fix(mir): make BackLink parent removal precise

mir/src/ir/nodes/ops/accessor.rs

@@ -70,6 +70,9 @@ impl Child for Accessor {
         self.parents.push(parent.into());
     }
     fn remove_parent(&mut self, parent: Link<Self::Parent>) {
-        self.parents.retain(|p| *p != parent.clone().into());
+        self.parents.retain(|p| match p.to_link() {
+            Some(link) => link != parent,
+            None => true,
+        });
     }
 }

mir/src/ir/nodes/ops/add.rs

@@ -33,10 +33,51 @@ impl Child for Add {
     fn get_parents(&self) -> Vec<BackLink<Self::Parent>> {
         self.parents.clone()
     }
+
     fn add_parent(&mut self, parent: Link<Self::Parent>) {
         self.parents.push(parent.into());
     }
     fn remove_parent(&mut self, parent: Link<Self::Parent>) {
-        self.parents.retain(|p| *p != parent.clone().into());
+        self.parents.retain(|p| match p.to_link() {
+            Some(link) => link != parent,
+            None => true,
+        });
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn add_remove_parent_removes_only_target() {
+        let span = SourceSpan::default();
+
+        let lhs: Link<Op> = Op::None(span).into();
+        let rhs: Link<Op> = Op::None(span).into();
+
+        let mut add = Add {
+            parents: Vec::new(),
+            lhs,
+            rhs,
+            _node: Singleton::default(),
+            _owner: Singleton::default(),
+            span,
+        };
+
+        let owner1: Link<Owner> = Owner::None(span).into();
+        let owner2: Link<Owner> = Owner::None(span).into();
+
+        add.add_parent(owner1.clone());
+        add.add_parent(owner2.clone());
+        assert_eq!(add.get_parents().len(), 2);
+
+        add.remove_parent(owner1.clone());
+
+        let parents = add.get_parents();
+        assert_eq!(parents.len(), 1);
+        let remaining =
+            parents[0].to_link().expect("BackLink<Owner> should upgrade to Link<Owner>");
+        assert_eq!(remaining, owner2);
     }
 }

mir/src/ir/nodes/ops/boundary.rs

@@ -52,6 +52,9 @@ impl Child for Boundary {
         self.parents.push(parent.into());
     }
     fn remove_parent(&mut self, parent: Link<Self::Parent>) {
-        self.parents.retain(|p| *p != parent.clone().into());
+        self.parents.retain(|p| match p.to_link() {
+            Some(link) => link != parent,
+            None => true,
+        });
     }
 }

mir/src/ir/nodes/ops/bus_op.rs

@@ -79,6 +79,9 @@ impl Child for BusOp {
         self.parents.push(parent.into());
     }
     fn remove_parent(&mut self, parent: Link<Self::Parent>) {
-        self.parents.retain(|p| *p != parent.clone().into());
+        self.parents.retain(|p| match p.to_link() {
+            Some(link) => link != parent,
+            None => true,
+        });
     }
 }

mir/src/ir/nodes/ops/call.rs

@@ -53,6 +53,9 @@ impl Child for Call {
         self.parents.push(parent.into());
     }
     fn remove_parent(&mut self, parent: Link<Self::Parent>) {
-        self.parents.retain(|p| *p != parent.clone().into());
+        self.parents.retain(|p| match p.to_link() {
+            Some(link) => link != parent,
+            None => true,
+        });
     }
 }

mir/src/ir/nodes/ops/enf.rs

@@ -36,6 +36,9 @@ impl Child for Enf {
         self.parents.push(parent.into());
     }
     fn remove_parent(&mut self, parent: Link<Self::Parent>) {
-        self.parents.retain(|p| *p != parent.clone().into());
+        self.parents.retain(|p| match p.to_link() {
+            Some(link) => link != parent,
+            None => true,
+        });
     }
 }

mir/src/ir/nodes/ops/exp.rs

@@ -39,6 +39,9 @@ impl Child for Exp {
         self.parents.push(parent.into());
     }
     fn remove_parent(&mut self, parent: Link<Self::Parent>) {
-        self.parents.retain(|p| *p != parent.clone().into());
+        self.parents.retain(|p| match p.to_link() {
+            Some(link) => link != parent,
+            None => true,
+        });
     }
 }

