Auto merge of #71556 - Dylan-DPC:rollup-9ll4shr, r=Dylan-DPC

Rollup of 7 pull requests

Successful merges:

 - #69041 (proc_macro: Stabilize `Span::resolved_at` and `Span::located_at`)
 - #69813 (Implement BitOr and BitOrAssign for the NonZero integer types)
 - #70712 (stabilize BTreeMap::remove_entry)
 - #71168 (Deprecate `{Box,Rc,Arc}::into_raw_non_null`)
 - #71544 (Replace filter_map().next() calls with find_map())
 - #71545 (Fix comment in docstring example for Error::kind)
 - #71548 (Add missing Send and Sync impls for linked list Cursor and CursorMut.)

Failed merges:

r? @ghost

Author: bors

Diff for: src/liballoc/boxed.rs

@@ -428,7 +428,12 @@ impl<T: ?Sized> Box<T> {
     #[stable(feature = "box_raw", since = "1.4.0")]
     #[inline]
     pub fn into_raw(b: Box<T>) -> *mut T {
-        Box::into_raw_non_null(b).as_ptr()
+        // Box is recognized as a "unique pointer" by Stacked Borrows, but internally it is a
+        // raw pointer for the type system. Turning it directly into a raw pointer would not be
+        // recognized as "releasing" the unique pointer to permit aliased raw accesses,
+        // so all raw pointer methods go through `leak` which creates a (unique)
+        // mutable reference. Turning *that* to a raw pointer behaves correctly.
+        Box::leak(b) as *mut T
     }
 
     /// Consumes the `Box`, returning the wrapped pointer as `NonNull<T>`.
@@ -451,6 +456,7 @@ impl<T: ?Sized> Box<T> {
     ///
     /// ```
     /// #![feature(box_into_raw_non_null)]
+    /// #![allow(deprecated)]
     ///
     /// let x = Box::new(5);
     /// let ptr = Box::into_raw_non_null(x);
@@ -460,24 +466,34 @@ impl<T: ?Sized> Box<T> {
     /// let x = unsafe { Box::from_raw(ptr.as_ptr()) };
     /// ```
     #[unstable(feature = "box_into_raw_non_null", issue = "47336")]
+    #[rustc_deprecated(
+        since = "1.44.0",
+        reason = "use `Box::leak(b).into()` or `NonNull::from(Box::leak(b))` instead"
+    )]
     #[inline]
     pub fn into_raw_non_null(b: Box<T>) -> NonNull<T> {
-        Box::into_unique(b).into()
-    }
-
-    #[unstable(feature = "ptr_internals", issue = "none", reason = "use into_raw_non_null instead")]
+        // Box is recognized as a "unique pointer" by Stacked Borrows, but internally it is a
+        // raw pointer for the type system. Turning it directly into a raw pointer would not be
+        // recognized as "releasing" the unique pointer to permit aliased raw accesses,
+        // so all raw pointer methods go through `leak` which creates a (unique)
+        // mutable reference. Turning *that* to a raw pointer behaves correctly.
+        Box::leak(b).into()
+    }
+
+    #[unstable(
+        feature = "ptr_internals",
+        issue = "none",
+        reason = "use `Box::leak(b).into()` or `Unique::from(Box::leak(b))` instead"
+    )]
     #[inline]
     #[doc(hidden)]
     pub fn into_unique(b: Box<T>) -> Unique<T> {
-        let b = mem::ManuallyDrop::new(b);
-        let mut unique = b.0;
-        // Box is kind-of a library type, but recognized as a "unique pointer" by
-        // Stacked Borrows.  This function here corresponds to "reborrowing to
-        // a raw pointer", but there is no actual reborrow here -- so
-        // without some care, the pointer we are returning here still carries
-        // the tag of `b`, with `Unique` permission.
-        // We round-trip through a mutable reference to avoid that.
-        unsafe { Unique::new_unchecked(unique.as_mut() as *mut T) }
+        // Box is recognized as a "unique pointer" by Stacked Borrows, but internally it is a
+        // raw pointer for the type system. Turning it directly into a raw pointer would not be
+        // recognized as "releasing" the unique pointer to permit aliased raw accesses,
+        // so all raw pointer methods go through `leak` which creates a (unique)
+        // mutable reference. Turning *that* to a raw pointer behaves correctly.
+        Box::leak(b).into()
     }
 
     /// Consumes and leaks the `Box`, returning a mutable reference,
@@ -523,7 +539,7 @@ impl<T: ?Sized> Box<T> {
     where
         T: 'a, // Technically not needed, but kept to be explicit.
     {
-        unsafe { &mut *Box::into_raw(b) }
+        unsafe { &mut *mem::ManuallyDrop::new(b).0.as_ptr() }
     }
 
