Address soundness hole in cycle prevention

src/deps.rs

@@ -11,52 +11,60 @@ use crate::builder::TaskBuilder;
 use crate::task::Task;
 use crate::types::{NodeId, TaskHandle};
 
+trait IntoNodeRef {
+    type Output;
+    fn into_node_ref(self) -> NodeId;
+}
+
+impl<T> IntoNodeRef for &TaskHandle<T> {
+    type Output = T;
+    fn into_node_ref(self) -> NodeId {
+        self.id
+    }
+}
+
+impl<T> IntoNodeRef for TaskHandle<T> {
+    type Output = T;
+    fn into_node_ref(self) -> NodeId {
+        self.id
+    }
+}
+
+impl<'runner, Tk: Task, Deps> IntoNodeRef for TaskBuilder<'runner, Tk, Deps> {
+    type Output = Tk::Output;
+
+    fn into_node_ref(self) -> NodeId {
+        self.id
+    }
+}
+
 pub(crate) trait DepsTuple<Input> {
-    fn to_node_ids(&self) -> Vec<NodeId>;
+    fn to_node_ids(self) -> Vec<NodeId>;
 }
 
 // Implementation for unit (no dependencies)
 impl DepsTuple<()> for () {
-    fn to_node_ids(&self) -> Vec<NodeId> {
+    fn to_node_ids(self) -> Vec<NodeId> {
         Vec::new()
     }
 }
 
 // Implementation for single dependency (all forms)
-impl<T> DepsTuple<T> for &TaskHandle<T> {
-    fn to_node_ids(&self) -> Vec<NodeId> {
-        vec![self.id]
+impl<T> DepsTuple<T::Output> for T
+where
+    T: IntoNodeRef,
+{
+    fn to_node_ids(self) -> Vec<NodeId> {
+        vec![self.into_node_ref()]
     }
 }
 
-impl<T> DepsTuple<T> for TaskHandle<T> {
-    fn to_node_ids(&self) -> Vec<NodeId> {
-        vec![self.id]
-    }
-}
-
-impl<T> DepsTuple<T> for (&TaskHandle<T>,) {
-    fn to_node_ids(&self) -> Vec<NodeId> {
-        vec![self.0.id]
-    }
-}
-
-impl<T> DepsTuple<T> for (TaskHandle<T>,) {
-    fn to_node_ids(&self) -> Vec<NodeId> {
-        vec![self.0.id]
-    }
-}
-
-// Support for &TaskBuilder
-impl<'a, Tk: Task, Deps> DepsTuple<Tk::Output> for &TaskBuilder<'a, Tk, Deps> {
-    fn to_node_ids(&self) -> Vec<NodeId> {
-        vec![self.id]
-    }
-}
-
-impl<'a, Tk: Task, Deps> DepsTuple<Tk::Output> for (&TaskBuilder<'a, Tk, Deps>,) {
-    fn to_node_ids(&self) -> Vec<NodeId> {
-        vec![self.0.id]
+impl<T> DepsTuple<T::Output> for (T,)
+where
+    T: IntoNodeRef,
+{
+    fn to_node_ids(self) -> Vec<NodeId> {
+        vec![self.0.into_node_ref()]
     }
 }
 
@@ -65,10 +73,6 @@ impl<'a, Tk: Task, Deps> DepsTuple<Tk::Output> for (&TaskBuilder<'a, Tk, Deps>,)
 /// This macro exists because Rust lacks variadic generics - we need separate implementations
 /// for each tuple size.
 ///
-/// For each tuple size, generates two implementations:
-/// - `(&TaskHandle<A>, &TaskHandle<B>, ...)` → `DepsTuple<(A, B, ...)>`
-/// - `(&TaskBuilder<TkA, _>, &TaskBuilder<TkB, _>, ...)` → `DepsTuple<(TkA::Output, TkB::Output, ...)>`
-///
 /// This allows flexible dependency specification:
 /// ```ignore
 /// // Using handles
@@ -78,37 +82,27 @@ impl<'a, Tk: Task, Deps> DepsTuple<Tk::Output> for (&TaskBuilder<'a, Tk, Deps>,)
 /// task.depends_on((&dag.add_task(TaskA), &dag.add_task(TaskB)))
 /// ```
 macro_rules! impl_deps_tuple {
-    ($($T:ident : $Tk:ident : $D:ident),+) => {
-        // For &TaskHandle tuples
-        impl<$($T),+> DepsTuple<($($T,)+)> for ($(&TaskHandle<$T>,)+) {
+    ($($T:ident),+) => {
+        // For tuples of any combination of &TaskHandle, TaskHandle, and TaskBuilder
+        impl<$($T: IntoNodeRef),+> DepsTuple<($($T::Output,)+)> for ($($T,)+) {
             #[allow(non_snake_case)]
-            fn to_node_ids(&self) -> Vec<NodeId> {
+            fn to_node_ids(self) -> Vec<NodeId> {
                 let ($($T,)+) = self;
-                vec![$($T.id,)+]
-            }
-        }
-
-        // For &TaskBuilder tuples
-        impl<'a, $($Tk: Task, $D),+> DepsTuple<($($Tk::Output,)+)> for ($(&TaskBuilder<'a, $Tk, $D>,)+) {
-            #[allow(non_snake_case)]
-            fn to_node_ids(&self) -> Vec<NodeId> {
-                let ($($T,)+) = self;
-                vec![$($T.id,)+]
+                vec![$($T.into_node_ref(),)+]
             }
         }
     };
 }
 
 // Generate DepsTuple implementations for tuples of size 2-8.
-// Each invocation generates 2 implementations (TaskHandle refs and TaskBuilder refs).
 // Supporting up to 8 elements covers the vast majority of use cases.
-impl_deps_tuple!(A:TkA:DA, B:TkB:DB);
-impl_deps_tuple!(A:TkA:DA, B:TkB:DB, C:TkC:DC);
-impl_deps_tuple!(A:TkA:DA, B:TkB:DB, C:TkC:DC, D:TkD:DD);
-impl_deps_tuple!(A:TkA:DA, B:TkB:DB, C:TkC:DC, D:TkD:DD, E:TkE:DE);
-impl_deps_tuple!(A:TkA:DA, B:TkB:DB, C:TkC:DC, D:TkD:DD, E:TkE:DE, F:TkF:DF);
-impl_deps_tuple!(A:TkA:DA, B:TkB:DB, C:TkC:DC, D:TkD:DD, E:TkE:DE, F:TkF:DF, G:TkG:DG);
-impl_deps_tuple!(A:TkA:DA, B:TkB:DB, C:TkC:DC, D:TkD:DD, E:TkE:DE, F:TkF:DF, G:TkG:DG, H:TkH:DH);
+impl_deps_tuple!(T1, T2);
+impl_deps_tuple!(T1, T2, T3);
+impl_deps_tuple!(T1, T2, T3, T4);
+impl_deps_tuple!(T1, T2, T3, T4, T5);
+impl_deps_tuple!(T1, T2, T3, T4, T5, T6);
+impl_deps_tuple!(T1, T2, T3, T4, T5, T6, T7);
+impl_deps_tuple!(T1, T2, T3, T4, T5, T6, T7, T8);
 
 #[cfg(test)]
 mod tests;