Fix ICE in utils::implements_trait

This only happend when debug_assertions were enabled in rustc

Author: flip1995

src/tools/clippy/clippy_lints/src/utils/mod.rs

@@ -365,6 +365,9 @@ pub fn implements_trait<'tcx>(
         return false;
     }
     let ty = cx.tcx.erase_regions(ty);
+    if ty.has_escaping_bound_vars() {
+        return false;
+    }
     let ty_params = cx.tcx.mk_substs(ty_params.iter());
     cx.tcx.type_implements_trait((trait_id, ty, ty_params, cx.param_env))
 }

src/tools/clippy/tests/ui/crashes/implements-trait.rs

@@ -0,0 +1,5 @@
+#[allow(clippy::needless_borrowed_reference)]
+fn main() {
+    let mut v = Vec::<String>::new();
+    let _ = v.iter_mut().filter(|&ref a| a.is_empty());
+}