Rollup of 6 pull requests

compiler/rustc_codegen_ssa/src/mir/retag.rs

@@ -151,7 +151,7 @@ impl<'a, 'tcx, V> RetagPlan<V> {
             let boxed_ty = layout.ty.expect_boxed_ty();
             let boxed_layout = bx.layout_of(boxed_ty);
             if let Some(mut plan) = Self::emit_retag(bx, boxed_layout, None, is_fn_entry) {
-                // `Unique<T>`
+                // `BoxRaw<T>`
                 let unique = layout.field(bx, 0);
                 assert_eq!(unique.fields.count(), 2);
                 plan = plan.for_field(FieldIdx::ZERO);

library/alloc/src/collections/btree/map.rs

@@ -205,16 +205,13 @@ pub struct BTreeMap<
 #[stable(feature = "btree_drop", since = "1.7.0")]
 unsafe impl<#[may_dangle] K, #[may_dangle] V, A: AllocatorClone> Drop for BTreeMap<K, V, A> {
     fn drop(&mut self) {
-        // Skip `into_iter` for an empty map: `dying_next` is too costly to inline, so the
-        // empty drop isn't optimised away (see #161375).
-        if self.root.is_some() {
-            // SAFETY: `self` is not used after this and none of its fields are dropped again:
-            // `alloc` is `ManuallyDrop` and `root` has no drop glue.
-            drop(unsafe { ptr::read(self) }.into_iter())
+        if let Some(root) = self.root.take() {
+            // SAFETY: The tree won't be used after this point.
+            // The allocator has not been moved out and will be moved into `drop_tree`.
+            unsafe { root.into_dying().drop_tree(ManuallyDrop::take(&mut self.alloc)) };
         } else {
-            // SAFETY: With no root there are no nodes to free, so only the allocator needs
-            // dropping. `self` is not used after this, and `alloc` is dropped only here.
-            unsafe { ManuallyDrop::drop(&mut self.alloc) }
+            // SAFETY: The allocator has not been moved out and won't be used after this point.
+            unsafe { ManuallyDrop::drop(&mut self.alloc) };
         }
     }
 }

library/alloc/src/collections/btree/map/tests.rs

@@ -2542,6 +2542,114 @@ fn test_into_iter_drop_leak_height_1() {
     }
 }
 
+#[test]
+fn test_drop_map_elements_multi_level() {
+    for size in [1, MIN_INSERTS_HEIGHT_1, MIN_INSERTS_HEIGHT_2] {
+        let keys = Vec::from_iter((0..size).map(CrashTestDummy::new));
+        let vals = Vec::from_iter((0..size).map(CrashTestDummy::new));
+        let map = {
+            let mut map = BTreeMap::new();
+
+            (0..size).map(|i| (keys[i].spawn(Panic::Never), vals[i].spawn(Panic::Never))).for_each(
+                |(k, v)| {
+                    map.insert(k, v);
+                },
+            );
+            map
+        };
+
+        drop(map);
+
+        for i in 0..size {
+            assert_eq!(keys[i].dropped(), 1);
+            assert_eq!(vals[i].dropped(), 1);
+        }
+    }
+}
+
+#[test]
+fn test_drop_empty_map_allocator() {
+    use core::alloc::{AllocError, Allocator, AllocatorClone, Layout};
+    use core::cell::Cell;
+    use core::ptr::NonNull;
+
+    struct CountedAllocator<'a>(&'a Cell<usize>);
+
+    impl Clone for CountedAllocator<'_> {
+        fn clone(&self) -> Self {
+            Self(self.0)
+        }
+    }
+
+    impl Drop for CountedAllocator<'_> {
+        fn drop(&mut self) {
+            self.0.set(self.0.get() + 1);
+        }
+    }
+
+    unsafe impl Allocator for CountedAllocator<'_> {
+        fn allocate(&self, layout: Layout) -> Result<NonNull<[u8]>, AllocError> {
+            Global.allocate(layout)
+        }
+
+        unsafe fn deallocate(&self, ptr: NonNull<u8>, layout: Layout) {
+            unsafe { Global.deallocate(ptr, layout) }
+        }
+    }
+
+    unsafe impl AllocatorClone for CountedAllocator<'_> {}
+
+    let dropped = Cell::new(0);
+    let map = BTreeMap::<i32, i32, _>::new_in(CountedAllocator(&dropped));
+    assert!(map.root.is_none());
+
+    drop(map);
+
+    assert_eq!(dropped.get(), 1);
+}
+
+#[test]
+#[cfg_attr(not(panic = "unwind"), ignore = "test requires unwinding support")]
+fn test_drop_map_elements_multi_level_panic() {
+    for size in [1, MIN_INSERTS_HEIGHT_1, MIN_INSERTS_HEIGHT_2] {
+        for panic_point in [0, size / 2, size - 1] {
+            for panic_in_key in [true, false] {
+                let keys = Vec::from_iter((0..size).map(CrashTestDummy::new));
+                let vals = Vec::from_iter((0..size).map(CrashTestDummy::new));
+                let map = {
+                    let mut map = BTreeMap::new();
+
+                    (0..size)
+                        .map(|i| {
+                            let key_panic = if panic_in_key && i == panic_point {
+                                Panic::InDrop
+                            } else {
+                                Panic::Never
+                            };
+                            let val_panic = if !panic_in_key && i == panic_point {
+                                Panic::InDrop
+                            } else {
+                                Panic::Never
+                            };
+                            (keys[i].spawn(key_panic), vals[i].spawn(val_panic))
+                        })
+                        .for_each(|(k, v)| {
+                            map.insert(k, v);
+                        });
+                    map
+                };
+
+                catch_unwind(move || drop(map)).unwrap_err();
+
+                for i in 0..size {
+                    assert_eq!(keys[i].dropped(), 1);
+                    assert_eq!(vals[i].dropped(), 1);
+                }
+            }
+        }
+    }
+}
+
 #[test]
 fn test_into_keys() {
     let map = BTreeMap::from([(1, 'a'), (2, 'b'), (3, 'c')]);

