cleanup imports

compiler/rustc_middle/src/traits/mod.rs

@@ -991,9 +991,3 @@ pub enum DefiningAnchor {
     /// Used to catch type mismatch errors when handling opaque types.
     Error,
 }
-
-#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash, HashStable)]
-pub enum IsNormalizesToHack {
-    Yes,
-    No,
-}