Deduplicate impls in impls_for_trait

This was duplicating impls in dependencies a lot...

1 files changed, 3 insertions, 2 deletions

diff --git a/crates/ra_hir/src/ty/traits.rs b/crates/ra_hir/src/ty/traits.rs
index f70a32575..4bbc99f0e 100644
--- a/crates/ra_hir/src/ty/traits.rs
+++ b/crates/ra_hir/src/ty/traits.rs
@@ -1,6 +1,7 @@
 //! Trait solving using Chalk.
 use std::sync::{Arc, Mutex};
 
+use rustc_hash::FxHashSet;
 use log::debug;
 use chalk_ir::cast::Cast;
 
@@ -31,7 +32,7 @@ pub(crate) fn impls_for_trait(
     krate: Crate,
     trait_: Trait,
 ) -> Arc<[ImplBlock]> {
-    let mut impls = Vec::new();
+    let mut impls = FxHashSet::default();
     // We call the query recursively here. On the one hand, this means we can
     // reuse results from queries for different crates; on the other hand, this
     // will only ever get called for a few crates near the root of the tree (the
@@ -42,7 +43,7 @@ pub(crate) fn impls_for_trait(
     }
     let crate_impl_blocks = db.impls_in_crate(krate);
     impls.extend(crate_impl_blocks.lookup_impl_blocks_for_trait(&trait_));
-    impls.into()
+    impls.into_iter().collect::<Vec<_>>().into()
 }
 
 fn solve(