Rollup of 10 pull requests

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@@ -114,6 +114,7 @@ James Deng <[email protected]> <[email protected]>
 James Miller <[email protected]> <[email protected]>
 James Perry <[email protected]>
 Jason Fager <[email protected]>
+Jason Liquorish <[email protected]> <[email protected]>
 Jason Orendorff <[email protected]> <[email protected]>
 Jason Orendorff <[email protected]> <[email protected]>
 Jason Toffaletti <[email protected]> Jason Toffaletti <[email protected]>

src/liballoc/alloc.rs

@@ -200,21 +200,27 @@ unsafe fn exchange_malloc(size: usize, align: usize) -> *mut u8 {
         align as *mut u8
     } else {
         let layout = Layout::from_size_align_unchecked(size, align);
-        let ptr = alloc(layout);
-        if !ptr.is_null() { ptr } else { handle_alloc_error(layout) }
+        match Global.alloc(layout) {
+            Ok(ptr) => ptr.as_ptr(),
+            Err(_) => handle_alloc_error(layout),
+        }
     }
 }
 
 #[cfg_attr(not(test), lang = "box_free")]
 #[inline]
+// This signature has to be the same as `Box`, otherwise an ICE will happen.
+// When an additional parameter to `Box` is added (like `A: AllocRef`), this has to be added here as
+// well.
+// For example if `Box` is changed to  `struct Box<T: ?Sized, A: AllocRef>(Unique<T>, A)`,
+// this function has to be changed to `fn box_free<T: ?Sized, A: AllocRef>(Unique<T>, A)` as well.
 pub(crate) unsafe fn box_free<T: ?Sized>(ptr: Unique<T>) {
-    let ptr = ptr.as_ptr();
-    let size = size_of_val(&*ptr);
-    let align = min_align_of_val(&*ptr);
+    let size = size_of_val(ptr.as_ref());
+    let align = min_align_of_val(ptr.as_ref());
     // We do not allocate for Box<T> when T is ZST, so deallocation is also not necessary.
     if size != 0 {
         let layout = Layout::from_size_align_unchecked(size, align);
-        dealloc(ptr as *mut u8, layout);
+        Global.dealloc(ptr.cast().into(), layout);
     }
 }
 

src/liballoc/boxed.rs

@@ -196,12 +196,14 @@ impl<T> Box<T> {
     #[unstable(feature = "new_uninit", issue = "63291")]
     pub fn new_uninit() -> Box<mem::MaybeUninit<T>> {
         let layout = alloc::Layout::new::<mem::MaybeUninit<T>>();
-        if layout.size() == 0 {
-            return Box(NonNull::dangling().into());
+        unsafe {
+            let ptr = if layout.size() == 0 {
+                NonNull::dangling()
+            } else {
+                Global.alloc(layout).unwrap_or_else(|_| alloc::handle_alloc_error(layout)).cast()
+            };
+            Box::from_raw(ptr.as_ptr())
         }
-        let ptr =
-            unsafe { Global.alloc(layout).unwrap_or_else(|_| alloc::handle_alloc_error(layout)) };
-        Box(ptr.cast().into())
     }
 
     /// Constructs a new `Box` with uninitialized contents, with the memory
@@ -264,15 +266,14 @@ impl<T> Box<[T]> {
     #[unstable(feature = "new_uninit", issue = "63291")]
     pub fn new_uninit_slice(len: usize) -> Box<[mem::MaybeUninit<T>]> {
         let layout = alloc::Layout::array::<mem::MaybeUninit<T>>(len).unwrap();
-        let ptr = if layout.size() == 0 {
-            NonNull::dangling()
-        } else {
-            unsafe {
+        unsafe {
+            let ptr = if layout.size() == 0 {
+                NonNull::dangling()
+            } else {
                 Global.alloc(layout).unwrap_or_else(|_| alloc::handle_alloc_error(layout)).cast()
-            }
-        };
-        let slice = unsafe { slice::from_raw_parts_mut(ptr.as_ptr(), len) };
-        Box(Unique::from(slice))
+            };
+            Box::from_raw(slice::from_raw_parts_mut(ptr.as_ptr(), len))
+        }
     }
 }
 
@@ -308,7 +309,7 @@ impl<T> Box<mem::MaybeUninit<T>> {
     #[unstable(feature = "new_uninit", issue = "63291")]
     #[inline]
     pub unsafe fn assume_init(self) -> Box<T> {
-        Box(Box::into_unique(self).cast())
+        Box::from_raw(Box::into_raw(self) as *mut T)
     }
 }
 
