Rollup of 21 pull requests

src/doc/unstable-book/src/SUMMARY.md

@@ -71,6 +71,7 @@
 - [repr_simd](repr-simd.md)
 - [rustc_attrs](rustc-attrs.md)
 - [rustc_diagnostic_macros](rustc-diagnostic-macros.md)
+- [rvalue_static_promotion](rvalue-static-promotion.md)
 - [sanitizer_runtime](sanitizer-runtime.md)
 - [simd](simd.md)
 - [simd_ffi](simd-ffi.md)

src/doc/unstable-book/src/allocator.md

@@ -51,6 +51,11 @@ pub extern fn __rust_allocate(size: usize, _align: usize) -> *mut u8 {
     unsafe { libc::malloc(size as libc::size_t) as *mut u8 }
 }
 
+#[no_mangle]
+pub extern fn __rust_allocate_zeroed(size: usize, _align: usize) -> *mut u8 {
+    unsafe { libc::calloc(size as libc::size_t, 1) as *mut u8 }
+}
+
 #[no_mangle]
 pub extern fn __rust_deallocate(ptr: *mut u8, _old_size: usize, _align: usize) {
     unsafe { libc::free(ptr as *mut libc::c_void) }

src/doc/unstable-book/src/rvalue-static-promotion.md

@@ -0,0 +1,23 @@
+# `rvalue_static_promotion`
+
+The tracking issue for this feature is: [#38865]
+
+[#38865]: https://github.com/rust-lang/rust/issues/38865
+
+------------------------
+
+The `rvalue_static_promotion` feature allows directly creating `'static` references to
+constant `rvalue`s, which in particular allowing for more concise code in the common case
+in which a `'static` reference is all that's needed.
+
+
+## Examples
+
+```rust
+#![feature(rvalue_static_promotion)]
+
+fn main() {
+    let DEFAULT_VALUE: &'static u32 = &42;
+    assert_eq!(*DEFAULT_VALUE, 42);
+}
+```

src/liballoc/arc.rs

@@ -287,17 +287,15 @@ impl<T> Arc<T> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(rc_raw)]
-    ///
     /// use std::sync::Arc;
     ///
     /// let x = Arc::new(10);
     /// let x_ptr = Arc::into_raw(x);
     /// assert_eq!(unsafe { *x_ptr }, 10);
     /// ```
-    #[unstable(feature = "rc_raw", issue = "37197")]
-    pub fn into_raw(this: Self) -> *mut T {
-        let ptr = unsafe { &mut (**this.ptr).data as *mut _ };
+    #[stable(feature = "rc_raw", since = "1.17.0")]
+    pub fn into_raw(this: Self) -> *const T {
+        let ptr = unsafe { &(**this.ptr).data as *const _ };
         mem::forget(this);
         ptr
     }
@@ -315,8 +313,6 @@ impl<T> Arc<T> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(rc_raw)]
-    ///
     /// use std::sync::Arc;
     ///
     /// let x = Arc::new(10);
@@ -332,11 +328,14 @@ impl<T> Arc<T> {
     ///
     /// // The memory was freed when `x` went out of scope above, so `x_ptr` is now dangling!
     /// ```
-    #[unstable(feature = "rc_raw", issue = "37197")]
-    pub unsafe fn from_raw(ptr: *mut T) -> Self {
+    #[stable(feature = "rc_raw", since = "1.17.0")]
+    pub unsafe fn from_raw(ptr: *const T) -> Self {
         // To find the corresponding pointer to the `ArcInner` we need to subtract the offset of the
         // `data` field from the pointer.
-        Arc { ptr: Shared::new((ptr as *mut u8).offset(-offset_of!(ArcInner<T>, data)) as *mut _) }
+        let ptr = (ptr as *const u8).offset(-offset_of!(ArcInner<T>, data));
+        Arc {
+            ptr: Shared::new(ptr as *const _),
+        }
     }
 }
 
@@ -448,7 +447,7 @@ impl<T: ?Sized> Arc<T> {
     // Non-inlined part of `drop`.
     #[inline(never)]
     unsafe fn drop_slow(&mut self) {
-        let ptr = *self.ptr;
+        let ptr = self.ptr.as_mut_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).
@@ -461,17 +460,13 @@ impl<T: ?Sized> Arc<T> {
     }
 
