Auto merge of rust-lang#121142 - GuillaumeGomez:rollup-5qmksjw, r=GuillaumeGomez

Rollup of 8 pull requests

Successful merges:

 - rust-lang#120449 (Document requirements for unsized {Rc,Arc}::from_raw)
 - rust-lang#120505 (Fix BTreeMap's Cursor::remove_{next,prev})
 - rust-lang#120672 (std::thread update freebsd stack guard handling.)
 - rust-lang#121088 (Implicitly enable evex512 if avx512 is enabled)
 - rust-lang#121104 (Ignore unsized types when trying to determine the size of the original type)
 - rust-lang#121107 (Fix msg for verbose suggestions with confusable capitalization)
 - rust-lang#121113 (Continue compilation even if inherent impl checks fail)
 - rust-lang#121120 (Add `ErrorGuaranteed` to `ast::LitKind::Err`, `token::LitKind::Err`.)

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors

alloc/src/collections/btree/map.rs

@@ -3247,9 +3247,15 @@ impl<'a, K: Ord, V, A: Allocator + Clone> CursorMutKey<'a, K, V, A> {
     #[unstable(feature = "btree_cursors", issue = "107540")]
     pub fn remove_next(&mut self) -> Option<(K, V)> {
         let current = self.current.take()?;
+        if current.reborrow().next_kv().is_err() {
+            self.current = Some(current);
+            return None;
+        }
         let mut emptied_internal_root = false;
         let (kv, pos) = current
             .next_kv()
+            // This should be unwrap(), but that doesn't work because NodeRef
+            // doesn't implement Debug. The condition is checked above.
             .ok()?
             .remove_kv_tracking(|| emptied_internal_root = true, self.alloc.clone());
         self.current = Some(pos);
@@ -3270,9 +3276,15 @@ impl<'a, K: Ord, V, A: Allocator + Clone> CursorMutKey<'a, K, V, A> {
     #[unstable(feature = "btree_cursors", issue = "107540")]
     pub fn remove_prev(&mut self) -> Option<(K, V)> {
         let current = self.current.take()?;
+        if current.reborrow().next_back_kv().is_err() {
+            self.current = Some(current);
+            return None;
+        }
         let mut emptied_internal_root = false;
         let (kv, pos) = current
             .next_back_kv()
+            // This should be unwrap(), but that doesn't work because NodeRef
+            // doesn't implement Debug. The condition is checked above.
             .ok()?
             .remove_kv_tracking(|| emptied_internal_root = true, self.alloc.clone());
         self.current = Some(pos);

alloc/src/rc.rs

@@ -1184,12 +1184,19 @@ impl<T: ?Sized> Rc<T> {
     /// Constructs an `Rc<T>` from a raw pointer.
     ///
     /// The raw pointer must have been previously returned by a call to
-    /// [`Rc<U>::into_raw`][into_raw] where `U` must have the same size
-    /// and alignment as `T`. This is trivially true if `U` is `T`.
-    /// Note that if `U` is not `T` but has the same size and alignment, this is
-    /// basically like transmuting references of different types. See
-    /// [`mem::transmute`][transmute] for more information on what
-    /// restrictions apply in this case.
+    /// [`Rc<U>::into_raw`][into_raw] with the following requirements:
+    ///
+    /// * If `U` is sized, it must have the same size and alignment as `T`. This
+    ///   is trivially true if `U` is `T`.
+    /// * If `U` is unsized, its data pointer must have the same size and
+    ///   alignment as `T`. This is trivially true if `Rc<U>` was constructed
+    ///   through `Rc<T>` and then converted to `Rc<U>` through an [unsized
+    ///   coercion].
+    ///
+    /// Note that if `U` or `U`'s data pointer is not `T` but has the same size
+    /// and alignment, this is basically like transmuting references of
+    /// different types. See [`mem::transmute`][transmute] for more information
+    /// on what restrictions apply in this case.
     ///
     /// The raw pointer must point to a block of memory allocated by the global allocator
     ///
@@ -1201,6 +1208,7 @@ impl<T: ?Sized> Rc<T> {
     ///
     /// [into_raw]: Rc::into_raw
     /// [transmute]: core::mem::transmute
+    /// [unsized coercion]: https://doc.rust-lang.org/reference/type-coercions.html#unsized-coercions
     ///
     /// # Examples
     ///
@@ -1220,6 +1228,20 @@ impl<T: ?Sized> Rc<T> {
     ///
     /// // The memory was freed when `x` went out of scope above, so `x_ptr` is now dangling!
     /// ```
+    ///
+    /// Convert a slice back into its original array:
+    ///
+    /// ```
+    /// use std::rc::Rc;
+    ///
+    /// let x: Rc<[u32]> = Rc::new([1, 2, 3]);
+    /// let x_ptr: *const [u32] = Rc::into_raw(x);
+    ///
+    /// unsafe {
+    ///     let x: Rc<[u32; 3]> = Rc::from_raw(x_ptr.cast::<[u32; 3]>());
+    ///     assert_eq!(&*x, &[1, 2, 3]);
+    /// }
+    /// ```
     #[inline]
     #[stable(feature = "rc_raw", since = "1.17.0")]
     pub unsafe fn from_raw(ptr: *const T) -> Self {
@@ -1344,13 +1366,20 @@ impl<T: ?Sized, A: Allocator> Rc<T, A> {
 
