Rollup of 10 pull requests

src/liballoc/boxed.rs

@@ -320,7 +320,7 @@ impl<T: ?Sized> Box<T> {
     /// This conversion does not allocate on the heap and happens in place.
     ///
     /// This is also available via [`From`].
-    #[unstable(feature = "box_into_pin", issue = "0")]
+    #[unstable(feature = "box_into_pin", issue = "62370")]
     pub fn into_pin(boxed: Box<T>) -> Pin<Box<T>> {
         // It's not possible to move or replace the insides of a `Pin<Box<T>>`
         // when `T: !Unpin`,  so it's safe to pin it directly without any

src/liballoc/collections/btree/map.rs

@@ -2032,7 +2032,7 @@ impl<K, V> BTreeMap<K, V> {
     /// assert_eq!(keys, [1, 2]);
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
-    pub fn keys<'a>(&'a self) -> Keys<'a, K, V> {
+    pub fn keys(&self) -> Keys<'_, K, V> {
         Keys { inner: self.iter() }
     }
 
@@ -2053,7 +2053,7 @@ impl<K, V> BTreeMap<K, V> {
     /// assert_eq!(values, ["hello", "goodbye"]);
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
-    pub fn values<'a>(&'a self) -> Values<'a, K, V> {
+    pub fn values(&self) -> Values<'_, K, V> {
         Values { inner: self.iter() }
     }
 
@@ -2557,8 +2557,8 @@ enum UnderflowResult<'a, K, V> {
     Stole(NodeRef<marker::Mut<'a>, K, V, marker::Internal>),
 }
 
-fn handle_underfull_node<'a, K, V>(node: NodeRef<marker::Mut<'a>, K, V, marker::LeafOrInternal>)
-                                   -> UnderflowResult<'a, K, V> {
+fn handle_underfull_node<K, V>(node: NodeRef<marker::Mut<'_>, K, V, marker::LeafOrInternal>)
+                               -> UnderflowResult<'_, K, V> {
     let parent = if let Ok(parent) = node.ascend() {
         parent
     } else {

src/liballoc/collections/btree/node.rs

@@ -394,7 +394,7 @@ impl<BorrowType, K, V, Type> NodeRef<BorrowType, K, V, Type> {
     }
 
     /// Temporarily takes out another, immutable reference to the same node.
-    fn reborrow<'a>(&'a self) -> NodeRef<marker::Immut<'a>, K, V, Type> {
+    fn reborrow(&self) -> NodeRef<marker::Immut<'_>, K, V, Type> {
         NodeRef {
             height: self.height,
             node: self.node,

src/liballoc/string.rs

@@ -552,7 +552,7 @@ impl String {
     /// assert_eq!("Hello �World", output);
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
-    pub fn from_utf8_lossy<'a>(v: &'a [u8]) -> Cow<'a, str> {
+    pub fn from_utf8_lossy(v: &[u8]) -> Cow<'_, str> {
         let mut iter = lossy::Utf8Lossy::from_bytes(v).chunks();
 
         let (first_valid, first_broken) = if let Some(chunk) = iter.next() {

src/libcore/intrinsics.rs

@@ -36,6 +36,8 @@
             issue = "0")]
 #![allow(missing_docs)]
 
+use crate::mem;
+
 #[stable(feature = "drop_in_place", since = "1.8.0")]
 #[rustc_deprecated(reason = "no longer an intrinsic - use `ptr::drop_in_place` directly",
                    since = "1.18.0")]
@@ -700,17 +702,15 @@ extern "rust-intrinsic" {
     /// which is unsafe unless `T` is `Copy`. Also, even if T is
     /// `Copy`, an all-zero value may not correspond to any legitimate
     /// state for the type in question.
+    #[unstable(feature = "core_intrinsics",
+               reason = "intrinsics are unlikely to ever be stabilized, instead \
+                         they should be used through stabilized interfaces \
+                         in the rest of the standard library",
+               issue = "0")]
+    #[rustc_deprecated(reason = "no longer used by rustc, will be removed - use MaybeUnint instead",
+                       since = "1.38.0")]
     pub fn init<T>() -> T;
 
-    /// Creates an uninitialized value.
-    ///
-    /// `uninit` is unsafe because there is no guarantee of what its
-    /// contents are. In particular its drop-flag may be set to any
-    /// state, which means it may claim either dropped or
-    /// undropped. In the general case one must use `ptr::write` to
-    /// initialize memory previous set to the result of `uninit`.
-    pub fn uninit<T>() -> T;
-
     /// Moves a value out of scope without running drop glue.
     pub fn forget<T: ?Sized>(_: T);
 
@@ -1331,6 +1331,26 @@ extern "rust-intrinsic" {
 // (`transmute` also falls into this category, but it cannot be wrapped due to the
 // check that `T` and `U` have the same size.)
 