     #[inline]
-    #[unstable(feature = "ptr_eq",
-               reason = "newly added",
-               issue = "36497")]
+    #[stable(feature = "ptr_eq", since = "1.17.0")]
     /// Returns true if the two `Arc`s point to the same value (not
     /// just values that compare as equal).
     ///
     /// # Examples
     ///
     /// ```
-    /// #![feature(ptr_eq)]
-    ///
     /// use std::sync::Arc;
     ///
     /// let five = Arc::new(5);
@@ -628,7 +623,7 @@ 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.as_mut_ptr();
             &mut inner.data
         }
     }
@@ -671,7 +666,7 @@ 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.as_mut_ptr();
                 Some(&mut inner.data)
             }
         } else {

src/liballoc/heap.rs

@@ -23,6 +23,7 @@ use core::intrinsics::{min_align_of_val, size_of_val};
 extern "C" {
     #[allocator]
     fn __rust_allocate(size: usize, align: usize) -> *mut u8;
+    fn __rust_allocate_zeroed(size: usize, align: usize) -> *mut u8;
     fn __rust_deallocate(ptr: *mut u8, old_size: usize, align: usize);
     fn __rust_reallocate(ptr: *mut u8, old_size: usize, size: usize, align: usize) -> *mut u8;
     fn __rust_reallocate_inplace(ptr: *mut u8,
@@ -59,6 +60,20 @@ pub unsafe fn allocate(size: usize, align: usize) -> *mut u8 {
     __rust_allocate(size, align)
 }
 
+/// Return a pointer to `size` bytes of memory aligned to `align` and
+/// initialized to zeroes.
+///
+/// On failure, return a null pointer.
+///
+/// Behavior is undefined if the requested size is 0 or the alignment is not a
+/// power of 2. The alignment must be no larger than the largest supported page
+/// size on the platform.
+#[inline]
+pub unsafe fn allocate_zeroed(size: usize, align: usize) -> *mut u8 {
+    check_size_and_alignment(size, align);
+    __rust_allocate_zeroed(size, align)
+}
+
 /// Resize the allocation referenced by `ptr` to `size` bytes.
 ///
 /// On failure, return a null pointer and leave the original allocation intact.
@@ -162,6 +177,23 @@ mod tests {
     use boxed::Box;
     use heap;
 
+    #[test]
+    fn allocate_zeroed() {
+        unsafe {
+            let size = 1024;
+            let mut ptr = heap::allocate_zeroed(size, 1);
+            if ptr.is_null() {
+                ::oom()
+            }
+            let end = ptr.offset(size as isize);
+            while ptr < end {
+                assert_eq!(*ptr, 0);
+                ptr = ptr.offset(1);
+            }
+            heap::deallocate(ptr, size, 1);
+        }
+    }
+
     #[test]
     fn basic_reallocate_inplace_noop() {
         unsafe {

src/liballoc/raw_vec.rs

@@ -82,6 +82,16 @@ impl<T> RawVec<T> {
     ///
     /// Aborts on OOM
     pub fn with_capacity(cap: usize) -> Self {
+        RawVec::allocate(cap, false)
+    }
+
+    /// Like `with_capacity` but guarantees the buffer is zeroed.
+    pub fn with_capacity_zeroed(cap: usize) -> Self {
+        RawVec::allocate(cap, true)
+    }
+
+    #[inline]
+    fn allocate(cap: usize, zeroed: bool) -> Self {
         unsafe {
             let elem_size = mem::size_of::<T>();
 
@@ -93,7 +103,11 @@ impl<T> RawVec<T> {
                 heap::EMPTY as *mut u8
             } else {
                 let align = mem::align_of::<T>();
-                let ptr = heap::allocate(alloc_size, align);
+                let ptr = if zeroed {
+                    heap::allocate_zeroed(alloc_size, align)
+                } else {
+                    heap::allocate(alloc_size, align)
+                };
                 if ptr.is_null() {
                     oom()
                 }

src/liballoc/rc.rs

@@ -364,17 +364,15 @@ impl<T> Rc<T> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(rc_raw)]
-    ///
     /// use std::rc::Rc;
     ///
     /// let x = Rc::new(10);
     /// let x_ptr = Rc::into_raw(x);
     /// assert_eq!(unsafe { *x_ptr }, 10);
     /// ```
-    #[unstable(feature = "rc_raw", issue = "37197")]
-    pub fn into_raw(this: Self) -> *mut T {
-        let ptr = unsafe { &mut (**this.ptr).value as *mut _ };
+    #[stable(feature = "rc_raw", since = "1.17.0")]
+    pub fn into_raw(this: Self) -> *const T {
+        let ptr = unsafe { &mut (*this.ptr.as_mut_ptr()).value as *const _ };
         mem::forget(this);
         ptr
     }
@@ -392,8 +390,6 @@ impl<T> Rc<T> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(rc_raw)]
-    ///
     /// use std::rc::Rc;
     ///
     /// let x = Rc::new(10);
@@ -409,11 +405,11 @@ impl<T> Rc<T> {
     ///
     /// // The memory was freed when `x` went out of scope above, so `x_ptr` is now dangling!
     /// ```
-    #[unstable(feature = "rc_raw", issue = "37197")]
-    pub unsafe fn from_raw(ptr: *mut T) -> Self {
+    #[stable(feature = "rc_raw", since = "1.17.0")]
+    pub unsafe fn from_raw(ptr: *const T) -> Self {
         // To find the corresponding pointer to the `RcBox` we need to subtract the offset of the
         // `value` field from the pointer.
-        Rc { ptr: Shared::new((ptr as *mut u8).offset(-offset_of!(RcBox<T>, value)) as *mut _) }
+        Rc { ptr: Shared::new((ptr as *const u8).offset(-offset_of!(RcBox<T>, value)) as *const _) }
     }
 }
 