     /// Converts a `Box<T>` into a `Pin<Box<T>>`

Diff for: src/liballoc/collections/btree/map.rs

@@ -923,15 +923,14 @@ impl<K: Ord, V> BTreeMap<K, V> {
     /// Basic usage:
     ///
     /// ```
-    /// #![feature(btreemap_remove_entry)]
     /// use std::collections::BTreeMap;
     ///
     /// let mut map = BTreeMap::new();
     /// map.insert(1, "a");
     /// assert_eq!(map.remove_entry(&1), Some((1, "a")));
     /// assert_eq!(map.remove_entry(&1), None);
     /// ```
-    #[unstable(feature = "btreemap_remove_entry", issue = "66714")]
+    #[stable(feature = "btreemap_remove_entry", since = "1.44.0")]
     pub fn remove_entry<Q: ?Sized>(&mut self, key: &Q) -> Option<(K, V)>
     where
         K: Borrow<Q>,

Diff for: src/liballoc/collections/linked_list.rs

@@ -143,7 +143,7 @@ impl<T> LinkedList<T> {
         unsafe {
             node.next = self.head;
             node.prev = None;
-            let node = Some(Box::into_raw_non_null(node));
+            let node = Some(Box::leak(node).into());
 
             match self.head {
                 None => self.tail = node,
@@ -184,7 +184,7 @@ impl<T> LinkedList<T> {
         unsafe {
             node.next = None;
             node.prev = self.tail;
-            let node = Some(Box::into_raw_non_null(node));
+            let node = Some(Box::leak(node).into());
 
             match self.tail {
                 None => self.head = node,
@@ -1133,11 +1133,9 @@ impl<T> IterMut<'_, T> {
                     Some(prev) => prev,
                 };
 
-                let node = Some(Box::into_raw_non_null(box Node {
-                    next: Some(head),
-                    prev: Some(prev),
-                    element,
-                }));
+                let node = Some(
+                    Box::leak(box Node { next: Some(head), prev: Some(prev), element }).into(),
+                );
 
                 // Not creating references to entire nodes to not invalidate the
                 // reference to `element` we handed to the user.
@@ -1450,7 +1448,7 @@ impl<'a, T> CursorMut<'a, T> {
     #[unstable(feature = "linked_list_cursors", issue = "58533")]
     pub fn insert_after(&mut self, item: T) {
         unsafe {
-            let spliced_node = Box::into_raw_non_null(Box::new(Node::new(item)));
+            let spliced_node = Box::leak(Box::new(Node::new(item))).into();
             let node_next = match self.current {
                 None => self.list.head,
                 Some(node) => node.as_ref().next,
@@ -1470,7 +1468,7 @@ impl<'a, T> CursorMut<'a, T> {
     #[unstable(feature = "linked_list_cursors", issue = "58533")]
     pub fn insert_before(&mut self, item: T) {
         unsafe {
-            let spliced_node = Box::into_raw_non_null(Box::new(Node::new(item)));
+            let spliced_node = Box::leak(Box::new(Node::new(item))).into();
             let node_prev = match self.current {
                 None => self.list.tail,
                 Some(node) => node.as_ref().prev,
@@ -1843,3 +1841,15 @@ unsafe impl<T: Send> Send for IterMut<'_, T> {}
 
 #[stable(feature = "rust1", since = "1.0.0")]
 unsafe impl<T: Sync> Sync for IterMut<'_, T> {}
+
+#[unstable(feature = "linked_list_cursors", issue = "58533")]
+unsafe impl<T: Sync> Send for Cursor<'_, T> {}
+
+#[unstable(feature = "linked_list_cursors", issue = "58533")]
+unsafe impl<T: Sync> Sync for Cursor<'_, T> {}
+
+#[unstable(feature = "linked_list_cursors", issue = "58533")]
+unsafe impl<T: Send> Send for CursorMut<'_, T> {}
+
+#[unstable(feature = "linked_list_cursors", issue = "58533")]
+unsafe impl<T: Sync> Sync for CursorMut<'_, T> {}

Diff for: src/liballoc/lib.rs

@@ -77,7 +77,6 @@
 #![feature(allocator_api)]
 #![feature(allow_internal_unstable)]
 #![feature(arbitrary_self_types)]
-#![feature(box_into_raw_non_null)]
 #![feature(box_patterns)]
 #![feature(box_syntax)]
 #![feature(cfg_sanitize)]

Diff for: src/liballoc/rc.rs

@@ -323,11 +323,9 @@ impl<T> Rc<T> {
         // pointers, which ensures that the weak destructor never frees
         // the allocation while the strong destructor is running, even
         // if the weak pointer is stored inside the strong one.
-        Self::from_inner(Box::into_raw_non_null(box RcBox {
-            strong: Cell::new(1),
-            weak: Cell::new(1),
-            value,
-        }))
+        Self::from_inner(
+            Box::leak(box RcBox { strong: Cell::new(1), weak: Cell::new(1), value }).into(),
+        )
     }
 
