diff options
| -rw-r--r-- | src/librustc_data_structures/obligation_forest/mod.rs | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/src/librustc_data_structures/obligation_forest/mod.rs b/src/librustc_data_structures/obligation_forest/mod.rs index df34891ff03..0d6cf260dcd 100644 --- a/src/librustc_data_structures/obligation_forest/mod.rs +++ b/src/librustc_data_structures/obligation_forest/mod.rs @@ -496,9 +496,14 @@ impl<O: ForestObligation> ObligationForest<O> { } } NodeState::Done => { - self.waiting_cache.remove(self.nodes[i].obligation.as_predicate()); - // FIXME(HashMap): why can't I get my key back? - self.done_cache.insert(self.nodes[i].obligation.as_predicate().clone()); + // Avoid cloning the key (predicate) in case it exists in the waiting cache + if let Some((predicate, _)) = self.waiting_cache + .remove_entry(self.nodes[i].obligation.as_predicate()) + { + self.done_cache.insert(predicate); + } else { + self.done_cache.insert(self.nodes[i].obligation.as_predicate().clone()); + } node_rewrites[i] = nodes_len; dead_nodes += 1; } |