Fix case where non FnOnce variables is marked callable

2 files changed, 14 insertions, 1 deletions

diff --git a/crates/hir/src/code_model.rs b/crates/hir/src/code_model.rs
index 63c1a8ebf..563145f92 100644
--- a/crates/hir/src/code_model.rs
+++ b/crates/hir/src/code_model.rs
@@ -1398,7 +1398,7 @@ impl Type {
         };
 
         let canonical_ty = Canonical { value: self.ty.value.clone(), kinds: Arc::new([]) };
-        method_resolution::implements_trait(
+        method_resolution::implements_trait_unique(
             &canonical_ty,
             db,
             self.ty.environment.clone(),
diff --git a/crates/hir_ty/src/method_resolution.rs b/crates/hir_ty/src/method_resolution.rs
index 8961df404..5a6f0c67f 100644
--- a/crates/hir_ty/src/method_resolution.rs
+++ b/crates/hir_ty/src/method_resolution.rs
@@ -740,6 +740,19 @@ pub fn implements_trait(
     solution.is_some()
 }
 
+pub fn implements_trait_unique(
+    ty: &Canonical<Ty>,
+    db: &dyn HirDatabase,
+    env: Arc<TraitEnvironment>,
+    krate: CrateId,
+    trait_: TraitId,
+) -> bool {
+    let goal = generic_implements_goal(db, env, trait_, ty.clone());
+    let solution = db.trait_solve(krate, goal);
+
+    matches!(solution, Some(crate::traits::Solution::Unique(_)))
+}
+
 /// This creates Substs for a trait with the given Self type and type variables
 /// for all other parameters, to query Chalk with it.
 fn generic_implements_goal(