Rollup of 13 pull requests

configure

@@ -717,18 +717,6 @@ if [ -n "$CFG_ENABLE_DEBUG_JEMALLOC" ]; then putvar CFG_ENABLE_DEBUG_JEMALLOC; f
 
 if [ -n "$CFG_ENABLE_ORBIT" ]; then putvar CFG_ENABLE_ORBIT; fi
 
-# A magic value that allows the compiler to use unstable features
-# during the bootstrap even when doing so would normally be an error
-# because of feature staging or because the build turns on
-# warnings-as-errors and unstable features default to warnings.  The
-# build has to match this key in an env var. Meant to be a mild
-# deterrent from users just turning on unstable features on the stable
-# channel.
-# Basing CFG_BOOTSTRAP_KEY on CFG_BOOTSTRAP_KEY lets it get picked up
-# during a Makefile reconfig.
-CFG_BOOTSTRAP_KEY="${CFG_BOOTSTRAP_KEY-`date +%H:%M:%S`}"
-putvar CFG_BOOTSTRAP_KEY
-
 step_msg "looking for build programs"
 
 probe_need CFG_CURLORWGET  curl wget

mk/main.mk

@@ -24,6 +24,17 @@ CFG_PRERELEASE_VERSION=.1
 # versions in the same place
 CFG_FILENAME_EXTRA=$(shell printf '%s' $(CFG_RELEASE)$(CFG_EXTRA_FILENAME) | $(CFG_HASH_COMMAND))
 
+# A magic value that allows the compiler to use unstable features during the
+# bootstrap even when doing so would normally be an error because of feature
+# staging or because the build turns on warnings-as-errors and unstable features
+# default to warnings. The build has to match this key in an env var.
+#
+# This value is keyed off the release to ensure that all compilers for one
+# particular release have the same bootstrap key. Note that this is
+# intentionally not "secure" by any definition, this is largely just a deterrent
+# from users enabling unstable features on the stable compiler.
+CFG_BOOTSTRAP_KEY=$(CFG_FILENAME_EXTRA)
+
 ifeq ($(CFG_RELEASE_CHANNEL),stable)
 # This is the normal semver version string, e.g. "0.12.0", "0.12.0-nightly"
 CFG_RELEASE=$(CFG_RELEASE_NUM)

src/doc/book/concurrency.md

@@ -127,9 +127,7 @@ thread may outlive the scope of `x`, leading to a dangling pointer.
 
 To fix this, we use a `move` closure as mentioned in the error message. `move`
 closures are explained in depth [here](closures.html#move-closures); basically
-they move variables from their environment into themselves. This means that `x`
-is now owned by the closure, and cannot be used in `main()` after the call to
-`spawn()`.
+they move variables from their environment into themselves.
 
 ```rust
 use std::thread;
@@ -164,7 +162,7 @@ The same [ownership system](ownership.html) that helps prevent using pointers
 incorrectly also helps rule out data races, one of the worst kinds of
 concurrency bugs.
 
-As an example, here is a Rust program that would have a data race in many
+As an example, here is a Rust program that could have a data race in many
 languages. It will not compile:
 
 ```ignore
@@ -197,6 +195,11 @@ thread, and the thread takes ownership of the reference, we'd have three owners!
 `data` gets moved out of `main` in the first call to `spawn()`, so subsequent
 calls in the loop cannot use this variable.
 
+Note that this specific example will not cause a data race since different array
+indices are being accessed. But this can't be determined at compile time, and in
+a similar situation where `i` is a constant or is random, you would have a data
+race.
+
 So, we need some type that lets us have more than one owning reference to a
 value. Usually, we'd use `Rc<T>` for this, which is a reference counted type
 that provides shared ownership. It has some runtime bookkeeping that keeps track

src/doc/book/crates-and-modules.md

@@ -118,7 +118,7 @@ build  deps  examples  libphrases-a7448e02a0468eaa.rlib  native
 `libphrases-hash.rlib` is the compiled crate. Before we see how to use this
 crate from another crate, let’s break it up into multiple files.
 
