---

yaml
---
r: 234750
b: refs/heads/tmp
c: fb690c7
h: refs/heads/master
v: v3

Author: Manishearth

[refs]

@@ -25,7 +25,7 @@ refs/tags/0.11.0: e1247cb1d0d681be034adb4b558b5a0c0d5720f9
 refs/tags/0.12.0: f0c419429ef30723ceaf6b42f9b5a2aeb5d2e2d1
 refs/heads/beta: d2e13e822a73e0ea46ae9e21afdd3155fc997f6d
 refs/tags/1.0.0-alpha: e42bd6d93a1d3433c486200587f8f9e12590a4d7
-refs/heads/tmp: 6fa0ff25bdc5aa5aae00dbe7c1cafc927b6806b6
+refs/heads/tmp: fb690c7af6949cf55766a0075a16c381a1f1de12
 refs/tags/1.0.0-alpha.2: 4c705f6bc559886632d3871b04f58aab093bfa2f
 refs/tags/homu-tmp: ab792abf1fcc28afbd315426213f6428da25c085
 refs/tags/1.0.0-beta: 8cbb92b53468ee2b0c2d3eeb8567005953d40828

branches/tmp/mk/dist.mk

@@ -77,6 +77,7 @@ $(PKG_TAR): $(PKG_FILES)
          -C $(S) \
          --exclude-vcs \
          --exclude=*~ \
+         --exclude=*.pyc \
          --exclude=*/llvm/test/*/*.ll \
          --exclude=*/llvm/test/*/*.td \
          --exclude=*/llvm/test/*/*.s \

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

@@ -26,8 +26,8 @@ to help us make sense of code that can possibly be concurrent.
 ### `Send`
 
 The first trait we're going to talk about is
-[`Send`](../std/marker/trait.Send.html). When a type `T` implements `Send`, it indicates
-to the compiler that something of this type is able to have ownership transferred
+[`Send`](../std/marker/trait.Send.html). When a type `T` implements `Send`, it
+indicates that something of this type is able to have ownership transferred
 safely between threads.
 
 This is important to enforce certain restrictions. For example, if we have a
@@ -42,13 +42,19 @@ us enforce that it can't leave the current thread.
 ### `Sync`
 
 The second of these traits is called [`Sync`](../std/marker/trait.Sync.html).
-When a type `T` implements `Sync`, it indicates to the compiler that something
+When a type `T` implements `Sync`, it indicates that something
 of this type has no possibility of introducing memory unsafety when used from
-multiple threads concurrently.
-
-For example, sharing immutable data with an atomic reference count is
-threadsafe. Rust provides a type like this, `Arc<T>`, and it implements `Sync`,
-so it is safe to share between threads.
+multiple threads concurrently through shared references. This implies that
+types which don't have [interior mutability](mutability.html) are inherently
+`Sync`, which includes simple primitive types (like `u8`) and aggregate types
+containing them.
+
+For sharing references across threads, Rust provides a wrapper type called
+`Arc<T>`. `Arc<T>` implements `Send` and `Sync` if and only if `T` implements
+both `Send` and `Sync`. For example, an object of type `Arc<RefCell<U>>` cannot
+be transferred across threads because
+[`RefCell`](choosing-your-guarantees.html#refcell%3Ct%3E) does not implement
+`Sync`, consequently `Arc<RefCell<U>>` would not implement `Send`.
 
 These two traits allow you to use the type system to make strong guarantees
 about the properties of your code under concurrency. Before we demonstrate
@@ -70,7 +76,7 @@ fn main() {
 }
 ```
 
-The `thread::spawn()` method accepts a closure, which is executed in a
+The `thread::spawn()` method accepts a [closure](closures.html), which is executed in a
 new thread. It returns a handle to the thread, that can be used to
 wait for the child thread to finish and extract its result:
 
@@ -215,29 +221,18 @@ fn main() {
 }
 ```
 
+Note that the value of `i` is bound (copied) to the closure and not shared
+among the threads.
 
-If we'd tried to use `Mutex<T>` without wrapping it in an `Arc<T>` we would have
-seen another error like:
-
-```text
-error: the trait `core::marker::Send` is not implemented for the type `std::sync::mutex::MutexGuard<'_, collections::vec::Vec<u32>>` [E0277]
- thread::spawn(move || {
-                  ^~~~~~~~~~~~~
-note: `std::sync::mutex::MutexGuard<'_, collections::vec::Vec<u32>>` cannot be sent between threads safely
- thread::spawn(move || {
-                  ^~~~~~~~~~~~~
-```
-
-You see, [`Mutex`](../std/sync/struct.Mutex.html) has a
-[`lock`](../std/sync/struct.Mutex.html#method.lock)
-method which has this signature:
+Also note that [`lock`](../std/sync/struct.Mutex.html#method.lock) method of
+[`Mutex`](../std/sync/struct.Mutex.html) has this signature:
 
 ```ignore
 fn lock(&self) -> LockResult<MutexGuard<T>>
 ```
 
-and because `Send` is not implemented for `MutexGuard<T>`, we couldn't have
-transferred the guard across thread boundaries on it's own.
+and because `Send` is not implemented for `MutexGuard<T>`, the guard cannot
+cross thread boundaries, ensuring thread-locality of lock acquire and release.
 
