Introduced unwind safety

Previous versions are unsound if closures in _with methods panic and the
unwinding panic runtime is used.

Cargo.toml

@@ -23,6 +23,7 @@ slotmap = {version = "0.4", optional = true}
 [features]
 default = [
     "std",
+    "unwind_safety",
     "alloc",
 
     "binary_tree",
@@ -33,6 +34,7 @@ default = [
     "slotmap",
 ]
 std = ["alloc"]
+unwind_safety = ["std"]
 alloc = []
 
 binary_tree = []
@@ -46,6 +48,7 @@ doc_cfg = []
 [package.metadata.docs.rs]
 features = [
     "std",
+    "unwind_safety",
     "alloc",
 
     "binary_tree",

README.md

@@ -36,7 +36,8 @@ By default, all trees use a technique called "sparse storage" to significantly s
 - As elements get removed, they will leave holes behind themselves. Those are usually cleaned up automatically as new elements are inserted, **but if you need to clean up all at once, you can use `defragment`.**
 
 ## Feature flags
-- `std` (**enabled by default**) - enables the full standard library, disabling `no_std` for the crate. Currently, this only adds [`Error`] trait implementations for some types.
+- `std` (**enabled by default**) — enables the full standard library, disabling `no_std` for the crate. Currently, this only adds [`Error`] trait implementations for some types.
+- `unwind_safety` (**enabled by default**) — **Must be enabled when using the unwinding panic implementation, otherwise using methods which accept closures is undefined behavior.** Requires `std`. Not a concern in `no_std` builds, since those do not have a panicking runtime by default.
 - `alloc` (**enabled by default**) — adds `ListStorage` trait implementations for standard library containers, except for `LinkedList`, which is temporarily unsupported. *This does not require standard library support and will only panic at runtime in `no_std` environments without an allocator.*
 - `smallvec` (**enabled by default**) — adds a `ListStorage` trait implementation for [`SmallVec`].
 - `slotmap` (**enabled by default**) — adds `Storage` trait implementations for [`SlotMap`], [`HopSlotMap`] and [`DenseSlotMap`].

src/binary_tree/node_ref.rs

@@ -7,7 +7,7 @@ use core::{
 };
 use crate::{
     storage::{Storage, DefaultStorage},
-    util::unreachable_debugchecked,
+    util::{unreachable_debugchecked, abort_on_panic},
     TryRemoveLeafError,
     TryRemoveBranchError,
     TryRemoveChildrenError,
@@ -513,7 +513,9 @@ debug key check failed: tried to reference key {:?} which is not present in the
                     // SAFETY: as above
                     ptr::write(
                         &mut self.tree.storage.get_unchecked_mut(&parent_key).value,
-                        NodeData::Leaf(f(old_payload)),
+                        NodeData::Leaf(
+                            abort_on_panic(|| f(old_payload))
+                        ),
                     );
                 }
             }
@@ -602,7 +604,9 @@ debug key check failed: tried to reference key {:?} which is not present in the
                     // SAFETY: as above
                     ptr::write(
                         &mut self.tree.storage.get_unchecked_mut(&parent_key).value,
-                        NodeData::Leaf(f(old_payload)),
+                        NodeData::Leaf(
+                            abort_on_panic(|| f(old_payload))
+                        ),
                     );
                 }
             }
@@ -711,7 +715,12 @@ debug key check failed: tried to reference key {:?} which is not present in the
         };
         unsafe {
             // SAFETY: as above
-            ptr::write(&mut self.node_mut().value, NodeData::Leaf(f(old_payload)));
+            ptr::write(
+                &mut self.node_mut().value,
+                NodeData::Leaf(
+                    abort_on_panic(|| f(old_payload))
+                )
+            );
         }
         Ok((left_child_payload, right_child_payload))
     }

src/lib.rs

@@ -30,7 +30,8 @@
 //! - As elements get removed, they will leave holes behind themselves. Those are usually cleaned up automatically as new elements are inserted, **but if you need to clean up all at once, you can use `defragment`.**
 //!
 //! # Feature flags
-//! - `std` (**enabled by default**) - enables the full standard library, disabling `no_std` for the crate. Currently, this only adds [`Error`] trait implementations for some types.
+//! - `std` (**enabled by default**) — enables the full standard library, disabling `no_std` for the crate. Currently, this only adds [`Error`] trait implementations for some types.
+//! - `unwind_safety` (**enabled by default**) — **Must be enabled when using the unwinding panic implementation, otherwise using methods which accept closures is undefined behavior.** Requires `std`. Not a concern in `no_std` builds, since those do not have a panicking runtime by default.
 //! - `alloc` (**enabled by default**) — adds `ListStorage` trait implementations for standard library containers, except for `LinkedList`, which is temporarily unsupported. *This does not require standard library support and will only panic at runtime in `no_std` environments without an allocator.*
 //! - `smallvec` (**enabled by default**) — adds a `ListStorage` trait implementation for [`SmallVec`].
 //! - `slotmap` (**enabled by default**) — adds `Storage` trait implementations for [`SlotMap`], [`HopSlotMap`] and [`DenseSlotMap`].
@@ -133,7 +134,6 @@
 #![deny(
     anonymous_parameters,
     bare_trait_objects,
-    clippy::exit,
 )]
 #![allow(clippy::use_self)] // FIXME reenable when it gets fixed
 #![cfg_attr(not(feature = "std"), no_std)]
@@ -170,6 +170,13 @@ pub mod quadtree;
 #[cfg_attr(feature = "doc_cfg", doc(cfg(feature = "quadtree")))]
 pub use quadtree::{Quadtree};
 
