> Option<ty::UpvarCapture> {
         Some(self.tables.borrow().upvar_capture_map.get(&upvar_id).unwrap().clone())
     }

branches/stable/src/librustc_driver/driver.rs

@@ -547,7 +547,7 @@ pub fn phase_2_configure_and_expand(sess: &Session,
                                                   sess.diagnostic()));
 
     krate = time(time_passes, "prelude injection", krate, |krate|
-                 syntax::std_inject::maybe_inject_prelude(krate));
+                 syntax::std_inject::maybe_inject_prelude(&sess.parse_sess, krate));
 
     time(time_passes, "checking that all macro invocations are gone", &krate, |krate|
          syntax::ext::expand::check_for_macros(&sess.parse_sess, krate));