     /// Constructs an `Rc<T, A>` from a raw pointer in the provided allocator.
     ///
-    /// The raw pointer must have been previously returned by a call to
-    /// [`Rc<U, A>::into_raw`][into_raw] where `U` must have the same size
-    /// and alignment as `T`. This is trivially true if `U` is `T`.
-    /// Note that if `U` is not `T` but has the same size and alignment, this is
-    /// basically like transmuting references of different types. See
-    /// [`mem::transmute`] for more information on what
-    /// restrictions apply in this case.
+    /// The raw pointer must have been previously returned by a call to [`Rc<U,
+    /// A>::into_raw`][into_raw] with the following requirements:
+    ///
+    /// * If `U` is sized, it must have the same size and alignment as `T`. This
+    ///   is trivially true if `U` is `T`.
+    /// * If `U` is unsized, its data pointer must have the same size and
+    ///   alignment as `T`. This is trivially true if `Rc<U>` was constructed
+    ///   through `Rc<T>` and then converted to `Rc<U>` through an [unsized
+    ///   coercion].
+    ///
+    /// Note that if `U` or `U`'s data pointer is not `T` but has the same size
+    /// and alignment, this is basically like transmuting references of
+    /// different types. See [`mem::transmute`][transmute] for more information
+    /// on what restrictions apply in this case.
     ///
     /// The raw pointer must point to a block of memory allocated by `alloc`
     ///
@@ -1361,6 +1390,8 @@ impl<T: ?Sized, A: Allocator> Rc<T, A> {
     /// even if the returned `Rc<T>` is never accessed.
     ///
     /// [into_raw]: Rc::into_raw
+    /// [transmute]: core::mem::transmute
+    /// [unsized coercion]: https://doc.rust-lang.org/reference/type-coercions.html#unsized-coercions
     ///
     /// # Examples
     ///
@@ -1383,6 +1414,23 @@ impl<T: ?Sized, A: Allocator> Rc<T, A> {
     ///
     /// // The memory was freed when `x` went out of scope above, so `x_ptr` is now dangling!
     /// ```
+    ///
+    /// Convert a slice back into its original array:
+    ///
+    /// ```
+    /// #![feature(allocator_api)]
+    ///
+    /// use std::rc::Rc;
+    /// use std::alloc::System;
+    ///
+    /// let x: Rc<[u32], _> = Rc::new_in([1, 2, 3], System);
+    /// let x_ptr: *const [u32] = Rc::into_raw(x);
+    ///
+    /// unsafe {
+    ///     let x: Rc<[u32; 3], _> = Rc::from_raw_in(x_ptr.cast::<[u32; 3]>(), System);
+    ///     assert_eq!(&*x, &[1, 2, 3]);
+    /// }
+    /// ```
     #[unstable(feature = "allocator_api", issue = "32838")]
     pub unsafe fn from_raw_in(ptr: *const T, alloc: A) -> Self {
         let offset = unsafe { data_offset(ptr) };