     /// Constructs a new `Rc` with uninitialized contents.
@@ -661,6 +659,7 @@ impl<T: ?Sized> Rc<T> {
     ///
     /// ```
     /// #![feature(rc_into_raw_non_null)]
+    /// #![allow(deprecated)]
     ///
     /// use std::rc::Rc;
     ///
@@ -670,6 +669,7 @@ impl<T: ?Sized> Rc<T> {
     /// assert_eq!(deref, "hello");
     /// ```
     #[unstable(feature = "rc_into_raw_non_null", issue = "47336")]
+    #[rustc_deprecated(since = "1.44.0", reason = "use `Rc::into_raw` instead")]
     #[inline]
     pub fn into_raw_non_null(this: Self) -> NonNull<T> {
         // safe because Rc guarantees its pointer is non-null

Diff for: src/liballoc/sync.rs

@@ -324,7 +324,7 @@ impl<T> Arc<T> {
             weak: atomic::AtomicUsize::new(1),
             data,
         };
-        Self::from_inner(Box::into_raw_non_null(x))
+        Self::from_inner(Box::leak(x).into())
     }
 
     /// Constructs a new `Arc` with uninitialized contents.
@@ -658,6 +658,7 @@ impl<T: ?Sized> Arc<T> {
     ///
     /// ```
     /// #![feature(rc_into_raw_non_null)]
+    /// #![allow(deprecated)]
     ///
     /// use std::sync::Arc;
     ///
@@ -667,6 +668,7 @@ impl<T: ?Sized> Arc<T> {
     /// assert_eq!(deref, "hello");
     /// ```
     #[unstable(feature = "rc_into_raw_non_null", issue = "47336")]
+    #[rustc_deprecated(since = "1.44.0", reason = "use `Arc::into_raw` instead")]
     #[inline]
     pub fn into_raw_non_null(this: Self) -> NonNull<T> {
         // safe because Arc guarantees its pointer is non-null

Diff for: src/libcore/num/mod.rs

@@ -8,6 +8,7 @@ use crate::convert::Infallible;
 use crate::fmt;
 use crate::intrinsics;
 use crate::mem;
+use crate::ops::{BitOr, BitOrAssign};
 use crate::str::FromStr;
 
 // Used because the `?` operator is not allowed in a const context.
@@ -110,6 +111,57 @@ assert_eq!(size_of::<Option<core::num::", stringify!($Ty), ">>(), size_of::<", s
                 }
             }
 
+            #[stable(feature = "nonzero_bitor", since = "1.43.0")]
+            impl BitOr for $Ty {
+                type Output = Self;
+                #[inline]
+                fn bitor(self, rhs: Self) -> Self::Output {
+                    // Safety: since `self` and `rhs` are both nonzero, the
+                    // result of the bitwise-or will be nonzero.
+                    unsafe { $Ty::new_unchecked(self.get() | rhs.get()) }
+                }
+            }
+
+            #[stable(feature = "nonzero_bitor", since = "1.43.0")]
+            impl BitOr<$Int> for $Ty {
+                type Output = Self;
+                #[inline]
+                fn bitor(self, rhs: $Int) -> Self::Output {
+                    // Safety: since `self` is nonzero, the result of the
+                    // bitwise-or will be nonzero regardless of the value of
+                    // `rhs`.
+                    unsafe { $Ty::new_unchecked(self.get() | rhs) }
+                }
+            }
+
+            #[stable(feature = "nonzero_bitor", since = "1.43.0")]
+            impl BitOr<$Ty> for $Int {
+                type Output = $Ty;
+                #[inline]
+                fn bitor(self, rhs: $Ty) -> Self::Output {
+                    // Safety: since `rhs` is nonzero, the result of the
+                    // bitwise-or will be nonzero regardless of the value of
+                    // `self`.
+                    unsafe { $Ty::new_unchecked(self | rhs.get()) }
+                }
+            }
+
+            #[stable(feature = "nonzero_bitor", since = "1.43.0")]
+            impl BitOrAssign for $Ty {
+                #[inline]
+                fn bitor_assign(&mut self, rhs: Self) {
+                    *self = *self | rhs;
+                }
+            }
+
+            #[stable(feature = "nonzero_bitor", since = "1.43.0")]
+            impl BitOrAssign<$Int> for $Ty {
+                #[inline]
+                fn bitor_assign(&mut self, rhs: $Int) {
+                    *self = *self | rhs;
+                }
+            }
+
             impl_nonzero_fmt! {
                 #[$stability] (Debug, Display, Binary, Octal, LowerHex, UpperHex) for $Ty
             }

