Pick methods from the right receivers

Previously we have been picking methods for receiver types even though
we are inspecting other receiver types that are several levels of
dereferences, which is wasted effort because there will never be matches
with these methods.

Signed-off-by: Xiangfei Ding <dingxiangfei2009@protonmail.ch>

Author: dingxiangfei2009

compiler/rustc_data_structures/src/intern.rs

@@ -2,6 +2,8 @@ use std::cmp::Ordering;
 use std::fmt::{self, Debug};
 use std::hash::{Hash, Hasher};
 use std::ops::Deref;
+#[cfg(not(bootstrap))]
+use std::ops::Receiver;
 use std::ptr;
 
 use crate::stable_hasher::{HashStable, StableHasher};
@@ -54,6 +56,11 @@ impl<'a, T> Deref for Interned<'a, T> {
     }
 }
 
+#[cfg(not(bootstrap))]
+impl<'a, T> Receiver for Interned<'a, T> {
+    type Target = T;
+}
+
 impl<'a, T> PartialEq for Interned<'a, T> {
     #[inline]
     fn eq(&self, other: &Self) -> bool {

compiler/rustc_data_structures/src/lib.rs

@@ -13,6 +13,7 @@
 #![cfg_attr(bootstrap, feature(array_windows))]
 #![deny(unsafe_op_in_unsafe_fn)]
 #![feature(allocator_api)]
+#![feature(arbitrary_self_types)]
 #![feature(ascii_char)]
 #![feature(ascii_char_variants)]
 #![feature(assert_matches)]