bug fixed with dependencies on deleted notes

src/graph.rs

@@ -48,15 +48,21 @@ impl Graph {
         }
     }
 
-    pub fn remove_node(&mut self, node : Id) -> bool {
+    /// Returns a boolean indicating if the graph was changed (it contained the node) and a
+    /// set of all dependents on the removed node.
+    pub fn remove_node(&mut self, node : Id) -> (bool, HashSet<Id>) {
+        let mut dependents = HashSet::new();
+
         if self.edges.remove(&node).is_some() {
-            for outgoing in self.edges.values_mut() {
+            for (&dependent, outgoing) in &mut self.edges {
-                outgoing.remove(&node);
+                if outgoing.remove(&node) {
+                    dependents.insert(dependent);
                 }
-            true
+            }
+            (true, dependents)
         }
         else {
-            false
+            (false, dependents)
         }
     }
 

src/main.rs

@@ -127,7 +127,14 @@ fn program() -> Result<(), error::Error> {
                 let task = tasks::Task::load(id, vault_folder, false)?;
                 let name = task.data.name.clone();
                 state.data.index.remove(task.data.name.clone(), task.data.id);
-                state.data.deps.remove_node(task.data.id);
+                // Removing the task from others which list it as a dependency.
+                if let (true, dependents) = state.data.deps.remove_node(task.data.id) {
+                    for dependent in dependents {
+                        let mut task = tasks::Task::load(dependent, vault_folder, false)?;
+                        task.data.dependencies.remove(&id);
+                        task.save()?;
+                    }
+                }
                 task.delete()?;
 
                 println!("Deleted task {} (ID: {})", format::task(&name), format::id(id));