Diff for: src/libcore/tests/nonzero.rs

@@ -141,3 +141,38 @@ fn test_from_str() {
         Some(IntErrorKind::Overflow)
     );
 }
+
+#[test]
+fn test_nonzero_bitor() {
+    let nz_alt = NonZeroU8::new(0b1010_1010).unwrap();
+    let nz_low = NonZeroU8::new(0b0000_1111).unwrap();
+
+    let both_nz: NonZeroU8 = nz_alt | nz_low;
+    assert_eq!(both_nz.get(), 0b1010_1111);
+
+    let rhs_int: NonZeroU8 = nz_low | 0b1100_0000u8;
+    assert_eq!(rhs_int.get(), 0b1100_1111);
+
+    let rhs_zero: NonZeroU8 = nz_alt | 0u8;
+    assert_eq!(rhs_zero.get(), 0b1010_1010);
+
+    let lhs_int: NonZeroU8 = 0b0110_0110u8 | nz_alt;
+    assert_eq!(lhs_int.get(), 0b1110_1110);
+
+    let lhs_zero: NonZeroU8 = 0u8 | nz_low;
+    assert_eq!(lhs_zero.get(), 0b0000_1111);
+}
+
+#[test]
+fn test_nonzero_bitor_assign() {
+    let mut target = NonZeroU8::new(0b1010_1010).unwrap();
+
+    target |= NonZeroU8::new(0b0000_1111).unwrap();
+    assert_eq!(target.get(), 0b1010_1111);
+
+    target |= 0b0001_0000;
+    assert_eq!(target.get(), 0b1011_1111);
+
+    target |= 0;
+    assert_eq!(target.get(), 0b1011_1111);
+}

Diff for: src/libproc_macro/lib.rs

@@ -351,14 +351,14 @@ impl Span {
 
     /// Creates a new span with the same line/column information as `self` but
     /// that resolves symbols as though it were at `other`.
-    #[unstable(feature = "proc_macro_span", issue = "54725")]
+    #[stable(feature = "proc_macro_span_resolved_at", since = "1.43.0")]
     pub fn resolved_at(&self, other: Span) -> Span {
         Span(self.0.resolved_at(other.0))
     }
 
     /// Creates a new span with the same name resolution behavior as `self` but
     /// with the line/column information of `other`.
-    #[unstable(feature = "proc_macro_span", issue = "54725")]
+    #[stable(feature = "proc_macro_span_located_at", since = "1.43.0")]
     pub fn located_at(&self, other: Span) -> Span {
         other.resolved_at(*self)
     }

Diff for: src/librustc_codegen_ssa/back/linker.rs

@@ -1127,11 +1127,7 @@ fn exported_symbols(tcx: TyCtxt<'_>, crate_type: CrateType) -> Vec<String> {
     }
 
     let formats = tcx.dependency_formats(LOCAL_CRATE);
-    let deps = formats
-        .iter()
-        .filter_map(|(t, list)| if *t == crate_type { Some(list) } else { None })
-        .next()
-        .unwrap();
+    let deps = formats.iter().find_map(|(t, list)| (*t == crate_type).then_some(list)).unwrap();
 
     for (index, dep_format) in deps.iter().enumerate() {
         let cnum = CrateNum::new(index + 1);

Diff for: src/librustc_errors/emitter.rs

@@ -285,21 +285,18 @@ pub trait Emitter {
         let has_macro_spans = iter::once(&*span)
             .chain(children.iter().map(|child| &child.span))
             .flat_map(|span| span.primary_spans())
-            .copied()
-            .flat_map(|sp| {
-                sp.macro_backtrace().filter_map(|expn_data| {
-                    match expn_data.kind {
-                        ExpnKind::Root => None,
+            .flat_map(|sp| sp.macro_backtrace())
+            .find_map(|expn_data| {
+                match expn_data.kind {
+                    ExpnKind::Root => None,
 
-                        // Skip past non-macro entries, just in case there
-                        // are some which do actually involve macros.
-                        ExpnKind::Desugaring(..) | ExpnKind::AstPass(..) => None,
+                    // Skip past non-macro entries, just in case there
+                    // are some which do actually involve macros.
+                    ExpnKind::Desugaring(..) | ExpnKind::AstPass(..) => None,
 
-                        ExpnKind::Macro(macro_kind, _) => Some(macro_kind),
-                    }
-                })
-            })
-            .next();
+                    ExpnKind::Macro(macro_kind, _) => Some(macro_kind),
+                }
+            });
 
         if !backtrace {
             self.fix_multispans_in_extern_macros(source_map, span, children);