Get it compiling again

Author: Aaron1011

compiler/rustc_data_structures/src/intern.rs

@@ -3,6 +3,8 @@ use std::hash::{Hash, Hasher};
 use std::ops::Deref;
 use std::ptr;
 
+use crate::stable_hasher::HashStableEq;
+
 mod private {
     #[derive(Clone, Copy, Debug)]
     pub struct PrivateZst;
@@ -52,6 +54,14 @@ impl<'a, T> Deref for Interned<'a, T> {
     }
 }
 
+// FIXME - is this right? Should we try to enforce this somehow?
+impl<'a, T: HashStableEq> HashStableEq for Interned<'a, T> {
+    fn hash_stable_eq(&self, other: &Self) -> bool {
+        // Pointer equality implies equality, due to the uniqueness constraint.
+        ptr::eq(self.0, other.0)
+    }
+}
+
 impl<'a, T> PartialEq for Interned<'a, T> {
     #[inline]
     fn eq(&self, other: &Self) -> bool {

compiler/rustc_middle/src/ty/mod.rs

@@ -43,7 +43,7 @@ use rustc_span::symbol::{kw, Ident, Symbol};
 use rustc_span::{sym, Span};
 use rustc_target::abi::Align;
 
-use std::hash::{Hash, Hasher};
+use std::hash::Hash;
 use std::ops::ControlFlow;
 use std::{fmt, str};