library/alloc/src/collections/btree/navigate.rs

@@ -852,3 +852,70 @@ impl<BorrowType: marker::BorrowType, K, V> NodeRef<BorrowType, K, V, marker::Lea
         }
     }
 }
+
+impl<K, V> NodeRef<marker::Dying, K, V, marker::LeafOrInternal> {
+    /// # Safety
+    /// - `self` must be the root.
+    /// - The tree shouldn't be accessed anymore.
+    pub(super) unsafe fn drop_tree<A: AllocatorClone>(self, alloc: A) {
+        struct DropGuard<K, V, A: AllocatorClone> {
+            node: Option<NodeRef<marker::Dying, K, V, marker::LeafOrInternal>>,
+            alloc: A,
+        }
+
+        impl<K, V, A: AllocatorClone> Drop for DropGuard<K, V, A> {
+            fn drop(&mut self) {
+                if let Some(cur) = self.node.take() {
+                    let mut next =
+                        // SAFETY: When unwinding reached this guard, all kvs in cur
+                        // have already been dropped in `drop_kvs`, while the node itself has not
+                        // yet been deallocated.
+                        unsafe { deallocate_and_next_postorder_node(cur, self.alloc.clone()) };
+
+                    while let Some(mut node) = next {
+                        // SAFETY: Every node only calls the function once
+                        unsafe { node.drop_kvs() };
+                        next =
+                            // SAFETY: `drop_kvs()` above only dropped kvs and the node is still accessible,
+                            // and also each node is deallocated exactly once.
+                            unsafe { deallocate_and_next_postorder_node(node, self.alloc.clone()) }
+                    }
+                }
+            }
+        }
+        /// Deallocates `node` and returns the next node in postorder traversal
+        ///
+        /// # Safety
+        ///
+        /// The node must be initialized, all kvs in node must have already
+        /// been dropped or moved out and its children must have already been deallocated.
+        /// Also the node can't be touched anymore.
+        unsafe fn deallocate_and_next_postorder_node<K, V, A: AllocatorClone>(
+            node: NodeRef<marker::Dying, K, V, marker::LeafOrInternal>,
+            alloc: A,
+        ) -> Option<NodeRef<marker::Dying, K, V, marker::LeafOrInternal>> {
+            // SAFETY: guaranteed by the caller
+            let parent = unsafe { node.deallocate_and_ascend(alloc) }?;
+
+            Some(match parent.right_kv() {
+                Ok(kv) => kv.right_edge().descend().first_leaf_edge().into_node().forget_type(),
+                Err(last_edge) => last_edge.into_node().forget_type(),
+            })
+        }
+
+        let node = self.first_leaf_edge().into_node().forget_type();
+        let mut guard = DropGuard { node: Some(node), alloc };
+        loop {
+            // SAFETY: all kvs of each node are dropped once
+            unsafe { guard.node.as_mut().unwrap().drop_kvs() };
+            // SAFETY: Nodes are deallocated in postorder, and each node is deallocated exactly once.
+            if let Some(next) = unsafe {
+                deallocate_and_next_postorder_node(guard.node.take().unwrap(), guard.alloc.clone())
+            } {
+                guard.node = Some(next);
+            } else {
+                return;
+            }
+        }
+    }
+}

library/alloc/src/collections/btree/node.rs

@@ -429,6 +429,45 @@ impl<K, V> NodeRef<marker::Dying, K, V, marker::LeafOrInternal> {
         }
         ret
     }
+    /// Drops all kvs in this node without deallocating the node itself
+    ///
+    /// # Safety
+    ///
+    /// - kvs in the node must be initialized and must not be accessed after this call.
+    /// - No kvs in the node can be accessed through any other path while this function is running.
+    pub(super) unsafe fn drop_kvs(&mut self) {
+        struct DropGuard<'a, K, V> {
+            node: &'a NodeRef<marker::Dying, K, V, marker::LeafOrInternal>,
+            idx: usize,
+        }
+        impl<'a, K, V> Drop for DropGuard<'a, K, V> {
+            fn drop(&mut self) {
+                let len = self.node.len();
+                for i in self.idx..len {
+                    // SAFETY: i < len and the kv has been initialized and
+                    // it won't use the i-th kv more than once.
+                    unsafe {
+                        let kv = Handle::new_kv(ptr::read(self.node), i);
+                        kv.drop_key_val();
+                    }
+                }
+            }
+        }
+        let len = self.len();
+        for idx in 0..len {
+            // If `kv.drop_key_val()` panics, the guard would drop
+            // the rest and skip the panicked kv.
+            let guard = DropGuard { node: self, idx: idx + 1 };
+            // SAFETY: idx < len and the kv has been initialized and
+            // it won't touch the idx-th more than once
+            unsafe {
+                let kv = Handle::new_kv(ptr::read(self), idx);
+                kv.drop_key_val();
+            }
+
+            core::mem::forget(guard);
+        }
+    }
 }
 
 impl<'a, K, V, Type> NodeRef<marker::Mut<'a>, K, V, Type> {

library/alloc/src/lib.rs

@@ -157,7 +157,6 @@
 #![feature(pin_coerce_unsized_trait)]
 #![feature(ptr_alignment_type)]
 #![feature(ptr_cast_slice)]
-#![feature(ptr_internals)]
 #![feature(ptr_metadata)]
 #![feature(random)]
 #![feature(raw_os_error_ty)]