+#[cfg(feature = "freeform_tree")]
+#[cfg_attr(feature = "doc_cfg", doc(cfg(feature = "freeform_tree")))]
+pub mod freeform_tree;
+#[cfg(feature = "freeform_tree")]
+#[cfg_attr(feature = "doc_cfg", doc(cfg(feature = "freeform_tree")))]
+pub use freeform_tree::{FreeformTree};
+
 pub mod traversal;
 pub use traversal::{Visitor, VisitorMut, Traversable, TraversableMut};
 
@@ -205,6 +212,14 @@ pub mod prelude {
         NodeRef as QuadtreeNodeRef,
         NodeRefMut as QuadtreeNodeRefMut,
     };
+    #[cfg(feature = "freeform_tree")]
+    #[cfg_attr(feature = "doc_cfg", doc(cfg(feature = "freeform_tree")))]
+    #[doc(no_inline)]
+    pub use crate::freeform_tree::{
+        FreeformTree,
+        NodeRef as FreeformTreeNodeRef,
+        NodeRefMut as FreeformTreeNodeRefMut,
+    };
 }
 
 pub(crate) mod util;

src/octree/node.rs

@@ -115,7 +115,7 @@ impl<B, L> MoveFix for Node<B, L, usize> {
                 return;
             }
         }
-        unsafe {
+        /*unsafe*/ {
             // SAFETY: this mismatch is assumed to never happen as a guarantee
             // of key validity
             unreachable_debugchecked("failed to find node in parent's child list")

src/octree/node_ref.rs

@@ -12,7 +12,7 @@ use crate::{
     TryRemoveChildrenError,
     MakeBranchError,
     traversal::algorithms,
-    util::ArrayMap,
+    util::{ArrayMap, abort_on_panic},
 };
 
 /// A reference to a node in an octree.
@@ -496,7 +496,9 @@ debug key check failed: tried to reference key {:?} which is not present in the
             // SAFETY: as above
             ptr::write(
                 &mut self.node_mut().value,
-                NodeData::Leaf( f(old_payload) ),
+                NodeData::Leaf(
+                    abort_on_panic(|| f(old_payload))
+                ),
             );
         }
         Ok(children_payloads)

src/quadtree/node.rs

@@ -116,7 +116,7 @@ impl<B, L> MoveFix for Node<B, L, usize> {
                 return;
             }
         }
-        unsafe {
+        /*unsafe*/ {
             // SAFETY: this mismatch is assumed to never happen as a guarantee
             // of key validity
             unreachable_debugchecked("failed to find node in parent's child list")

src/quadtree/node_ref.rs

@@ -12,7 +12,7 @@ use crate::{
     TryRemoveChildrenError,
     MakeBranchError,
     traversal::algorithms,
-    util::ArrayMap,
+    util::{ArrayMap, abort_on_panic},
 };
 
 /// A reference to a node in a quadtree.
@@ -485,7 +485,9 @@ debug key check failed: tried to reference key {:?} which is not present in the
             // SAFETY: as above
             ptr::write(
                 &mut self.node_mut().value,
-                NodeData::Leaf( f(old_payload) ),
+                NodeData::Leaf(
+                    abort_on_panic(|| f(old_payload))
+                ),
             );
         }
         Ok(children_payloads)

src/util.rs

@@ -109,4 +109,18 @@ pub unsafe fn unreachable_debugchecked(msg: &str) -> ! {
     } else {
         hint::unreachable_unchecked()
     }
+}
+
+#[inline]
+pub fn abort_on_panic<R>(f: impl FnOnce() -> R) -> R {
+    #[cfg(feature = "unwind_safety")]
+    {
+        std::panic::catch_unwind(
+            std::panic::AssertUnwindSafe(f)
+        ).unwrap_or_else(|_| std::process::exit(101))
+    }
+    #[cfg(not(feature = "unwind_safety"))]
+    {
+        f()
+    }
 }