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Author: lcnr

compiler/rustc_trait_selection/src/solve/search_graph.rs

@@ -204,6 +204,10 @@ impl<'tcx> SearchGraph<'tcx> {
                 break 'global;
             };
 
+            // If we're building a proof tree and the current cache entry does not
+            // contain a proof tree, we do not use the entry but instead recompute
+            // the goal. We simply overwrite the existing entry once we're done,
+            // caching the proof tree.
             if !inspect.is_noop() {
                 if let Some(revisions) = proof_tree {
                     inspect.goal_evaluation_kind(