-# Multiple file crates
+# Multiple File Crates
 
 If each crate were just one file, these files would get very large. It’s often
 easier to split up crates into multiple files, and Rust supports this in two
@@ -190,13 +190,19 @@ mod farewells;
 ```
 
 Again, these declarations tell Rust to look for either
-`src/english/greetings.rs` and `src/japanese/greetings.rs` or
-`src/english/farewells/mod.rs` and `src/japanese/farewells/mod.rs`. Because
-these sub-modules don’t have their own sub-modules, we’ve chosen to make them
-`src/english/greetings.rs` and `src/japanese/farewells.rs`. Whew!
-
-The contents of `src/english/greetings.rs` and `src/japanese/farewells.rs` are
-both empty at the moment. Let’s add some functions.
+`src/english/greetings.rs`, `src/english/farewells.rs`,
+`src/japanese/greetings.rs` and `src/japanese/farewells.rs` or
+`src/english/greetings/mod.rs`, `src/english/farewells/mod.rs`,
+`src/japanese/greetings/mod.rs` and
+`src/japanese/farewells/mod.rs`. Because these sub-modules don’t have
+their own sub-modules, we’ve chosen to make them
+`src/english/greetings.rs`, `src/english/farewells.rs`,
+`src/japanese/greetings.rs` and `src/japanese/farewells.rs`. Whew!
+
+The contents of `src/english/greetings.rs`,
+`src/english/farewells.rs`, `src/japanese/greetings.rs` and
+`src/japanese/farewells.rs` are all empty at the moment. Let’s add
+some functions.
 
 Put this in `src/english/greetings.rs`:
 

src/doc/book/lifetimes.md

@@ -56,8 +56,8 @@ To fix this, we have to make sure that step four never happens after step
 three. The ownership system in Rust does this through a concept called
 lifetimes, which describe the scope that a reference is valid for.
 
-When we have a function that takes a reference by argument, we can be implicit
-or explicit about the lifetime of the reference:
+When we have a function that takes an argument by reference, we can be
+implicit or explicit about the lifetime of the reference:
 
 ```rust
 // implicit

src/liballoc/arc.rs

@@ -124,9 +124,7 @@ const MAX_REFCOUNT: usize = (isize::MAX) as usize;
 #[unsafe_no_drop_flag]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct Arc<T: ?Sized> {
-    // FIXME #12808: strange name to try to avoid interfering with
-    // field accesses of the contained type via Deref
-    _ptr: Shared<ArcInner<T>>,
+    ptr: Shared<ArcInner<T>>,
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -144,9 +142,7 @@ impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<Arc<U>> for Arc<T> {}
 #[unsafe_no_drop_flag]
 #[stable(feature = "arc_weak", since = "1.4.0")]
 pub struct Weak<T: ?Sized> {
-    // FIXME #12808: strange name to try to avoid interfering with
-    // field accesses of the contained type via Deref
-    _ptr: Shared<ArcInner<T>>,
+    ptr: Shared<ArcInner<T>>,
 }
 
 #[stable(feature = "arc_weak", since = "1.4.0")]
@@ -198,7 +194,7 @@ impl<T> Arc<T> {
             weak: atomic::AtomicUsize::new(1),
             data: data,
         };
-        Arc { _ptr: unsafe { Shared::new(Box::into_raw(x)) } }
+        Arc { ptr: unsafe { Shared::new(Box::into_raw(x)) } }
     }
 
     /// Unwraps the contained value if the `Arc<T>` has exactly one strong reference.
@@ -230,11 +226,11 @@ impl<T> Arc<T> {
         atomic::fence(Acquire);
 
         unsafe {
-            let ptr = *this._ptr;
+            let ptr = *this.ptr;
             let elem = ptr::read(&(*ptr).data);
 
             // Make a weak pointer to clean up the implicit strong-weak reference
-            let _weak = Weak { _ptr: this._ptr };
+            let _weak = Weak { ptr: this.ptr };
             mem::forget(this);
 
             Ok(elem)
@@ -263,6 +259,7 @@ impl<T: ?Sized> Arc<T> {
         loop {
             // check if the weak counter is currently "locked"; if so, spin.
             if cur == usize::MAX {
+                cur = this.inner().weak.load(Relaxed);
                 continue;
             }
 
@@ -274,7 +271,7 @@ impl<T: ?Sized> Arc<T> {
             // synchronize with the write coming from `is_unique`, so that the
             // events prior to that write happen before this read.
             match this.inner().weak.compare_exchange_weak(cur, cur + 1, Acquire, Relaxed) {
-                Ok(_) => return Weak { _ptr: this._ptr },
+                Ok(_) => return Weak { ptr: this.ptr },
                 Err(old) => cur = old,
             }
         }
@@ -303,13 +300,13 @@ impl<T: ?Sized> Arc<T> {
         // `ArcInner` structure itself is `Sync` because the inner data is
         // `Sync` as well, so we're ok loaning out an immutable pointer to these
         // contents.
-        unsafe { &**self._ptr }
+        unsafe { &**self.ptr }
     }
 