@@ -346,7 +347,7 @@ impl<T> Box<[mem::MaybeUninit<T>]> {
     #[unstable(feature = "new_uninit", issue = "63291")]
     #[inline]
     pub unsafe fn assume_init(self) -> Box<[T]> {
-        Box(Unique::new_unchecked(Box::into_raw(self) as _))
+        Box::from_raw(Box::into_raw(self) as *mut [T])
     }
 }
 

src/libcore/alloc.rs

@@ -853,6 +853,59 @@ pub unsafe trait AllocRef {
         result
     }
 
+    /// Behaves like `realloc`, but also ensures that the new contents
+    /// are set to zero before being returned.
+    ///
+    /// # Safety
+    ///
+    /// This function is unsafe for the same reasons that `realloc` is.
+    ///
+    /// # Errors
+    ///
+    /// Returns `Err` only if the new layout
+    /// does not meet the allocator's size
+    /// and alignment constraints of the allocator, or if reallocation
+    /// otherwise fails.
+    ///
+    /// Implementations are encouraged to return `Err` on memory
+    /// exhaustion rather than panicking or aborting, but this is not
+    /// a strict requirement. (Specifically: it is *legal* to
+    /// implement this trait atop an underlying native allocation
+    /// library that aborts on memory exhaustion.)
+    ///
+    /// Clients wishing to abort computation in response to a
+    /// reallocation error are encouraged to call the [`handle_alloc_error`] function,
+    /// rather than directly invoking `panic!` or similar.
+    ///
+    /// [`handle_alloc_error`]: ../../alloc/alloc/fn.handle_alloc_error.html
+    unsafe fn realloc_zeroed(
+        &mut self,
+        ptr: NonNull<u8>,
+        layout: Layout,
+        new_size: usize,
+    ) -> Result<NonNull<u8>, AllocErr> {
+        let old_size = layout.size();
+
+        if new_size >= old_size {
+            if let Ok(()) = self.grow_in_place_zeroed(ptr, layout, new_size) {
+                return Ok(ptr);
+            }
+        } else if new_size < old_size {
+            if let Ok(()) = self.shrink_in_place(ptr, layout, new_size) {
+                return Ok(ptr);
+            }
+        }
+
+        // otherwise, fall back on alloc + copy + dealloc.
+        let new_layout = Layout::from_size_align_unchecked(new_size, layout.align());
+        let result = self.alloc_zeroed(new_layout);
+        if let Ok(new_ptr) = result {
+            ptr::copy_nonoverlapping(ptr.as_ptr(), new_ptr.as_ptr(), cmp::min(old_size, new_size));
+            self.dealloc(ptr, layout);
+        }
+        result
+    }
+
     /// Behaves like `alloc`, but also ensures that the contents
     /// are set to zero before being returned.
     ///
@@ -904,6 +957,31 @@ pub unsafe trait AllocRef {
         self.alloc(layout).map(|p| Excess(p, usable_size.1))
     }
 
+    /// Behaves like `alloc`, but also returns the whole size of
+    /// the returned block. For some `layout` inputs, like arrays, this
+    /// may include extra storage usable for additional data.
+    /// Also it ensures that the contents are set to zero before being returned.
+    ///
+    /// # Safety
+    ///
+    /// This function is unsafe for the same reasons that `alloc` is.
+    ///
+    /// # Errors
+    ///
+    /// Returning `Err` indicates that either memory is exhausted or
+    /// `layout` does not meet allocator's size or alignment
+    /// constraints, just as in `alloc`.
+    ///
+    /// Clients wishing to abort computation in response to an
+    /// allocation error are encouraged to call the [`handle_alloc_error`] function,
+    /// rather than directly invoking `panic!` or similar.
+    ///
+    /// [`handle_alloc_error`]: ../../alloc/alloc/fn.handle_alloc_error.html
+    unsafe fn alloc_excess_zeroed(&mut self, layout: Layout) -> Result<Excess, AllocErr> {
+        let usable_size = self.usable_size(&layout);
+        self.alloc_zeroed(layout).map(|p| Excess(p, usable_size.1))
+    }
+
     /// Behaves like `realloc`, but also returns the whole size of
     /// the returned block. For some `layout` inputs, like arrays, this
     /// may include extra storage usable for additional data.
@@ -934,6 +1012,37 @@ pub unsafe trait AllocRef {
         self.realloc(ptr, layout, new_size).map(|p| Excess(p, usable_size.1))
     }
 
+    /// Behaves like `realloc`, but also returns the whole size of
+    /// the returned block. For some `layout` inputs, like arrays, this
+    /// may include extra storage usable for additional data.
+    /// Also it ensures that the contents are set to zero before being returned.
+    ///
+    /// # Safety
+    ///
+    /// This function is unsafe for the same reasons that `realloc` is.
+    ///
+    /// # Errors
+    ///
+    /// Returning `Err` indicates that either memory is exhausted or
+    /// `layout` does not meet allocator's size or alignment
+    /// constraints, just as in `realloc`.
+    ///
+    /// Clients wishing to abort computation in response to a
+    /// reallocation error are encouraged to call the [`handle_alloc_error`] function,
+    /// rather than directly invoking `panic!` or similar.
+    ///
+    /// [`handle_alloc_error`]: ../../alloc/alloc/fn.handle_alloc_error.html
+    unsafe fn realloc_excess_zeroed(
+        &mut self,
+        ptr: NonNull<u8>,
+        layout: Layout,
+        new_size: usize,
+    ) -> Result<Excess, AllocErr> {
+        let new_layout = Layout::from_size_align_unchecked(new_size, layout.align());
+        let usable_size = self.usable_size(&new_layout);
+        self.realloc_zeroed(ptr, layout, new_size).map(|p| Excess(p, usable_size.1))
+    }
+
     /// Attempts to extend the allocation referenced by `ptr` to fit `new_size`.
     ///
     /// If this returns `Ok`, then the allocator has asserted that the
@@ -983,6 +1092,34 @@ pub unsafe trait AllocRef {
         if new_size <= u { Ok(()) } else { Err(CannotReallocInPlace) }
     }
 