+/// Checks whether `ptr` is properly aligned with respect to
+/// `align_of::<T>()`.
+pub(crate) fn is_aligned_and_not_null<T>(ptr: *const T) -> bool {
+    !ptr.is_null() && ptr as usize % mem::align_of::<T>() == 0
+}
+
+/// Checks whether the regions of memory starting at `src` and `dst` of size
+/// `count * size_of::<T>()` overlap.
+fn overlaps<T>(src: *const T, dst: *const T, count: usize) -> bool {
+    let src_usize = src as usize;
+    let dst_usize = dst as usize;
+    let size = mem::size_of::<T>().checked_mul(count).unwrap();
+    let diff = if src_usize > dst_usize {
+        src_usize - dst_usize
+    } else {
+        dst_usize - src_usize
+    };
+    size > diff
+}
+
 /// Copies `count * size_of::<T>()` bytes from `src` to `dst`. The source
 /// and destination must *not* overlap.
 ///
@@ -1420,7 +1440,11 @@ pub unsafe fn copy_nonoverlapping<T>(src: *const T, dst: *mut T, count: usize) {
     extern "rust-intrinsic" {
         fn copy_nonoverlapping<T>(src: *const T, dst: *mut T, count: usize);
     }
-    copy_nonoverlapping(src, dst, count);
+
+    debug_assert!(is_aligned_and_not_null(src), "attempt to copy from unaligned or null pointer");
+    debug_assert!(is_aligned_and_not_null(dst), "attempt to copy to unaligned or null pointer");
+    debug_assert!(!overlaps(src, dst, count), "attempt to copy to overlapping memory");
+    copy_nonoverlapping(src, dst, count)
 }
 
 /// Copies `count * size_of::<T>()` bytes from `src` to `dst`. The source
@@ -1480,6 +1504,9 @@ pub unsafe fn copy<T>(src: *const T, dst: *mut T, count: usize) {
     extern "rust-intrinsic" {
         fn copy<T>(src: *const T, dst: *mut T, count: usize);
     }
+
+    debug_assert!(is_aligned_and_not_null(src), "attempt to copy from unaligned or null pointer");
+    debug_assert!(is_aligned_and_not_null(dst), "attempt to copy to unaligned or null pointer");
     copy(src, dst, count)
 }
 
@@ -1561,6 +1588,8 @@ pub unsafe fn write_bytes<T>(dst: *mut T, val: u8, count: usize) {
     extern "rust-intrinsic" {
         fn write_bytes<T>(dst: *mut T, val: u8, count: usize);
     }
+
+    debug_assert!(is_aligned_and_not_null(dst), "attempt to write to unaligned or null pointer");
     write_bytes(dst, val, count)
 }
 

src/libcore/lib.rs

@@ -74,6 +74,7 @@
 #![feature(concat_idents)]
 #![feature(const_fn)]
 #![feature(const_fn_union)]
+#![feature(custom_inner_attributes)]
 #![feature(doc_cfg)]
 #![feature(doc_spotlight)]
 #![feature(extern_types)]

src/libcore/marker.rs

@@ -498,7 +498,7 @@ macro_rules! impls{
 /// #     end: *const T,
 /// #     phantom: PhantomData<&'a T>,
 /// # }
-/// fn borrow_vec<'a, T>(vec: &'a Vec<T>) -> Slice<'a, T> {
+/// fn borrow_vec<T>(vec: &Vec<T>) -> Slice<'_, T> {
 ///     let ptr = vec.as_ptr();
 ///     Slice {
 ///         start: ptr,

src/libcore/mem/mod.rs

@@ -450,8 +450,7 @@ pub const fn needs_drop<T>() -> bool {
 #[inline]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub unsafe fn zeroed<T>() -> T {
-    intrinsics::panic_if_uninhabited::<T>();
-    intrinsics::init()
+    MaybeUninit::zeroed().assume_init()
 }
 
 /// Bypasses Rust's normal memory-initialization checks by pretending to
@@ -476,8 +475,7 @@ pub unsafe fn zeroed<T>() -> T {
 #[rustc_deprecated(since = "1.38.0", reason = "use `mem::MaybeUninit` instead")]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub unsafe fn uninitialized<T>() -> T {
-    intrinsics::panic_if_uninhabited::<T>();
-    intrinsics::uninit()
+    MaybeUninit::uninit().assume_init()
 }
 