     // Non-inlined part of `drop`.
     #[inline(never)]
     unsafe fn drop_slow(&mut self) {
-        let ptr = *self._ptr;
+        let ptr = *self.ptr;
 
         // Destroy the data at this time, even though we may not free the box
         // allocation itself (there may still be weak pointers lying around).
@@ -367,7 +364,7 @@ impl<T: ?Sized> Clone for Arc<T> {
             }
         }
 
-        Arc { _ptr: self._ptr }
+        Arc { ptr: self.ptr }
     }
 }
 
@@ -435,15 +432,15 @@ impl<T: Clone> Arc<T> {
 
             // Materialize our own implicit weak pointer, so that it can clean
             // up the ArcInner as needed.
-            let weak = Weak { _ptr: this._ptr };
+            let weak = Weak { ptr: this.ptr };
 
             // mark the data itself as already deallocated
             unsafe {
                 // there is no data race in the implicit write caused by `read`
                 // here (due to zeroing) because data is no longer accessed by
                 // other threads (due to there being no more strong refs at this
                 // point).
-                let mut swap = Arc::new(ptr::read(&(**weak._ptr).data));
+                let mut swap = Arc::new(ptr::read(&(**weak.ptr).data));
                 mem::swap(this, &mut swap);
                 mem::forget(swap);
             }
@@ -456,7 +453,7 @@ impl<T: Clone> Arc<T> {
         // As with `get_mut()`, the unsafety is ok because our reference was
         // either unique to begin with, or became one upon cloning the contents.
         unsafe {
-            let inner = &mut **this._ptr;
+            let inner = &mut **this.ptr;
             &mut inner.data
         }
     }
@@ -488,7 +485,7 @@ impl<T: ?Sized> Arc<T> {
             // the Arc itself to be `mut`, so we're returning the only possible
             // reference to the inner data.
             unsafe {
-                let inner = &mut **this._ptr;
+                let inner = &mut **this.ptr;
                 Some(&mut inner.data)
             }
         } else {
@@ -557,7 +554,7 @@ impl<T: ?Sized> Drop for Arc<T> {
         // This structure has #[unsafe_no_drop_flag], so this drop glue may run
         // more than once (but it is guaranteed to be zeroed after the first if
         // it's run more than once)
-        let thin = *self._ptr as *const ();
+        let thin = *self.ptr as *const ();
 
         if thin as usize == mem::POST_DROP_USIZE {
             return;
@@ -638,7 +635,7 @@ impl<T: ?Sized> Weak<T> {
 
             // Relaxed is valid for the same reason it is on Arc's Clone impl
             match inner.strong.compare_exchange_weak(n, n + 1, Relaxed, Relaxed) {
-                Ok(_) => return Some(Arc { _ptr: self._ptr }),
+                Ok(_) => return Some(Arc { ptr: self.ptr }),
                 Err(old) => n = old,
             }
         }
@@ -647,7 +644,7 @@ impl<T: ?Sized> Weak<T> {
     #[inline]
     fn inner(&self) -> &ArcInner<T> {
         // See comments above for why this is "safe"
-        unsafe { &**self._ptr }
+        unsafe { &**self.ptr }
     }
 }
 
@@ -681,7 +678,7 @@ impl<T: ?Sized> Clone for Weak<T> {
             }
         }
 
-        return Weak { _ptr: self._ptr };
+        return Weak { ptr: self.ptr };
     }
 }
 
@@ -713,7 +710,7 @@ impl<T: ?Sized> Drop for Weak<T> {
     /// } // implicit drop
     /// ```
     fn drop(&mut self) {
-        let ptr = *self._ptr;
+        let ptr = *self.ptr;
         let thin = ptr as *const ();
 
         // see comments above for why this check is here
@@ -885,7 +882,7 @@ impl<T: ?Sized + fmt::Debug> fmt::Debug for Arc<T> {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: ?Sized> fmt::Pointer for Arc<T> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        fmt::Pointer::fmt(&*self._ptr, f)
+        fmt::Pointer::fmt(&*self.ptr, f)
     }
 }
 
@@ -930,7 +927,7 @@ impl<T> Weak<T> {
                issue = "30425")]
     pub fn new() -> Weak<T> {
         unsafe {
-            Weak { _ptr: Shared::new(Box::into_raw(box ArcInner {
+            Weak { ptr: Shared::new(Box::into_raw(box ArcInner {
                 strong: atomic::AtomicUsize::new(0),
                 weak: atomic::AtomicUsize::new(1),
                 data: uninitialized(),