Move ICH to rustc_query_system.

compiler/rustc_middle/src/middle/privacy.rs

@@ -3,7 +3,9 @@
 //! which are available for use externally when compiled as a library.
 
 use rustc_data_structures::fx::FxHashMap;
+use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_macros::HashStable;
+use rustc_query_system::ich::{NodeIdHashingMode, StableHashingContext};
 use rustc_span::def_id::LocalDefId;
 use std::hash::Hash;
 
@@ -53,3 +55,12 @@ impl<Id> Default for AccessLevels<Id> {
         AccessLevels { map: Default::default() }
     }
 }
+
+impl<'a> HashStable<StableHashingContext<'a>> for AccessLevels {
+    fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
+        hcx.with_node_id_hashing_mode(NodeIdHashingMode::HashDefPath, |hcx| {
+            let AccessLevels { ref map } = *self;
+            map.hash_stable(hcx, hasher);
+        });
+    }
+}