alloc/src/sync.rs

@@ -1333,12 +1333,19 @@ impl<T: ?Sized> Arc<T> {
     /// Constructs an `Arc<T>` from a raw pointer.
     ///
     /// The raw pointer must have been previously returned by a call to
-    /// [`Arc<U>::into_raw`][into_raw] where `U` must have the same size and
-    /// alignment as `T`. This is trivially true if `U` is `T`.
-    /// Note that if `U` is not `T` but has the same size and alignment, this is
-    /// basically like transmuting references of different types. See
-    /// [`mem::transmute`][transmute] for more information on what
-    /// restrictions apply in this case.
+    /// [`Arc<U>::into_raw`][into_raw] with the following requirements:
+    ///
+    /// * If `U` is sized, it must have the same size and alignment as `T`. This
+    ///   is trivially true if `U` is `T`.
+    /// * If `U` is unsized, its data pointer must have the same size and
+    ///   alignment as `T`. This is trivially true if `Arc<U>` was constructed
+    ///   through `Arc<T>` and then converted to `Arc<U>` through an [unsized
+    ///   coercion].
+    ///
+    /// Note that if `U` or `U`'s data pointer is not `T` but has the same size
+    /// and alignment, this is basically like transmuting references of
+    /// different types. See [`mem::transmute`][transmute] for more information
+    /// on what restrictions apply in this case.
     ///
     /// The user of `from_raw` has to make sure a specific value of `T` is only
     /// dropped once.
@@ -1348,6 +1355,7 @@ impl<T: ?Sized> Arc<T> {
     ///
     /// [into_raw]: Arc::into_raw
     /// [transmute]: core::mem::transmute
+    /// [unsized coercion]: https://doc.rust-lang.org/reference/type-coercions.html#unsized-coercions
     ///
     /// # Examples
     ///
@@ -1367,6 +1375,20 @@ impl<T: ?Sized> Arc<T> {
     ///
     /// // The memory was freed when `x` went out of scope above, so `x_ptr` is now dangling!
     /// ```
+    ///
+    /// Convert a slice back into its original array:
+    ///
+    /// ```
+    /// use std::sync::Arc;
+    ///
+    /// let x: Arc<[u32]> = Arc::new([1, 2, 3]);
+    /// let x_ptr: *const [u32] = Arc::into_raw(x);
+    ///
+    /// unsafe {
+    ///     let x: Arc<[u32; 3]> = Arc::from_raw(x_ptr.cast::<[u32; 3]>());
+    ///     assert_eq!(&*x, &[1, 2, 3]);
+    /// }
+    /// ```
     #[inline]
     #[stable(feature = "rc_raw", since = "1.17.0")]
     pub unsafe fn from_raw(ptr: *const T) -> Self {
@@ -1496,13 +1518,20 @@ impl<T: ?Sized, A: Allocator> Arc<T, A> {
 
     /// Constructs an `Arc<T, A>` from a raw pointer.
     ///
-    /// The raw pointer must have been previously returned by a call to
-    /// [`Arc<U, A>::into_raw`][into_raw] where `U` must have the same size and
-    /// alignment as `T`. This is trivially true if `U` is `T`.
-    /// Note that if `U` is not `T` but has the same size and alignment, this is
-    /// basically like transmuting references of different types. See
-    /// [`mem::transmute`] for more information on what
-    /// restrictions apply in this case.
+    /// The raw pointer must have been previously returned by a call to [`Arc<U,
+    /// A>::into_raw`][into_raw] with the following requirements:
+    ///
+    /// * If `U` is sized, it must have the same size and alignment as `T`. This
+    ///   is trivially true if `U` is `T`.
+    /// * If `U` is unsized, its data pointer must have the same size and
+    ///   alignment as `T`. This is trivially true if `Arc<U>` was constructed
+    ///   through `Arc<T>` and then converted to `Arc<U>` through an [unsized
+    ///   coercion].
+    ///
+    /// Note that if `U` or `U`'s data pointer is not `T` but has the same size
+    /// and alignment, this is basically like transmuting references of
+    /// different types. See [`mem::transmute`][transmute] for more information
+    /// on what restrictions apply in this case.
     ///
     /// The raw pointer must point to a block of memory allocated by `alloc`
     ///
@@ -1513,6 +1542,8 @@ impl<T: ?Sized, A: Allocator> Arc<T, A> {
     /// even if the returned `Arc<T>` is never accessed.
     ///
     /// [into_raw]: Arc::into_raw
+    /// [transmute]: core::mem::transmute
+    /// [unsized coercion]: https://doc.rust-lang.org/reference/type-coercions.html#unsized-coercions
     ///
     /// # Examples
     ///
@@ -1535,6 +1566,23 @@ impl<T: ?Sized, A: Allocator> Arc<T, A> {
     ///
     /// // The memory was freed when `x` went out of scope above, so `x_ptr` is now dangling!
     /// ```
+    ///
+    /// Convert a slice back into its original array:
+    ///
+    /// ```
+    /// #![feature(allocator_api)]
+    ///
+    /// use std::sync::Arc;
+    /// use std::alloc::System;
+    ///
+    /// let x: Arc<[u32], _> = Arc::new_in([1, 2, 3], System);
+    /// let x_ptr: *const [u32] = Arc::into_raw(x);
+    ///
+    /// unsafe {
+    ///     let x: Arc<[u32; 3], _> = Arc::from_raw_in(x_ptr.cast::<[u32; 3]>(), System);
+    ///     assert_eq!(&*x, &[1, 2, 3]);
+    /// }
+    /// ```
     #[inline]
     #[unstable(feature = "allocator_api", issue = "32838")]
     pub unsafe fn from_raw_in(ptr: *const T, alloc: A) -> Self {