+    /// Behaves like `grow_in_place`, but also ensures that the new
+    /// contents are set to zero before being returned.
+    ///
+    /// # Safety
+    ///
+    /// This function is unsafe for the same reasons that `grow_in_place` is.
+    ///
+    /// # Errors
+    ///
+    /// Returns `Err(CannotReallocInPlace)` when the allocator is
+    /// unable to assert that the memory block referenced by `ptr`
+    /// could fit `layout`.
+    ///
+    /// Note that one cannot pass `CannotReallocInPlace` to the `handle_alloc_error`
+    /// function; clients are expected either to be able to recover from
+    /// `grow_in_place` failures without aborting, or to fall back on
+    /// another reallocation method before resorting to an abort.
+    unsafe fn grow_in_place_zeroed(
+        &mut self,
+        ptr: NonNull<u8>,
+        layout: Layout,
+        new_size: usize,
+    ) -> Result<(), CannotReallocInPlace> {
+        self.grow_in_place(ptr, layout, new_size)?;
+        ptr.as_ptr().add(layout.size()).write_bytes(0, new_size - layout.size());
+        Ok(())
+    }
+
     /// Attempts to shrink the allocation referenced by `ptr` to fit `new_size`.
     ///
     /// If this returns `Ok`, then the allocator has asserted that the

src/librustc/mir/interpret/error.rs

@@ -128,10 +128,9 @@ impl<'tcx> ConstEvalErr<'tcx> {
         }
     }
 
-    /// Sets the message passed in via `message`, then adds the span labels for you, before applying
-    /// further modifications in `emit`. It's up to you to call emit(), stash(..), etc. within the
-    /// `emit` method. If you don't need to do any additional processing, just use
-    /// struct_generic.
+    /// Sets the message passed in via `message` and adds span labels before handing control back
+    /// to `emit` to do any final processing. It's the caller's responsibility to call emit(),
+    /// stash(), etc. within the `emit` function to dispose of the diagnostic properly.
     fn struct_generic(
         &self,
         tcx: TyCtxtAt<'tcx>,

src/librustc/query/mod.rs

@@ -669,26 +669,29 @@ rustc_queries! {
             no_force
             desc { "computing whether `{}` is `Copy`", env.value }
         }
+        /// Query backing `TyS::is_sized`.
         query is_sized_raw(env: ty::ParamEnvAnd<'tcx, Ty<'tcx>>) -> bool {
             no_force
             desc { "computing whether `{}` is `Sized`", env.value }
         }
+        /// Query backing `TyS::is_freeze`.
         query is_freeze_raw(env: ty::ParamEnvAnd<'tcx, Ty<'tcx>>) -> bool {
             no_force
             desc { "computing whether `{}` is freeze", env.value }
         }
-
-        // The cycle error here should be reported as an error by `check_representable`.
-        // We consider the type as not needing drop in the meanwhile to avoid
-        // further errors (done in impl Value for NeedsDrop).
-        // Use `cycle_delay_bug` to delay the cycle error here to be emitted later
-        // in case we accidentally otherwise don't emit an error.
-        query needs_drop_raw(env: ty::ParamEnvAnd<'tcx, Ty<'tcx>>) -> NeedsDrop {
-            cycle_delay_bug
+        /// Query backing `TyS::needs_drop`.
+        query needs_drop_raw(env: ty::ParamEnvAnd<'tcx, Ty<'tcx>>) -> bool {
             no_force
             desc { "computing whether `{}` needs drop", env.value }
         }
 
+        /// A list of types where the ADT requires drop if and only if any of
+        /// those types require drop. If the ADT is known to always need drop
+        /// then `Err(AlwaysRequiresDrop)` is returned.
+        query adt_drop_tys(_: DefId) -> Result<&'tcx ty::List<Ty<'tcx>>, AlwaysRequiresDrop> {
+            cache_on_disk_if { true }
+        }
+
         query layout_raw(
             env: ty::ParamEnvAnd<'tcx, Ty<'tcx>>
         ) -> Result<&'tcx ty::layout::LayoutDetails, ty::layout::LayoutError<'tcx>> {