 /// Swaps the values at two mutable locations, without deinitializing either one.

src/libcore/ops/index.rs

@@ -105,7 +105,7 @@ pub trait Index<Idx: ?Sized> {
 /// impl Index<Side> for Balance {
 ///     type Output = Weight;
 ///
-///     fn index<'a>(&'a self, index: Side) -> &'a Self::Output {
+///     fn index(&self, index: Side) -> &Self::Output {
 ///         println!("Accessing {:?}-side of balance immutably", index);
 ///         match index {
 ///             Side::Left => &self.left,
@@ -115,7 +115,7 @@ pub trait Index<Idx: ?Sized> {
 /// }
 ///
 /// impl IndexMut<Side> for Balance {
-///     fn index_mut<'a>(&'a mut self, index: Side) -> &'a mut Self::Output {
+///     fn index_mut(&mut self, index: Side) -> &mut Self::Output {
 ///         println!("Accessing {:?}-side of balance mutably", index);
 ///         match index {
 ///             Side::Left => &mut self.left,

src/libcore/ptr/mod.rs

@@ -625,42 +625,50 @@ pub unsafe fn read<T>(src: *const T) -> T {
 /// [read-ownership]: ./fn.read.html#ownership-of-the-returned-value
 /// [valid]: ../ptr/index.html#safety
 ///
-/// # Examples
+/// ## On `packed` structs
 ///
-/// Access members of a packed struct by reference:
+/// It is currently impossible to create raw pointers to unaligned fields
+/// of a packed struct.
 ///
-/// ```
-/// use std::ptr;
+/// Attempting to create a raw pointer to an `unaligned` struct field with
+/// an expression such as `&packed.unaligned as *const FieldType` creates an
+/// intermediate unaligned reference before converting that to a raw pointer.
+/// That this reference is temporary and immediately cast is inconsequential
+/// as the compiler always expects references to be properly aligned.
+/// As a result, using `&packed.unaligned as *const FieldType` causes immediate
+/// *undefined behavior* in your program.
 ///
+/// An example of what not to do and how this relates to `read_unaligned` is:
+///
+/// ```no_run
 /// #[repr(packed, C)]
 /// struct Packed {
 ///     _padding: u8,
 ///     unaligned: u32,
 /// }
 ///
-/// let x = Packed {
+/// let packed = Packed {
 ///     _padding: 0x00,
 ///     unaligned: 0x01020304,
 /// };
 ///
 /// let v = unsafe {
-///     // Take the address of a 32-bit integer which is not aligned.
-///     // This must be done as a raw pointer; unaligned references are invalid.
-///     let unaligned = &x.unaligned as *const u32;
-///
-///     // Dereferencing normally will emit an aligned load instruction,
-///     // causing undefined behavior.
-///     // let v = *unaligned; // ERROR
+///     // Here we attempt to take the address of a 32-bit integer which is not aligned.
+///     let unaligned =
+///         // A temporary unaligned reference is created here which results in
+///         // undefined behavior regardless of whether the reference is used or not.
+///         &packed.unaligned
+///         // Casting to a raw pointer doesn't help; the mistake already happened.
+///         as *const u32;
 ///
-///     // Instead, use `read_unaligned` to read improperly aligned values.
-///     let v = ptr::read_unaligned(unaligned);
+///     let v = std::ptr::read_unaligned(unaligned);
 ///
 ///     v
 /// };
-///
-/// // Accessing unaligned values directly is safe.
-/// assert!(x.unaligned == v);
 /// ```
+///
+/// Accessing unaligned fields directly with e.g. `packed.unaligned` is safe however.
+// FIXME: Update docs based on outcome of RFC #2582 and friends.
 #[inline]
 #[stable(feature = "ptr_unaligned", since = "1.17.0")]
 pub unsafe fn read_unaligned<T>(src: *const T) -> T {
@@ -789,38 +797,48 @@ pub unsafe fn write<T>(dst: *mut T, src: T) {
 ///
 /// [valid]: ../ptr/index.html#safety
 ///
-/// # Examples
+/// ## On `packed` structs
 ///
-/// Access fields in a packed struct:
+/// It is currently impossible to create raw pointers to unaligned fields
+/// of a packed struct.
 ///
-/// ```
-/// use std::{mem, ptr};
+/// Attempting to create a raw pointer to an `unaligned` struct field with
+/// an expression such as `&packed.unaligned as *const FieldType` creates an
+/// intermediate unaligned reference before converting that to a raw pointer.
+/// That this reference is temporary and immediately cast is inconsequential
+/// as the compiler always expects references to be properly aligned.
+/// As a result, using `&packed.unaligned as *const FieldType` causes immediate
+/// *undefined behavior* in your program.
 ///
+/// An example of what not to do and how this relates to `write_unaligned` is:
+///
+/// ```no_run
 /// #[repr(packed, C)]
-/// #[derive(Default)]
 /// struct Packed {
 ///     _padding: u8,
 ///     unaligned: u32,
 /// }
 ///
 /// let v = 0x01020304;
-/// let mut x: Packed = unsafe { mem::zeroed() };
-///
-/// unsafe {
-///     // Take a reference to a 32-bit integer which is not aligned.
-///     let unaligned = &mut x.unaligned as *mut u32;
+/// let mut packed: Packed = unsafe { std::mem::zeroed() };
 ///
-///     // Dereferencing normally will emit an aligned store instruction,
-///     // causing undefined behavior because the pointer is not aligned.
-///     // *unaligned = v; // ERROR
+/// let v = unsafe {
+///     // Here we attempt to take the address of a 32-bit integer which is not aligned.
+///     let unaligned =
+///         // A temporary unaligned reference is created here which results in
+///         // undefined behavior regardless of whether the reference is used or not.
+///         &mut packed.unaligned
+///         // Casting to a raw pointer doesn't help; the mistake already happened.
+///         as *mut u32;
 ///
-///     // Instead, use `write_unaligned` to write improperly aligned values.
-///     ptr::write_unaligned(unaligned, v);
-/// }
+///     std::ptr::write_unaligned(unaligned, v);
 ///
-/// // Accessing unaligned values directly is safe.
-/// assert!(x.unaligned == v);
+///     v
+/// };
 /// ```
+///
+/// Accessing unaligned fields directly with e.g. `packed.unaligned` is safe however.
+// FIXME: Update docs based on outcome of RFC #2582 and friends.
 #[inline]
 #[stable(feature = "ptr_unaligned", since = "1.17.0")]
 pub unsafe fn write_unaligned<T>(dst: *mut T, src: T) {

