hack

Author: pierwill

chalk-solve/src/coherence.rs

@@ -109,7 +109,6 @@ where
     fn build_specialization_forest(&self) -> Result<Graph<ImplId<I>, ()>, CoherenceError<I>> {
         // FIXME(pierwill): Previously, the forest was built as a GraphMap
         // so that we never add multiple nodes with the same ItemId.
-        // Will need to add a check for this.
         let mut forest = DiGraph::new();
 
         // Find all specializations (implemented in coherence/solve)
@@ -119,7 +118,24 @@ where
             let l = forest.add_node(less_special);
             let m = forest.add_node(more_special);
 
-            forest.add_edge(l, m, ());
+            // attempt to handle FIXME above...
+            let (nodes, _) = forest.clone().into_nodes_edges();
+            let mut already_exists = false;
+            for x in nodes {
+                // this isn't doing what we want...
+                // `ItemId`? 🤔
+                if !(less_special != x.weight && more_special != x.weight) {
+                    already_exists = true;
+                }
+            }
+            println!("Already exists? {}", already_exists);
+            if !already_exists {
+                println!(
+                    "adding an edge from {:?} to {:?}",
+                    less_special, more_special
+                );
+                forest.add_edge(l, m, ());
+            }
         })?;
 
         Ok(forest)