@@ -543,25 +539,21 @@ impl<T: ?Sized> Rc<T> {
     #[stable(feature = "rc_unique", since = "1.4.0")]
     pub fn get_mut(this: &mut Self) -> Option<&mut T> {
         if Rc::is_unique(this) {
-            let inner = unsafe { &mut **this.ptr };
+            let inner = unsafe { &mut *this.ptr.as_mut_ptr() };
             Some(&mut inner.value)
         } else {
             None
         }
     }
 
     #[inline]
-    #[unstable(feature = "ptr_eq",
-               reason = "newly added",
-               issue = "36497")]
+    #[stable(feature = "ptr_eq", since = "1.17.0")]
     /// Returns true if the two `Rc`s point to the same value (not
     /// just values that compare as equal).
     ///
     /// # Examples
     ///
     /// ```
-    /// #![feature(ptr_eq)]
-    ///
     /// use std::rc::Rc;
     ///
     /// let five = Rc::new(5);
@@ -631,7 +623,7 @@ impl<T: Clone> Rc<T> {
         // reference count is guaranteed to be 1 at this point, and we required
         // the `Rc<T>` itself to be `mut`, so we're returning the only possible
         // reference to the inner value.
-        let inner = unsafe { &mut **this.ptr };
+        let inner = unsafe { &mut *this.ptr.as_mut_ptr() };
         &mut inner.value
     }
 }
@@ -677,7 +669,7 @@ unsafe impl<#[may_dangle] T: ?Sized> Drop for Rc<T> {
     /// ```
     fn drop(&mut self) {
         unsafe {
-            let ptr = *self.ptr;
+            let ptr = self.ptr.as_mut_ptr();
 
             self.dec_strong();
             if self.strong() == 0 {

src/liballoc_jemalloc/lib.rs

@@ -38,6 +38,10 @@ mod imp {
                        target_os = "dragonfly", target_os = "windows"),
                    link_name = "je_mallocx")]
         fn mallocx(size: size_t, flags: c_int) -> *mut c_void;
+        #[cfg_attr(any(target_os = "macos", target_os = "android", target_os = "ios",
+                       target_os = "dragonfly", target_os = "windows"),
+                   link_name = "je_calloc")]
+        fn calloc(size: size_t, flags: c_int) -> *mut c_void;
         #[cfg_attr(any(target_os = "macos", target_os = "android", target_os = "ios",
                        target_os = "dragonfly", target_os = "windows"),
                    link_name = "je_rallocx")]
@@ -56,6 +60,8 @@ mod imp {
         fn nallocx(size: size_t, flags: c_int) -> size_t;
     }
 
+    const MALLOCX_ZERO: c_int = 0x40;
+
     // The minimum alignment guaranteed by the architecture. This value is used to
     // add fast paths for low alignment values. In practice, the alignment is a
     // constant at the call site and the branch will be optimized out.
@@ -91,6 +97,16 @@ mod imp {
         unsafe { mallocx(size as size_t, flags) as *mut u8 }
     }
 
+    #[no_mangle]
+    pub extern "C" fn __rust_allocate_zeroed(size: usize, align: usize) -> *mut u8 {
+        if align <= MIN_ALIGN {
+            unsafe { calloc(size as size_t, 1) as *mut u8 }
+        } else {
+            let flags = align_to_flags(align) | MALLOCX_ZERO;
+            unsafe { mallocx(size as size_t, flags) as *mut u8 }
+        }
+    }
+
     #[no_mangle]
     pub extern "C" fn __rust_reallocate(ptr: *mut u8,
                                         _old_size: usize,
@@ -135,6 +151,11 @@ mod imp {
         bogus()
     }
 
+    #[no_mangle]
+    pub extern "C" fn __rust_allocate_zeroed(_size: usize, _align: usize) -> *mut u8 {
+        bogus()
+    }
+
     #[no_mangle]
     pub extern "C" fn __rust_reallocate(_ptr: *mut u8,
                                         _old_size: usize,