src/libcore/slice/mod.rs

@@ -25,7 +25,7 @@
 use crate::cmp::Ordering::{self, Less, Equal, Greater};
 use crate::cmp;
 use crate::fmt;
-use crate::intrinsics::{assume, exact_div, unchecked_sub};
+use crate::intrinsics::{assume, exact_div, unchecked_sub, is_aligned_and_not_null};
 use crate::isize;
 use crate::iter::*;
 use crate::ops::{FnMut, Try, self};
@@ -5228,7 +5228,7 @@ unsafe impl<'a, T> TrustedRandomAccess for RChunksExactMut<'a, T> {
 #[inline]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub unsafe fn from_raw_parts<'a, T>(data: *const T, len: usize) -> &'a [T] {
-    debug_assert!(data as usize % mem::align_of::<T>() == 0, "attempt to create unaligned slice");
+    debug_assert!(is_aligned_and_not_null(data), "attempt to create unaligned or null slice");
     debug_assert!(mem::size_of::<T>().saturating_mul(len) <= isize::MAX as usize,
                   "attempt to create slice covering half the address space");
     &*ptr::slice_from_raw_parts(data, len)
@@ -5249,7 +5249,7 @@ pub unsafe fn from_raw_parts<'a, T>(data: *const T, len: usize) -> &'a [T] {
 #[inline]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub unsafe fn from_raw_parts_mut<'a, T>(data: *mut T, len: usize) -> &'a mut [T] {
-    debug_assert!(data as usize % mem::align_of::<T>() == 0, "attempt to create unaligned slice");
+    debug_assert!(is_aligned_and_not_null(data), "attempt to create unaligned or null slice");
     debug_assert!(mem::size_of::<T>().saturating_mul(len) <= isize::MAX as usize,
                   "attempt to create slice covering half the address space");
     &mut *ptr::slice_from_raw_parts_mut(data, len)

src/librustc/query/mod.rs

@@ -422,11 +422,6 @@ rustc_queries! {
                 "const-evaluating `{}`",
                 tcx.def_path_str(key.value.instance.def.def_id())
             }
-            cache_on_disk_if(_, opt_result) {
-                // Only store results without errors
-                // FIXME: We never store these
-                opt_result.map_or(true, |r| r.is_ok())
-            }
         }
 
         /// Results of evaluating const items or constants embedded in