 Let's examine the body of the thread more closely:
 
@@ -317,22 +312,24 @@ use std::sync::mpsc;
 fn main() {
     let (tx, rx) = mpsc::channel();
 
-    for _ in 0..10 {
+    for i in 0..10 {
         let tx = tx.clone();
 
         thread::spawn(move || {
-            let answer = 42;
+            let answer = i * i;
 
             tx.send(answer);
         });
     }
 
-   rx.recv().ok().expect("Could not receive answer");
+    for _ in 0..10 {
+        println!("{}", rx.recv().unwrap());
+    }
 }
 ```
 
-A `u32` is `Send` because we can make a copy. So we create a thread, ask it to calculate
-the answer, and then it `send()`s us the answer over the channel.
+Here we create 10 threads, asking each to calculate the square of a number (`i`
+at the time of `spawn()`), and then `send()` back the answer over the channel.
 
 
 ## Panics

branches/tmp/src/librustc/diagnostics.rs

@@ -298,10 +298,18 @@ const FOO: i32 = { 0 }; // but brackets are useless here
 ```
 "##,
 
+// FIXME(#24111) Change the language here when const fn stabilizes
 E0015: r##"
 The only functions that can be called in static or constant expressions are
-`const` functions. Rust currently does not support more general compile-time
-function execution.
+`const` functions, and struct/enum constructors. `const` functions are only
+available on a nightly compiler. Rust currently does not support more general
+compile-time function execution.
+
+```
+const FOO: Option<u8> = Some(1); // enum constructor
+struct Bar {x: u8}
+const BAR: Bar = Bar {x: 1}; // struct constructor
+```
 
 See [RFC 911] for more details on the design of `const fn`s.
 

branches/tmp/src/librustc/lint/mod.rs

@@ -161,9 +161,6 @@ pub trait LateLintPass: LintPass {
     fn check_lifetime_ref(&mut self, _: &LateContext, _: &hir::Lifetime) { }
     fn check_lifetime_def(&mut self, _: &LateContext, _: &hir::LifetimeDef) { }
     fn check_explicit_self(&mut self, _: &LateContext, _: &hir::ExplicitSelf) { }
-    // Note that you shouldn't implement both check_mac and check_ast_mac,
-    // because then your lint will be called twice. Prefer check_ast_mac.
-    fn check_mac(&mut self, _: &LateContext, _: &ast::Mac) { }
     fn check_path(&mut self, _: &LateContext, _: &hir::Path, _: ast::NodeId) { }
     fn check_attribute(&mut self, _: &LateContext, _: &ast::Attribute) { }
 
@@ -209,7 +206,6 @@ pub trait EarlyLintPass: LintPass {
     fn check_lifetime_ref(&mut self, _: &EarlyContext, _: &ast::Lifetime) { }
     fn check_lifetime_def(&mut self, _: &EarlyContext, _: &ast::LifetimeDef) { }
     fn check_explicit_self(&mut self, _: &EarlyContext, _: &ast::ExplicitSelf) { }
-    fn check_mac(&mut self, _: &EarlyContext, _: &ast::Mac) { }
     fn check_path(&mut self, _: &EarlyContext, _: &ast::Path, _: ast::NodeId) { }
     fn check_attribute(&mut self, _: &EarlyContext, _: &ast::Attribute) { }
 

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

@@ -39,6 +39,7 @@ use util::nodemap::NodeMap;
 use rustc_front::hir;
 use syntax::ast;
 use syntax::codemap::Span;
+use syntax::feature_gate::UnstableFeatures;
 use rustc_front::visit::{self, FnKind, Visitor};
 
 use std::collections::hash_map::Entry;
@@ -709,10 +710,21 @@ fn check_expr<'a, 'tcx>(v: &mut CheckCrateVisitor<'a, 'tcx>,
             if !is_const {
                 v.add_qualif(ConstQualif::NOT_CONST);
                 if v.mode != Mode::Var {
-                    span_err!(v.tcx.sess, e.span, E0015,
-                              "function calls in {}s are limited to \
-                               constant functions, \
-                               struct and enum constructors", v.msg());
+                    // FIXME(#24111) Remove this check when const fn stabilizes
+                    if let UnstableFeatures::Disallow = v.tcx.sess.opts.unstable_features {
+                        span_err!(v.tcx.sess, e.span, E0015,
+                                  "function calls in {}s are limited to \
+                                   struct and enum constructors", v.msg());
+                        v.tcx.sess.span_note(e.span,
+                                             "a limited form of compile-time function \
+                                              evaluation is available on a nightly \
+                                              compiler via `const fn`");
+                    } else {
+                        span_err!(v.tcx.sess, e.span, E0015,
+                                  "function calls in {}s are limited to \
+                                   constant functions, \
+                                   struct and enum constructors", v.msg());
+                    }
                 }
             }
         }

branches/tmp/src/test/borrowck-loan-of-static-data-issue-27616.rs renamed to branches/tmp/src/test/compile-fail/borrowck-loan-of-static-data-issue-27616.rs

@@ -23,7 +23,7 @@ fn evil(mut s: &'static mut String)
     let alias: &'static mut String = s;
     let inner: &str = &alias;
     // free value
-    *s = String::new(); //~ ERROR cannot assign
+    *s = String::new(); //~ ERROR use of moved value
     let _spray = "0wned".to_owned();
     // ... and then use it
     println!("{}", inner);