proc_macro/src/bridge/mod.rs

@@ -337,7 +337,11 @@ pub enum LitKind {
     ByteStrRaw(u8),
     CStr,
     CStrRaw(u8),
-    Err,
+    // This should have an `ErrorGuaranteed`, except that type isn't available
+    // in this crate. (Imagine it is there.) Hence the `WithGuar` suffix. Must
+    // only be constructed in `LitKind::from_internal`, where an
+    // `ErrorGuaranteed` is available.
+    ErrWithGuar,
 }
 
 rpc_encode_decode!(
@@ -352,7 +356,7 @@ rpc_encode_decode!(
         ByteStrRaw(n),
         CStr,
         CStrRaw(n),
-        Err,
+        ErrWithGuar,
     }
 );
 

proc_macro/src/lib.rs

@@ -1451,7 +1451,7 @@ impl Literal {
                 f(&["cr", hashes, "\"", symbol, "\"", hashes, suffix])
             }
 
-            bridge::LitKind::Integer | bridge::LitKind::Float | bridge::LitKind::Err => {
+            bridge::LitKind::Integer | bridge::LitKind::Float | bridge::LitKind::ErrWithGuar => {
                 f(&[symbol, suffix])
             }
         })

std/src/sys/pal/unix/thread.rs

@@ -847,11 +847,31 @@ pub mod guard {
             let stackptr = get_stack_start_aligned()?;
             let guardaddr = stackptr.addr();
             // Technically the number of guard pages is tunable and controlled
-            // by the security.bsd.stack_guard_page sysctl, but there are
-            // few reasons to change it from the default. The default value has
-            // been 1 ever since FreeBSD 11.1 and 10.4.
-            const GUARD_PAGES: usize = 1;
-            let guard = guardaddr..guardaddr + GUARD_PAGES * page_size;
+            // by the security.bsd.stack_guard_page sysctl.
+            // By default it is 1, checking once is enough since it is
+            // a boot time config value.
+            static LOCK: crate::sync::OnceLock<usize> = crate::sync::OnceLock::new();
+            let guard = guardaddr
+                ..guardaddr
+                    + *LOCK.get_or_init(|| {
+                        use crate::sys::weak::dlsym;
+                        dlsym!(fn sysctlbyname(*const libc::c_char, *mut libc::c_void, *mut libc::size_t, *const libc::c_void, libc::size_t) -> libc::c_int);
+                        let mut guard: usize = 0;
+                        let mut size = crate::mem::size_of_val(&guard);
+                        let oid = crate::ffi::CStr::from_bytes_with_nul(
+                            b"security.bsd.stack_guard_page\0",
+                        )
+                        .unwrap();
+                        match sysctlbyname.get() {
+                            Some(fcn) => {
+                                if fcn(oid.as_ptr(), &mut guard as *mut _ as *mut _, &mut size as *mut _ as *mut _, crate::ptr::null_mut(), 0) == 0 {
+                                    return guard;
+                                }
+                                return 1;
+                            },
+                            _ => { return 1; }
+                        }
+                    }) * page_size;
             Some(guard)
         } else if cfg!(target_os = "openbsd") {
             // OpenBSD stack already includes a guard page, and stack is