mir/src/ir/nodes/ops/fold.rs

@@ -65,6 +65,9 @@ impl Child for Fold {
         self.parents.push(parent.into());
     }
     fn remove_parent(&mut self, parent: Link<Self::Parent>) {
-        self.parents.retain(|p| *p != parent.clone().into());
+        self.parents.retain(|p| match p.to_link() {
+            Some(link) => link != parent,
+            None => true,
+        });
     }
 }

mir/src/ir/nodes/ops/for_op.rs

@@ -62,6 +62,9 @@ impl Child for For {
         self.parents.push(parent.into());
     }
     fn remove_parent(&mut self, parent: Link<Self::Parent>) {
-        self.parents.retain(|p| *p != parent.clone().into());
+        self.parents.retain(|p| match p.to_link() {
+            Some(link) => link != parent,
+            None => true,
+        });
     }
 }

mir/src/ir/nodes/ops/if_op.rs

@@ -65,6 +65,9 @@ impl Child for If {
         self.parents.push(parent.into());
     }
     fn remove_parent(&mut self, parent: Link<Self::Parent>) {
-        self.parents.retain(|p| *p != parent.clone().into());
+        self.parents.retain(|p| match p.to_link() {
+            Some(link) => link != parent,
+            None => true,
+        });
     }
 }

mir/src/ir/nodes/ops/matrix.rs

@@ -45,6 +45,9 @@ impl Child for Matrix {
         self.parents.push(parent.into());
     }
     fn remove_parent(&mut self, parent: Link<Self::Parent>) {
-        self.parents.retain(|p| *p != parent.clone().into());
+        self.parents.retain(|p| match p.to_link() {
+            Some(link) => link != parent,
+            None => true,
+        });
     }
 }

mir/src/ir/nodes/ops/mul.rs

@@ -37,6 +37,9 @@ impl Child for Mul {
         self.parents.push(parent.into());
     }
     fn remove_parent(&mut self, parent: Link<Self::Parent>) {
-        self.parents.retain(|p| *p != parent.clone().into());
+        self.parents.retain(|p| match p.to_link() {
+            Some(link) => link != parent,
+            None => true,
+        });
     }
 }

mir/src/ir/nodes/ops/parameter.rs

@@ -83,6 +83,9 @@ impl Child for Parameter {
         self.parents.push(parent.into());
     }
     fn remove_parent(&mut self, parent: Link<Self::Parent>) {
-        self.parents.retain(|p| *p != parent.clone().into());
+        self.parents.retain(|p| match p.to_link() {
+            Some(link) => link != parent,
+            None => true,
+        });
     }
 }

mir/src/ir/nodes/ops/sub.rs

@@ -37,6 +37,9 @@ impl Child for Sub {
         self.parents.push(parent.into());
     }
     fn remove_parent(&mut self, parent: Link<Self::Parent>) {
-        self.parents.retain(|p| *p != parent.clone().into());
+        self.parents.retain(|p| match p.to_link() {
+            Some(link) => link != parent,
+            None => true,
+        });
     }
 }

mir/src/ir/nodes/ops/value.rs

@@ -50,7 +50,10 @@ impl Child for Value {
         self.parents.push(parent.into());
     }
     fn remove_parent(&mut self, parent: Link<Self::Parent>) {
-        self.parents.retain(|p| *p != parent.clone().into());
+        self.parents.retain(|p| match p.to_link() {
+            Some(link) => link != parent,
+            None => true,
+        });
     }
 }
 

mir/src/ir/nodes/ops/vector.rs

@@ -44,6 +44,9 @@ impl Child for Vector {
         self.parents.push(parent.into());
     }
     fn remove_parent(&mut self, parent: Link<Self::Parent>) {
-        self.parents.retain(|p| *p != parent.clone().into());
+        self.parents.retain(|p| match p.to_link() {
+            Some(link) => link != parent,
+            None => true,
+        });
     }
 }